Gottlieb System 80

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1 Introduction

Gottlieb® System 80 Board Set - 1st Generation

Gottlieb's® second generation of solid state pinballs is System 80. Capabilities were increased in terms of controllable lamps, solenoids, gameplay, and sound. No longer tied to an EM-esque platform, Gottlieb® started to introduce games with more unconventional asymmetric playfields. System 80 marked a foray into double and triple level playfields, speech, and multiball. Unfortunately, it also represented a lateral step in reliability, with battery corrosion, connectors, and bad grounding plaguing the design. Nearly all the same issues as were present with the System 1 platform.

Gottlieb® System 80 Board Set - 2nd Generation

Just like the System 1 games, the System 80 / 80A / 80B design relied solely on connectors and daisy-chained wiring to transport the ground lines from board to board. The exception is that the large ground plane used with System 1 games was no longer used behind the boards with the System 80 games. Gottlieb® still opted to use plastic standoffs to elevate and secure the boards to the backbox or the back side of the lamp box insert. Thus, if a single ground connector failed in the chain, the logic ground could fail for one or several of the circuit boards. This could potentially lead to locked on coils, relays, and / or controlled lamps. In turn, transistors and chips would fail.

Gottlieb® System 80A Board Set

The System 80 platform was used for a total of nine years from 1980-1989. During this period, there were three main versions of the boardset. These three versions are referred to as: System 80, System 80A, and System 80B. System 80 was used from 1980-1982, System 80A was used from 1982-1985, and System 80B was used from 1985-1989. The easiest way to differentiate between the three versions is by looking at the style of displays which were used. System 80 used 6-digit displays for scoring, and in some instances, for bonus values or timers. System 80A used 7-digit displays for scoring, and 6-digit displays for bonus values or timers too. Both the 6-digit and 7-digit displays were limited to displaying numeric values. System 80B differed the most by using two 20-digit alpha-numeric displays, which were stacked on top of each other.

Gottlieb® System 80B Board Set - Early

Shortly after the onset of using the System 80B boardset, it was evident that the complexity of playfield designs had quickly outgrown the boardset. Remote satellite boards, and transistors littered the underside of the playfield and inside the cabinet, because the driver board was too undersized to handle these extra duties. A new boardset, known as the System 3 platform, was under development, but was not released until nearly 4 years later in 1990.

Gottlieb® System 80B Board Set - Typical

Gottlieb® System 80B Board Set - Later Games (Hot Shots, Bad Girls, and Big House

Once a System 80 / 80A / 80B game has been methodically gone through with board design grounding flaws and connectors corrected, they are just as reliable as any of their contemporaries.

2 Games

2.1 System 80 1st Generation

Title	Date of Release	Production #	Model #	Sound	Display	Notes
The Amazing Spiderman	05-1980	7625	653	Sound only	6-digit
Panthera	06-1980	5220	652	Sound only	6-digit
Circus	06-1980	1700	654	Sound only	6-digit	Ultra Widebody
Counterforce	06-1980	3870	656	Sound only	6-digit
Star Race	08-1980	870	657	Sound only	6-digit	Ultra Widebody

2.2 System 80 2nd Generation

Title	Date of Release	Production #	Model #	Sound	Display	Notes
James Bond	10-1980	3625	658	Sound only	6-digit
Time Line	12-1980	3167	659	Sound only	6-digit
Force II	12-1981	2000	661	Sound only	6-digit
Pink Panther	03-1981	2840	664	Sound only	6-digit
Mars God of War	03-1981	5240	666	Sound & Speech	6-digit	First Gottlieb® with speech, lane change, and multi-ball
Volcano	09-1981	3655	667	Sound & Speech	6-digit	Export games used sound only board
Black Hole	10-1981	8774	668	Sound & Speech	6-digit	First Gottlieb® with 2-Level playing area, Export games used sound only board.
Haunted House	06-1982	6835	669	Sound only	6-digit	First game with 3-Level playing area, Sound only, but used sound & speech board w/o the speech chip installed.
Eclipse	1982	193	671	Sound only	6-digit	Production game and available as a kit for James Bond 007

2.3 System 80A

Title	Date of Release	Production #	Model #	Sound	Display	Notes
Devil's Dare	08-1982	3832	670	Sound & Speech	7-digit	Export games used the sound only board
Caveman	09-1982	1800	PV810	Sound & Speech	7-digit	Pinball / Video game hybrid
Rocky	09-1982	1504	672	Sound & Speech	7-digit
Spirit	11-1982	1230	673	Sound only	7-digit	Sound only, but used sound & speech board
Punk!	12-1982	959	674	Sound only	7-digit	Sound only, but used sound & speech board
Striker	11-1982	910	675	Sound only	7-digit	Sound only, but used sound & speech board
Krull	02-1983	10	676	Sound only	7-digit
Goin' Nuts	02-1983	10	682	Sound only	7-digit	Sound only, but used sound & speech board
Q*bert's Quest	03-1983	884	677	Sound & Speech	7-digit
Super Orbit	05-1983	2100	680	Sound Only	7-digit	Sound only, but uses the less populated sound & speech board
Royal Flush Deluxe	06-1983	2000	681	Sound Only	7-digit	Sound only, but uses the less populated sound & speech board
Amazon Hunt	09-1983	1515	684	Sound Only or Sound Only	7-digit	Sound only, but uses the less populated sound & speech board. Later production games used the sound only piggyback sound board
Rack 'Em Up!	11-1983	1762	685	Sound Only	7-digit
Ready... Aim... Fire!	11-1983	390	686	Sound Only	7-digit
Jacks to Open	05-1984	2350	687	Sound Only	7-digit
Alien Star	06-1984	1065	689	Sound Only	7-digit	689A Denotes a revision in the ROM code
The Games	08-1984	1768	691	Sound Only	7-digit
Touchdown	10-1984	711	688	Sound Only	7-digit
El Dorado City of Gold	09-1984	905	692	Sound Only	7-digit
Ice Fever	02-1985	1585	695	Sound Only	7-digit

2.4 System 80B

Title	Date of Release	Production #	Model #	Sound	Display	Notes
Chicago Cubs Triple Play	05-1985	~1365	696	Sound Only	Alphanumeric; MA-644
Bounty Hunter	07-1985	1220	694	Sound Only	Alphanumeric; MA-644
Tag Team Pinball	09-1985	1220	698	Sound Only	Alphanumeric; MA-644
Rock	10-1985	1875	697	Sound Only	Alphanumeric; MA-644
Raven	03-1986	3550	702	Sound Only	Alphanumeric; MA-644
Rock Encore	04-1986	245	704	Sound Only	Alphanumeric; MA-644	Production game using same playfield art as Rock, but mainly available as a conversion kit for Rock
Hollywood Heat	06-1986	3400	703	Sound Only	Alphanumeric; MA-644
Genesis	09-1986	3500	705	Sound Only	Alphanumeric; MA-644
Gold Wings	10-1986	3260	707	Sound Only	Alphanumeric; MA-644
Spring Break	04-1987	3550	706	Sound Only	Alphanumeric; MA-644
Monte Carlo	02-1987	4315	708	Sound Only	Alphanumeric; MA-644
Arena	06-1987	3099	709	Sound Only	Alphanumeric; MA-644
Victory	10-1987	3315	710	Sound & Speech	Alphanumeric; MA-644
Diamond Lady	02-1988	2700	711	Unknown	Alphanumeric; MA-644
TX Sector	03-1988	2336	712	Sound & Speech	Alphanumeric; MA-644
Robo-War	04-1988	2130	714	Sound & Speech	Alphanumeric; MA-644
Excalibur	11-1988	1710	715	Unknown	Alphanumeric; MA-644
Bad Girls	11-1988	2500	717	Sound & Speech	Alphanumeric; MA-999
Big House	04-1989	1977	713	Sound & Speech	Alphanumeric; MA-999
Hot Shots	04-1989	2342	718	Sound & Speech	Alphanumeric; MA-999
Bone Busters Inc.	08-1989	2000	719	Sound & Speech	Alphanumeric; MA-999	Uses 3 sound boards - uses 50v to power flippers

Game date of release, production numbers, and model number provided by the Internet Pinball Database - http://www.ipdb.org

3 Technical Info

3.1 System 80 / 80A / 80B Board Set

Clicking the link above will direct you to a new page showing all of the System 80/80A/80B boards.

3.2 System 80 / 80A / 80B Satellite Boards

Clicking the link above will direct you to a new page showing all of the System 80/80A/80B satellite boards.

3.3 Power Supply

3.3.1 System 80 / 80A Power Supply

System 80 / 80A Power Supply

System 80 / 80A Power Supply - Showing the Large Heat Sink

The System 80 / 80A power supply is very similar to the System 1 power supply, where as the circuit board is secured to a large "hot plate" heat sink. This style power supply is used for all System 80 and 80A games from Spiderman to Ice Fever, and is the source of the following:

+5 VDC logic power
+8 VDC offset voltage needed for the displays
+60 VDC for the 6 or 7 digit displays
+42 VDC for the status display
Ground from earth ground located on the transformer panel

Unlike the System 1 power supply, the +5 VDC logic power is no longer rectified and filtered on the power supply itself. This process is now handled by a bridge rectifier and a large filtering capacitor located on the transformer panel. The System 80 power still employs a crowbar circuit for the logic power, which protects from over-voltage situations.

Although these power supplies are fairly reliable, there are some drawbacks to the design. By incorporating a large heat sink for the PMD10K40 / 2N6059 TO-3 transistor on the board, a lot of heat is dissipated throughout the whole board. This in turn will limit the life expectancy of the other electronic components on the board. Equally, the heat sink must be removed in order to perform component level repairs to the board.

3.3.2 System 80 / 80A Sound & Speech Power Supply

A sound & speech board (S&S) is used starting with Mars God of War (MGOW). Because of the voltages needed to drive some of the components on the S&S board, this secondary power supply is added to the power train. The voltages generated from this board are:

+12 VDC used for the analog inverters and voice synthesizer chip
-12 VDC used for the analog inverters
+30 VDC used by the sound amplifier (LM379)

System 80 Sound & Speech Power Supply (1st Generation)

There are two different variations of this power supply. The first style is used only with MGOW and Volcano, and is not a printed circuit board (PCB). The electronic components were screwed to a block of wood, which is located on the left wall of the lower cabinet. Conducting tests and repairs to this style power supply can be awkward and difficult.

System 80 / 80A Sound & Speech Power Supply

Starting with Black Hole, the S&S power supply is now on a circuit board, which is located in the head of the game with the other circuit boards. Even though each style of S&S power supply uses different components for the generation of +12 VDC, the end result is the same. The S&S power supply was no longer used when Gottlieb® went a step backwards, and installed the System 80A sounds only board with the piggyback board. This change occurred during the run of Amazon Hunt.

3.3.3 System 80B Power Supplies

Starting with Chicago Cubs, the Gottlieb® power train went through a bit of a face lift. The System 80B platform uses two separate boards to supply power. This design change is mainly due to the single display board, which rectifies the high voltage on the board itself.

System 80B +5 VDC Power Supply

The small power supply with the finned heat sink is only used to generate +5 VDC for logic power. Although, removing the heat sink is not necessary to work on the board, this power supply has its own set of issues. First, it does not have a crow bar circuit. If the LM338K voltage regulator fails, and fails whereas the voltage increases drastically, it can destroy electronic components on the other circuit boards. Secondly, it's not as bad, but heat is still dissipated throughout the board. Third, the adjustable potentiometer (pot) on the power supply is prone to failure, due to dirt, dust, and contaminants. Finally, it is typical for the header pins on the input and output of the board to develop cracked solder joints. The two latter problems can easily be overcome, and will be addressed in the Recommended Repairs for the System 80B Power Supply Board section below.

System 80B Auxiliary Power Supply

Starting with Rock, the second power supply is added, and is referred to as the auxiliary power supply. The primary functions of this board is used to power the sound board, and amplify the audio output. A breakdown of the voltages supplied by the auxiliary power supply are as follows:

-12 VDC
+12 VDC

System 80B Auxiliary Power Supply with .156 headers versus edge connector

A BoneBusters Inc specific Auxiliary Power Supply

This Auxiliary Power Supply board changed with the release of Bad Girls. Edge connections were no longer used. Instead, .156" header pins were added to the board as shown at left. Note that the System 80B Auxiliary Power Supply board is slightly different from the System 3 Auxiliary Power Supply board. The System 80B board uses a 1K ohm, 2 watt resistor at R8. The System 3 board uses a 330 ohm 1/2 watt resistor at that location.

Bone Busters Inc. uniquely used a modified Auxiliary Power Supply board as pictured at right. A connection was made between pin 12 and the intersection of R1 and R2 to connect the audio output of the second, less populated sound board to the amplifier circuitry. A 1.8K ohm 1/4 watt resistor makes the connection while balancing the audio level from this input. No other game used pin 12 or this configuration.

3.4 CPU Board

Gottlieb® System 80 CPU Board

The System 80 CPU board is a 6502 based microprocessor system. The 6502 microprocessor (the very same one used in the first Apple computer and the Atari 2600) executes the basic operating system contained in the masked ROMs at U2/U3. The masked ROMs at U2 and U3 have the same code for all of the different generations of the System 80 platform. U2 and U3 code changed with the System 80A platform. The game code "personality" augments the basic operating system PROM(s). Early System 80 games which used two ROMs at PROM1 and PROM2 positions were masked ROMs. Later, when the game code could be held in a single 2716, an EPROM was used instead. Battery-backed memory for audits and adjustable game parameters is added via a 5101 256x4 bit CMOS memory at Z5. "Scratchpad" memory is contained in the three 6532 RIOTs.

Control of peripheral devices (in this case lamps, displays, solenoids, switches and sound) is accomplished via three 6532 RIOTs (RAM-I/O-Timer) at U4, U5, and U6. Each RIOT in turn controls it's own "subsystem" to drive these devices.

Switch matrix (U4)
Displays (U5)
Solenoids (U6)
Lamps (U6)
Sound (U6)

There are four generations of the System 80 board. All of the CPU boards can be easily identified by their revision numbers notated just below the operator adjustable dip switches.

3.4.1 1st Generation CPU Board

System 80 CPU Board - 1st Generation

The first generation CPU is used in the first 5 System 80 games, and is marked with the following:

ASSY PB03-D100-001
DET PB03-D102-001
REV B

This board uses two masked PROM chips for the game code. The chips are typically labeled with the three digit game model number followed by /1 or /2, designating the game PROM position. An example of this naming convention is shown in the pic to the left. 652/1X and 652/2X are game PROM 1 and PROM 2 for Panthera. The "X" in this case designates a code revision. The masked ROMs at position U2 and U3 are not socketed on this board.
With some simple modifications, this board is upward compatible to use a single 2716 EPROM placed in the PROM 1 socket of the board. With the change of U2 and U3, this board can be used in System 80A games. The board could potentially be used in a System 80B game with many modifications, and the addition of a daughter board, however, it is not recommended.

The corrected trace layout error in the 1St generation System 80 MPU

This generation of board has a trace layout error that was corrected by a cut and jumper which moves the trace that terminates at Z5 (5101) pin 20 from Z36 pin 10 to pin 9.

System 80 CPU Board - 1st Generation (Front)

System 80 CPU Board - 1st Generation (Back)

The "skeletal", semi-populated board scans can be very useful when having to replace or follow traces on a CPU board. Although the scans are of the 1st generation CPU board, most areas can be used for other generation CPU boards too.

3.4.2 2nd Generation CPU Board

Placeholder for System 80 CPU Board - 2nd Generation

The second generation CPU is used in some System 80 games, and is marked with the following:

ASSY PB03-D100-??? - check boards for the suffix
DETAIL PB03-D107-001

This board uses a single 2716 EPROM chip for the game code located at the PROM 1 socket position. The chips are typically labeled with the three digit game model number. Occasionally, the chip's game number label will be followed by /1, /2, /3, or even /4. In this case, the number following the slash is the code revision number. An example of this naming convention is 658 /2, which is a game PROM for James Bond - code revision 2. The masked ROMs at position U2 and U3 are not socketed on this board either.
With the change of U2 and U3, this board can be used in System 80A games. The board could potentially be used in a System 80B game with many modifications, and the addition of a daughter board, however, it again is not recommended. The second generation CPU is backward compatible, provided a doubled up, single game PROM is used at the PROM 1 position.

3.4.3 3rd Generation CPU Board

System 80 CPU Board - 3rd Generation

The third generation CPU is used in some System 80 games, and is marked with the following:

ASSY PB03-D100-011
DETAIL PB03-D107-003

This board is essentially the same as the second generation board, except an eyelet ground trace was placed just above Z33 on the board. This ground trace was never used. All information which applies to the second generation CPU board, applies to this board. The third generation CPU is backward compatible, provided the same is done to it as the 2nd generation board.

3.4.4 4th Generation CPU Board (System 80A)

System 80A CPU Board

The fourth generation CPU is used in all System 80A games, and is marked with the following:

D 20869

This board is the same as the third generation board, except the U2 and U3 masked ROM chips have different code, and are now socketed. The PROM 2 socket is no longer populated on the board. The fourth generation CPU is backward compatible, provided the System 80 ROM code is installed at U2 and U3. If used on a game with the 1st generation CPU, the game code must be doubled up on a 2716 EPROM, and installed at the PROM 1 position. This board is forward compatible with System 80B, provided all of the above outlined modifications are performed. Out of all the System 80 CPU boards, this is the most compatible with System 80B, due to using the same base circuit board.

3.4.5 5th Generation CPU Board (System 80B)

System 80B CPU Board

The fifth generation CPU is used in all System 80B games, and is marked with the following:

D 20869

Even though the base circuit board is identical to the fourth generation CPU board, it's being named the fifth generation board, due to all of the major changes. The U2 and U3 masked ROM and sockets have been replaced with a piggyback daughter board soldered via header pins mounted in the U3 position. The daughter board uses a 2764 EPROM. Most of the related display segment and digit chips are no longer populated. This is due to the single display board handling these functions on its own board. The missing chips once used for the displays are Z19, Z21, Z22, Z23, Z24, and Z25. Equally, jumpers have been placed where Z19 and Z21 once resided. The fifth generation CPU is backward compatible, after the daughter board has been removed, and the missing display chips populated.

Any of the Gottlieb® System 80 / 80A / 80B CPU boards are compatible cross platform. It's just matter of how much work must be done to modify each board.

3.5 Driver Board

The System 80A / 80B Driver Board

The System 80 Driver board is responsible for all controlled lamps, relays, and all solenoids in the game. The CPU controls the driver board operation via a simple interface between A1J4 on the CPU and A3J1 on the driver board. Although the driver board went through some minor changes over the years, the same board can be adapted for all of the System 80 platforms.

To control the games' total of 52 lamp circuits, the interface provides "device select" signals for each of the 74175s (Quad-D Flip-Flops) on the driver board, and 4 "bits" of data that is loaded (or "clocked") into a particular 74175 via the aforementioned device selects. Each lamp is driven discretely by a particular output of a particular 74175, which in turn drives an MPS-A13 or MPS-U45 transistor, (NDS-U45 transistors were used in place of MPS-U45s in some cases). Gottlieb® did not implement a "lamp matrix" as some other manufacturers did.

It is noteworthy that there are some dedicated lamp transistors, which control specific game relays across the System 80 / 80A platforms. Relays such as the game over, tilt, and coin lockout relays are controlled by Q1, Q2, and Q3 respectively. The tilt and game over relays use the same designation for the System 80B platform, however, the use of a coin lockout relay was abandoned by this time. One neat feature of the driver board circuitry is that lamp "n" is driven by transistor Q"n+1". i.e. L12 is driven by Q13.

Driver Board with Coin Counter Transistors Highlighted

To control the games' solenoids circuits, the driver board uses signals directly from the CPU to enable transistors on the driver board which turn on up to 9 solenoids. For solenoid control, the driver board uses MPS-U45, 2N3055, and 2N6043 transistors. Starting and ending with the System 80 platform, (games from Spiderman to Haunted House), three transistors were reserved to drive optional mechanical coin counters. These mechanical coin counter solenoids and associated transistors are: solenoid 3 (Q54), 4 (Q55), and 7 (Q56). Starting with the System 80A platform, (Devil's Dare), these transistors were no longer reserved for coin counters, and were used for other functions. Equally, the 3 diodes associated with these 3 transistors were changed to 3 zero ohm jumpers.

The games' sound signals (S1, S2, S4, S8) also pass through the driver board at Z13, a 7404 Hex Inverter. See below for S16 and S32.

3.5.1 Repurposed Driver Board Circuits

A Typical Remote Transistor Mounted Under the Playfield

Since quite a few System 80 games employ more than 9 solenoids, and since the original driver board design will drive a maximum of 9 solenoids, Gottlieb® repurposed some lamp outputs to drive "under-playfield transistors" which drive additional solenoids.

A Typical Transistor Driver Board

Once playfields became littered with numerous "under-playfield transistors", Gottlieb® opted to merge some of these transistors into a transistor driver board. The transistor driver board started to appear on Gottlieb® games nearly midway through the System 80B platform, with the game Victory.

The sound S16 and S32 signals are also repurposed lamp outputs. For instance, Haunted House and Black Hole both repurpose L9 to S16. Robo-War repurposes lamp 4 to S16. Note that S16 is not consistently implemented across the System 80 family. Note also that references to the usage of S32 are difficult to find.

3.6 Auxiliary Lamp Driver Boards

A Typical Aux. Lamp Driver Board Using MPS-U45 Transistors (Maximum Control of 10 Lamps

A Typical Aux. Lamp Driver Board Using 2N6043 Transistors (Controls a Maximum of 20 Lamps

Starting with Time Line, several System 80/80A/80B platform games use auxiliary lamp driver boards. These boards are commonly referred to as "chaser boards" or "lamp chaser boards". The reason for either of these nicknames is because these boards are used to control lamps for effect. They are either placed in the backbox or under the playfield. With later System 80B games, they were located in the lower cabinet. Location is typically dependent upon what lamps are being controlled. The aux. lamp driver boards are not controlled by the CPU. The only signals needed for an aux. lamp driver board to function is +5V and ground.

There are several different variants of auxiliary lamp driver boards used. The earliest versions use MPS-U45 transistors to control a maximum of three lamps per transistor. Both 15 and 30 lamp versions (5 or 10 transistors) of this board exist. Some later boards use NDS-U45 transistors instead of MPS-U45 transistors. It is assumed this is due to a the cost or lack of MPS-U45 transistors during production. Either of these style of boards are interchangeable with one another. Finally, there are some boards used in later games which use 2N6043 transistors. These are designed to control #67 flashlamps, but this is not always the case. This style board was used to control lamps also. These boards are equally compatible with previous designed boards, when used as a complete, drop-in replacement. However, MPS-U45, NDS-U45, and CEN-U45 transistors are not 1-to-1 compatible with 2N6043 transistors. A viable replacement transistor for the 2N6043 is the TIP102.

The main difference between any of the auxiliary lamp boards is the amount of transistors used to drive lamps, and the resistor (R13) used to control the rate at which the lamps flash or "chase". Boards using 2N6043 transistors have different resistor values for resistors R2-R11 than boards which use MPS-U45s or NDS-U45s. A table of auxiliary lamp driver boards used on most games is shown below.

Game	Part #	Total Transistors	Total Lamps Controlled	R13 Resistor Value	Controls	Location	Notes
Time Line		10	?	820K Ohm	Chaser lamps behind nuclear symbol on backglass	In backbox
Mars:God of War		10	28	330K Ohm	Backglass perimeter chaser lamps	In backbox	1 of 2
Mars:God of War		5	10 (LEDs)	330K Ohm	LEDs behind tube	Under PF	2 of 2
Volcano		10	20	560K Ohm	Upper backglass perimeter chaser lamps and volcano effect behind backglass	In backbox
Black Hole		10	28	270K Ohm	Backglass perimeter chaser lamps	In backbox
Haunted House		10	21	270K Ohm	Behind backglass lightning effect lamps	In backbox
Rocky		10	19	560K Ohm	Behind backglass	In backbox
Spirit		10	20	Varies	Behind backglass	In backbox
Tag Team Pinball		10	20	820K Ohm	Multiball insert illumination	Under PF
Rock		10	18	680K Ohm	Extra ball insert path	Under PF
Rock Encore		10	18	680K Ohm	Extra ball insert path	Under PF
Raven		10	20	680K Ohm	Inserts leading to ramp	Under PF
Hollywood Heat		10	20	680K Ohm	Ramp insert illumination	Under PF
Genesis		10	10 (#67 Flashers)	680K Ohm	In top of backbox	Under PF	Uses 2N6043
Genesis		10	10 (#67 Flashers)	680K Ohm	Around playfield window	Under PF	Uses 2N6043
Gold Wings		10	8 (#67 Flashers)	680K Ohm	Flashers in topper	Under PF	1 of 3
Gold Wings		10	6 (#67 Flashers)	680K Ohm	Flashers in topper	Under PF	2 of 3
Gold Wings		10	10	680K Ohm	Inserts leading to ramp	Under PF	3 of 3
Monte Carlo		10	5	680K Ohm	Behind $10,000,000 sign	Under PF	1 of 2
Monte Carlo		10	30	680K Ohm	Lamps around perimeter of topper	Under PF	2 of 2
Spring Break		10	30	680K Ohm	In topper	Under PF	1 of 2; only if topper present?
Spring Break		10	20	680K Ohm	Special shot and shooter loop	Under PF	2 of 2
Arena	MA-936	None	10 (LEDs)	560K Ohm	LED strip under shooter lane wireform	Under PF
Victory		10	10 (#86 bulbs)	680K Ohm	Next to left ramp	Under PF	1 of 2
Victory		10	10 (#86 bulbs)	680K Ohm	Next to right ramp	Under PF	2 of 2
Robo-War		10	20	680K Ohm	Inserts in lower portion of playfield	Lower cabinet	(1 of 2) Uses 2N6043
Robo-War		10	10	680K Ohm	Under playfield glass stop	Lower cabinet	(2 of 2) Uses 2N6043
Bad Girls		10	5	680K Ohm	Drop target illumination	Lower cabinet	1 of 2
Bad Girls		10	10	10M Ohm	Under playfield glass stop	Lower cabinet	2 of 2
Bone Busters	MA-789	10	12	680K Ohm	Playfield inserts	Under PF	(1 of 2) Uses NSD-U45
Bone Busters	MA-866	10	20 (#67 flashers)	680K Ohm	Backbox lamp insert	In backbox	(2 of 2) Uses 2N6043

3.7 Sound Boards

Gottlieb® uses different sound boards throughout the course of all System 80 platforms. Several of the sound boards cross platforms too. Out of all of the sound boards used, there is really only about three base units total with variations made to each one.

