Gottlieb System 80
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1 Introduction
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.
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.
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.
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.
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 | Notes |
|---|---|---|---|---|---|
| The Amazing Spiderman | 05-1980 | 7625 | 653 | Sound only | |
| Panthera | 06-1980 | 5220 | 652 | Sound only | |
| Circus | 06-1980 | 1700 | 654 | Sound only | Ultra Widebody |
| Counterforce | 06-1980 | 3870 | 656 | Sound only | |
| Star Race | 08-1980 | 870 | 657 | Sound only | Ultra Widebody |
2.2 System 80 2nd Generation
| Title | Date of Release | Production# | Model # | Sound | Notes |
|---|---|---|---|---|---|
| James Bond | 10-1980 | 3625 | 658 | Sound only | |
| Time Line | 12-1980 | 3167 | 659 | Sound only | |
| Force II | 12-1981 | 2000 | 661 | Sound only | |
| Pink Panther | 03-1981 | 2840 | 664 | Sound only | |
| Mars God of War | 03-1981 | 5240 | 666 | Sound & Speech | First Gottlieb® with speech, lane change, and multi-ball |
| Volcano | 09-1981 | 3655 | 667 | Sound & Speech | Export games used sound only board |
| Black Hole | 10-1981 | 8774 | 668 | Sound & Speech | First Gottlieb® with 2-Level playing area, Export games used sound only board |
| Haunted House | 06-1982 | 6835 | 669 | Sound only | 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 | Production game and available as a kit for James Bond 007 |
2.3 System 80A
| Title | Date of Release | Production# | Model # | Sound | Notes |
|---|---|---|---|---|---|
| Devil's Dare | 08-1982 | 3832 | 670 | Sound & Speech | Export games used the sound only board |
| Caveman | 09-1982 | 1800 | PV810 | Sound & Speech | Pinball / Video game hybrid |
| Rocky | 09-1982 | 1504 | 672 | Sound & Speech | |
| Spirit | 11-1982 | 1230 | 673 | Sound only | Sound only, but used sound & speech board |
| Punk! | 12-1982 | 959 | 674 | Sound only | Sound only, but used sound & speech board |
| Striker | 11-1982 | 910 | 675 | Sound only | Sound only, but used sound & speech board |
| Krull | 02-1983 | 10 | 676 | Sound only | |
| Goin' Nuts | 02-1983 | 10 | 682 | Sound only | Sound only, but used sound & speech board |
| Q*bert's Quest | 03-1983 | 884 | 677 | Sound & Speech | |
| Super Orbit | 05-1983 | 2100 | 680 | Sound Only | Sound only, but uses the less populated sound & speech board |
| Royal Flush Deluxe | 06-1983 | 2000 | 681 | Sound Only | Sound only, but uses the less populated sound & speech board |
| Amazon Hunt | 09-1983 | 1515 | 684 | Sound Only or Sound Only | 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 | |
| Ready... Aim... Fire! | 11-1983 | 390 | 686 | Sound Only | |
| Jacks to Open | 05-1984 | 2350 | 687 | Sound Only | |
| Alien Star | 06-1984 | 1065 | 689 | Sound Only | 689A Denotes a revision in the ROM code |
| The Games | 08-1984 | 1768 | 691 | Sound Only | |
| Touchdown | 10-1984 | 711 | 688 | Sound Only | |
| El Dorado City of Gold | 09-1984 | 905 | 692 | Sound Only | |
| Ice Fever | 02-1985 | 1585 | 695 | Sound Only |
2.4 System 80B
| Title | Date of Release | Production# | Model # | Sound | Notes |
|---|---|---|---|---|---|
| Chicago Cubs Triple Play | 05-1985 | ~1365 | 696 | Sound Only | |
| Bounty Hunter | 07-1985 | 1220 | 694 | Sound Only | |
| Tag Team Pinball | 09-1985 | 1220 | 698 | Sound Only | |
| Rock | 10-1985 | 1875 | 697 | Sound Only | |
| Raven | 03-1986 | 3550 | 702 | Sound Only | |
| Rock Encore | 04-1986 | 245 | 704 | Sound Only | 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 | |
| Genesis | 09-1986 | 3500 | 705 | Sound Only | |
| Gold Wings | 10-1986 | 3260 | 707 | Sound Only | |
| Spring Break | 04-1987 | 3550 | 706 | Sound Only | |
| Monte Carlo | 02-1987 | 4315 | 708 | Sound Only | |
| Arena | 06-1987 | 3099 | 709 | Sound Only | |
| Victory | 10-1987 | 3315 | 710 | Sound & Speech | |
| Diamond Lady | 02-1988 | 2700 | 711 | Unknown | |
| TX Sector | 03-1988 | 2336 | 712 | Sound & Speech | |
| Robo-War | 04-1988 | 2130 | 714 | Sound & Speech | |
| Excalibur | 11-1988 | 1710 | 715 | Unknown | |
| Bad Girls | 11-1988 | 2500 | 717 | Sound & Speech | |
| Big House | 04-1989 | 1977 | 713 | Sound & Speech | |
| Hot Shots | 04-1989 | 2342 | 718 | Sound & Speech | |
| Bone Busters Inc. | 08-1989 | 2000 | 719 | Sound & Speech | Used 3 sound boards |
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 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 to a new page showing all of the System 80/80A/80B satellite boards.