3.7.1 Sounds Only Board

Gottlieb® System 80 Sound Board (Sounds only)

The first System 80 sound board is capable of sound only. Based on the 6503 CPU architecture, this sound board is very similar to the System 1 Multi-Mode sound board. However, there are a couple of differences between the two boards. First, the +12VDC is no longer rectifed on the sound board. The +12VDC power comes from the power supply. Secondly, the +5VDC is no longer regulated on the sound board. The System 80 sound receives +5VDC from the power supply also. Finally, the pin outs for the System 1 sound board and the System 80 sound board are completely different. Even though either board will plug into either platform, DO NOT PLUG A SYSTEM 1 SOUND BOARD INTO A SYSTEM 80 GAME AND VICE VERSA!!! If you do, bad stuff will happen. Unfortunately, there are two chips (6503 and 6530) on this style of board which are very difficult to source.

This sounds only board was used in the export versions of Black Hole, Volcano, and Devils Dare.

3.7.2 Sound & Speech Board

Gottlieb® System 80 / 80A B-20887-2 Sound & Speech Board

Gottlieb® System 80 / 80A B-20887-3 Sound & Speech Board

Starting with Mars God of War, the second System 80 sound board has the the capability of speech. Ironically, this board is commonly referred to as the "sound and speech board", and was brought over from the Gottlieb® video game division at the time. Fortunately, Gottlieb® chose the 6502 CPU architecture just like the CPU board. There is a 6532 RIOT used also. The downside to this board is the now rare LM379S amp and SC-01 phoneme speech chip are both difficult to acquire.

There are approximately three renditions of this board. Each will be marked with B-20887-X. The "X" denotes a suffix of 1, 2, or 3. If the board has wire wrap or resistors added to the solder side of the board, do not assume that it is some sort of diabolical, weird hack. These were recommended upgrades either done by the factory or out in the field. With each higher revision number, less wire wrap and resistors are present on the solder side of the board. However, each board revision typically has some degree of wire wrap added to it.

Schematics corresponding to the -1 revision of the board can be found in the Mars, God of War and Volcano manuals.
Schematics corresponding to the -3 revision of the board can be found in the Black Hole and Haunted House manuals.

3.7.3 Sound Only Board

Gottlieb® System 80 / 80A Sound Board w/ MA-483 Piggyback Board (replaces LM379S amp)

Gottlieb® MA-483 Piggyback Board

To reduce costs, Gottlieb® abandoned the speech option, and went a step backwards with a board generating sounds only. In doing so, they used the same B-20887-3 base board as the most current sound and speech board. The SC-01 speech chip socket in addition to the 74xx TTL chips, one of the LM741 op amps, and discrete components associated with the speech circuit were not installed on the board. By the time this board was first used, the LM379S amp was too costly and difficult to source. The solution was to add a single-side, piggyback board (as shown in the picture) with a TDA2002 amplifier and other necessary components.

If this board is used as a replacement in a game which uses a sound & speech power supply, (Haunted House for example), modifications to the s&s power supply must be made. This is due to the higher voltages necessary to operate the LM379S amp versus the TDA2002. If this board is installed in a game where the sound and speech board power supply was not modified, the guarantee of destroying the TDA2002 amp is inevitable.

3.7.4 Sound Only Board with Piggyback

Gottlieb® System 80A / 80B Sound Board w/ MA-488 Piggyback Board (Sounds only)

Gottlieb® System 80A / 80B Sound Board w/ Factory Trace Wire

To reduce costs even more, Gottlieb® started using a modified sound only board, which was first used with Spiderman in 1980. This "new" sound board was first used during the production of Amazon Hunt, and continued until Tag Team Pinball. The main modification of the board was the addition of a piggyback board. The piggyback board was used to increase the size of the sound ROM by using a 2716 EPROM.

Two other noteworthy modifications are an added factory trace wire on the solder side of the board, and a cut trace between pin 8 of U7 (7404) and a header pin on the component side of the board. The added trace wire runs from pin 3 of U1 (6503 CPU) to pin 18 of U2 (piggyback header pins). Both of these modifications should remain intact for the board to function properly.

It is also worth mentioning that this is one of the few instances where Gottlieb® used a double-sided piggyback board. The benefit of using a double-sided board is the decreased chance of cracked header pins, where the header pins attach to the underside of the piggyback board.

3.7.5 System 80B Sound Board (two button)

Gottlieb® System 80B MA-766 Sound Board

And now for something completely different. Well, not really. The MA-766 sound board hit the scene with Rock, but a similar design was already used prior by the Gottlieb® video game division (Mylstar) when it existed. It is based on the 6502 CPU architecture, but uses two 6502s instead of one.

Two momentary push button switches are present on the board - SW1 and SW2. Upon pushing SW1, the sound board should output a single blip (tone). SW2 is used to manually reset the CPU on the sound board. A bank of 4 dipswitches is located adjacent to SW1. Dipswitches 1-3 should always be off, while dipswitch 4 should remain on for proper function.

3.7.6 System 80B Sound Board (one button)

Gottlieb® System 80B MA-886 Sound Board

The MA-886 board is essentially the same as the previous sound board, except it uses 2 separate .156" header pin connections instead of edge connectors for inputs / outputs. Some other obvious changes are the omission of momentary test button SW1, the omission of the 4-bank dipswitch, the omission of YROM2 socket, and the addition of a socket at position S4 on some boards. Momentary test button SW2 is still preset, and is still used to manually reset the board's processor. The lack of YROM2 is because the MA-886 board allows for the use of larger EPROMs. The S4 socket has been added on some boards, and is used to transfer data via a ribbon cable to an auxiliary sound board.

3.8 Displays

3.8.1 System 80

File:GTB 6 digit display.JPG

Gottlieb® 6 Digit Display

Gottlieb® 6 Digit Display (Back)

Gottlieb® 4 Digit Display

Gottlieb® 4 Digit Display (Back)

3.8.1.1 Display Test - System 80

Display test is step number 19 System 80 games. Each display, including the credit/match display participates in "walking" each digit (0 through 9 beginning with 0) across each display. The "walking" begins at the match side of the credit/match display, then moves to players 1 and 3, then to players 2 and 4. After a "9" is walked through all displays, the cycle starts again with "0".

3.8.2 System 80A

Gottlieb® System 80A 7 Digit Display

Gottlieb® System 80A 7 Digit Display (Back)

Gottlieb® 4 Digit Display

Gottlieb® 4 Digit Display (Back)

3.8.2.1 Display Test - System 80A

Display test is step number 19 System 80A games. Each display lights every position, and advances through all of the numbers starting with "0" and ending with "9". Once "9" is reached, the process starts over at "0" again.

3.8.3 System 80B

Gottlieb® System 80B MA-644 Display Component Side

Gottlieb® System 80B MA-644 Display Solder Side

System 80B games introduced the 20 alphanumeric character dual line display module. These displays evolved over time. The one pictured here was used in games Chicago Cubs Triple Play until Excalibur. The two large ICs found on this board (Rockwell 10941 segment driver and Rockwell 10939 digit driver) are long obsolete and very hard to obtain. Other components on the board are readily available.

The board rectifies 32VAC via diodes CR1-CR4 to produce -45VDC and -15VDC for use by the segment and digit drivers. Should one or more of these diodes fail, the foil trace on the board sometimes acts like a fuse, and burns itself up. The picture at right shows a board that experienced this failure, along with a jumper to repair the damaged trace.

Gottlieb System 80B MA-999 Alpha-Numeric Display Board with header pin connections. (Bad Girls)

The last System 80B games (Hot Shots, Big House, Bad Girls, and Bone Busters) all used a larger alphanumeric vacuum fluorescent display assembly. This type of display used two sets of .156" header pins instead of the more familiar edge connection.

3.8.3.1 Display Test - System 80B

Simulation of System 80B display test

Display test is test number 20 for System 80B. All 40 of the alpha-numeric "digits" (both the top and bottom displays) will light starting with a "0", next a "+", then an "X", and finally a ",". In doing this, all possible segments of all the display digits are lit at one point during display test.

3.9 Reset Board

Gottlieb® System 80 / 80B Reset Board

Starting with Devil's Dare, the first System 80A game, the reset board became a staple of the Gottlieb® design to automatically reset the CPU board should the CPU lock up. Apparently games locking up on location was an issue with System 80 games. The reset board was created to resolve this issue, should the game lock up, and no one is present to manually reset the game by shutting it off and turning it back on.

The reset board is a small footprint PCB with the board designation of A24, and is located adjacent to the TC1 connector of the CPU board. The connection on the reset board is A24P1, while the connection for TC1 of the CPU board is A24P2. As long as someone can turn the game off, should it lock up, there is no need to keep the reset board connected. In most cases, the aged reset boards are more troublesome if allowed to remain connected.

Connection at TC1 to the reset board.

A 3.0Kohm resistor, added between pins 7 and 11 of TC1.

Along with adding the reset board, Gottlieb® added a 3.0Kohm resistor across pins 7 and 11 of the reset board connection at MPU connector TC1. If not using the reset board, it's advised to add this resistor to the back of the board, as shown at right. This resistor pulls the R/W (read/write) line high when not pulled down by the 6502.

The reset board connector also has a 1N270 diode soldered to it. There is no need to add this diode to the MPU since it's part of the reset board function.

If using connector A24-P2, do not add the 3.0Kohm resistor. Doing so will change the value of the combined resistors.

3.10 Recommended Documentation

A game manual. Pinball Resource has many factory originals still left, and reprints of everything else.
Gottlieb tended to publish a lot of game-specific information in parts catalogs. These have exploded diagrams of assemblies, particularly in earlier games that had the thinner, much less helpful manuals. Playfield parts, lamps, and switches are all diagrammed out. These also have collected service bulletins. Reprints are available from Pinball Resource.
- 1982 Parts Catalog, Gottlieb. Covers System 1 games and System 80 games.
- 1987 Parts Catalog, Premier Technology.
- 1992 Parts Catalog, Premier Technology. Covers 80B games starting from Gold Wings and the first 9 System 3 titles (games #706-#730).

3.11 The Wiring Color Code

Unlike every other pinball manufacturer, which adopted a two-color wiring code system, Gottlieb® used three colors. Most wiring in a Gottlieb® game used a white base color, which is the wire's insulation color, and three "striped" traces on each wire. I state most cases, because there are some wires which only used two colors - the green insulated ground lines which have a single yellow trace, or only one color - the white ground wires used in System 80B games with no trace at all. Below is the Gottlieb® color chart.

	0	1	2	3	4	5	6	7	8	9
Color	Black	Brown	Red	Orange	Yellow	Green	Blue	Purple	Gray	White

Does the color chart look familiar? Well, if you have an electronics background, it should. The Gottlieb® wire code system is the same as the resistor color coding system.

Here are some examples of the color coding system. The color wire code for switch strobe line 0 is 400. 400 would be a white insulated wire with a yellow trace and two black traces, or commonly referred to as a yellow-black-black wire. The ground lines in early System 80 games are code 54. 54 would be a green insulated wire with one yellow trace.

There is one word of caution, which should be pointed out. If the connections on A1J2 and A1J3 are being replaced, there are wire colors on these connections which are very similar. Although each wire is located on a different housing, please proceed with caution, as it can be difficult to see all three traces without spinning the wire around. The wires which come to mind are 344 and 677 on A1J2, and 433 and 766 on A1J3.

3.12 Connector Designations

All Gottlieb® machines have a common naming convention for all of the connectors in the game. A specific connection uses two parts - a prefix and a suffix. The prefix is the board number or an inline wire junction, and the suffix is the connection on the board or a sequential wire junction number. When referencing a specific connector pin within a housing, a dash follows the connection number. For example, the connector pin for the slam switch signal on the CPU board is A1J5-10. The coin door connection used on Devil's Dare is A15P1 and A15J1 - the connector pin for switch return 7 on the coin door is A15J1-8.

The following boards are assigned the same numbers throughout the System 80 / 80A / 80B platforms.

CPU Board - A1
Power Supply - A2
Driver Board - A3
Sound Board - A6
Pop Bumper Driver Boards - A8
Reset Board - A24

There are several other board designations used, however, they change from game to game.

3.13 Switch Matrix

Gottlieb® System 80 Switch Matrix

The Gottlieb® System 80 / 80A / 80B switch matrix consists of a maximum of 64 switches. There are a total of 8 switch strobes and 8 switch returns. However, not every switch in the matrix is used on every System 80 game.

Just like the System 1 switch numbering system, the System 80 switch numbers have a similar naming convention. Except, the System 80 switch numbering system is the opposite of System 1. If you are accustomed to working on System 1 games, pay close attention. With Gottlieb® System 80 switches the first number of the switch is its strobe number, while the second number is switch's return number. An example would be switch 54. Switch 54 is located on strobe 5 and return 4 of the switch matrix.

	Strobe 0 (A1J6-1 / A1J5-2)	Strobe 1 (A1J6-2 / A1J5-3)	Strobe 2 (A1J6-3 / A1J5-4)	Strobe 3 (A1J6-4 / A1J5-5)	Strobe 4 (A1J6-5 / A1J5-6)	Strobe 5 (A1J6-6 / A1J5-7)	Strobe 6 (A1J6-7)	Strobe 7 (A1J6-8 / A1J5-9)
Return 0 (A1J6-10)	00	10	20	30	40	50	60	70
Return 1 (A1J6-11)	01	11	21	31	41	51	61	71
Return 2 (A1J6-12)	02	12	22	32	42	52	62	72
Return 3 (A1J6-13)	03	13	26	33	43	53	63	73
Return 4 (A1J6-14)	04	14	24	34	44	54	64	74
Return 5 (A1J6-15)	05	15	25	35	45	55	65	75
Return 6 (A1J6-16 / A1J5-8)	06	16	26	36	46	56	66	76
Return 7 (A1J6-17 / A1J5-1)	07	17	27	37	47	57	67	77

3.13.1 The "Missing" Gottlieb® System 80 Switches

With the Gottlieb® System 80 series of games, there are some switch assignments that are designated the same throughout the System 80, 80A, and 80B platforms. These switches are typically not listed in the switch matrix portion of the manual. You have to review the cabinet schematics, and decipher what switches use what return and strobe. However, it appears that Gottlieb® / Premier® changed this section of the schematic starting with Excalibur or Bad Girls by no longer listing the strobes for these switches. So, below are the "missing" switch assignments for any Sys80B. All the info applies for Sys80 and Sys80A, except the two advance buttons, which weren't used prior to Sys80B.
06 - left advance button (Sys80B only)
07 - play / test switch
16 - right advance button (Sys80B only)
17 - left coin switch
27 - right coin switch
37 - center coin switch
47 - replay button
57 - plumb bob and ball roll tilts (these have the same switch assignment as the playfield tilt switch)

Black Hole is one exception. The switch assigned for the tilt on Black Hole is 26.

Note: The coin door slam switch is not part of the switch matrix.

3.13.2 Enabling Free Play

Free play options were unavailable in the original System 80/80A/80B game code. However, there are some hardware modifications that can be done, stacked switches can be added to the start/credit button, or EPROMs with free play code can replace original PROMs.

3.13.2.1 Free Play EPROMs

For system 80/80A, the U2/U3 PROMs can be replaced with an EPROM with free play code. Replacing U2/U3 will require an adapter, such as the module from GreatPlainsElectronics, a custom adapter board, or the Swemmer Electornics U2/U3 Adapter.

For System 80B, the game PROM can be replaced with an EPROM with free play code.

3.13.2.2 Free Play for System 80 Games

Early Gottlieb® solid state pinball machines, prior to 1990, did not have a free play option available within the game settings. With this simple modification, a game can be set up for free play. First, identify the diode strip in the bottom of the cabinet. Once the diode strip is found, locate the credit button and coin switch strobe line wires. The wires will be located on the left of the diode strip - the non-banded side of the diodes. Below is a list of the wires.

Credit button wire - Green-Yellow-Yellow
Left coin switch wire - Green-Brown-Brown
Center coin switch wire - Green-Orange-Orange
Right coin switch wire - Green-Red-Red

Typical location of System 80 diode board in cabinet

Gottlieb® System 80 Black Hole diode board with jumper (yellow wire) to implement free play

Solder a small lead wire from the credit button wire to any of the coin switch wires. The wires will change to different colors on the other side of the diode. You want to solder to the side of the diode (non-banded) with the color wire specified above.

Make certain that the diode, credit button wire, and coin switch wire are still soldered securely to the diode strip terminal when finished. If soldering is not an option, use a small alligator clip test lead. Now, when the credit button is pressed, a credit will be incremented and decremented. A game can be easily started without the need to open the coin door to trip the coin switches anymore.

Please note that this modification does not apply to Gottlieb® System 80A and System 80B machines. System 80A and 80B machines use diode boards with edge connections, which are typically located on the cabinet wall near the left flipper cabinet switch. Jumpering the diodes on System 80A and 80B games do not give the intended free play results of jumpered System 80 diodes. This is attributed to how the diode boards are physically placed differently in circuit with respect to the switches.

Gottlieb® System 80 Time Line diode board with jumper (the red wire...I mean...it's a red flippin' wire. You HAVE to be able to see it!) to implement free play

The picture at left ties the center coin chute wire (Green-Orange-Orange) to the credit button wire (Green-Yellow-Yellow).

3.13.2.3 Free Play for System 80A Games

There is no method to implement free play for System 80A games at this time, other than "stacking" the credit button switch with one of the coin drop switches.

3.13.2.4 Free Play for System 80B Games

Typical location of System 80B diode board on cabinet wall

Added jumper to back of diode board

A System 80B cannot be set on free play, but there is way to add credits without having to open the coin door and tripping the coin switches.

Locate the diode board used for all of the coin door switches. Remove the diode board. Add a jumper between pin 4 and pin 10 of the diode board on the solder side of the board, (this can be done on the component side instead). Make certain that the jumper is soldered onto the banded side of the diodes. This jumper essentially ties the right advance button on the front of the cabinet to the center coin switch.

Now, when the right advance button is pressed, credits will be added to the game. There have not been any ill side effects observed when the right advance button is pressed while scrolling through characters used to enter high score initials.

This modification should work on games from Chicago Cubs Triple Play to Excalibur. It is unknown if it will work on Hot Shots, Bad Girls, Big House, and Bone Busters, Inc.

Another option is a free play ROM, produced by a group of kindly fellows in France. By burning the revised image into a 2764, and installing the new ROM on the daughter card, the game will now be on free play. Their implementation notices when zero credits are on the game and the credit button has been pressed. The new code then adds 20 credits to the game, and starts a game. The System 80B free play ROMs can be found here.

3.14 Bookkeeping & Diagnostics

Gottlieb® System 80 Coin Door Test Button Highlighted

To enter the bookkeeping / diagnostic mode, open the coin door and press the red momentary switch. (Note this switch has no credit function) Depending on the particular game, the self test button may be mounted on a bracket located on the coin door or just inside the cabinet near the coin door hinge. Upon pressing this button, the 4-digit status display used with System 80 and System 80A games will display "00" in the credit window. Pressing the self test button again will advance to the next step in the bookkeeping.

There is an option to bypass all of the bookkeeping functions, entering diagnostic mode directly. To achieve this, the self test button must first be pressed. "00" will shown on the status display. Then, the credit / start button should be pressed once. The status display should now show "16". "16" is the first test in diagnostic mode.

Bookkeeping (System 80/80A)
1 - Coins thru left chute
2 - Coins thru right chute
3 - Coins thru center chute
4 - Total plays
5 - Total replays
6 - Game percentage
7 - Extra ball
8 - Total tilts
9 - Total slam tilts
10 - Number of times the HSTD has been beaten
11 - First high score level
12 - Second high score level
13 - Third high score level
14 - High score to date score
15 - Average game time

Diagnostics
16 - Lamp test
17 - Coil test (will cycle and display coil number of coils used in the game. Coin counter coils, if installed, are excluded)
18 - Switch test. (99 = no fault) You can check switch numbers by pressing them on the playfield during this step.
19 - Display test. The displays will cycle through each digit
20 - Memory test. (99 = no fault)

Gottlieb® System 80 "7641" Error

An example of a ROM image checksum error (or perhaps a ROM memory access error) displayed during test 20 is pictured at left. During test 20, if a checksum error is detected, the ROM code in U2/U3 will indicate "7641-X" in the player 1 display window, with "X" being "1" to indicate PROM 1 or "2" to indicate PROM 2. If you have followed the procedure to combine the original game ROMs into a single 2716, this error message is an indicator that the checksum of either the 1st half or the 2nd half of that ROM failed. Replace the ROM.

System 80B uses the same process as System 80/80A to enter bookkeeping / diagnostics. The only difference is upon pushing the self test button the first time, the top alphanumeric display will display "TEST MODE". Pressing the self test button again will enter bookkeeping mode, while pressing the credit / start button will enter diagnostics mode. After entering either mode, pressing the self test button will advance through each step in the appropriate mode.

Any of the tests in diagnostics can be repeated by simply pressing the credit / start button. This applies to all versions of System 80 platforms.

The following also applies to all System 80 platforms. To exit bookkeeping or diagnostics, the slam switch or tilt switch can be triggered. Equally, waiting 60 seconds will reset the CPU back to attract mode. This is probably the only benefit in keeping the slam switch functional. However, considering the sometimes strange side effects, which can arise from a maladjusted or malfunctioning slam switch, disabling the slam switch would probably the better approach.

3.14.1 Pausing the Lamp and Solenoid Test (System 80B Only)

The left advance button on a System 80B Game

The following only applies to System 80B lamp and solenoid tests. A little known fact is that the lamp and solenoid tests can be "paused" on a single lamp or single solenoid. To stop whichever item is being tested during lamp or solenoid test, and repeat the test on the particular item, simply push and hold in the left advance button located on the front of the cabinet, as shown in the picture to the left. The left advance button can then be released, pressed, and held in again to step to the next item in the test. This is a particularly nice feature, because the lamps and solenoids or relays tend to be pulsed rather quickly in test, and cannot be observed very well, until the test repeats itself.

3.15 Rubber Ring Chart

Although the Gottlieb® System 80 game manuals do list the location and part numbers for rubber rings used, some fail to list the actual rubber ring size. Below is a handy chart, which lists the Gottlieb® rubber OEM number and its size.

Gottlieb® #	Description
A-14793	23/64" White Mini-Post
A-15705	27/64" White Mini-Post
A-10217	5/16" White Ring
A-17493	7/16" White Ring
A-10218	3/4" White Ring
A-10219	1" White Ring
A-10220	1-1/2" White Ring
A-10221	2" White Ring
A-10222	2-1/2" White Ring
A-10223	3" White Ring
A-10224	3-1/2" White Ring
A-10225	4" White Ring
A-10226	5" White Ring
A-13151	3/8 x 1-1/2" Standard Red Flipper
A-13149	3/8 x 1" - Small Beaded Red Flipper
A-1344	Rebound Rubber
1872	Shooter Tip

4 Problems and Solutions

4.1 Connectors, Connectors, Connectors

Connectors, connectors, connectors!!! Since the Gottlieb® System 80/80A/80B boardset primarily relies on Molex connectors to pass data and voltages from board to board, the connectors should be addressed first. Before even attempting to turn a Gottlieb® System 80/80A/80B game on for the first time, worn or corroded edge connector contacts must be replaced. Cleaning or burnishing connector contacts is not a viable option to ensure a game's reliability.

Poor connector contacts are the number one reason why System 80/80A/80B games do not function properly. Poor or missing connector contacts have a cascading effect too. The end results of bad connector contacts can be, but are not limited to:

voltages which mysteriously disappear and reappear
increased resistance
specific switches not functioning
lamps locking on
lamps not turning on
displays not properly functioning
coils not turning on
coils locking on
CPU boards not booting, booting sporadically, or randomly resetting
driver boards not functioning or functioning sporadically

So, it is very important that the connector contacts are shiny, have proper spring tension, and are properly crimped for the over all reliability of the game. Random, flaky issues which happen either sporadically or all the time are attributed to poor connector contacts in nearly every case.

System 80 Connector (J6), The Good, The Bad, and The Ugly
An example of pins in desperate need of rehab.
Ahhh...Much nicer after repinning.

4.1.1 Replacing (Repinning) System 80 Connectors

Replacing connectors in a pinball machine somehow adopted the term repinning. Repinning a System 80 connector housing isn't too bad overall. On a difficulty scale of 1 to 10 (1 being the easiest to do) compared to all other makes and platforms made, System 80 connector replacement is about a 3. One benefit regarding the System 80 IDC housings is that they are reusable. Below are the steps to remove the connector from its housing.

First, grasp the housing in one hand. Use a small "pocket" flat blade screwdriver. add pic later---> (http://www.absorbentprinting.com/tools-and-knives/screwdrivers/pocket-screwdrivers/level-rite-regular-blade-options).
Next, push the connector's ear down, so the connector can be released.
Finally, pull gently but firmly on the wire.

Sometimes the connector comes out, and sometimes the wire pops out of the connector. If the latter, use a small jeweler's screwdriver to gently pry the very end of the connector against the rectangular opening in the connector housing. You're trying to get the IDC "ears" of the connector to clear the housing. Sometimes the connector will easily come right out. If it doesn't, use some small needle nose pliers, and grab the "ear" of the connector, and pull it out.

File:MolexPinExtractionTool.jpg

A Molex Contact Extraction Tool, Molex part number 11-03-0016

Some system 80 connector housings are "double sided" edge connectors. All of the connector housings that are double sided are black from the factory (blue colored housings are typically Jamma connectors used as replacements, and do not apply to this section of this guide). To remove pins from these connector housings, you need a pricey yet effective tool called a Molex contact extraction tool, (commonly referred to as a Molex extractor). The Molex part number for the extractor is 11-03-0016, and can be purchased from Great Plains Electronics or other electronics vendors. Slide the extractor behind the pin to release the "tang" that holds the pin in. Firmly grip the wire and pull the pin out of the connector.

4.1.2 Alternate Method of Replacing (Repinning) System 80 Connectors

The repining on a single sided connector

The repining on a double sided connector

Some System 80 (and most System 1) connectors do not have the slot for depressing the pin ear. Most guides (as in the previous section) recommend purchasing a ridiculously expensive tool to insert and depress the ear. This procedure is tedious and often doesn't work. Even if the ear is correctly depressed, usually you need to pull the wire with a pair of pliers. If you have a decently equipped shop which includes a drill press (a hand drill will also work) then repining these difficult connectors is very easy. Using this procedure, you can expect to replace each pin in less then a minute. I repined an entire A1-J4 / A3-J1 harness in about 40 mins.

The procedure is to drill out the depression ear and pull out the pin:

Install a 1/16" bit in your drill.
Set up a jig by clamping a straight edge to your drill press table. Set the jig so the hole will be 1/4" from the edge of the connector.
Drill through the plastic housing on the back/bottom side.
When you feel resistance from the metal pin, gently continue to drill until you feel and hear it destroy the pin ear.
Repeat for the remaining pins.
Gently pull wire by hand and it will come out very easily. Pliers shouldn't be required.

The newly installed pins ears will correctly lock in place regardless of the holes.

4.2 The CPU / Driver Board Interconnect Harness

The A1-J4 / A3-J1 Interconnect Harness

There are 33 discrete signals which pass from the CPU board to the driver board via this connection. Two of the connectors pass ground and +5v logic to the driver board (two more can be added). The remaining signals are for lamp, solenoid, relay and sound control. It is extremely important to have solid connectors installed in the CPU / driver board interconnect harness. Without decent connections, lamps, coils, relays, and sound can either lock on or not turn on at all.

4.2.1 Adding Ground and 5V Connections to Interconnect Harness

Yet one more power/ground update to make is to "double up" the 5VDC and ground connections between the MPU and the driver board. The OEM harness contains only one connection between the MPU and driver board for 5VDC and one connection for logic ground. This is an easy upgrade since spare connection positions are available in the connectors that lead to the correct edge contacts on each board. Approximately 8 inches of wire and four bifurcated crimp on pins (bifurcated style, Molex 4366 series, Product Family KK, product ID: 08-03-0304 at Great Plains Electronics) are needed.

Crimp a pin to each end of each wire. The connectors at each end should face opposite directions. Doing this will avoid twisting the wire as you insert the pins into the connector housing. In the picture below, the red wire carries 5VDC, blue wire carries logic ground. These colors were chosen for illustrative purposes only. Any color wire will do, of course.

MPU-to-Driver Board Harness Upgrade
Pins crimped to extra wires.
Spare pin positions in harness.
5VDC and ground upgraded.

4.3 Ground updates

4.3.1 Recommended Ground Improvements for System 80/80A/80B Boards

When the Gottlieb® System 80 board set was designed, for whatever reason, the designers did not physically attach each board to a common ground plane via a conductive back panel, standoffs and screws as Bally and Williams did. Instead, Gottlieb® relied on connectors and wires between each board to create a common ground. A poor connection due to dirty/damaged/fatigued connector pins will sever the ground between system components resulting in all sorts of odd behavior.

To address this problem, it is important to examine each connector to ensure each pin is clean, and making solid contact with the card edge conductor. The ultimate (and recommended) insurance is to add an additional wire from each board's ground to a common ground point. Historically, the recommended location to join separate board grounds is at the power supply. That ground is then connected to the ground strip or transformer assembly in the cabinet bottom.

These ground upgrades were initially recommended and published on the Internet by John Robertson of John's Jukes.

Recommended Board Ground Wire Locations
System 80/80A Power Supply
System 80B 5V Power Supply
System 80B Auxiliary Power Supply
MPU Board
Driver Board
System 80 Sound Only Board
Sound and Speech Board
Sound and Speech Power Supply
System 80A/80B Sound Only Board
System 80B Sound Board (edge connector)
System 80B Sound Board (header connector)
Chaser Lamp Board

Another design decision was to provide separate ground wires for groups of lamps and coils on the driver board. There are several variations used to tie the driver board lamp and solenoid discrete ground wires to the ground plane. The most common method Gottlieb® used was passing the ground wires through a large, inline Molex connector. If a group of lamps and/or coils are not working, there is a significant probability that a ground is missing.

Tying all board ground together at a single point, on a System 80 or 80A game.

Using the +5V power supply heatsink as a tie point for the added grounds.

Once all of the board grounds have been installed, tie them all together to a single point, as shown at left on a Gottlieb System 80 or 80A game. Here, one of the screws on the power supply is a handy attach point. Note that the coating on the cold plate at that screw point should be sanded bare, as discussed in step 9 of this procedure.

For 80B games, use the +5V power supply heatsink as a tie point. Then, run a lead from the heatsink to the lower right bolt in the backbox. This bolt will have the factory ground straps secured to it. Make certain to sand or use a Dremel to remove the anodized coating from the heatsink where the grounds will be connected.

Connecting all the grounds to cabinet ground (green/yellow wire).

With the grounds all tied together at the power supply, tie that ground to the ground strip in the cabinet bottom. In the picture at left, the wire joined to all other grounds at the power supply is tied to a cabinet ground point (in this case the speaker housing). Cabinet ground points generally have a green wire with yellow tracer attached.

System 80 Cabinet Bottom Ground Strip

The bottom board ground strap is where all grounds should come together for System 80 games.

4.3.1.1 Grounds Improvements for System 80A at Transformer Panel

System 80A Grounds Cabinet Bottom Ground Strip

Grounds at Transformer Panel (Alien Star)

Gottlieb® did secure the grounds correctly on one particular game. As seen in the adjacent pic, the grounds on Alien Star were attached discretely on the transformer panel. These ground lines did not pass through a Molex connector like games before or games after. Why Gottlieb® did not continue this practice is unknown.

4.3.2 Recommended Ground Improvements for System 80B

4.3.2.1 Grounds Improvements for System 80A / 80B at the Transformer Panel - "The Games" to "Bounty Hunter"

Grounds at Transformer Panel (Chicago Cubs Triple Play)

After Alien Star, Gottlieb® soldered wire leads directly to the transformer panel, and used square, inline 9-pin Molex connectors to connect to the wiring harness. These connections, if the pins in the connectors are in good shape, are solid and do not require upgrade or modification.

4.3.2.2 Grounds Improvements for System 80B at the Transformer Panel - "Rock" to "Spring Break"

Ground connections used on System 80B games from Rock to Spring Break are the most unreliable style of ground connections Gottlieb® ever used. These connections consist of two (sometimes three) small boards each with two gangs of 9-pin male connections. The boards are fastened to the left side of the transformer panel's metal chassis. One problem with this is that the 9-pin female connection becomes loose, and in turn, ground connections become intermittent. Another problem is the male pins on the boards suffer from cracked solder connections.

One common symptom of poor ground connections is multiple solenoids not functioning. If removing the 9-pin Molex plug from the ground board, rotating it 90 degrees, and reconnecting it causes non-working solenoids to function, the ground connections are bad. Whether or not this test proves that the ground connections are bad, it is highly recommended to improve the ground connections for future reliability.

The purpose of these changes is to remove one potentially failed connection out of the equation. The grounds will then be secured directly to the transformer chassis via solderless eyelet crimp connectors.

These ground upgrades were initially recommended and published on the Internet by John Robertson of John's Jukes. Below are the steps to properly upgrade the grounds.

Gottlieb® System 80B Ground Upgrades (Rock to Spring Break)
The stock ground connections plugged into the ground connection boards on the left side of the transformer panel. This pic is a view from the left side.
Remove all connections from the transformer panel. Then, unscrew the four 5/16" hex head screws which secure the transformer panel from the bottom of the cabinet. Turn the transformer panel on its side. This will allow better access to secure the ring terminals to the side of the chassis.
Cut all of the ground wires as close as possible to the 9-pin connection. Remove the two boards with the 9-pin male wafer connections. As can be seen in the pic, Gottlieb® did actually secure the discrete transformer panel grounds to the panel's chassis with a single, soldered eyelet connector.
All the ground wires are to have their insulation stripped back longer than usual - approximately 3/4". Solderless ring terminals are crimped onto the ground wires. The connections used in this particular application are Motormite #85443. Motormite brand does not have to be used. This particular brand and part number are mentioned due to the difficulty in finding the correct connectors to use. Most common ring terminals have a #10 or larger screw eyelet, which will not work effectively, if the eyelets are fastened to the side of the transformer panel chassis. The ring terminals shown here are made for #12-#10 gauge wire with an eyelet for a #8 screw.
The ground Molex plugs and connection boards which were formerly fastened to the transformer panel's metal chassis. The four ground connector plugs (some games only use three total) were cut off from the incoming ground wires.
Keep wires which were common to one connector together (driver board ground wires, playfield ground wires, and backbox ground wires). In doing this, future disassembly will be possible, should any of the individual wiring harnesses need attention or the playfield removed from the game. The ground wires are then twisted together and crimped. From experience, a maximum of 4 larger gauge wires can be crimped in one connection. Lighter gauge wires can be paired with or without heavier gauge wires. When doing this, the maximum effective grouping of wires increases slightly.
The screws which were removed from the ground bus board should be reused to secure the eyelets to the transformer panel.
The transformer is fastened to the bottom of the cabinet with the ground upgrades in place.
Pay close attention when securing the transformer panel to the cabinet. All four mounting screws typically have flat ground straps with an eyelet. These eyelet connections *must* be secured to the transformer panel. Otherwise, the earth grounds will not all be tied together anymore. Two of these ground connections are circled in the pic. There are two more located on the backside of the transformer panel.

4.4 Power Problems

4.4.1 Replacing the Orange Filtering Capacitor

A worn out original 6800uf/25V Gottlieb® filter capacitor

If your System 80 or early System 80A game still has the original, orange 12VDC filtering capacitor in the cabinet bottom, it should be replaced. It's 30+ years old, has served the game well for a long time, and deserves a rest. Replace it with a new capacitor, valued from 6800uf to 12,000uf and at least 25V. Don't forget to acquire the right sized bracket to secure the cap to the bottom board.

A very nice replacement for this capacitor, specified at 12,000uf, can be found here.

This capacitor filters the rectified 12VDC which is supplied to the power supply board for regulation down to 5VDC which is used by the every board in the game, including the MPU. Solid 5VDC power is critical for the game to operate properly. Hence the need for a properly working cap.

4.4.2 Recommended Updates and Repairs for the System 80/80A Power Supply Board

If CR7 on your Gottlieb power supply looks like this, the board should be rehabbed immediately.

The System 80 Power Supply board is a pretty tough bugger. Still, after years of steady operation, they do fail, and they require refurbishment.
The test point values are silk screened on the System 80 power supply board. They are +5VDC, +8VDC, +42VDC, and +60VDC. Ground, or "common" is also labeled.
Given that the parts to refurbish the power supply are cheap and readily available, and that taking the power supply apart is a bit of a pain, a good strategy is to replace all failure prone parts, whether the parts have failed or not, to avoid disassembling the power supply more than once.

Parts you will need are:

.156 male header pins without friction lock, 9-pin, 7-pin, 6-pin, or break to size.
500 ohm resistor cermet trimmer potentiometer. A quality sealed one like the one pictured is advised.
3 inches of 18 gauge wire
470, 510, 560, or 620 ohm 1/2 watt resistor (R10, originally a 30 ohm 2W resistor and must be replaced if CR7 is replaced)
1N4738 8.2V 1 watt zener diode (CR7, originally a 1N3445 8.2V 2W zener)
12K ohm, 1/2 watt resistor (R3)
1N4746 18V 1 watt zener diode (CR6, optional)
47uf, 100V axial capacitor (optional)
LM723 voltage regulator and 14-pin socket (optional if the 5V section is operational)
2N6057, 2N6059, or 2N6284 Darlington transistor (Q3, optional if the 5V section is operational)
heat sink compound (optional as required)
TO-3 mica insulator or heat sink gasket (optional as required)
TO-3 transistor spacer (optional as required)
2N5550 or 2N5551 transistor (Q2, optional)
TIP31C TO-220 NPN transistor (Q2, optional)
TO-220 mica insulator (optional as required)
Green LEDs (optional...use if you want to identify the board as having been reworked)

Procedure:

Remove the 4 screws that fasten the PCB to the cold plate (heat sink).
Remove the 2 screws that fasten the back mounted transistor Q3 to the PCB and cold plate.
Use your favorite solder removal tool to remove the solder from the legs of Q3 that extend through the PCB. This is the toughest part of the job. If the board had been really hacked, you may need two irons and a friend to accomplish this.
Once the cold plate and Q3 have been removed, set those parts to the side.
Replace parts on the PCB as recommended and advised by the particular failure.
On the solder side of the PCB, solder a 3" wire from the ground trace to the screw mount, as shown in the picture below.
When replacing the original round header pins with new square header pins, you may have to enlarge the holes slightly using a pick as shown in the picture below. Key pins must be removed prior to installation as the PCB has no holes at the key pin position.
Recheck all of your work.
Sand the black insulating coating from the top/right screw hole on the front of the cold plate, as shown in the picture below. The insulating coating is very tough. A drum sander attachment on a Dremel works very well for this. To ensure you've sanded enough, use your meter to "buzz" between screw holes. You will use this screw hole later to tie the ground from each PCB together.
Install Q3 (note that it will only install one way) onto the cold plate using the transistor spacer, mica insulator, and heat sink compound.
Mate the two halves of the power supply together and reinstall the two screws which secure Q3.
Solder the leads of Q3 to it's through-holes.
To ensure continuity at each leg's solder joint, "buzz" the connection between the left leg of Q3 and the top leg of R9.
Also "buzz" the connection between the right leg of Q3 and the bottom leg of R11.
Install the remaining 4 screws around the perimeter of the power supply board.
Lastly, ensure there is NO continuity between Q3 and the cold plate, as shown in the picture below. This is an essential step to ensure proper operation.

System 80/80A Power Supply Repair
Parts Required
Front Side, Parts Removed and Board Cleaned Up
Back Side, Parts Removed
Enlarging Header Pin Holes
Parts Replaced, Front Side
Parts Replaced and Ground Updated, Back Side
Strain Relief for R10
All Done
Ensuring no continuity between Q3 and the cold plate

Once fully assembled, reinstall the power supply into your game. Connect ONLY J1 (the lower 9-pin connector) at this time. Power your game on, looking for the two LEDs to light. If they do not light, you have rework to perform. Assuming that they do light, test each of the voltages that the power supply creates to ensure the correct power is being generated/regulated. Since the power is not "under load", each of the voltages may read 10% or so high. While measuring the 5V test point, adjust the 5V trim pot to about 5.1VDC.

That's it! You're done.
Note: once you connect the other boards to the power supply, the 5V may sag some. Measure the 5V across the electrolytic cap just to the right of the MPU power connector. Using the 5V trim pot, adjust the 5V power to between 5.0 and 5.1VDC.

4.4.3 Recommended Repairs for the System 80B Power Supply Board

System 80B +5 VDC Power Supply. The adjustment POT is at the top of the PCB.

Step one to improving power supply reliability is to replace the original 500 ohm 1 watt adjustment pot. This procedure can be done easily without removing the large heat sink. A replacement sealed pot is recommended, but not completely necessary.

Next, remove all the old solder from the all of the .156" header pins, and reflow new solder onto the joints. The top header pins (J2) supply +5VDC to the majority of the associated circuit boards in the back box. Provided that the power supply is delivering acceptable voltages in the +5VDC range, these two relatively simple repairs are the only things needed for this board.

However, if you've adjusted the pot as much as possible in the appropriate direction, and the power supply is still delivering voltages higher or lower than around +5VDC, it's probably time to look at replacing the LM338K voltage regulator. While not a frequent occurrence, the voltage regulator will sometimes fail.

If the voltages measured are less than 1VDC, the grounds for the power supply (located at the transformer panel) will more than likely need attention. Once the grounds at the transformer panel are better secured, recheck the voltage at the power supply.

Note: When measuring the +5VDC provided by the power supply, first disconnect J2 on the power supply. Measure power at the J2 male headers first. Once within an acceptable range, turn power off and reconnect J2. Measure power across C1, the 100uf/10V capacitor that is next to J1 (power connector) on the MPU. The MPU may drag the +5VDC supply down a bit. If you find this to be the case, adjust the trim pot on the power supply until a steady +5VDC is seen at the MPU. Poor connections between the +5VDC power supply and the MPU board may also reduce the voltage measured at the MPU.

4.4.4 Optional Bling...Adding Power Indicating LED's to Boards

4.4.4.1 CPU Board LED

How to add a "+5 volt" indicator for the Gottlieb System 80 Generation 1 CPU board (the D102 board). This will light up when + 5 volts are present on the CPU board.

Materials needed:

1 Red LED, Jameco # 2125309 or Radio Shack # 276-209 or 1 Green LED, Jameco Electronics # 2125296 (9 cents each) or Radio Shack # 276-022 ($1.69 for a 2 pack)
1 Resistor, 330 ohms, quarter watt, Radio Shack # 271-1315

Drill two 1/16" diameter holes spaced about 3mm apart in the spot indicated just below power connector J1. This area has no traces to interfere with drilling.
Install LED into board with flat side facing toward the power connector J1.
Bend the flat side's lead to the negative (ground) point shown in the picture and solder it.
The other lead of the LED will connect to one side of the 330 ohm resistor. The other end of the resistor will be soldered to the positive trace shown in the picture. You're done.

Now whenever the machine is powered on, this LED will indicate that the CPU board is receiving +5 volts from the power supply.

Holes drilled on front of board

Holes drilled on rear of board

Circled areas are where to drill the two holes for the LED. Any color of LED can be used, but red or green are preferred.

Wiring on solder side of board

LED installed on board

Wiring of the resistor and LED. Note the location of the flat side of the LED.

Finished installation of LED

Completed installation with LED lit up indicating the +5 volts is present on the CPU board.

4.4.4.2 Driver Board LED

Adding a "+5 volt" indicator to the System 80 Driver Board.

Materials needed:

1 Red LED, Jameco # 2125309 or Radio Shack # 276-209 or 1 Green LED, Jameco Electronics # 2125296 (9 cents each) or Radio Shack # 276-022 ($1.69 for a 2 pack)
1 Resistor, 330 ohm quarter watt, Radio Shack # 271-1315

Drill two 1/16" holes spaced about 3mm apart in the board at the location shown in the pictures to the left of the electrolytic capacitor near chip Z1. There should be no traces at that area.
Install the red LED with the flat side facing the trace going to the negative side of the electrolytic capacitor. Bend the LED's flat side lead down to that trace and scrape away some of the green paint at the point you will be soldering it. Now solder that lead to the trace.
Solder one end of the 330 ohm resistor to the other lead of the LED.
The other end of the resistor will now get soldered to the trace that goes to the positive side of the electrolytic capacitor. Again, be sure to scrape some of the green paint off of the trace where the resistor lead will be soldered. You are done.

Now whenever the machine is on, the LED will be lit indicating that the driver board is receiving +5 volts from the CPU board.

Drilled holes on front of board

Drilled holes on the rear of board

Views of the holes drilled for the LED looking from the front and rear of the System 80 driver board.

Wiring of the LED and resistor

Finished installation

Wiring of the resistor and LED. Notice the location of the flat side of the LED. Any color of LED can be used, but red or green is prefered.

Finished installation with LED lit

Completed installation showing the LED lit up indicating +5v power is present on the driver board.

4.4.4.3 Auxilliary Lamp Driver Board LED

Adding a "+5 volt" LED indicator for the MA-234 auxilliary lamp driver board used in Black Hole and Haunted House.

Materials needed:

1 Red or green LED, Jameco Electronics # 2125296 (9 cents each) or Radio Shack # 276-022 ($1.69 for a 2 pack)
1 Resistor, 330 ohms, 1/4 watt

Drill two 1/16" diameter holes about 3mm apart in the locations indicated in the pictures.
Mount LED with the flat side toward the edge of the board.
The lead from the LED's flat side will be soldered to pin 2 (ground) of connector A11P1. Be sure to slide a piece of heat shrink tubing over this lead so it does not accidently short to the other connector pins.
The other lead of the LED will be soldered to one end of the 330 ohm resistor.
The other end of the resistor will be soldered to pin 4 (+5 volts) of connector A11P1.

Whenever the machine is on, the LED should be lit, indicating the auxilliary lamp driver board is receiving power.

Drilled holes on front of board

Drilled holes on rear of board

View of the holes drilled for the LED as viewed from the front and rear of the board.

LED installed on board

Resistor and LED wiring

Wiring of the resistor and LED on the rear of the board. Notice the location of the flat side of the LED.

LED is lit up

Finished installation with LED lit up indicating presence of +5 volts power on the board.

4.4.4.4 Sound/Speech Power Supply Board LED's

The Sound/Speech power supply board will get a total of four LED's! These are to indicate the presence of -12 volts, +12 volts, and +30 volts going out to the actual sound/speech board and also to indicate +24 volts coming in to the power supply board.

Materials needed:

4 Red or green LED's
2 Resistors, 1 k, 1/4 watt
1 Resistor, 2.2k, 1/4 watt
1 Resistor, 3.0 k, 1/4 watt

Drill a total of eight 1/16" holes at the points shown in the pictures near connector A7P1. Lead spacing per LED is about 3mm. Be sure the LED's are not too close to each other to interfere with sitting flat against the board. The +12 and +30 volt LED's will mount with the flat side facing diagonally (7 o'clock) toward the lower left board mounting hole.
The -12 volt LED will have the lead of the round side (anode) soldered to the heavy ground trace of the board. You'll need to scrape some of the green paint off the trace first. The other lead of this LED will be soldered to one end of a 1k resistor. The other end of this resistor will be soldered to the junction point of resistor R2 and the anode of zener diode CR2.
The +24 volt LED will have the lead from the flat side (cathode) of the LED soldered to the heavy ground trace on the board. You'll need to scrape a bit of the green paint off the trace first. The other lead of the LED will be soldered to one end of a 2.2k resistor. The other end of the resistor will be soldered to the trace going to connector A7P1 pin 6 (+24 volts). Again, you'll need to scrape some of the green paint from the trace first.
The +12 volt LED will have the lead from the flat side (cathode) of the LED soldered to the heavy ground trace. You will need to scrape some of the green paint off the trace first. The other lead of the LED will be soldered to one end of a 1k resistor. The other end of this resistor will be soldered to to the trace going to connector A7P1 pin 1 (+12 volts). You will need to scrape some of the green paint off of the trace first.
The +30 volt LED will have the lead of the flat side (cathode) soldered to the heavy ground trace. You will need to scrape off some of the green paint from the trace first. The other lead of the LED will be soldered to one end of a 3 k resistor. The other end of this resistor will be soldered to the trace going to connector A7P1 pin 2 (+30 volts). You will need to scrape some of the green paint from the trace first.
These LED's above are all optional. The board never originally came with anything to indicate presence of voltages. If you only want to install one, that's fine. I chose to install all four so I can see at a glance that all four voltages are present. You don't have to install all four if you don't want to.

In the picture of the finished front of the board the LED's from top to bottom are:

-12v
+24v
+12v
+30v

In the picture of the wiring on the back (foil) side of the board, the resistors top to bottom are:

1K
2.2K
1K
3K

Drilled holes for the LED's on the front of board

Drilled holes for the LED's on the rear of board

Views of the drilled holes for the LED's looking from the front and rear of the board.

+12 and +30 LED's installed on front

-12 and +24 LED's installed on front

All four LED's installed on the front of the board. Notice the location of the flat sides of all the LED's.

Wiring of the resistors on the rear of board

All four LED's installed on front of board

Wiring of the resistors and LED's on the rear of the board. All four LED's installed on front of board.

Finished and all LED's lit

All four LED's installed and lit up indicating the presence of the four different voltages.

4.4.4.5 System 80/80A Power Supply Board LED

The System 80 and System 80A power supply board already has LED's installed to indicate the +5 volts and +12 volts. This project will add an LED to indicate the presence of the +60 volts which is used to operate the score displays.

Materials needed:

1 LED, any color
1 Resistor, 10k, 2 watts

Drill a total of four 1/16" diameter holes at the points indicated between the foil traces in the pictures. Try to keep the holes in a straight line.The LED installs in the top two holes and with the flat (cathode) side facing downward toward the bottom end of the board. The resistor will install in the other remaining two holes which are the also the farthest spaced. Be sure to scrape the paint off of the foil traces at the points shown in the pictures.

Holes drilled viewed from front of board

Holes drilled as viewed from rear of board

Wiring it all up:

The flat (cathode) side of the LED will be soldered to the top end of the 10k 2 watt resistor. Be sure to keep all component leads pressed down as close to the foil traces as possible to prevent shorting to the metal frame when the board is re-assembled to the metal frame. There is very little clearance between the board and the metal frame when everything is re-assembled. The lower end of the resistor will be soldered to the foil trace that goes to connector J3, pins 4 and 5 (ground). The round (anode) side of the LED will be soldered to the foil trace that goes to connector J3 pin 1 (the +60 volts). Put a short piece of heat shrink tubing or sleeving over that lead to prevent it from shorting to the trace it crosses over. Now carefully bend that lead of the LED down onto the correct foil trace as shown in the pictures and solder it. Be sure to label the new LED on the parts side of the board as "+60V". This completes the wiring.

Resistor and LED mounted on board

Parts soldered to foil traces

The new LED should be lit at all times the machine is turned on. It indicates that +60 volts DC is present to operate the score displays. The other display voltage, +42 volts, is derived from the +60 volts.

Finished installation with +60v marking

4.4.4.6 System 80 First Generation "Sounds Only" Sound Board LED's

This board was used in early System 80 games such as Panthera. It operates on three power sources, -12 volts, +12 volts, and +5 volts. The +12 volts is obtained from the bottom panel in the machine. The +5 volts is obtained from the game's power supply board. The -12 volts is generated on this sounds only board by receiving ac power input on J1 pins 3 and 4. You can measure the -12 volts by connecting your volt meter across zener diode CR5 (1N4742A).

MATERIALS NEEDED

2 LED's, any color
1 Resistor, 1k @ 1/4 watt
1 Resistor, 330 ohm @ 1/4 watt
1 Short piece of small diameter heat shrink tubing

Drill two pairs of holes 1/16" diameter and about 3mm apart at the locations as shown in the pictures. Be sure not to drill through any foil traces.
The +12 volt LED will have the flat side (cathode) of the LED soldered to the ground trace coming from pin 6 of connector J1. You'll need to scrape a bit of green paint off of the trace first in order to solder it. The other lead of the LED will be soldered to one end of a 1k @ 1/4 watt resistor. The other end of the resistor will be soldered to pin 1 of connector J1 (the +12 volt source). Be sure to slide a short piece of heat shrink tubing over this end of the resistor before soldering since this lead will pass over a couple of traces. This will prevent the resistor lead from shorting to those traces and causing damage.
The +5 volt LED will have the flat side (cathode) of the LED soldered to the ground trace coming from pin 6 of connector J1. You'll need to scrape a bit of the green paint off of the trace first in order to solder it. The other end of the LED will be soldered to one end of a 330 ohm @ 1/4 watt resistor. The other end of the resistor will be soldered to pin 5 of connector J1 (the +5 volt source).
When finished, be sure to note that the flat sides of both LED's will be facing each other on the front side of the board.

Holes drilled in front of board

Holes drill in rear of board

LED's installed on board with flat sides facing each other

Wiring on solder side of board

4.4.5 F2 Fuse Blows At Power Up on 80A games

If the F2 fuse blows at power up, there is one overlooked problem that is good to check. This could also apply to 80B games, but a different fuse may blow.

On the transformer panel, there is a pair of cement resistors are soldered to a solder tab, which is screwed down to a small square plastic post. Check to make sure that this has not been moved to another screw hole in the metal of the transformer panel. Screwing this line to the metal of the transformer panel ties one of the AC lines to ground. Since this line is shorted/tied to ground, it also has the side effect of making the bridge rectifier test bad, since there is a tab tied to ground when there shouldn't be one. It is likely that the bridge rectifier will test good as soon as the solder tab is moved to the correct place.

Correct place to screw the solder tab (on the square plastic post)
Incorrect place to screw the solder tab. This causes a short.

4.5 MPU boot issues

There are a large and varied number of reasons that a System 80 MPU will fail to boot. Unfortunately, as has been said before, "this is not a Bally world". That is, unlike "classic" Bally and Stern MPUs the System 80 MPU provides absolutely no indication as to why it may have failed to boot.

Debugging a non-booting MPU is somewhat of an art. A few basic steps are listed below.

Ensure your game is providing a solid 5VDC power source
Replace the orange electrolytic cap in the cabinet bottom if still original
Take the board to the bench
Examine the board for Alkaline damage. If present, clean up
Ensure the reset section of the board is working. Pin 40 of the 6502 should begin "low", then after about 1/2 second, transition to "high"
Check the clock signals at the 6502
Check the IRQ signal at the 6502. Ensure it isn't "stuck"
Check the R/W (read/write) signal at the 6502. Again, ensure it isn't stuck
Check the address and data lines to ensure that they are pulsing
Feel each of the masked ROM chips at U2 and U3 as well as the 6532 RIOT chips at U4, U5, and U6. If the IC is too hot to touch, it has probably failed and should be replaced. Note that the 6532 RIOTs run hot normally. If one is noticeably hotter than the other, that may be an indication of failure.
Test each of the 74XX chips in the switch matrix (Z11 - Z15) using this procedure.
If the board has the original masked game ROM(s), replacement with the appropriately sized ROM is advised (generally a 2716).

4.5.1 Power on "Thunk"

Some System 80 games exhibit a "thunk" upon power up. The manifestation of this is the unpredictable lighting of lamps, running of motors, and actuation of coils. Some games will thunk the ball release gate, serving a ball to the shooter lane. Others will thunk a motor or flasher. The symptom is unpredictable in that swapping either the driver or the MPU board might change the behavior.

The "thunk" can be suppressed via a tedious process, detailed here by John Robertson.

Since the "thunk" is really just a minor irritation, most owners don't think the juice is worth the squeeze.

4.5.2 Erratic Boot Issues with Later 80B Games (Hot Shots, Bad Girls, and Big House)

Some erratic boot issues have been observed with the following games: Hot Shots, Bad Girls, and Big House, however, the list of games may be more extensive. The issues included are a locked on display with garbage characters shown, no display illuminating at all, sound board not booting (LED stuck on), locked on lamps, no controlled lamps, locked on coils, etc. The source of the problem is caused by the fluorescent tube starter located in the backbox. It is unknown why exactly this anomaly occurs. Removal of the fluorescent bulb or starter will resolve the booting issues. Unfortunately, this is the only resolution known at this time.

4.5.3 Battery Leakage and Corrosion

Like most any other pinball machine manufactured, Gottlieb® uses batteries to supply power to the non-volatile RAM memory. Certain game settings, high score thresholds (including high score to date), audit information, and bookkeeping information are all options which are saved when the game is powered off. And unless some kind soul, who worked on your machine before, either removed the battery and mounted it remotely away from circuit boards, or just plain removed the battery, there will be some variety of a 3.6v Nickel Cadmium (NiCad) rechargeable battery soldered onto your CPU board.

So, what's so bad about having a battery on the CPU board? Well, nothing really, unless it's forgotten, and in most cases, it is. While you let your pinball machine sit unplayed for weeks, months, or even years at a time, the battery remains perched on the circuit board like a ticking time bomb. I'm not saying the battery is going to blow up, although some replacement non-rechargeable batteries could overheat and / or explode if not correctly installed. The battery is like a ticking time bomb, because it is a threat to the overall health of the electronic components, traces, and connectors attached to your CPU board.

Now that I have your attention regarding the whole battery thing, let's talk about the battery, and what happens. . .WHEN GOOD BATTERIES GO BAD. It's not that some batteries were born on the wrong side of the tracks or anything. Any good battery can go bad without much warning. It takes time, but eventually you will find that your battery has crossed over to the "dark side". That particular time is typically when you turn your game on, the lights come on, and that's it. The displays don't light up. The start up sounds don't resonant. And, the silver ball stays in its comfy little home. Nada...nothing...no signs of anything resembling a fun game of pinball. UH-OH! So what happened? The pinball machine worked fine the last time you played it.

Well, while you were out having a good time and enjoying life, the poor, aged, neglected battery decided to wreak havoc all over the reset section, clock section, or possibly more regions on your CPU board. The CPU battery spewing its guts all over the place is akin to the batteries in the flashlight you haven't turned on since the last power outage a year or two ago. You go to turn on the flashlight when you need it most, and find out there's something wrong. So being the curious type, you open the flashlight's battery compartment only to find some kind of blue-green funk leaking all over, or the batteries now look like they need a shave. The resolution to the flashlight scenario is pretty simple. Throw it away, and buy a new one. Your CPU board problem can be resolved the same way, except it will be a lot more costly, and is not recommended to just pitch it in the trash. If the battery damage to the CPU board is not overly extensive, attempt to repair it.

Typical Battery Found on a System 80 CPU Board

It's unfortunate, but every battery has a life expectancy. The only silver lining is that some of the Ni-Cad batteries installed on Gottlieb® CPU boards can last longer than others. Probably the worst culprit of board destruction is the Data Sentry pack, and its associated knock-offs. This battery comes in a black rectangular plastic package.

Typical Battery Found on a System 80A / 80B CPU Board

Another battery pack style which looks very similar to the NiCad battery packs found in "old school" cordless phones. It is actually three small NiCad cells wrapped separately in an orange poly material, which is wrapped in a outer white poly material. These don't leak nearly as badly, but they still have the potential to fail.

Typical NiCad Battery Which was Replaced

The final common battery style is a what looks like an AA battery on steroids. This style is a fraction longer and fatter than an AA battery's physical form, and has two soldered leads on either end. If you find one of these, it means the battery was previously replaced. The good news is that this battery is newer than the original. However, the same results of battery seepage can occur. The only benefit of this type of battery is that it can be carefully cut (in most cases) from the board without removing the board from your game. This is a plus if no battery damage has occurred.

NiCad Battery Damage to a System 80A CPU Board
(Note: This is considered very mild damage!)

Damage from the battery may also occur on the back side of the board, especially on the edge connection fingers

So what happens if you don't heed the above warnings, and the battery is allowed to remain on the board? Plain and simple - THE BATTERY WILL LEAK! It's only a matter of time. Equally, the path of destruction is uncertain. Batteries don't just leak - they release caustic, alkaline fumes. These fumes attack wherever there is copper, even tinned or soldered copper. The end results are:

solder joints which become green or gray and crusty as opposed to a shiny silver
connectors which are also now green / gray or potentially broken
solder mask, the green covering the electronic traces, on the circuit board has either flaked off or is partially delaminating (lifting)
insulated wire becomes less flexible and brittle
sometimes the alkaline "cloud" in the game's backbox causes every board in the head to be affected.

Electronic components, related solder joints, circuit board traces, connectors, and even insulated wire will become unreliable and/or fail. In all cases, the affected components are less conductive.

If battery damage has occurred, the related parts must now be replaced. Attempting to remove soldered through components on the circuit board is now even more of a task. The green / gray dull solder does not transfer heat well. Battery damaged solder does not flow like clean solder. Also, crimped connectors are more difficult to remove from their housings, and have a tendency to break before they can be successfully pulled out.

After all the effected electronic components are removed, the board must be treated. This process starts by sanding the traces and solder pads until shiny copper is exposed. It is worth mentioning that a battery damaged board can be treated by bead blasting instead of sanding, however, most people do not have access to such a machine. After the copper areas of the board have been either sanded or bead blasted, an acidic bath of 50% vinegar and 50% (preferably distilled) water is applied to the board. A small brush like a toothbrush can be used to scrub the board's area. The purpose of introducing an acid to the effected area is to neutralize what the battery has left behind. The liquid and fumes from the battery are actually a base, not an acid. Next, rinse the area of the board with water. Once the board is clean, isopropyl alcohol (the higher the alcohol percentage the better) is applied to the same area to rinse away the acid bath, and hopefully dissipate any remaining water. Finally, the board is either blown dry or air dried. This may be a given, but DO NOT ATTEMPT TO APPLY POWER TO THE BOARD IF IT IS STILL WET! Most liquids are conductive to some extent. After the previous steps are performed, the task of installing the new components begins. If any traces or solder pads were damaged, see the Repairing Traces portion of this Wiki guide on to to fix them.

The point I'm trying to ultimately make is this...regardless of age, shape, or form, remove the battery from the CPU board, as soon as it realized that there is a battery on the board. If not, the board can be damaged, nonfunctional, and become more difficult or even impossible to repair.

4.5.4 Relocating the battery from the MPU board

The first thing that should be done to any System 80 MPU is remove the rechargeable NiCad battery from the MPU board. All batteries leak. They are like ticking bombs. It is merely a matter of when they will leak and possibly damage (sometimes irreplaceable) boards.

There are at least five methods of relocating and/or replacing the battery on a System 80/80A/80B MPU.

Remove the battery completely without replacing it. The 5101 memory will not store information from power-on to power-on and therefore, high scores, replay levels, and credits will be lost.

Remote Battery

Mount a remote battery pack that uses standard AA batteries (x3) to protect your board. A blocking diode must be installed (1N4004, although a 1N4001 will work just as well) to prevent the game circuitry from attempting to charge the batteries. Install the blocking diode in series with the positive lead of the battery pack, with the band oriented toward the MPU.

Here a 5.5V, 1F Super Cap is used to retain 5101 memory for up to 30 days

Replace the battery with a 1F 5.5V "SuperCap". The capacitor will never leak, will charge during power-on cycles, and will retain 5101 memory for about 30 days. If you've sanded traces as was done in the picture, use a non-conductive material to cover the trace under the cap to ensure that the negative side of the cap doesn't short a trace (such as clear nail polish, green overcoat pen, electrical tape, or fishpaper). Cut the tape in a circular shape and poke the capacitor leads through it so it can't fall off in the future. (Electric tape is notorious for slipping.) An alternate solution would be get a piece of fishpaper insulator, cut that into a circle and poke holes in it for the capacitor leads.

Alternate method for installing a memory cap

Tying the negative lead of the memory cap to the negative pad on the MPU board

The memory cap can also be installed in the two leftmost holes, where the Ni-Cad battery formerly resided. The negative lead of the memory cap will then have to be tied to the negative (ground) through hole of the MPU.

Remotely mount a replacement NiCad battery in a location that, should it leak, won't damage valuable circuit boards.

a CR2032 Lithium "Button Cell" Battery Installed

A 1N4004 Blocking Diode Installed "inline" with the Positive Connection

Replace the original NiCad battery with a Lithium button cell CR2032 battery and holder. The holes for the original battery can be repurposed to connect the button cell holder and to add the necessary blocking diode in the positive side of the circuit.

4.5.5 Using a Reset Generator for the CPU Reset Section

If you find that the battery has leaked, alkaline damage can be cleaned up, traces repaired, and new components installed with kits available from several sources, including Great Plains Electronics.

An alternative to replacing a great many of the components is to use the Dallis/Maxim DS1811 reset generator. The DS1811-10 has a typical trip point of 4.35VDC. You may also use the Microchip Technology equivalent, part number MCP130-460DI/TO, available from Great Plains Electronics. Remove all reset section components, clean up residual alkaline damage, add four jumpers, and install the reset generator as pictured below.

After jumpers and the reset generator are added, make certain there is continuity between the three legs of the reset generator and the appropriate locations on the circuit board. Below is a list of the reset generator legs and the board locations. Pin 1 of the reset generator is the left leg, when the flat side of the unit is facing towards the user.

Pin 1 of reset generator to pin 2 of Z4
Pin 2 of reset generator to +5VDC line (lower leg of C2)
Pin 3 of reset generator to ground (upper leg of C2)

Using the Dallas Maxim 1811 Reset Generator
A System 80 MPU with alkaline damage repaired/cleaned. Reset circuitry replaced with the much simpler Dallas Maxim 1811
Illustrated picture of components to remove, keep, and jumpers to add.
The same image, but with indications of jumper locations (yellow dots) and where to install the Dallas Maxim 1811, flat side facing the bottom of the board.
Note: View at full resolution

MCP120 reset generator installed with 4.7K pullup resistor

If a reset generator with an internal pullup resistor (MCP130 series) is not available, an MCP120 reset generator can be installed. However, an external resistor must be installed between the reset and +5v. The easiest location to install the resistor is between the through hole where the top leg of Q4 was, and through hole where the bottom leg of Q2 was. In the adjacent image, an MCP120-460DI/TO is installed with the 4.7K 1/4 watt external pullup resistor highlighted.

When installing this type of reset generator, remove all of the components, and add all of the jumpers related to the installation of an MCP130-460DI/TO reset generator. Adding the external pullup resistor is the only additional step. Failure to add the pullup resistor will result in the reset signal not going high, and the board will not boot.

4.5.6 Slam Switch Modification

In order to test the CPU board on the test bench, a modification must be made to the CPU board to make the CPU think that the slam switch is closed. If the CPU thinks that the slam switch is not closed, the CPU will not complete the boot process, instead booting into a mode where the displays flicker all zeros at a very rapid rate (System 80 and 80A). See the image here for a depiction of what you'll see. When the slam switch is open on a System 80B game, (the appropriate games where the slam switch is supposed to be closed), an "OPEN SLAM SWITCH" message will be shown on the display.

Gottlieb® designed the slam switch as a normally closed switch. That is, the switch must be closed for the machine to operate normally. When a brute kicks the machine, the slam switch will open from the inertial force on the weight attached to the switch, and the slam switch will open. Since the CPU is on the bench, we need a way to have this switch closed at all times to properly test the board.

Additionally, slam switches themselves fail. It's a good idea to implement this change as a preemptive fix for slam switch failures.

Slam Switch Mod

The slam switch can effectively be permanently closed by making a small solder bridge across two traces to the right of Z26 (which is on the lower right side of the CPU board). To permanently close the switch, remove the solder mask by scraping with a sharp knife or screwdriver. Create the solder bridge between the two now bare traces. This change will connect pin 13 of Z26 to ground, permanently closing the switch.

Alternative Slam Switch Mod

An alternate method of achieving the same results is to solder a clipped resistor leg across the bottom of capacitor (C30) and resistor (R20), both immediately to the left of Z26.

Keep in mind that the last 4 Gottlieb® System 80B games were released with normally open slam switches. Do not perform the slam switch modification on these games. This includes the following games:

Bad Girls
Big House
Hot Shots
Bonebusters, Inc.

Regardless of what platform the game is based on, there is only one slam switch used in a System 80/80A/80B game. It is the weighted switch located on the coin door. There is some confusion that the ball roll tilt and weighted tilt switch on the playfield are slam switches. They are not. These switches along with the pendulum tilt are all tilt switches.

4.5.7 System 80B Daughter Card Solder Joints

A typical System 80B CPU Board, showing the location of the "daughter card".

A closeup of Gottlieb® System 80B Daughter Card Male Header Pins with fractured solder joints. This board was cleanly removed from the CPU with great care.

System 80B game CPUs feature a "daughter card" to accommodate the 2764 game ROM as shown in the picture on the left. The daughter card connects to the CPU board at the location occupied by U3 in System 80/80A CPUs, via a 24 pin male header. That connection is a two-sided solder joint that can fail. As can be seen in the picture at right, these same header pins connect to the daughter card via a single sided solder joint. Since the daughter card is cantilevered over both the former location of U2 and U3, pressing on this board over time commonly results in fractured solder joints (as seen, right) at the single sided joint and sometimes at the two-sided joint.

Typical symptoms of fractured solder joints at this location are failure to boot, random resets, and random lockups. Sometimes pressing on the daughter card will "fix" the issue temporarily. This is a sure indication of fractured solder joints.

Correction of this issue is easier said than done. And, if you do not possess the tools, skills, and experience to desolder the daughter card, this task is best left to a professional pinball circuit board repairman. Desoldering the 24 pin male header pins from the delicate solder pads without damaging the pads or pulling traces is non-trivial.

Replacement daughter card engineered by Great Plains Electronics. Image used with permission from Great Plains Electronics.

A recommended replacement for the daughter card is the re-engineered daughter card from Great Plains Electronics, which can be found at: http://www.greatplainselectronics.com/proddetail.asp?prod=140-101. This card is designed to be fitted into both the U2 and U3 location, eliminating the problem of board flex and cracked solder joints. It is recommended to fit the replacement card into quality machine pin sockets, then fit the entire assembly into the CPU board for soldering. The card is also designed with redundant traces for all but a few of the signals as almost all signals are present at both the U2 and the U3 location.

4.5.8 Connecting a logic probe to the MPU

A great place to source power for your logic probe while diagnosing the board is across the filter capacitor in the vicinity of connector J1. Connect the black lead of your logic probe to the negative lead of the capacitor for ground. Connect the red lead of your logic probe to the positive lead of the capacitor for 5V. The red lead can also connect to E1, the vertically-aligned 5V jumper wire, below the 6502 chip. Take care to ensure that the clips don't short to adjacent components.

4.5.9 Using a PC Power Supply For Bench Testing

Future Update****This section works for now, but we can generalize bench power supply construction here: Building a flexible power supply for bench testing PCBs

The MPU board is much easier to work on if it is removed from the backbox and placed on the test bench. An AT-style PC power supply can be used to power the MPU board on the bench.

Obtain an old PC power supply. If you don't have an old computer laying around, head on off to the thrift store and pick one up. Remove the power supply from the case by unscrewing the appropriate screws. Be careful not to unscrew the power supply case itself.

Power Supply

Clip one of the connectors from the power supply wire bundle and clearly mark on the power supply box the value of each of the colored wires from the power supply. Typically, the yellow wire is 12V, red is 5V, and the black is ground. Strip insulation from the end of the red wire and the black wire as the System 80 MPU requires only 5V and ground to boot. Use alligator clips to connect 5v and ground to the appropriate J1 connection. I use larger alligator clips to make the connection easier.

J1 Connector

Mark connector J1 where the positive and negative (common) connection is for the five volts from the computer power supply. The ground connection is on the top of the connector, the 5V connection is on the bottom. The image shows A1J1 with the markings. I took the picture with the board still mounted in the machine. Connect the 5v supply with alligator clips to the positive connector on J1 and the black wire (ground) to the negative connector of J1. That's it! you're good to go!

4.5.10 List of Acceptable TTL Chip Substitutes on a System 80 CPU Board

Several years ago, Ed from GPE replied to a System 80 chip substitution question on rec.games.pinball. The original reply is located here. In case RGP is no longer archived at some point, the same info from that reply is summarized below.

"Most of the parts can be freely substituted. But many cannot. The clock oscillator circuit (Z3) is one example of a part that cannot be subbed. Also, some IC's have hefty loads and cannot be subbed (some of the 7404's and a 7432). The 7474 in question on this board can be freely subbed with a 74LS74 or a 74HCT74. I went through all the standard logic devices on the Gottlieb System 80 MPU. Based on loading and output characteristics, this is what I get as valid subs for the System 80 MPU. Of course, substituting some of the parts will ripple through and allow others to be substituted as well - but this can get quite convoluted."

Chip Designation	Part #	Substitute (Y/N)	Acceptable Substitutes
Z1	4528	N
Z2	7474	Y	74LS74 and 74HCT74
Z3	7404	N
Z4	4081	N
Z7	74LS04	Y	74HCT04
Z8	7402	Y	74LS02 and 74HCT02
Z9	7400	Y	74LS00 and 74HCT00
Z10	74LS05	N
Z11	7404	N
Z12	7404	N
Z13	7400	Y	74LS00 and 74HCT00
Z14	7400	Y	74LS00 and 74HCT00
Z15	7432	Y	74F32 and 74S32
Z16	7404	N	*See note below
Z17	7404	Y	74LS04 and 74HCT04
Z18	74175	Y	74LS175 and 74HCT175
Z19	7448	Y	74LS48
Z20	74175	Y	74LS175 and 74HCT175
Z21	7448	Y	74LS48
Z22	74175	Y	74LS175 and 74HCT175
Z23	7448	Y	74LS48
Z24	7404	Y	74LS04 and 74HCT04
Z25	74154	Y	74LS154 and 74HCT154
Z26	7404	Y	74LS04 and 74HCT04
Z27	7404	Y	74LS04 and 74HCT04
Z28	74LS139	Y	74HCT139
Z29	7416	Y	7406
Z30	7416	Y	7406
Z31	7408	Y	74LS08 and 74HCT08
Z32	7417	Y	7407
Z33	74154	Y	74LS154 and 74HCT154
Z34*	7404	Y	74LS04 and 74HCT04
Z35	7404	Y	74LS04 and 74HCT04
Z36	4069	N

*Note: Had issues with a 74LS04 installed at Z34 in a Haunted House. The side effects were the lower playfield VUK would fire and partially lock on when the lower playfield 5-bank drop target would reset. Also, the 5-bank drop target would continuously tried to reset when the lower playfield VUK switch was closed. The issue acted as if there was a switch matrix issue, but there wasn't.

Note: If Z18, 20, and 22 are 74175, do not substitute. If Z18, 20, and 22 are 74LS175 or 74HCT175, acceptable subs are 74LS04 and 74HCT04

4.5.11 Replacing the quartz crystal with a TTL Oscillator

Alkaline corrosion may damage the board in such a way that it's advantageous to replace the original quartz crystal oscillator with a TTL oscillator.

Clock section of the system 80 MPU

The original crystal, Z3, and a few resistors may be replaced with a 900 kHz TTL Oscillator that is packaged like this 16Mhz version.

The System 80 clock signal is produced by a 3.57Mhz crystal, a few resistors, and Z3 (a 7404). Z2 divides the clock by 4, resulting in a clock signal of approximately 900 KHz, which is provided at pin 9 of Z2.

If you cannot find a 900 KHz TTL oscillator (I couldn’t) you can also use the 1MHz variant, and tune your pin up a little bit. ;-) Game play shouldn't be impacted, as long as the game doesn't have a timer related feature, like Timeline. Even games like Timeline will be minimally impacted.

The original clock section as found on every System 80, 80A and 80B MPU

The clock section after installing a TTL oscillator.

To accomplish this mod, remove the following parts

Y1 (Crystal)
Z2 (TTL 7474)
R3, R4 und R5 ( the three resistors above Z2).

Z3 is still needed for other functions. Leave it in place. Now place the oscillator in the Z2 position, with the ‘dot’ in the upper left corner (Pin 1). Because we need the clock signal at pin 9, jumper from pin 8 to pin 9 at the original Z2 position.

4.6 Game Resets

System 80 games sometimes exhibit "resets", especially when high power coils fire. Assuming you've updated the power supply grounds and reflowed or replaced the header pins on the Power Supply, there are a few typical causes for System 80 resets.

Gottlieb® System 80A Filtering Capacitors

The 12VDC filter capacitor in the cabinet bottom which, if still original, should always be replaced. Originally, this was a 6800uf/25V capacitor. Replace with a 6800uf to 12,000uf/25V cap such as this one from Great Plains Electronics. The filtered 12VDC is regulated down to 5VDC on the power supply board. Note that some games have two of these capacitors (as shown). Note: purchase a VR3A capacitor clamp from Great Plains Electronics when replacing the large capacitor for a clean looking job.
The bridge rectifier that originates the 12VDC
Missing, broken, or failed coil diodes
Poor 5VDC power connections between the power supply and the MPU. The female connector on the MPU connects 5VDC to the MPU via molex crimp-on pins and a "double-wide" edge connector pad. Ground is connected in the same way. But you've done the ground mods, right?

4.6.1 System 80A / 80B Resets

A failed or failing reset board can cause resets. The reset board may cause problems all of the time, or just when the game is under stress, like multiball.

To see if the reset board is the problem, disconnect it. If disconnecting the reset board resolves the issue, there are two fixes:

Replace the large caps (C3 and C4). These have dried out over the years and screw up the timing of these boards.
Leave the reset board disconnected—if someone will always be in the general vicinity of the game to turn it off should the CPU lock up.

When first trying to get a System 80A or System 80B game to boot properly, it is best to disconnect the reset board until the game is working.

Electrolytic capacitors C3 and C4 are both 470 uf @ 16 volts. C1 is a 47 uf @ 16 volts. Be careful when unsoldering these capacitors as the foil traces are very delicate. The connector pins also develop bad solder joints so it is wise to resolder it.

4.7 Updating a dual game PROM MPU (1st generation) to a single game PROM configuration (2nd generation)

As noted earlier, the first five system 80 games used both sockets at PROM1 and PROM2, populating them with 512 byte masked ROMs. Should one of these ROMs fail, you may be able to find a replacement, but they are becoming more pricey, more difficult to find, and are still prone to failure as they age.

A more flexible solution would be to update the MPU to use a single 2716 UVEPROM at the PROM1 socket.

Modifications must be made to both the solder side and the component side of the board. See the pictures below.

Component side modification:

Cut the trace that extends from the left of Z10 between pins 6 and 7. A Dremel with a "ball shaped" cutter bit works beautifully for this. In the second picture below, the cut has already been made. I've filled the cut hole with black Sharpie! to better show the location of the cut.

Solder side modifications:

Cut the traces leading to PROM1 socket, pins 19 and 21. Again, the cuts have been highlighted with black Sharpie!
Jumper from the PROM1 socket, pin 19, to the PROM2 socket, pin 21 (connects A10)
Jumper from the PROM1 socket, pin 21, to the PROM2 socket, pin 24 (connects +5V to Vpp)
Jumper from the PROM1 socket, pin 22, to the PROM2 socket, pin 18 (connects A9)
Jumper from Z10, pin 13 to the via just below and to the right of Z9 (as you view the back of the board)

Your MPU board is now configured for any System 80 game. All that remains is to acquire a 2716 EPROM containing the game's code. If you have the original ROM images, the DOS command to combine them is shown below. Modify as appropriate to match the file names you have.

copy /b prom1.bin + prom2.bin combined.716

The MPU may also be used in a System 80A game if U2/U3 are updated, and in a System 80B game if considerably more mods are made which frankly, just aren't worth it.

System 80 1st Generation to 2nd Generation Board Updates
Dremel Tool with "Ball Cutter"
Cut in trace extending Left from Z10
PROM2-to-PROM1 Socket Cuts and Jumpers
Jumper connecting Z10, pin 13 to a "via"

4.8 Using a 2732 at the PROM2 position in a System 80B MPU

4.8.1 ...in games that "normally" use a 2716

It is easy to use a 2732 at position PROM2 with an MPU jumpered to use a 2732 for a game that normally populates that position with a 2716. Simply "double-up" the 2716 ROM image, and burn it into a 2732.

The DOS command to accomplish this is ... copy /b image.2716 + image.2716 image.2732

4.8.2 ...using an MA-1133 or MA-774 MPU in games that REQUIRE a 2732

Some System 80B games require 4K of code space at PROM2, which dictates a 2732 EPROM. An MPU built to use a 2716 EPROM at PROM2 can be modified to work, as is discussed below.

The CPU schematics of game manuals, such as "Bad Girls" and "Big House", state that E3 is directly connected to AB15 (address bus 15). However, there is no mention of the factory modification (outlined below) performed on CPU boards stamped MA-1133. Equally, should the user have an MA-774 CPU board, (used in games starting with Chicago Cubs Triple Play and ending with Excalibur), this modification can be performed to use the board in the following games.

Bad Girls
Big House
Hot Shots
Bone Busters, Inc.

PROM2 is actually located at the socket marked "PROM 1" on the PCB. The area on the board marked "PROM 2", which has solder pads but no socket, is a legacy carried over from the first generation System 80 CPU board.

The following information was taken from a service bulletin located in the back of the 1992 Gottlieb® parts catalog. This modification makes AB15 available to PROM2, allowing the use of a 2732 EPROM at this position.

This procedure can be used in reverse if you have an MA-1133 board and you need to use a 2716 at position PROM2.

Procedure:

If jumper E4 is installed, remove it. You will find the top of the E4 jumper located immediately to the right of the socket marked "PROM 1".
Install a jumper at E3. This connects the pad marked E3 to the dual pad marked E4.
On the solder side of the board, follow the trace from the pad marked E3 Southeast 1/8 inch, then South about 1/2 inch to a via.
Find this via on the component side of the board. It will extend to the left to another via.
Cut the trace between the two vias.
On the solder side of the board, install a jumper from TC1, pin 35 to the right solder pad of the via which was just cut.
All other jumpers should remain installed.

System 80B PROM 2 2732 Update
E4 removed, E3 installed, and trace cut below E3
Jumper from TC1 pin 35 to E3

4.9 Solenoid problems

4.9.1 The Driver Board

The System 80A / 80B Driver Board

The System 80 Driver board is responsible for all controlled lamps, relays, and all solenoids in the game. The CPU controls the driver board operation via a simple interface between A1J4 on the CPU and A3J1 on the driver board. Although the driver board went through some minor changes over the years, the same board can be adapted for all of the System 80 platforms.

To control the games' total of 52 lamp circuits, the interface provides "device select" signals for each of the 74175s (Quad-D Flip-Flops) on the driver board, and 4 "bits" of data that is loaded (or "clocked") into a particular 74175 via the aforementioned device selects. Each lamp is driven discretely by a particular output of a particular 74175, which in turn drives an MPS-A13 or MPS-U45 transistor, (NDS-U45 transistors were used in place of MPS-U45s in some cases).

It is noteworthy that there are some dedicated transistors, which control specific game relay coils across the System 80 / 80A platforms. Relays such as the game over, tilt, and coin lockout relays are controlled by Q1, Q2, and Q3 respectively. The tilt and game over relays use the same designation for the System 80B platform, however, the use of a coin lockout relay was abandoned by this time.

Driver Board with Coin Counter Transistors Highlighted

To control the games' solenoids circuits, the driver board uses signals directly from the CPU to enable transistors on the driver board which turn on up to 9 solenoids. For solenoid control, the driver board uses MPS-U45, 2N3055, and 2N6043 transistors. Starting and ending with the System 80 platform, (games from Spiderman to Haunted House), three transistors were reserved to drive optional mechanical coin counters. These mechanical coin counter solenoids and associated transistors are: solenoid 3 (Q54), 4 (Q55), and 7 (Q56). Starting with the System 80A platform, (Devil's Dare), these transistors were no longer reserved for coin counters, and were used for other functions. Equally, the 3 diodes associated with these 3 transistors were changed to 3 zero ohm jumpers.

The games' sound signals (S1, S2, S4, S8) also pass through the driver board at Z13, a 7404 Hex Inverter. See below for S16 and S32.

4.9.2 Repurposed Driver Board Circuits

A Typical Remote Transistor Mounted Under the Playfield

Since quite a few System 80 games employ more than 9 solenoids, and since the original driver board design will drive a maximum of 9 solenoids, Gottlieb® repurposed some lamp outputs to drive "under-playfield transistors" which drive additional solenoids.

A Typical Transistor Driver Board

Once playfields became littered with numerous "under-playfield transistors", Gottlieb® opted to merge some of these transistors into a transistor driver board. The transistor driver board started to appear on Gottlieb® games nearly midway through the System 80B platform, with the game Victory.

The sound S16 and S32 signals are also repurposed lamp outputs. For instance, Haunted House and Black Hole both repurpose L9 to S16. Robo-War repurposes lamp 4 to S16. Note that S16 is not consistently implemented across the System 80 family. Note also that references to the usage of S32 are difficult to find.

Nuts / Screws Which Secure the 2N3055s Collector to Drive Line

Make certain to inspect and tighten the screws which secure the 2N3055 TO-3 transistors to the driver board. Specifically, the screws / nuts as marked in the pic. They tie the transistor cases (collector) to the respective solenoid drive lines. If these cases are not secured, the transistors will not function as intended.

4.9.3 Remote Mounted Transistors

Under Playfield Transistor, with Emitter, Base, and Collector Labeled

System 80 games have just nine dedicated solenoid circuits on the driver board. To overcome this threshold, Gottlieb® added step-up transistors mounted to brackets underneath the playfield. Early on, a lamp driven transistor is used to "pre-drive" the larger solenoid transistor. However, there are instances where a solenoid transistor is used to pre-drive a remoted mounted transistor. Eventually, Premier got smart and started mounting up to three transistors to PCBs, but only on later 80B games (Arena and newer). These PCBs were mounted behind the game's display board or on the side wall of the lower cabinet. In some cases, primarily 80B games, the game's diagnostics will drive these transistors during test.

On System 80 games, under playfield transistors were originally 2N5875s or 2N5879s. The failure rate of the original transistors tends to be rather high. 30 years can be a long time for a transistor of that technology. Should one fail, it can be replaced with its beefier siblings—2N5883 or 2N5884. An MJE2955 will work also.

System 80B games used a mix of 2N5879 transistors and MJ2955 transistors for driving flash lamps and coils.

A ground wire is always connected to the tip of the transistor (collector) and leads to ground. On System 80 games, this wire is green/yellow (Gottlieb® wire color code 54). On 80B games, ground wires are plain white with no trace (Gottlieb® wire color code 9).
The "emitter" should be connected to the lug of the coil that has the non-banded side of the diode facing it (black-blue-blue in this picture).
The "base" should be connected to the drive wire from the driver board (brown-red-red in this picture).

Solenoids which use a remote mounted transistor cannot be enabled by temporarily grounding the pre-drive transistor's tab to ground. This test is typically performed to check the integrity of the wiring from the drive transistor to the solenoid. This test however does not confirm if the drive transistor is good or not.

4.9.3.1 Remote Mounted Transistor Update

Gottlieb® Remote Transistor Circuit

During the run of Black Hole, Gottlieb® released a service bulletin recommending that the existing 10Kohm pullup resistor be changed to a 4.7Kohm resistor when changing from a 2N5875 to a 2N5879 or equivalent. Affected Black Hole games were marked serial number 6271 to 9160. However, there were several games prior to and after Black Hole, where a pullup resistor was never installed. It is highly recommended to add this resistor. This upgrade will decrease the chances of particular solenoids, which use a remote mounted transistor, from locking on when the game is powered up. <br=clear all>

Gottlieb® Remote Transistor Circuit w/ Pull Up Resistor Upgrade

The 4.7K resistor is soldered to the base of the remote mounted transistor, and then tied to the 24vdc solenoid bus.

4.9.4 Correcting Solenoid Problems

Gottlieb's implementation to control solenoids was, at a top level, identical to every other game manufacturer. Power is present at the coil, sometimes routed through the "Game Over" relay. A path to ground is switched on by a transistor which is enabled by upstream TTL logic. For the System 80 platform, this TTL logic is located on the MPU board. Signals are conveyed from the MPU to the driver board via the A1J4-to-A3J1 wire harness. These signals directly switch a path to ground on for one of the 9 designed-in solenoid circuits.

As noted above, to accommodate game implementations needing more than 9 solenoids, Gottlieb repurposed some of the lamp driver circuits, driving 2N5875 (generally) transistors either screwed to the bottom of the playfield, or located on dedicated transistor boards.

Solenoid problems can be divided into two simple categories, solenoids that do not engage and solenoids that are "locked on". Correcting these two situations is discussed below.

4.9.4.1 Solenoid Doesn't Turn On

First, note that not all solenoids are always tested by the built in solenoid diagnostics. The first example of this is the coin counter solenoids (numbered 3, 4, and 7). To avoid artificially incrementing the coin drop counters, these coils are not pulsed. Other coils may be pulsed during lamp test. This is most often the case with System 80B games, using repurposed lamp driver circuits.

Problem Determination Procedure

With the game turned on and a game started, use a DMM to measure for coil power at the coil lug (generally either 24 or 38VDC). Power should be present at both lugs of the coil. If present on the coil lug attached to the banded side of the diode and not present at the coil lug attached to the non-banded side of the diode, then the coil winding or it's attachment to one of the coil lugs is open.
Next, test paths to ground for the coil. Attach a wire with clip leads to game ground. Any green wire with yellow stripe will work fine. First, BRIEFLY touch the other end of the wire to the non-banded side of the coil lug. The coil should pull in. If it does not, then either the coil winding is open or the coil wire is not securely attached to the coil lug. Next, identify the driver board transistor that switches ground for the solenoid in question. BRIEFLY touch the other end of the wire to the tab (MPS-U45 or 2N6043) or case (2N3055) of that transistor. The solenoid should pull in. If it does, this proves the path from the coil to the transistor, but doesn't prove anything about the transistor. If it doesn't pull in, then there is a break in continuity between the transistor and the coil. Likely suspects are the connector pins, the IDC connection of the wire to the connector, and the actual wire itself.
At this point in the process, we know that the coil has power, and the path to ground via the transistor is valid. The next step is to test the actual transistor.

Testing an MPS-U45 (or NDS-U45) or an MPS-A13 transistor

Set the DMM to diode check
Place the black lead on the center leg
Place the red lead on each of the flanking legs in turn
A measurement between .5 and .7 should be displayed for one of the flanking legs.
A measurement between 1.2 and 1.4 should be displayed for the other flanking leg.
Readings outside of these ranges (generally dead shorts, sometimes opens) indicate the part has failed.

Testing a 2N6043 transistor

Set the DMM to diode check
Place the black lead on the center leg
Place the red lead on each of the flanking legs in turn
A measurement between .5 and .7 should be displayed for each flanking leg
Readings outside of this range (generally dead shorts) indicate the part has failed.

Emitter, Base, and Collector parts of a TO-3 form transistor, like the 2N3055. Note that the emitter and the base pins are closer to one end of the TO-3 case.

Testing a 2N3055 transistor

Set the DMM to diode check.
Place the black lead on the metal casing of the transistor.
Place the red lead on each of the legs in turn.
A measurement between .5 and .7 should be displayed for one of the legs.
A measurement of "null" (no reading) should be displayed for the other leg.
Place the red lead on the "base" lead of the transistor.
Place the black lead on the other lead of the transistor (the "emitter").
A measurement between .5 and .7 should be displayed.
Place the black lead on the case of the transistor (the "collector").
A measurement between .5 and .7 should be displayed.
Readings outside of these ranges (generally dead shorts, sometimes opens) indicate the part has failed.

Test the output signal from the MPU at the driver board. This test completes the test of the driver board circuitry. If this test doesn't identify a problem, then the problem must lie upstream with the inter-board harness or on the MPU board itself. With a logic probe, and the game in solenoid test, probe the following points for solenoids 1 through 9. 1 - non-banded side of CR6, 2 - R53, 3 - non-banded side of CR2, 4 - non-banded side of CR4, 5 - R56, 6 - R59, 7 - non-banded side of CR4, 8 non-banded side of CR1, 9 - non-banded side of CR5. With the game in Solenoid test, each solenoid should be pulsed in order, with the pulse easily detectable with a logic probe on the appropriate spot. Note that the coin counter solenoids will not be pulsed in test, and games that don't use every solenoid won't pulse unused solenoid circuits. Consult the manual for solenoid numbering for a particular game.
Test the output signal of the TTL circuitry on the MPU. Solenoids 1 through 9 are all enabled via signals from Z29 and Z30 on the MPU board. Both ICs are 7416s. Z29 pins 2, 4, 10, and 12 drive solenoids 1 through 4 respectively. Z30 pins 2, 4, 6, 10 and 12 drive solenoids 5, 6, 8, 9, and 7 respectively (note the order is not strictly ascending). If the output signal on the MPU is present, but the signal is not present on the driver board, then the problem is probably the inter-board connector.

4.9.4.2 Solenoid Locked On

A solenoid (or flasher) that is "locked on" is caused by coil power having a continuous path to ground. Remember, coil power is always present at the coil when a game is started and the game over relay is powered (for System 80/80A/80B games). 99.9% of the time, this continuous path to ground is caused by a shorted drive transistor; either an under-playfield transistor, a transistor on a transistor board, or a transistor on the driver board itself.

Generally, a locked on coil will heat up, burn through the insulation on the coil windings, and cause direct shorts between windings. This effectively reduces the length of the wire and hence, the resistance. Once the resistance is reduced to less than 2 ohms or so, the continuous current through the transistor and the coil cause both to be irreparably damaged. For this reason, if you find a transistor shorted, check the associated coil. Likewise, if you find a coil shorted, or with significantly reduced resistance (ohms), check the associated transistor.

Some solenoid driver circuits, like solenoid 8 that uses a 2N3055, are "pre-driven" by an MPS-U45 (or NDS-U45). Be sure to test the associated pre-driver transistor too.

4.10 Lamp problems

Lamp problems are common with most any pinball machine, and Gottlieb® System 80/A/B games are no exception.

For controlled and GI lamps, Gottlieb® System 80/A/B games use either a #44 or #47 lamp. The choice of which lamp to use is the preference of the game owner.

For games with flash lamps, a #67 bulb is used.

It is highly recommended not to replace or remove lamps with the power to the game on. There are primarily two reasons for this.

Some lamp sockets must have their mounting brackets bent back to access the bulb for replacement. In turn, the potential of inadvertently shorting one lamp socket to another is possible.
Lamps are constructed of an equal balance of glass and conductive metal. If a bulb slips out of one's grasp when trying to remove or install with the power on, there are many areas in the bottom of the cabinet, where the metal of the bulb can short across. A short across other circuits could potentially lead to other unplanned or otherwise unnecessary repairs needed to perform.

So in short, change or remove bulbs with the game's power off, just to be safe.
All System 80 games have three separate lamp circuits, and some have a fourth. The circuits are comprised of:

General illumination for the backbox
General illumination for the playfield
Controlled lamps for primarily the playfield, although, there can be four controlled lamps located in the backbox (shoot again, high score game to date, tilt, and game over), depending on the era of the game.
Auxiliary lamps used for effect, such as chaser lamps used around the backglass border of Mars God of War and Black Hole. Auxiliary lamps are not used on all games. Jump to the Auxiliary Lamp Board section to see what games use auxiliary lamps.

Below are several approaches used to determine the source of a lamp problem, and how it can be resolved.

4.10.1 Bad Bulbs

The first thing when troubleshooting lamp problems, and this may seem blatantly obvious, but determine whether the lamp is good or not. The bulk of all lamp problems are simply burned out light bulbs. Always try a known good bulb as the solution first. Don't rely on the bulb being brand new either. The ratio of brand new, bad bulbs is slim, but there is that chance a new bulb is not good.

Making certain an old 9v battery is putting out an acceptable lower voltage

Testing a 6v bulb with a dying 9v battery

The bulbs used in a System 80/A/B game are powered by ~6 volts, (the exception is the bulbs powered for the lower playfield illumination on Black Hole and Haunted House). A great way to quickly test a bulb is to use a dying 9v battery. Don't use a fresh 9v battery, or you will shorten the life of the bulb. Find a battery that is roughly putting out 7v - 8.25v. An old battery from a smoke detector works pretty well.

Place the tip of the bulb on one of the battery terminals, and cock the outer metal casing of the bulb to touch the other terminal. Orientation of the bulb with regards to the positive and negative terminals does not make a difference in this case. Do not hold the bulb across the battery terminals for very long. Just long enough to determine if the bulb's filament is lighting or not.

You may also use a known working socket to test bulbs in...but that requires the game to be on while testing...which always presents some risk and is not recommended. However, if there is no other option but to use a known good socket for testing bulbs, the preferred method is to use a socket located in the backbox lamp insert panel. This unfortunately does not pertain to 65% of the System 80B games, because a fluorescent lamp was used for backbox illumination for them.

Games that have not been played in a long time develop a film of corrosion between the lamp "nipple" and the lamp socket which prevents conductivity. Simply removing the lamp and scratching the nipple with something abrasive (like rubbing it on the lockdown bar receiver) may fix many "lamp out" problems. In some cases, a light socket cleaning stick (available from the Pinball Resource here) may be useful for cleaning the lamp socket. Gottlieb® lamp sockets are comparatively beefy and do not fail often.

4.10.2 Lamp Power Issues

Next, make certain there is power at the lamp socket. The game will have to be turned on for the following procedures.

4.10.2.1 General Illumination Lamp Power Issues

GI lamps are powered by ~6VAC. When testing a GI lamp socket for power, each lead of the DMM (now set in AC mode) will be placed on the two leads of the lamp socket. If there isn't power at the lamp socket, suspect a bad fuse first. Keep in mind that the playfield GI and backbox GI for System 80, 80A, and a few 80B games (the first 3 80B games and the last 2), have two separate fuses located on the transformer board in the bottom of the cabinet. These are typically higher amperage rated fast-blo fuses. The backbox GI on a System 80 game is always on when the game is turned on. If the backbox GI fuse is good, and no backbox lights are lit, the inline connection which feeds the GI could possibly be bad. Unfortunately, this connection is not standard from game to game.

Gottlieb® System 80 Tilt Relay with GI Lamps/Tilt Lamp Make-Break Switch Highlighted. This tilt relay is from a Gottlieb® Spiderman

The playfield GI is always powered on too, except when the game is in tilt mode. If the game was not tilted and /or the tilt switches are not stuck closed, check the switch stack on the tilt relay. These switches can sometimes get bent or misaligned. If the playfield GI fuse is good and the tilt relay switches are good, the inline connections may be suspect.

If the fuse to a particular GI circuit is bad, and continues to blow every time a new fuse is installed, a short is probably causing the issue. A shorted lamp GI circuit is probably the worst and most difficult lamp related issue to resolve. In most cases, the GI power lines are uninsulated wiring, which make them susceptible to shorted circuits. First, determine if the GI short originates on the backbox lamp insert or on the playfield. GI shorts on the playfield are typically more common than backbox lamp insert shorts. Pop bumper lamps are generally not CPU controlled, and are included in the playfield GI string (some System 80B games are the exception, RoboWar being an example). Also, depending on the game, star rollover lamps and kickout hole lamps are sometimes part of the playfield GI circuit. Consult the game manual for these particulars.

Although it can be a pain and time consuming, the best approach is to remove all of the bulbs in the associated shorted GI string. In removing all of the bulbs, we are trying to isolate whether the problem is a bad, defective bulb, or one of the GI power lines is shorting.

4.10.2.2 Controlled Lamp Power Issues

Controlled lamps are powered by ~6VDC. When testing a controlled lamp socket, the red lead of the DMM (now set in DC mode) will be placed on the lamp socket mounting bracket. The bare wire soldered to the lamp socket's mounting bracket is the power bus not the ground bus, so be careful. The black lead of the DMM will be placed on ground. If working under the playfield, the ground plate in the bottom of the cabinet is a good place to connect to ground. If working in the backbox, find where one of the green wires with a yellow trace is screwed to the metalwork, and place the lead on it. Depending on the game, System 80 side rails, lockdown bar assemblies, and other associated trim metalwork, except the coin door, were not grounded from the factory like Bally, Williams, and Stern. Therefore, using any of these as a ground reference is not recommended. Gottlieb® did start grounding the metalwork at the start of the System 80A platform.

If there isn't any power at the lamp socket, suspect a bad fuse first. The controlled lamp circuit has a separate fuse on the transformer board, and is normally a 5 amp slo-blo fuse. If the fuse tests fine, there is a separate set of switch leaves on the tilt relay, which pass the controlled lamp power to the playfield lamps. Inspect and adjust these switches if necessary. If the controlled lamp fuse and the switches on the tilt relay both test good, there may be an issue with the source power connection to the rectified DC circuit on the game transformer board. Unfortunately, System 80/80A/80B used different connector designations for controlled lamp source power for different games. Consult the game manual / schematics to find the source of 6VDC on the transformer board power supply.

If the fuse for the controlled lamps is bad, and continues to blow after a new fuse is installed, suspect a bad controlled lamp bridge rectifier. The lamp bridge rectifier is located on the transformer board. Please see the Testing a Bridge Rectifier portion of the PinWiki guides. Before testing the bridge rectifier, try to isolate it as much as possible. By isolating it, this will minimize the possibly skewed readings caused by attached devices (lamps and the power transformer). Two key things to do would be to remove the lines which connect the bridge to the playfield and backbox lights, and remove the controlled lamp fuse. Keep in mind that a bridge rectifier can fail in such a way where it may not blow the controlled lamp fuse. Although, a failed bridge blowing a fuse is a tad more common than not.

If all of the above tests good, there may be a short on the controlled lamp bus line. This is not a very common occurrence, but it can happen. Inspect the underside of the playfield for any wires or brackets touching the controlled lamp bus line, which shouldn't be touching.

4.10.3 Bad Lamp Sockets

Third, determine if the lamp socket is good. Some games have been through the wringer, and the sockets didn't hold up too well due to abuse, a damp environment, or other various reasons. Start by turning the power to the game off. If the socket has some corrosion, try using a lamp socket cleaning tool first. If a lamp socket cleaning tool is not available, a small wire brush used for cleaning copper fittings, a rolled up piece of 220 grit sandpaper, or a Dremel tool with a small wire brush attachment can all be used. After the socket has been cleaned, place the bulb in the socket for the following procedures.

If testing a GI lamp socket, use the dying 9v battery trick again. Remove the fuse of the particular GI circuit which the lamp socket being tested is located. Connect the terminals of the 9v battery to the bulb socket with alligator clip leads. Be careful not to short the alligator clips to each other at the battery's terminals. Equally be very careful not to short the clip leads to an adjacent switch on the pinball machine, or anything else for that matter. One clip will connect to one side of the socket, and the other lead will go to the other side of the socket. DO NOT ALLOW THE BATTERY TO STAY CONNECTED VERY LONG. Since this is a GI lamp circuit, other lamps in the string will be powered by the battery. If the battery is connected to the string for too long, the battery will start to get hot. The battery does not have enough power to light a string of bulbs for very long. The lamp may only glow dimly, but that is enough to determine if the socket is good or not.

If testing a controlled lamp socket, remove all of the connector housings from the bottom of the driver board first (A3-J2/J3/J4). Then remove the fuse for the controlled lamp circuit. Clip one lead of the battery to the lamp socket mounting bracket and the other to the solder tab. The orientation of the negative and positive leads of the battery terminals makes no difference. Again, keep the battery connected just long enough to see if the lamp lights to determine whether the lamp socket is good or not.

4.10.4 Controlled Lamp Issues

4.10.4.1 Lamp(s) Will Not Turn On

So, the bulb is good; the socket is good; there's power at the socket; and the lamp still won't light. Well, this occurrence can only really happen if there is a controlled lamp involved. If all three of the above things apply, it can only mean one thing - the bulb is not getting properly grounded, and will not turn on. The source of this problem may be due to several different issues. But, it is best to start at the bulb socket, and work backward towards the CPU board.

Determine if the connector and wiring from the output of the driver board to the lamp socket is good. While the wires are usually solid, the single sided edge connectors are a frequent cause for loss of conductivity. Simply "buzzing" the connection from the lamp socket back to and onto the driver board may uncover the issue. With the power off, check the continuity between the solder tab of the lamp socket and the collector (right leg) of the associated lamp transistor.

If there is continuity, it’s time to test the transistor. Transistors fail "open" (lamp never lights) and "shorted" (lamp is constantly on). A simple comparison of "diode check" readings between "same type" transistors on the driver board can identify failed transistors.

Testing an MPS-A13 transistor.

Set your DMM to diode test
Place the red lead of your DMM on the center leg
Place the black probe on left leg (viewing the component side of the board). That leg should read about 1.3
Move the black probe to the right leg. That leg should read about .7
Readings close to these, or even similar to adjacent like components, indicate a good component. Failure to obtain these readings means the component has failed.

Testing an MPS-U45 transistor (or NDS-U45 or CEN-U45 which are equivalents).

Set your DMM to diode test
Measure on the solder side of the board, with J5 and J6 oriented toward you
Place the red lead of your DMM on the center leg
Place the black probe on left leg. That leg should read about 1.3
Move the black probe to the right leg. That leg should read about .7
Readings close to these, or even similar to adjacent like components, indicate a good component. Failure to obtain these readings means the component has failed.

An NDS-U45 replaced by the less expensive MPS-A13. This replacement is advised ONLY if the transistor drives a single lamp.

The System 80/80A/80B architecture does not utilize a lamp matrix. Controlled lamps are driven by individual transistors on the driver board, exactly like Gottlieb® System 1 games and Bally/Stern 6800 games. Driver board operation is pretty simple. The CPU places a signal on Logical Device lines 1 through 4 (LD1...LD4) and "strobes" the appropriate 74175 device select pin to latch the LDx values into the 74175 Quad FlipFlop's outputs. These outputs then drive the associated transistor(s) on, providing a path to ground for the lamp. That's all there is to it.

The transistors on the driver board are a mix of 2N6043s, MPS-U45s (or NDS-U45s), 2N3055s, and MPS-A13s. 2N6043s drive coils. Generally, the MPS-U45 transistors drive coils, pre-drive coils via remote mounted transistors and 2N3055s, or drive more than one lamp. The 2N3055s drive coils (in some cases, not all 3 of these are used in a game). The MPS-A13s generally drive a single lamp.

MPS-A13 transistors are still widely available and cheap. MPS-U45s are obsolete but may be replaced with CEN-U45 transistors available from Great Plains Electronics and Mouser. A much cheaper MPS-A13 may sometimes be substituted for the less common and more expensive MPS-U45, as shown in the pic at left for Q22. Although this will work, you must ensure that the transistor is driving only a single lamp. This obviously limits the "portability" of the driver board. If Q22 were used to switch anything other than a single lamp on, it will be destroyed. Substitute with caution.

2N6043 transistors used on the driver board are still available but becoming pricey. 2N6043s can be replaced by a TIP-102.

Note: A nice convention Gottlieb® used with System 80 games is that lamp "n" is driven by transistor "n+1" on the driver board. This is always true.

If the transistor tests fine, a gate on the 74175 may be bad, which is rare but does happen. Use a logic probe on the input and output of the associated lamp gate to check definitively. Again, comparing the signal between different drive pins can help identify a failed driver circuit. 74175s can easily and reliably be tested using the procedure in the "General for all games" section, here.

If more than one controlled lamp is not lighting, check the game’s manual / schematics to see if the bulbs are related in some way.

When four lamps are not lighting, it may appear that the 74175 which controls the lamp transistors is at fault. This can happen, but the more commonly related issue is that the device select signal for a particular 74175 is lost between the CPU and driver board. This can be due to a bad connection at A1J4 or A3J1. See the chart below for the lamp device select signal path.
When a whole group of lamps fail to light, review the schematics to see if the lamp transistors share a common ground path. Again, poor connections at the driver board, or the path to ground (generally green with yellow tracer or solid white wire) on the bottom board ground strap may be the root cause.

If the connections, associated 74175, and lamp transistors are all correct, the circuitry on the CPU board is probably at fault. Again, using a logic probe to determine which component on the CPU board has failed is the best course of action.

Device Select	CPU Connector	Driver Input	Driver Quad Flip-Flop (74175)	Transistor #s	Lamp #s
DS1	A1J4-C	A3J1-C	Z1	Q1-Q4	Game Over relay, Tilt relay, coin lockout, L3
DS2	A1J4-3	A3J1-3	Z2	Q5-Q8	L4-L7
DS3	A1J4-E	A3J1-E	Z3	Q9-Q12	L8, sound 16, L10, L11
DS4	A1J4-D	A3J1-D	Z4	Q13-Q16	L12-L15
DS5	A1J4-H	A3J1-H	Z5	Q17-Q20	L16-L19
DS6	A1J4-F	A3J1-F	Z6	Q21-Q24	L20-L23
DS7	A1J4-K	A3J1-K	Z7	Q33-Q36	L24-L27
DS8	A1J4-J	A3J1-J	Z8	Q37-Q40	L28-L31
DS9	A1J4-M	A3J1-M	Z9	Q41-Q44	L32-L35
DS10	A1J4-L	A3J1-L	Z10	Q41-Q44	L36-L39
DS11	A1J4-N	A3J1-N	Z11	Q41-Q44	L40-L43
DS12	A1J4-P	A3J1-P	Z12*	Q45-Q48 & Q49-Q52	L44-L47 & L48-L51 (inverse of L44-L47)

*Z12 not only outputs four lamp signals like all the other 11 74175s, but it also outputs four inverted lamp signals. These signals are typically used for lamps located on opposite sides of the playfield which alternate on / off between each other.

4.10.4.2 Lamp(s) Will Not Turn Off

If a single lamp is involved, or only a handful of lamps with different lamp device select signals, suspect the lamps' associated drive transistors. If a group of four lamps will not turn off, and they are all controlled by the same 74175, suspect the associated 74175 or the device select for that 74175 ("DS" on the schematics). If numerous groups of four lamps will not turn off, suspect the associated 7404 on the CPU board.

Z17 for DS1-DS5 device select signals or,
Z24 for DS6-DS11 device select signals or,
Z26 for DS12-DS16 device select signals.

If the lamps involved originate from more than one group of device select signals, suspect the 74154 at Z25 or, backing up one more step, the 6532 RIOT at U5.

4.11 Flash Lamps

Flash lamps are #67 powered by the 24VDC solenoid bus. They are controlled like any of the coils that have a under-playfield transistor. To step down 24V to a more lamp-friendly 13V, the power is routed through a single 4 ohm 7 watt resistor for powering paired flash lamps wired in parallel. An 8 ohm 5 watt resistor is used for powering single flash lamps.

On early 80B games, the power resistors are mounted to a small bakelite board under the playfield (up to 4), and the transistors are mounted to a bracket (up to 6). On later games, starting with Arena, new PCBs were introduced that had the transistor, power resistor, and 4.7K pullup resistor all on the same board (up to 3).

If lamps are locked on, or won't work, the remote mounted transistors associated with them have failed. Generally, the pre-drive transistor on the driver board has also failed.

Under-playfield flash lamp transistors are 2N5879s or MJ2955s.

4.12 Auxiliary Lamp Problems

Reflowed Header Pins on Auxiliary Lamp Driver Board

For issues with lamps controlled by the auxiliary lamp driver board, follow the troubleshooting section for controlled lamps above. Additionally, make certain that +5vdc and ground are present on the auxiliary driver board. If either are missing, the potential for cracked header connections is possible. Remove the existing solder from the header connections, and resolder the header pins.

4.12.1 Unconventional Lamps

System 80B games added quite a few special lighting effects. Gottlieb® never used software when hardware would do. This is probably harkens back to their electromechanical days. So, there are usually some creative, different ways used to control lamps. For instance:

Monte Carlo and Spring Break have Auxiliary Lamp Driver boards where power to a bunch of #44 lamps is switched by a relay.
Genesis drives #67 lamps with an auxiliary power board. Power to this board is controlled via a relay that turns itself to activate the "reveal"; this relay is activated by a lamp driver, but the relay will keep itself on until one revolution of the reveal gimmick is done.
Spring Break has eight #44 lamps controlled by one relay; the relay is controlled with a lamp driver.

Diagnosing these is generally the same as other lamps, but first, understand the peculiar arrangement for the game in question.

4.13 Switch problems

4.13.1 Switch Matrix Operation

The Gottlieb System 80 switch matrix is implemented via the 6532 RIOT (RAM, I/O, Timer) at U4, strobe ICs at Z11 and Z12 (7404), return ICs at Z13 and Z14 (7400), and DIP switch "read enables" at Z15. The switch matrix simply provides a TTL "low" pulse on a single switch matrix column, then listens for a "low" return on the switch rows. Closed switches complete the circuit and enable a switch matrix return. Switch returns are processed then the next column is strobed. The game software "debounces" all switches to accommodate less than electrically and mechanically perfect switches.

4.13.2 Common Switch Matrix Faults

4.13.2.1 Isolating Switch Problems to the MPU or the Game Wiring

Since Gottlieb uniquely used edge connectors instead of more common header pins, isolating switch matrix issues to either the MPU or to the game wiring is not quite as easy. However, "jumping" from a switch column to a switch row is possible using the same technique.

Place the game into switch test
Using a short length of wire, short each column drive to each row return, one at a time
A single switch closure should be shown as each connection is made.

If a single switch closure is shown for each and every connection made, then the MPU circuitry is probably undamaged, and the playfield wiring, switches, and diodes should be examined. If a switch closure isn't registered, or more than one switch closure is reported, then the MPU circuitry is damaged.

4.13.2.2 MPU Switch Matrix Issues

4.13.2.2.1 Blown Switch Matrix ICs

Identifying the System 80 MPU switch matrix ICs.

The most prevalent reason for switch matrix failures is shorting high voltage (i.e. coil voltage) to the switch matrix. As always, it's inadvisable to work on your game with the power on. Sometimes, "fish paper" designed to isolate switch blades from higher voltage conductors becomes displaced, shorting high voltage to the switch matrix, and damaging some/all of the switch matrix ICs. An example of such a switch is the kicking target under the upper playfield in Haunted House.

A quick check of Z11 through Z15 using the diode test will reveal failed ICs easily.

Using this same diode test on U4, comparing the results to U5 and U6, may help to identify a failed RIOT.

4.13.2.2.2 Alkaline Damaged Connectors

Playfield switch wiring is connected to MPU edge connector J6, which is sometimes directly below, but at the very least in close proximity, of the OEM NiCad battery. These batteries frequently leak their corrosive contents onto the board, affecting nearby connectors, including the switch matrix connectors at J6 (playfield) and J5 (cabinet). Close examination of the friction pins in the connector as well as the copper traces at the edge connector may reveal alkaline corrosion impacting proper switch matrix operation.

4.13.2.3 Playfield Switch Matrix Issues

Once the switch matrix issue has been isolated to the playfield, follow the tips listed in the Switch Matrix Diagnosis section.

One additional item to note is that Gottlieb did not attach isolation diodes directly to switches. Instead, isolation diodes are collected on "diode boards" which are screwed to the playfield underside or the cabinet bottom.

4.14 Display Problems

The blue Futaba display glasses used by Gottlieb® System 1 and 80 machines are a fairly reliable, long-lasting display. Although, they can and do still fail. It's just a matter of diagnosing the symptoms of a failed display.

Display problems can primarily be classified into the following categories:

Power problems
Display glass failure
Data problems
Tired displays

Gottlieb® System 80 Display Diagram

Gottlieb® System 80A Display Diagram

4.14.1 Display Power Problems

Before even attempting to work on System 80/80A/80B displays, there are two caveats to heed. First and foremost, the displays function due to the necessity of several voltages, including high voltage. IF YOU ARE UNCOMFORTABLE WORKING ON HIGH VOLTAGE CIRCUITS, THEN DO NOT WORK ON THESE DISPLAYS! High voltage can hurt or even kill you. If you don't feel comfortable working around this type of scenario, then hire a professional to do the work. Secondly, any time a display connector needs to be disconnected, DO NOT REMOVE ANY DISPLAY RELATED CONNECTOR WITH THE POWER ON! This goes for the connectors located directly at the display, connectors A1J2 and A1J3 on the CPU board, A2J3 on the power supply board, and A7J3 / A7P3 (early System 80 up to Mars God of War), A10J1 / A10P1 (when used), A12J4 / A12P4 (Black Hole and after), or A10J7 / A10P7 (when used) from the transformer. Removing connectors with the power on can damage the display, the CPU board, and / or you. Sorry to "yell", but it is extremely important to stress the above two statements. Now that this is out of the way, let's move on.

As stated above, the displays need several sources of voltage to function properly. The display voltages used are broken down by the type of display: +60VDC, +8VDC offset, and 5VAC are used for the 6-digit displays; +42VDC, +4VDC offset, +5VDC logic (for the 7432 chip - Z1), and 3VAC are used for the 4-digit status display. When using a 6 digit display with DI513 Dionics chips, +5VDC is necessary for RP1 and RP2 8.2K resistor networks. Likewise, 7 digit displays also have a 7432 chip on them, and +5VDC is needed for them too. If any of the above voltages are missing, the display will never light.

Prior to plugging in and turning the game on for the very first time, it is a good practice to check all of the fuse values located on the transformer board first. There is a 1/4 amp slo-blo fuse used for the display voltage, which is located on the transformer board in the bottom of the cabinet. With the game unplugged from the wall outlet, remove the fuse from its fuse holder. When checking fuses, never "eyeball" a fuse. Your eyes may tell you that the fuse is good, but your eyes can fool you. Use a digital multi-meter (DMM) or a continuity tester to check fuses. Put each lead of DMM on opposite ends of the fuse. A tone should be heard. If not, the fuse is bad, and should be replaced with the same value. Fuses are used to protect equipment, the surroundings, and you. Installing fuse values with higher ratings is very dangerous. DO NOT USE A FUSE RATED AT A HIGHER RECOMMENDED VALUE! If the existing fuse is blown, it may not necessarily mean there is a problem. Fuses do get stressed, and sometimes just fail. However, there is more than likely a problem somewhere in the display power train.

With the game still unplugged, the next course of action is to place connector A2J1 on the power supply. A2P1 is the bottom connection on the power supply, and receives all voltages directly from the transformers and a single ground from the ground strip. Once A2J1 is connected, remove any other connections from the power supply (A2J2 and A2J3). All voltages should be tested before any boards or displays are connected to them.

System 1 Power Supply with A2J3 highlighted

At this point, plug the game in, and turn it on. Using a DMM or volt meter, check all of the voltages at A2P3. For the +60VDC (A2P3-1) and +42VDC (A2P3-3), any ground connection can be used as a reference. The +42VDC is derived from the +60VDC. If there is +60VDC, but not +42VDC, The 18v CR6 zener diode or the R5 resistor may have failed.

If the two high voltages test all right, it's time to check the offset voltages. The offset voltages are +5VDC (A2P1-6) and +8VDC (A2P1-9). Use any ground connection as a ground reference to test these voltages.

If displays are not lighting, but either the +42VDC is present on the display (status display) or the +60VDC is present on the 6 digit or 7 digit displays, check for the presence of AC voltage used to power the display filament. Do not use ground as a reference when measuring these voltages, as they are AC. Measurements must be taken from the send and return lines. If the AC voltage is missing, check the in-line connection at A7J3 / A7P3 (early System 80 up to Mars God of War) or A12J4 / A12P4 (Black Hole and after). Also, some games have more connectors which pass the AC voltages. These additional connectors are A10J7 / A10P7 or A10J1 / A10P1. Check the voltages on the input and output of the connector to see if fatigued connectors are the source of the voltage loss.

If all the display voltages are satisfactory, it is time to move onto the next step of visually inspecting the display boards for obvious defects.

4.14.2 Display Glass Failure

Display with a good display glass

A cheap and easy way to protect your nipples

The simplest and easiest problem to identify is display glass failure. All of the 6 digit displays used by Gottlieb® System 80, and 7 digit displays used by System 80A games will have a black "blotch", for lack of a better term, in the upper left and lower right corner of the glass. The 4-digit status display typically has only one black blotch. The evidence of a black blotch or blotches is good.

Display with Broken Nipple on Back

However, if there is a muted white blotch visible at the corners of the display, it means the display's "vacuum" has been compromised, either due to a cracked glass or broken nipple. If this is the case, the display glass can not be repaired and is useless.
A simple, cheap, and effective way to protect the glass nipple is to cut a ring of hose (garden hose was used in the picture at right), place it around the nipple, and then fill the ring with silicon caulk (preferred) or hot glue.

Display with Broken Top Filament. Note that this is the Dionics chipset version of the display.

The display filaments within the glass can also break. The end result will be segments with missing sections or "hot spots" when the display is powered. The "hot spots" are caused by the "dangling", broken filament shorting to other good filaments. If a display filament breaks, do not use the display as shorted displays can damage other game components.

Example Display with Failed Filament
Another example of a broken filament. This one has broken and shorted to another part of the display.
The same display, showing a dark line across the center where the filament has failed.
Closeup of same display.

Even though the glass itself is bad, the chips on the display board may still be good. So don't necessarily discount the display as being all bad. UDN6118A and 7432, (chip used on status display only), chips are getting more costly, and Dionics DI513s are very scarce. Since the display board is single sided, removal of the chips is quite easy. Plus, the display PCBs are no longer being made. The display board and / or chips may come in handy some time in the future.

4.14.3 UDN6118 and Other Display Logic Chip Failures

The majority of 4 and 6 digit displays utilize two UDN6118 "Vacuum Fluorescent Display Drivers". These ICs do not fail often. However, when they do fail shorted, they can affect the performance of the rest of the display set.

Test method for a UDN6118 or UDN7180 display driver. Colored dots represent DMM probe locations (red lead, black lead)

UDN6118 driver ICs can be tested using a DMM. Click on the image at left for the procedure.

A Blown UDN6118 Display Driver
Damage is hard to photograph, but the outline of the overheated chip core can be seen.
A much more visible image of the heat damage.

A 4 digit display with segment "c" locked on, caused by a failed 7432 on the board

Gottlieb 4 digit displays use two UDN6118s and a single 7432. The 7432 can fail in such a way as to cause segments to lock on, as shown in the pciture at left showing segment "c" locked on.

4.14.4 Display Data Problems

When there are display issues, one first has to determine whether there is a problem with the display itself, the connectors involved, or the chips on the CPU board that control it.

NOTE: Do not connect or disconnect the display connectors or connectors A1J2 and A1J3 on the MPU (right hand side) with the power on! Doing so WILL damage the MPU board display logic ICs.

The following applies to System 80 and 80A displays. For information regarding the System 80B display board, scroll down to the end of this section.

An excellent image to show both digit and segment problems. Note the red circles showing the same digit out on for players 1 and 3. Also note the yellow circles showing segment "g" out for players 1 and 2.

Display Issue Isolated to a Single Display
If the problem is only showing up one display, suspect that the connector at the display itself is problematic, or there is an issue on the display board. Problems on the display board can consist of a bad solder joint, a broken display lead from the display glass, or faults with the driver chips on the board (Sprague UDN6118 or Dionics DI513, if an old System 1 display is used). The exception is if only 4 displays and a status display are used, which is common to most System 80/80A games. In this display configuration, if there is a segment issue with the status display, there may be an issue with the segment drive chip on the CPU board.

An example of a display showing segment "h" locked on. The segment was locked on for both the player 3 and player 4 displays. This was caused by a failure of the 7404 at Z16. This picture was snapped right after pressing the diagnostic button on the coin door. The display should be blank.

Display Issue With Multiple Displays
If the problem shows up on two or more displays, suspect one of the two connectors on the CPU board (A1J2 or A1J3), one of the two connectors on the two displays (they are daisy-chained with an IDC connector), or the chips which control the display data on the CPU board. If there is a digit issue, the issue will be present on player 1 and 3 or player 2 and 4 displays. If there is a segment issue, the issue will be present on player 1 and 2 or player 3 and 4 displays, and the status display. If more than 4 scoring displays are used, on games such as Pink Panther, Black Hole, Haunted House, Devil's Dare, etc., consult the game manual for display digit and segment mapping.

The charts listed below, map out each signal to each specific display. The first chart maps the display digit information, while the second and third charts map the display segment information. This information only applies to games where 4 scoring displays and 1 status display are used, although digit group names have been added, if more displays are used. All of the charts apply to System 80 and 80A, but not 80B.

Display Digit Information

Digit Number	Display(s)	CPU Pin Connection	Chip on CPU Board - Pin
D1	Players 1 & 3 (Group D)	A1J3-1	Z17-4
D2	Players 1 & 3 (Group D)	A1J3-2	Z17-6
D3	Players 1 & 3 (Group D)	A1J3-3	Z17-12
D4	Players 1 & 3 (Group D)	A1J3-4	Z17-10
D5	Players 1 & 3 (Group D)	A1J3-5	Z17-8
D6	Players 1 & 3 (Group D)	A1J3-6	Z24-2
D7	Players 2 & 4 (Group E)	A1J3-7	Z24-4
D8	Players 2 & 4 (Group E)	A1J3-8	Z24-6
D9	Players 2 & 4 (Group E)	A1J3-9	Z24-12
D10	Players 2 & 4 (Group E)	A1J3-10	Z24-10
D11	Players 2 & 4 (Group E)	A1J3-11	Z24-8
D12	Players 2 & 4 (Group E)	A1J3-12	Z26-2
D13	Status (Group F)	A1J3-13	Z26-4
D14	Status (Group F)	A1J3-14	Z26-6
D15	Status (Group F)	A1J3-15	Z26-10
D16	Status (Group F)	A1J3-16	Z26-8

Display Segment Group A Information

Segment	Display Group	CPU Pin Connection	Chip on CPU Board - Pin
a	Segment Group A	A1J2-1	Z19-13
b	Segment Group A	A1J2-2	Z19-12
c	Segment Group A	A1J2-3	Z19-11
d	Segment Group A	A1J2-4	Z19-10
e	Segment Group A	A1J2-5	Z19-9
f	Segment Group A	A1J2-6	Z19-15
g	Segment Group A	A1J2-7	Z19-14
h	Segment Group A	A1J2-8	Z16-12

Display Segment Group B Information

Segment	Display Group	CPU Pin Connection	Chip on CPU Board - Pin
a	Segment Group B	A1J2-9	Z21-13
b	Segment Group B	A1J2-10	Z21-12
c	Segment Group B	A1J2-11	Z21-11
d	Segment Group B	A1J2-12	Z21-10
e	Segment Group B	A1J2-13	Z21-9
f	Segment Group B	A1J2-14	Z21-15
g	Segment Group B	A1J2-15	Z21-14
h	Segment Group B	A1J2-16	Z16-10

Display Segment Group C Information

Segment	Display Group	CPU Pin Connection	Chip on CPU Board - Pin
a	Segment Group C	A1J2-17	Z23-13
b	Segment Group C	A1J2-18	Z23-12
c	Segment Group C	A1J2-19	Z23-11
d	Segment Group C	A1J2-20	Z23-10
e	Segment Group C	A1J2-21	Z23-9
f	Segment Group C	A1J2-22	Z23-15
g	Segment Group C	A1J2-23	Z23-14
h	Segment Group C	A1J2-24	Z17-2

4.14.5 System 80B Display Issues

A System 80B Display edge connector. One data conductor to the display was not "making" across the connection due to a corrosion "divot". This caused the entire display to remain blank. Reflowing the edge connector solder corrected the issue. Image courtesy of Chris Hibler.

System 80Bs displays are completely different how the digits and segments are decoded and driven. Unlike System 80 and 80A, where the decoder chips are located on the CPU board, the System 80B display has a single segment (U3) and two digit decoder chips (U1 & U2) located on the display board itself. Unfortunately, both of these chips (10941 & 10939 respectively) were a product of Rockwell International, and are not that prevalent.

It has been observed that if any of the display data signals are missing between the CPU board and the 7417 inverters on the display board, the two displays will not illuminate at all. If voltages on the display board are within spec, it may be advantageous to check all of the data signal edge connector pins on the CPU board and the display board. If both the edge connector and the female connectors look good, use a logic probe to ensure signals are getting to the input side of both 7417 (or later 74LS367) inverters on the board.

4.14.6 Rejuvenating Tired Displays

Rejuvenating tired System 1/80 displays

System 80 displays, especially those that haven't been turned on for a long time, sometimes fade. These displays can be rejuvenated by applying voltage to the outside pins of the display glass. Note that voltage should be applied to the display glass pins, NOT the card edge pins. This process "burns" the impurities that accumulate on the filaments off.

In the picture at left, general illumination power (7VAC) from the lamp insert panel is being used to rejuvenate a display.

Procedure:
1. Turn the game off
2. Remove the connector from the display
3. Connect jumper clips from a voltage source to each of the outside pins of the display glass. Note that the lower the voltage applied, the longer the display can tolerate this "rejuvenation".
That is why some techs choose to use the lower GI AC voltage for this purpose.
4. Power the game on for 1 minute.
5. Disconnect the jumper wires and reconnect the display.
6. Power on to test the display.
7. If the display still isn't bright enough, repeat this process for 1 minute each time, until the display is satisfactorily bright.

Note that if the display filaments, which run across the display horizontally begin to glow orange (or worse, white), too much voltage is being applied or the display has been connected too long. This risks burning one or more of the display filaments out and ruining the display. A cautious, 1 minute at a time, process is warranted.

Note also that one particular System 80 tech ("System 80, not just a job, it's an adventure") suggests that merely leaving the game powered on for 24 hours will accomplish the same rejuvenation.

4.14.7 Display Does Not Light

Broken legs on display glass

If the glass of a 6 or 7-digit display does not light, but there are no white spots in the corners (white spots indicate bad glass), the outer-most legs on the glass may be broken. A magnifying glass may be necessary to inspect the pins since the gap in the breaks may be extremely small. The outer-most legs are responsible for supplying power to the glass, which is why the glass would not light in this situation.

These legs may be broken especially on displays that have a green or blue plastic filter covering them. These legs can get broken after someone presses down on the plastic cover of the display when pushing the display onto the PCB supports mounted on the light board in the backbox.

To repair, line up the two broken halves of the leg with needle-nose pliers, heat, and solder. If the solder isn't sticking, lightly sand back some of the black tarnish with fine sandpaper or a fiberglass eraser.

4.14.8 Individual 6-digit Display Interferes With Other Displays

Sometimes, a particular display can interfere with the operation of other 6-digit/4-digit displays no matter which game or player position it is plugged into. These symptoms can include:

Causing digits to go missing on other displays
Causing certain digits to dim significantly on other displays
Causing certain digits to display garbage or non-numbers

The cause of these symptoms is a bad R1 resistor. When powered off, the resistor will give the correct reading. However, the resistor may fail when power is applied. The R1 resistor (10k ohm, 1/2 Watt, 5% resistor) may need to be replaced if the above symptoms are present.

4.14.9 Individual 7-digit Display Causes Other Displays To Go Blank

Sometimes, a particular display can interfere with the operation of the other 7-digit/4-digit displays no matter which game or player position it is plugged into.

If a particular display causes all other displays to go blank, the likely cause is a failure of the Z2 6118P chip, which drives the digits of the display. This chip can be replaced with the more commonly found UDN6118A chip. Also keep in mind that it's possible the 7448 and the other 6118P controlling the segments could be damaged as well, so be prepared for that.

4.15 All Other Display Issues (Not Caused by Displays)

There are several issues which appear to be display related, however, they ultimately are not. In these instances, the displays are used instead as a visual identifier of a particular issue.

4.15.1 Open Slam Switch

If after turning a System 80 game on, and the scoring displays turn on immediately without a 5 second delay, there is a problem. However, if the displays are showing all of the outer segments (all segments necessary to display a zero) lit, and "strobing" or "rolling" rapidly as simulated in the image below, this isn't a display problem. The cause of this problem is an open slam switch on the coin door. To address this issue, see the PinWiki section Slam Switch Modification.

Simulation of displays indicating an open slam switch. Note the "rolling" perimeter display segments.

4.16 Sound problems

Before doing any kind of work, or blaming the sound board for not putting out sound, review the Basic Sound Troubleshooting section first.

In particular for System 80 games, ensure that the dip switches that enable sound are set correctly. And, ensure that the dip switch actually works. Games like Spiderman use one of the 32 MPU dip switches to enable background and scoring sounds. Games like Haunted House, Black Hole, etc use dipswitch 5 on the Sound and Speech board to enable background sound.

4.16.1 The Long and Winding Road of the Sound Signals

The sound signals follow very roundabout path before reaching their destination on the sound board. Sounds S1, S2, S4, and S8 are originated on the MPU board by RIOT U6. These 4 sound signals then pass through a 7404 inverter (Z27), pass through a 7408 2 input AND (Z31), and exit the MPU board via the A1J4 connection (MPU / driver board interconnect harness). The signals enter the driver board via A3J1, pass through another 7404 inverter (Z13), and exit the driver board via A3J5. Finally, they enter the sound board via the only connection on the sound board, A6J1.

If any of the sound signals are lost, this potentially happens due to poor edge connections, however, 7404s are known to fail too. The best way to check for discontinuity is to use a DMM or ohmmeter to check the path from the exiting chip to the chip it enters on the following board. Another method for checking for signal loss is a logic probe. This method is not as simple though, because some generations of System 80s do not have a sound test. Therefore, waiting for a particular signal to trigger can be tricky. The benefit of using a logic probe is to determine if a particular signal is entering and exiting a specific chip, and if the signal transforms (if it is supposed to) like intended (ie. the 7404 will invert the signal from high to low or low to high).

Some sound boards use a fifth sound signal, known as S16. S16 is actually driven by an MPS-A13 like any other single lamp drive. S16 can follow a very convoluted path too, depending on the particular game. For example, Haunted House uses S16. It originates on the MPU with all of the other lamp signals, and becomes lamp drive Q10 on the driver board. It exits the driver board via A3J2, passes through a inline connector, A10J4, passes through another inline connector, A12P4, and finally reaches the sound board at A6J1. That is a lot of mileage for just 1 little sound signal!

System 80B games, starting with Rock, which use the dual 6502 processor sound boards, use Q5 as sound signal S16. Please be aware that the System 80B documentation does not always notate this information regarding S16!!! In this case, S16 follows a much simpler path. It exits the driver board via A3J2 and goes directly to the sound board at A6J1.

So, if appears that certain sound signals are missing or the wrong sounds are triggered, suspect a bad connection first. Then, suspect a bad 7404 within the sound signal path. Then, check all other potential problems.

It is noteworthy that the 7404 U7 located on early System 80 sound boards (sound only) do fail also.

4.16.2 System 80 Sounds Only Board

Gottlieb® System 80 Sound Board (Sounds only)

This board, first used in Panthera, is problematic to fix. The main issue is that the board uses the long since obsolete 6503 processor (think of it as a short 6502) and a "masked ROM/RIOT" 6530. The 6530 was specifically programmed for Gottlieb sound boards. They are therefore, impossible to replace unless you can scavenge a working one from another sound board.

The only replacement option at this time, other than sourcing a used board, is Pascal Janin's reproduction board. This board is a bit pricey but is engineered quite well. The board can be found here: http://www.flippp.fr/pifx.php?lg=en.

Audio filter cap removed, corrosion removed, traces tinned. The leaky cap can be seen in the top of the picture.

This board operates on three different voltages: +5v, +12v, and -12v. The +5 volts comes in on J1 pin 5 from the machine's power supply board. The +12 volts comes in on J1 pin 1 from the machine's bottom panel. The -12 volts is generated on the sounds only board and it receives AC power input on J1 pins 3 and 4. You can measure the -12 volts by connecting your volt meter across zener diode CR5 (1N4742A).

The test button on this era sound board will only work if the two dipswitches are set in opposite positions on the sound board.

As noted above, this board is tough to repair. If the 6530 is dead...you're SOL. A dead 6503 might be replaced. The other ICs on the board, like the LM380 amp and the 555 timer are still readily available. The biggest issue with the board seems to be the leaky large capacitor on the board. Fortunately, this is easy to repair. Remove the old cap. Abate the corrosion as shown in the picture at right. Replace the cap. When this cap leaks, it can completely sever the sound signal path. Sounds might sound scratchy or incomplete too. The cap is easy to remove and replace. It's worth a shot.

4.16.3 System 80 / 80A Sound and Speech Board

4.16.3.1 Different Revisions of the Sound and Speech Boards

Revisions of the Gottlieb Sound and Speech board
B20887-1
B20887-2
B20887-3

B-20887-3 Sound and Speech Board with Resistors Highlighted

With the third revision sound and speech board, the resistors which were added to the solder side of the -1 and -2 boards were now incorporated in the board design.

4.16.3.2 Sound and Speech Board Operation

The sound and speech board represents the high point in the System 80 family as far as sound generation is concerned. By combining sound and voice circuitry, the board is flexible enough to be used in several different games, with different voice calls, all generated via the Votrax SC-01 speech synthesizer.

The sound and speech board is itself a single board computer, and should be debugged similar to any non-working MPU.

The board interfaces with the System 80 MPU via a 6 bit (S1, S2, ..., S32) wide "data bus". The 6 interface bits form a binary code which define specific sounds (or speech) to play. This enables 63 separate sounds to be played. Each communication between the MPU and the Sound and Speech board is "stand alone". That is, the system does not make use of successive sound commands to mean different things as the Bally Squawk and Talk implementation does. In practice, since S32 is never used, a maximum of 31 unique sounds are commanded.

Four of the bits in the interface are controlled (grounded) by circuitry on the MPU (starting at the U6 RIOT) and a "pass through" 7404 inverter on the driver board (Z13). The remaining two bits are implemented via "lamp drive" transistors (Q10 for S16) on the driver board, and comparator circuitry on the S&S board (U24).

Sound select signals are fielded by the S&S board's 6532 RIOT which generates an interrupt to the 6502 processor. The 6502 reads the sound number commanded from the 6532 as it services the interrupt.

The S&S board's 6502's program code, as well as sound data, is stored in two 2716 EPROMs, PROM 1 and PROM 2. These EPROMs are typically labeled at the factory with the model number of the game they are for, and the suffixes /S1 & /S2. For example "668/S1" is the label on one of the Black Hole sound ROMs. Although the board can be strapped for two 2732 EPROMs, in practice, this was never done.

The sound and speech board can field and queue sound commands at the same time as it is driving the sound and speech circuitry lanes. The board will never interrupt or prematurely terminate a sound being played. The board will also never reorganize the queue of sounds to be played. Each sound to be played will be played until it's conclusion. The 6502 knows when "sounds" have completed playing since it is solely in control of the sound lane. The 6502 knows when "speech" calls have completed processing by the SC-01 via a non-maskable interrupt sent via the SC-01's ~A/R signal to the 6502's NMI pin. Timing to sequence speech phonemes together rapidly is critical, hence the use of the non-maskable interrupt.

The 6502 creates "sounds" via one circuitry lane. It creates "speech" through a second, separate circuitry lane. At the end of each lane, just prior to input to the main LM379S amplifier, sound and speech is summed. The relative volume of each lane can be tuned via 10K trim pots at the top of the board, R15 and R16.

Sound Lane
Simple sounds (not voice) are created by the 6502 reading data from the sound ROMs and latching it into two 74LS75 data latches. The 74LS75s latch the data when selected via a 74LS02 (NOR gate) at U10 which NORs the R/W signal along with a device select signal from the 74LS138 at U4. the device select signal selects U7 and U8 simultaneously to latch data bus signals DB0 - DB7 all at once.

The two 74LS75s provide the data to a 1408 D-to-A (digital to analog) converter at U20. In this way, 511 different digital codes can be converted to analog levels by the 1408. The analog output of the 1408 can be attenuated via a 10K "variable resistor" at R13. The signal is then amplified and inverted by an LM741 analog inverter (U22). The analog signal is then fed to the LM379S for final amplification. Note that the 1408 DAC is obsolete, but may be replaced by the more available DAC0808.

Speech Lane
Speech is ultimately created by the Votrax SC-01 voice chip. The SC-01 accepts "phoneme" codes and renders the analog speech output to the LM379S for final amplification. The phoneme codes are placed on the 6502 data bus and pass through a 74LS05 "level shifter" and inverter at U13. The codes are accepted by the SC-01 on pins 9 through 14 when pin 7 is strobed (the phoneme code is latched on the rising edge of the strobe). The "pitch" of the SC-01 voice is controlled by I1/I2 (pins 3 and 2). Frequency and timing control is achieved via MCK and MCR (pins 15 and 16, which are tied together). Frequency and timing are controlled via nearly identical circuitry as is used in the "sound" lane. Frequency and timing are referred to in the schematics as the "Voice Clock".

Reset signal
The reset circuit is pretty simple. A 470uf/50V cap charges when power is applied. Once charged, the originating 5VDC power is twice inverted and cleaned up via a Schmitt Trigger at U1, and finally presented to the ~RESET signal (pin 40) of the 6502.

Test button
The test button, located on the upper left side of the S&S board, grounds pin 17 of the 6532 RIOT. After reading the RIOT data, the 6502 process then plays the appropriate test sound, which varies by game.

SC-01 pinout

Pin Number(s)	Signal Name	Signal Purpose
1	Vdd	Input Voltage
2-3	I1, I2	Instantaneous pitch adjustment. Will change pitch of phoneme being spoken.
7	S	Strobe to indicate a phoneme code is ready
8	~A/R	Acknowledge receipt of phoneme strobe, indicate completion of phoneme processing
9-14	P5-P0	Phoneme number select (from fixed phoneme table)
15-16	MCK/MCR	External Clock Signal (probably used to alter phoneme pronunciation via varying the clock)
20-22	CB, AF, AO	Audio Output
18	Ground	Ground

4.16.3.3 Sounds and Speech board DIP switch settings

The Sound and Speech board has a bank of DIP switches. For at least Black Hole, the function of these switches is as follows:

DIP-1 - Used in self-test only
DIP-2 - Not used
DIP-3/4 - Attract mode speech frequency
- OFF/OFF - disabled
- ON/OFF - attract mode speech every 10 seconds
- OFF/ON - attract mode speech every 2 minutes
- ON/ON - attract mode speech every 4 minutes
DIP-5 - ON = background sound enabled, OFF = background sound disabled
DIP-6 - ON = all speech enabled, OFF = all speech disabled
DIP-7 - Not used
DIP-8 - Not used

4.16.3.4 Sound "Locks Up" after certain switch closures

The long since obsolete, pricey, and hard to find SC-01 speech chip. This one is an SC-01-A, said to be a little beefier.

This problem may be caused by a malfunctioning or missing SC-01 (or SC-01-A) speech chip.

Games such as Black Hole, Mars God of War, and Volcano utilized the SC-01 phoneme speech chip. These games require a working SC-01 to be present, not only for the speech portions of the sound, but for the sound to not "lock up" after the first time that a speech call is made. The CPU relies on an interrupt from the 6532 RIOT to restart sound command processing. That interrupt originates from an "all done" signal from the SC-01 speech chip (shown as ~A/R in the schematics, SC-01 pin 8). If the RIOT never receives an "all done" signal (at PB7) then it will not interrupt the processor and no further speech or sound will be created.

It is also possible that the 2N2222 at Q3 has failed, not allowing the interrupt signal to reach the RIOT. Q3 inverts the ~A/R signal and conveys it to the RIOT as A/~R and also to the MPU as a non-maskable interrupt (U3 6502, pin 6).

4.16.3.5 Game background sound continues after game over

This has been noticed in "Mars, God of War" predominately, but other System 80 games that use the Speech and Sound board may exhibit similar symptoms.

The cause of the problem is MPU DIP switch 25. The switch MUST be ON, as noted in the manual. Even if the switch appears to be "on", buzz across the switch solder pads on the back side of the board to ensure that the switch has not failed. Gottlieb sometimes used "rocker" switches, which seem to have a high failure rate.

An "On Target" newsletter from June, 1981 discusses something similar to this problem.

4.16.3.6 Sound is "garbled" or phonemes appear jumbled

4.16.3.7 Using the MA-483 Sound Amp Board on a Sound and Speech Board

Gottlieb® MA-483 Piggyback Board

Gottlieb® Sound and Speech Power Supply with components highlighted

If using the MA-483 sound amp board on a Sound and Speech board, or if the sounds only System 80A sound board is going to be used, the factory Sound and Speech power supply cannot be used without modification. The reason is because the original LM379S amp is powered by 30vdc, and the TDA2002 amp on the MA-483 only needs 16vdc. If the TDA2002 was powered by 30vdc, it would be destroyed.

The modification is quite simple, and is done by replacing only two components (R1 and CR1). R1 is 430 ohm 1/2 watt and CR1 is 1N4751A 30v 1 watt zener diode. R1 should be replaced with a 1.5Kohm 1/2 watt resistor and CR1 should be replaced with 1N4746A 18V 1 watt zener diode.

4.16.3.8 Replacing the Obsolete LM379S Amplifier with a Modern Amplifier

This information originally published by J. "kirb" Kirby. Additional pictures and some editing provided by Chris Hibler. Used with permission.

Gottlieb System 80 Audio Amp Replacment...why?

Gottlieb® System 80 Sound & Speech Board as used on Mars, God of War, Black Hole, Haunted House, Volcano, and some video games

The Gottlieb® Sound and Speech board uses an LM379 or LM379s audio amp in the final amplification section. This amp became hard to find around 1983. Gottlieb® provided an alternative for this amp (see prior section) and discontinued using the Speech and Sound board further.

Their solution was to buy a piggyback board from Gottlieb® that used an LM2002 or a TDA2002 amp. But the LM2002 or TDA2002 amps require 16VDC to operate (instead of the 30VDC used by the LM379). This necessitated a change to the sound board power supply. There were many components to replace or remove, not to mention that you would have to make the piggyback board yourself.

SOLUTION? Find a newer amp that required fewer components. A replacment amp can be put together using only the following parts which can be easily sourced.

LM1875T Audio Amp
14 pin DIP socket
Heat sink
Heat sink compound

Once you've sourced these parts, a replacement amp is easy to construct and only requires removal of the old LM379 amp and addition of one jumper (to provide 12VDC, covered later).

Let's start with the basics. System 80 games used 4 different sound boards. This amp replacement applies only to the Sound and Speech board used in Mars: God of War, Black Hole (domestic version), Haunted House, Volcano, Devil's Dare, Caveman, Rocky, Q*bert's Quest, Super Orbit, Royal Flush Deluxe (early production), Amazon Hunt (early production), and video games like Q*bert.

LM379 Audio Amp Testing

First of all, is your amp really bad? Basic tests to identify a failed amp...

With the game on, turn the volume pot up as high as it will go. Do you hear a hum? This is normal and is an indicator that your amp is working.
Check the voltages at the sound board. 30VDC is required to power the amp. Verify that this is working correctly or your amp won't work at all.
Make sure the speakers are connected and working right. You can test speakers using a "D" size battery. Briefly connect the battery across the speaker and you should see the speaker's cone push out. Do this for only a second or two...speakers don't like DC voltages.
Make sure the volume adjustment pot is connected correctly and working properly. A dirty pot will make sounds junky, but they usually don't completely fail. You can "twizzle" the pot to remove oxidation that may have formed on the internal conductors.
Headphones can be used to see if the sounds are getting to the amp. Connect one of the headphone conductors (the one closest to the headphone "handle") to ground. Connect one of the other two headphone conductors (assuming stereo headphones) to the center leg of R15 or R16. You should be able to hear sounds that the board is making through the headphones. Your amp is probably bad if you can hear sounds at R15 or R16, but not through the speakers, assuming you've tested the speaker to be good and you have 30VDC power at the sound board.

LM379 Audio Amp Replacement Procedure

Mark the "top" of the heat sink so you can later determine orientation of the original amp should this be necessary. Pin 1 of the amp can't be identifed without removing the two screws that secure the finned heat sink to the chips integrated heat sink.

Remove the LM379 amp and heat sink assembly from the board. Desolder all 14 pins and pull the amp off the board. The LM379 heat sink may be soldered to the board so you'll need to remove that solder too. Be forewarned, the solder pads are delicate and easily damaged. Note how the LM379 is upside-down in relation to other chips on the board. This will be important later.

Building the New Amp Assembly

Solder the new amp to the 14 pin DIP. Use the diagram below as a guide. The pinouts are as follows:

Amp Pin	Socket Pin	Purpose
pin 1	pin 9	+ amp input
pin 2	pin 8	- amp input
pin 3	pin 4	Ground
pin 4	pin 10	Audio out
pin 5	pin 1	Vcc (+30VDC)

It will take some fancy bending to connect all of the amp legs in a way that they do not touch one another, but it can be done. It is important that the amp stands straight up and that the pins don't touch each other. See the diagram below for better info. Don't worry about the 12VDC connection right now. We'll connect that later.

Pinout schematic to attach the LM1875 amp to a 14 pin DIP socket

One Tech's Implementation (Heat Sink Added Later)
Front side.
Rear side.

Attaching the heat sink

First, yes, you need a heat sink. Audio amps run hot. Without a heat sink, the amps life will be dramatically shortened.

Mount the heat sink to the amp/socket assembly. You may have to modify your heat sink so that it doesn't contact anything but the LM1875 amp.

Heat sink compound should be spread on any metal to metal surface that is to conduct heat. This will improve the heat sink's efficiency and is a must on this device to work right. Without the compound, the amp will overheat and shutdown. It may even be damaged.

Kirb's original completed assembly
Side view.
Front view.

The Final Steps

The completed assembly, mounted to the Sound and Speech Board.

Solder the new amp assembly directly to the board. Normally you would use a socket, but that will lead to audio problems. It is better just to solder it into the board.

ACHTUNG! Remember that pin 1 of the amp solder pads on the board is upside-down relative to every other IC on the board, and you need to install your new amp assembly with pin 1 "down". Make sure this is done right. There is a 1 screened to the back of the board that should help you orient the assembly.

Connecting 12VDC to the amp.

Now that the pins are soldered to the board, we have to connect 12VDC to pin 14 of the socket. This is easily found at the positive (+) side of C39. This 12VDC biases the +IN so that it won't saturate. Your amp will only work for about 30 seconds without this 12VDC.

Check all of your work one more time, then test the amp and see what you get. If you've followed these steps correctly, your sound should be loud and clear!

4.16.4 System 80A Sound Only Board

4.16.4.1 Sound Cutting Out / No Sound

Piggyback Amplifier Board w/ Cracked Header Pins

Gottlieb® had a tendency of using single-sided boards for their "piggy back" / daughter boards, and these boards are susceptible to cracked header pin solder joints. The MA-483 amplifier board is no different. If the sound appears to be cutting out or their are no sounds at all, the header joints on the MA-483 may have developed cracks.

Before suspecting the daughter board header joints, review the Basic Sound Troubleshooting section located in the "General for all games" section.

4.16.5 System 80A / 80B Sound with Piggyback Board

The System 80A / 80B sound board is nearly the same as the first generation System 80 sound only sound board. It utilizes a 2716 EPROM versus a masked ROM like the System 80 sound board. This was potentially due to the Harris 7643 masked ROM being obsolete. The 80A / 80B board does not use a test button.

Like the System 80 sounds only board, this board has 2 obsolete chips on it, the CPU (6503) and the RRIOT (6530). On the plus side, these boards did not get destroyed nearly as much as the original System 80 sounds only boards (plugging the System 80 sounds only board into a System 1 game would destroy it in a very short time).

4.16.6 System 80B Sound Board (MA-766)

This sound board has two independent 6502 CPUs. One exclusively drives a DAC (digital-to-analog converter). The other drives the speech chip, Orator, (not used for speech on this generation of sound board, but it is used to generate sounds), and two AY-3-8912 sound chips. Each is pretty much independent, sharing essentially only the sound select lines, the reset signal, and the output section. The gates of one TTL chip are used by both 6502s to communicate between the subsystems via the NMI signal to each 6502 among other functions. The ROMs, CPUs, and accessory chips, are all localized to the particular subsystem other than the inter-processor communication just mentioned.

Note that the LED and test switch are only relevant for the CPU that operates the speech and synthesizer chips, not the chip connected directly to the DAC. With this in mind, it should be possible to troubleshoot this board using a divide-and-conquer approach. For instance, if the LED isn't blinking in/off at about a 50% duty cycle, then the subsystem for the 6502 that controls the LED has to have a fault, but the other subsystem may be fine.

Since this sound board is really just a more complex MPU board, or single board computer, the usual diagnostic steps are in order.

Verify the ROM images are valid.
Ensure that the reset signal begins low and then transitions to high after about 1/2 second.
Ensure that the external clock signal is present at pin 37 of both 6502 processors.
Ensure that the data lines on the 6502 (pins 33 through 26) are pulsing.
Ensure that the address lines on the 6502 (pins 9 through 20, 22 through 25) are pulsing.
Ensure that the external clocks are pulsing at pins 3 and 39 of the 6502 processors.

4.16.7 System 80B Sound Board (MA-886)

A repaired MA-886 sound board. Resistors R15, R16, R14, and R13 (top to bottom) are shown with blue Sharpie marks on their left ends, the end to probe when testing the sound channel. The other two components in the rectangle are high frequency ceramic filter capacitors which rarely fail.

The MA-886 is generally the same board as the MA-766 sound board. The main differences are that the MA-886 uses .156" header pins instead of edge connections, the Orator chip was no longer used, and SW1 was abandoned.

Troubleshooting this board is nearly identical to the steps noted above for the MA-766 board.

One useful aspect of the board is that 4 channels of sound are summed by the LM324 at B1 before final amplification offboard.

Channel 1 is the output from the 7528 DAC at E2. An example of the sounds that this channel makes is the "Destroy Alpha One" and other voices used in Robowar. This channel also contributes the "skittering" sound when the ball pass the rollunder on the ramp wireform and the "energy pulse" sound when the ball rolls over any of the top 4 lane rollovers. This signal passes through R16 before summing.
Channel 2 is the output from the AY-3-8913 at H4. This signal passes through R14 before summing.
Channel 3 is the output from the AY-3-8913 at K4. This signal passes through R13 before summing.
Channel 4 is the output from the MF-4 at E5. This signal passes through R15 before summing.

Placing an oscilloscope probe on the end of these resistors attached to the sound generating circuitry for that channel should show a purposeful signal (versus noise). If not, it's a good bet that one of the devices in that sound channel has failed.

4.17 Flipper Problems

Placeholder for System 80 Flippers

Gottlieb® System 80 flipper assemblies are very well engineered, and very little goes wrong with them. Due to this, they are considered to be the "Sherman Tanks" of flippers.

Gottlieb® System 80/80A/80B games other than Bone Busters utilize the traditional "fat" flipper bat design (similar to Bally, Chicago Coin, and Stern), which is a carry over from the last flipper design of Gottlieb® System 1 games. The 3" plastic flipper bat is technically called a "flipper island" (Gottlieb® part number A-13150), and uses a 3/8" wide rubber ring versus the more common 1/2" wide rubber all other manufacturers use. Another anomaly regarding Gottlieb® flippers from this era is that they are the only flipper design that uses an upper and lower flipper bushing system. Neither bushing protrudes through the playfield.

System 80/80A/80B flippers (other than Bone Busters) use an A-17875 (standard), A-24161 (stronger), or A-20095 (strongest) dual wound flipper coil. The general design is a coil with two windings, the "power stroke" (low resistance) and "hold" (high resistance) windings, just like most other flipper coil designs. However, only a single diode is used with this serial winding design versus others which employ a dual diode, parallel winding design. Here's how it all works. When initially engaged via the flipper cabinet button switches, both the power stroke and hold windings receive power, however, the hold winding is bypassed or shorted by the end of stroke (EOS) switch (electricity follows the path of least resistance). As the flipper actuates and opens the EOS switch, the power is then transferred to both the power and hold windings (the resistance sum of the two windings), creating a very high resistance. The high resistance allows the coil to remain turned on without creating stress on the low resistance power winding. Hence, the coil can stay turned on indefinitely in theory.

Gottlieb® System 80/80A/80B flipper systems do not use a flipper relay per se. Flipper power flows through switch pairs on Q & T relays located under the playfield, along with other non-computer controlled coils like slingshots.

For problems and resolutions for the flippers used in Bone Busters, please see the Flipper Problems section in the Gottlieb System 3 repair guide.

4.17.1 Flippers Won't Work at All

Like any flipper issue, it has be determined whether the problem is electrical or mechanical in nature. Start with obvious first. Look for broken wires at the flipper coil, EOS switch, and cabinet switch first.

During visual inspection, make certain that the flipper EOS switch is closed (use an ohmmeter to determine this), and the switch pairs on the tilt and game over relays are properly gapped and closed. Equally, inspect the switch pairs to see if any of the switch blades are broken or missing their contacts.

Since high current passes through all of the switches which enable the flipper, any of the switches may be suspect. It is somewhat common for games which have been sitting dormant for years that the cabinet switch and / or EOS switch become so fouled, the flipper will not budge at all. The remedy is to file these switches with an ignition file. See the How to Properly File Switch Contacts section. A flexstone will not work for this job, as the cabinet and EOS switch contacts are very hard.

Inspect the cabinet switches for broken female spade connectors where the cabinet wiring attaches to the switch.

Finally, look at the flipper plunger / link assembly. The plunger link is a hefty plastic piece which inserted into at hollowed out end of the flipper plunger. The link is connected to the plunger with a small roll pin. The link can break or the roll pin can fall out, due to vibration. If the link is no longer connected to the plunger, the flipper will not move at all. Refrain from trying to engage the flipper with the cabinet switches. Continuing to enable the flipper coil will stress the coil, because the EOS switch will not open, transferring power. The end result is an overheated flipper or damaged flipper coil.

4.17.2 Flippers are Weak, Sluggish, or Erratic

A Gottlieb® System 80/80A/80B Flipper Plunger/Link/Crank Parts. Note the "hogged out" part of the link

Worn Flipper Link
The design of the flipper crank and flipper link / plunger is peculiar to Gottlieb® games. Gottlieb® games from the System 80/80A/80B era use a very meaty flipper link, which does not have a pivot point between it and the connected plunger. To achieve the necessary fulcrum, the flipper link has an oval opening at the point where the link and flipper crank connect. The two pieces are simply connected with a roll pin protruding through the two parts. Over time, the roll pin can sometimes cut into the opening in the link, and the roll pin will catch as the flipper crank pivots. The result is a weak flipper or a flipper which does not return to the at rest position. Using a roll pin punch tool, remove the roll pin, and replace the flipper link / plunger assembly. Pay close attention when installing the roll pin into the new plunger link. It is very easy to cut into the link with the roll pin, deeming the new link / plunger worthless.

Flipper Crank Installed Incorrectly
Reassembling a flipper bat / shoe incorrectly can result in a weak flipper. Before tightening the two set screws which hold the flipper shaft in place, make certain that the flipper crank is centered equidistant between the upper and lower flipper bushings. If placed too close to the upper bushing, it will "sandwich" the upper bushing between the crank and bat. If placed too close to the lower bushing, the crank will have friction between it and the lower bushing. The end result is a weak flipper or a flipper which does not return to the at rest position.

Fouled / Pitted Switch Contacts
Fouled switch contacts can reduce current, which in turn reduces power / strength. Make certain that the EOS switch, cabinet switch, and switch pairs on the game over (Q) and tilt (T) relays are all clean and not pitted. Filing the contacts with an ignition file will remedy the problem, provided that the contacts are not heavily pitted.

Bad Connection to Cabinet Switch
Another problem related to the cabinet switches is the female spade connector used to connect the cabinet wiring to the switch. These spade connectors can sometimes become sloppy or break. In most cases, the break is not evident, until the connector is removed and reinstalled on the cabinet switch tab. The spade connector can be removed and a new one crimped on, or the better solution is to solder the cabinet switch wires to the tabs on the cabinet switch.

Worn Flipper Plunger
A mushroomed flipper plunger can create excessive drag within the coil sleeve. When replacing the plunger / link, replace the coil sleeve and coil stop too.

Broken Coil Stop
The coil stop "slug" is pressed into the coil stop bracket. It is somewhat common for the slug to become detached from the coil stop bracket. The coil stop slug will then be "free floating" within the coil sleeve. This can create some interesting problems, but the most noticeable are reduction in flipper power, decrease in flipper stroke or both.

Incorrect Flipper Rubber Installed
Gottlieb® used 3/8" wide rubber on flippers. It fits perfectly into the groove on the plastic flipper bat. Everybody else used 1/2" wide rubber, and that tended to get installed on the Gottlieb® games, too. When a 1/2" wide ring is used, it almost fits, but because of the groove, it will present a funny angle to the ball instead of a flat plane. The results are either air balls, or the flipper will smack the ball downward into the playfield.

Cracked / Broken Plastic Bat
Sometimes the flipper bat cracks. Replacements are available. The screw that holds the plastic flipper bat on the metal shoe is located on the underside of the flipper. Loosen the two set screws on the flipper crank, and the shoe and bat will come free.

Broken Hold Winding
Erratic flipper function is defined as a flipper which will not remain in the up (hold) position when activated. The flipper will move rapidly up and down as if it is "machine gunning". This is typically the result from a break in the hold winding right at the flipper coil lug. One resolution is to locate the broken coil winding (this will be the thinner of the two windings), and unwind one turn from the coil. This can be accomplished if the side of the winding is not connected to the common lug of the flipper coil. Note that the power winding cannot be unwound if it breaks. This is because the power winding is wound on the coil bobbin first, and is located beneath the hold winding. Once one turn of the hold winding is unwound from the coil, the excess length must be shortened. After the correct length is determined, the portion of the winding which will be soldered to the coil lug must have its insulation stripped off. The red or green hue on the coil winding is actually a thin insulation, which is used to keep the winding from shorting to adjacent windings. Gently scrape the coating off the winding by using an exacto or utility knife, exposing the copper wire of the winding. Then wrap the uninsulated winding around the coil lug, and solder it. If a single winding cannot be removed from the existing coil, complete coil replacement is the solution.

4.17.3 Flippers Will not Return to at Rest Position

The EOS switch assembly is actuated by the pointed part of the flipper crank assembly. This is a metal-on-metal contact point. Due to the design of the flipper crank, it will eventually wear a hole in the EOS actuating blade. The fix is to replace the EOS switch assembly. About halfway through the System 80B games (around TX-Sector or so), the EOS switch was slightly relocated, and a modified flipper crank actuates the switch with a roller. An MA-988 or MA-989 kit can be purchased to perform this upgrade on any System 80/80A/80B game.

As mentioned in the previous section, the flipper link can become cut by the roll pin which secures it to the flipper crank. This can also cause the flipper to not return to the rest position.

Also mentioned in the previous section, the flipper coil stop slug can detach from the coil stop bracket, causing the flipper not to return completely.

If the flipper return spring has become stretched or is no longer connected to the flipper crank or coil stop anymore, the flipper will not return properly.

4.18 Pop bumper problems

Corrected/Modified Gottlieb® System 80/80A/80B Pop Bumper Driver Board

The pop bumpers on all System 80 / 80A / 80B games are controlled by an under playfield mounted board known as the pop bumper driver board (PBDB). Remote pop bumper driver boards are unique to Gottlieb® System 80 games. No other manufacturer made this design decision. The reason Gottlieb® did this is probably to supplement the number of coil drive circuits as well as to solve the common problem of pop bumpers locking on with subsequent damage to the games components.

Each pop bumper has its own board. Each board provides a consistent, strong pop regardless of how long the spoon switch is activated, and ensures (when working properly) only a single pop per actuation of the spoon switch.

These boards are single-sided construction, where the traces are located only the solder side of the board. Due to this construction, the solder connections crack easily. Reflowing the solder of the header pins on any suspect boards is recommended to ensure a good mechanical and electrical connection. The components should be inspected as well, because they can also have cracked solder connections that will need to be touched up.

If the pop bumper fires but does not score, examine the secondary switch on each pop bumper to see if it needs cleaning or adjustment. This switch is part of the switch matrix, and can be tested by manually pulling the pop bumper rod and ring down to activate it.

4.18.1 Updating the Pop Bumper Driver Board

Gottlieb® issued a service bulletin to correct a design error with the PBDB. A great many of these boards were delivered in games prior to correcting the design at the factory. Examine the PBDBs to ensure that they have been updated. See the pictures below, noting the differences. A dead giveaway would be the lack of a jumper to replace CR1.

System 80/80A/80B PBDB Before/After Modification
Unmodifed PBDB
Modifed PBDB

Gottlieb® System 80/80A/80B PBDB Update

Should your PBDB require update, follow this procedure:

Acquire the following parts
- Cut to length .156 Molex male header pins with locking ramp (you'll need a 6 pin length)
- 100uf/10V electrolytic capacitor (C4)
- 4.7uf/10V capacitor (C3, tantalum or electrolytic, may be axial or radial)
- Jumper material (use the remaining leg cut from C4 when you install it)
Remove CR1, C3, and C4
Replace the Molex connector or reflow the solder on each header pin
Install C4 (100uf/10V) with the negative side facing the male header pins
Use the remaining part of the capacitor leg from C4 as a jumper to replace CR1. Any jumper wire will work...the cap leg is convenient, available, and looks professional when installed nice and straight.
Install C3 (4.7uf/10V), reversing the original polarity so that the positive side faces the jumper just installed and the negative side faces the nearest board edge. Note that C3 may be axial (leads from both ends along the components "axis") or radial (leads on one end of the component). The board is designed to accept either style.
Ensure that the large can transistor (2N6057, 2N6059, PMD10K40 or PMD10K60) solder joints are solid and that the bolted end is making good contact with the PCB trace.
Test the large can transistor...
- DMM set to "diode test"
- Black lead on the nut that secures the transistor
- Red lead on each leg of the transistor
- A measurement between .5 and .7 should be seen. Readings significantly outside of these ranges indicate a failed transistor which should be replaced.
Examine the remaining solder joints on the board to ensure good solid joints and no lifted traces. Note that the trace between the jumper that replaces CR1 and R2 is particularly susceptible to damage and if broken, will cause the associated pop bumper to lock on.
Reinstall the PBDB and test.

There is an update for the PBDB that gives the board a bit more "pop". Simply replace R1 (1.5Kohms) with a 10Kohm 1/4W resistor and replace C1 (0.01mfd) with a 1 mfd 100 volt (non polarized) capacitor.

Also, to avoid random, uncommanded pops caused by "noise" on the switch line, you can add an electrolytic capacitor to the solder side of the board. Use a 4.7 mfd 16 volt radial capacitor (both leads on one end). Solder the negative lead of the capacitor to pin 4. Solder the positive lead of the capacitor to pin 5.

4.18.1.1 Replacing the 2N6057 with a TIP-102

Tip102 on PBDB

Closer view of a TIP 102 installed

The 2N6057 used on Gottlieb games is obsolete, so it is hard-to-find and expensive. A cheap and effective substitute for the 2N6057 as used on the PBDB is a TIP102 transistor. It's not the most elegant "hack", but it works well.

4.19 Drop Target Problems

4.19.1 Early System 80 / 80A Drop Target Removal

For now, please review the drop target removal guide available at PAPinball.com.

4.19.2 Later System 80B Drop Target Removal

This is a stub

4.20 Vari-Target Problems

The single largest problem with vari-targets is adjusting the spring tension, which returns the vari-target to the at rest position. The spring can be adjusted by hooking it to one of two screws which hold the spring in place. In most cases, there is only one screw, but two screw holes are placed 180 degreees from one another within the vari-target frame. Spring adjustment should be made so that the vari-target barely returns to the home position, when the playfield is upright (resting against the backbox). Once the playfield is placed in its proper position, gravity will help with the extra "bump" that the vari-target needs to return home.

Also, the switch leaves of the vari-target, which "ride" along the rivet board need enough tension to make good solid contact with the rivets. Since it's impossible to bend the switch leaves closer to the rivet board with the rivet board in place, removal of the vari-target rivet board must be done to make this adjustment.

Vari-targets seldom require adjustment as they were correctly adjusted at the factory. It is possible to move parts of the mechanism so that the switch no longer comes to rest on a rivet when the vari-target "gear" is stopped by the reset relay armature.

Vari-targets are a rare example of where lubrication helps the operation of the mechanism. A thin film of lithium grease on the rivets helps the switch blade "wipe" cleanly across them. Like Brylcreem, "a little dab'll do ya". Note: That's humor son...Brylcreem is not a suitable lubricant...for pinball machines. :-)

4.21 Roto Target Problems

By the time System 80 games first came out, the roto target was a dying assembly. The believed reason is due to the amount of playfield "real estate" in which it used underneath a playfield. Circus is the only System 80 game which used the roto target.

5 Game Specific Problems and Fixes

Black Hole issues have been moved to the dedicated Black Hole page.

5.1 Alien Star Game Start Failure

Alien Star has a major fault when running the original 689 code. For the game to properly start, one ball must be in the trough and one ball in the outhole. If both balls are located in the trough, only the single trough switch will be closed, and not the outhole switch. When only the trough switch is closed, the game *thinks* that only one ball is installed, (2 balls total are needed), and will do absolutely nothing.

It has not been verified, but running 689A code may resolve this issue.

5.2 Haunted House Upkicker Plastic Tube Mounting Bracket

Mounting bracket for the plastic tube.

The metal mounting bracket that secures the longer plastic upkicker tube to the main playfield breaks its tabs (ears) off allowing the tube to flop around loose. This bracket is actually an electrolytic capacitor mounting bracket for computer grade capacitors. If broken, Mouser Electronics sells this item as part number 539-VR4. The OEM part is a VR4, which is manufactured by Cornell-Dublier (Mallory).

5.3 Devil's Dare - All Displays out except status display

Burnt 200 Ohm resistor on +60VDC display power line

Replacement 200 Ohm 2 watt resistor on +60VDC display power line

If the game in question is a Devil's Dare, and all of the displays are out except for the status display, and the +60VDC is present at the power supply, but not at the displays, the following may apply. Some Devil's Dare games, (it is unknown exactly which ones at this point), have a 200 ohm resistor installed in series with the +60VDC power line for the displays. The resistor is located on the lamp insert board, just behind the lower right 6 digit display. The resistor is soldered to two solder eyelets, so replacement is relatively easy. It is unknown what the purpose of this resistor is, but it is fairly common for the resistor to overheat and potentially fail. The recommended replacement for this is a 200 ohm 2 watt resistor.

There is no information regarding the value or placement of this resistor in the Devil's Dare manual / schematics.

5.4 Mars God of War (MGOW) - Background Sound Continues After Game is Over

If the background sound continues after the game is over, this may solve the issue. Even though the manual states that dipswitch 25 on the CPU board is not used, try placing switch 25 in the "on" position.

5.5 Volcano Kick Back Ends Prematurely

The Volcano kickback mechanism.

The kickback mechanism in Volcano, once enabled by a playfield feature, remains available until the player uses the feature by pressing the green cabinet button in front of the flipper switch. The game knows that the feature has been used by sensing the switch at the rear of the mechanism. As the plunger pulls in, the normally closed switch is opened by the ring on the rear of the plunger. If this normally closed switch isn't "making" solidly, the game will think that the plunger has pulled in. The kickback feature will be considered used and hence disabled.

The behavior looks like the feature has timed out prematurely.

5.6 Games with Playfield Windows: Black Hole, Haunted House, Genesis, Monte Carlo, etc.

Playfield windows use foam washers that provide "counter force" to help keep the window flush with the playfield. If the window isn't flush with the playfield, the "lip" of the sunken window in its mount will cause airballs and/or the edge of the playfield will wear excessively.

After a couple decades, springy foam washers turn into hard, crumbly foam washers. Weatherstripping ("beer seal"), cut really small, works in a pinch, but the Pinball Resource stocks the proper foam washers.

6 Repair Logs

Did you do a repair? Log it here as a possible solution for others.

6.1 Game Displays 000000 On Power Up and It's Not The Slam Switch

If you power the game on and all of the displays immediately display all zeros without strobing the problem is usually with the slam switch. However, if the slam switch modification has been done or the slam switch is working properly there is a problem with the switch matrix.

I had this problem on my Haunted House machine. I finally found that chip Z15 (7432) was bad.

I was fixing a kicker solenoid on the playfield, the playfield was still in the machine and fully in the upright position. While I was soldering the wire to the new solenoid I did not adequately protect the components below from a solder drip. Well, I did have a solder drip that landed right on a pop bumper driver board connector and shorted the connector. The short caused more than just this problem but for this narrative we will restrict to the slam/switch matrix problem.

Reading in other materials I recognized the problem as the slam switch issue. I used a logic probe to test other components and found the CPU board working, mostly as it should except for acting like the machine was slam tilted. There was little written about the problem outside of the slam switch. I decided to check the matrix by doing a diode check on all of the diodes in the switch matrix. When I did this, I found that many of the diodes were testing bad. These were being tested with the board removed from the machine.

Having replacement diodes in my parts drawer I decided that these must have gone bad during the short. I began unsoldering a few of the diodes. Once disconnected from the circuit board I remeasured the removed diodes and found the correct values on my meter, they were not bad. I then noticed that the bad diodes were all in the same row on the switch matrix. They all traced back to the Z15 chip. I replaced the Z15 7432 and the problem was resolved.

6.2 Game Displays a single 0 or 1 on Displays

If an 80A game does not boot and displays just a single zero, just a single 1, or alternates between a single zero and single 1, this may indicate one or more bad IC(s) on the MPU:

CPU
Z7
Z8

The CPU itself may still output data that can be picked up with a logic probe, but still might be bad.

Animation of symptom of alternating 0 and 1

Symptom of the displays showing a single zero

6.3 Testing the Q relay

Had a problem with my Black Hole - Q relay didn't activate. Played a bit with wires, did ground mods, .. After a while I noticed it did work but didn't stay enabled - at the start of a game it closed, 1 coil (ball drain) kicked and the Q relay deactivated again. Noticed this with the playfield in up position, no pinballs installed. Finally tested with playfield down - and pinballs installed - suddenly the behaviour was different: ball drain coil kicked and then the next coil also that put a coil in the shooter lane. Seems the Q relay did work all this time, but will only stay enabled when pinballs are installed in the game ?!

6.4 Results of a locked on coil

Melted coil sleeve

Burnt paper

If a coil locks on (due for example to a bad driver board transistor), the coil will burn. Here is a coil which had locked on. Note the burn marks on the paper wrapping and the melted coil sleeve, which prevented the coil plunger from moving through the coil. The resistance of this coil was 0.9 ohms (the specified resistance for this particular coil should be 3.35 ohms), also indicating it's bad due to an internal short (adjacent windings shorted together due to overheating the coil wire insulation).

6.5 Black Hole top rollover switches

When Black Hole serves a ball, it must go through the top rollovers before hitting any other switch. The playfield design ensures this. But if it doesn't (I had the glass off and started testing some other feature), things get very weird: suddenly, I seemed to be in a 3-ball, 4-player game with some of the score displays blank.

This isn't usually a problem in practice but it is worth making sure that the three top rollovers have clean switches.

6.6 Replacing the 80B 5V pot

I got a Monte Carlo and replaced the 5V adjustment pot on the regulator. It was working fine. After the old one had been chopped off, I discovered it was the same as the new one. It had already been replaced! A bunch of rework on the regulator, and ground mods on the transformer frame, should have been my clue.

6.7 80B sound doesn't work

I got a Spring Break and the sound didn't work. The LED didn't light in any predictable way, and the game put out a lot of white noise. At one point I thought I heard some sounds underneath.

Fortunately, I had a Monte Carlo sitting next to it where the sound did work. I spent some time trying to understand the problem, and finally just swapped all the socketed chips (three EPROMs and the "Orator" speech synthesizer). The problem followed the EPROMs, not the board. Ultimately I replaced all three ROMs, although it seems likely that only one was likely bad.

Note that the sound board has two separate CPUs, and only one controls the LED, so it is likely one of the two EPROMs associated with that CPU that is actually bad.

6.8 Two flash lamp problems

Monte Carlo has four pairs of flashers controlled by "lamp" drive transistors, stepped up by under-playfield transistors. On my game, I had two unrelated problems with different flash banks.

The two sockets by the roulette wheel were missing their lamps, and the under playfield was a little burned near where the lamps had been. Apparently they were locked on, and someone had pulled the bulbs rather than fix the problem. I replaced Q17, which was out of spec according to the measurements on this page. I didn't replace the under-playfield MJ2955 because it seemed to measure correctly. One down, one to go.

The other flasher, the two on the left side, just didn't work. Lamp bulbs were fine, and all transistors seemed OK by the tests given above. I checked for continuity in the wiring and even tried grounding the transistor side of the circuit, but no lamps lit. Finally, I pulled the plastic off to take the bulb out (to measure at the socket) and I found that the two lugs of the socket were bent and touching! So the lamp was a short, but because of the resistor, not short enough to blow the fuse or fry the transistor. A little bending back seems to have fixed it. -- ts4z (talk) 16:29, 7 February 2014 (CST)

6.9 80B Display has garbage on one display glass

Chicago Cubs had garbage/nonsensical characters on just the lower score display. I found chip U2 (type 10939) which controls the lower display to be bad. Replacing the chip cured the problem. I also installed a 40 pin IC socket for the replacement chip. If by chance you encounter the same symptom except that it is on the upper display, then chip U1 (type 10939) is bad. U1 controls the upper score display.

6.10 Rebuilt 80/80A Power supply, solenoid fuse blows on power up

If a System 80/80A power supply has been rebuilt and the solenoid fuse blows as soon as the game is turned on, take a look at the power supply capacitor at C1. It might have been installed in the wrong direction. Make sure the (-)side on the capacitor matches the (-) side notated on the PCB.

6.11 Haunted House ten thousand digit out on several displays

Encountered the ten thousand digits missing on three displays: player 1, player 3, and bonus display. Tried several known good cpu boards and problem remained. Tried swapping displays and problem remained. I traced the problem to the wiring harness on the main playfield. At the playfield mounted transistor Q2, the transistor mounting bracket had cut into the wiring harness. I repaired the harness with electrical tape and routed the harness farther away from that bracket with a couple of wire ties. Problem fixed and all displays are now working correctly.