3.3 Recommended Documentation
this is a stub
3.4 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.
3.5 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.
3.6 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 |
3.6.1 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.
3.6.2 Setting up a Game for Free Play
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
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.
The picture at left ties the center coin chute wire (Green-Orange-Orange) to the credit button wire (Green-Yellow-Yellow).
3.7 Power Supply
3.7.1 System 80 / 80A Power Supply
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 is very beneficial.
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.
3.7.2 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 for amplification
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.
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.
3.7.3 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.
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.
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
This board changed with Bad Girls. Edge connections were no longer used. Instead, .156" header pins were added to the board. The pic to the left depicts a System 3 aux. power supply. Although the System 80B and System 3 boards are slightly different, the pic is being used for illustration purposes at the moment.
3.8 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) 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 ROMs at both the PROM1 and PROM2 positions were masked ROMs. When only the single PROM1 position was used, EPROMs were 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.
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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.
3.8.1 1st Generation CPU Board
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.
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.
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.
3.8.2 2nd Generation CPU Board
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.
3.8.3 3rd Generation CPU Board
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.
3.8.4 4th Generation CPU Board (System 80A)
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.
3.8.5 5th Generation CPU Board (System 80B)
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.
3.9 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.
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.
3.9.1 Repurposed Driver Board Circuits
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.
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.
3.10 Auxiliary Lamp Driver Boards
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. 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 | 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 PF | 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 | Unknown | 1 of 2 |
| Spring Break | 10 | 20 | 680K Ohm | Special shot and shooter loop | Under PF | 2 of 2 |
| Arena | 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 | 10 | 12 | 680K Ohm | Playfield inserts | Unknown | 1 of 2 |
| Bone Busters | 10 | 20 (#67 flashers) | 680K Ohm | Backbox lamp insert | In backbox | (2 of 2) Uses 2N6043 |
3.11 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.
3.11.1 Sounds Only Board
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.
3.11.2 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.
3.11.3 Sound Only 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.
3.11.4 Sound Only Board with Piggyback
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.
3.11.5 System 80B 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.
3.11.6 System 80B 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.
3.12 Displays
3.12.1 System 80 - 6 Digit Displays
3.12.2 System 80A - 7 Digit Displays
3.12.3 System 80B - 20 Digit Displays
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 like Robowar and Rock. Variations included larger display characters, (as used in later games like Hot Shots or Big House for instance), and the use of .156 male header pins vice the card edge connector shown here. 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.
3.13 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.
3.14 Bookkeeping & Diagnostics
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)
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 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.
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.
4.2 The CPU / Driver Board 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
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 in the cabinet bottom.
It should be noted that 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 
Chaser Lamp Board Tie to Cabinet Bottom Ground Strip 
Cabinet Bottom Ground Strip
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.
4.3.1.1 Ground Improvements for System 80 at Ground Strip
This is a stub
4.3.1.2 Grounds Improvements for System 80A at Transformer Panel
This is a stub
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 80B at Transformer Panel - Rock to Monte Carlo
Ground connections used on System 80B games from Rock to Monte Carlo are probably the most unreliable style of ground connections Gottlieb® ever used. This type of System 80B ground connection consists of two small boards with two gangs of 9-pin male connections. These boards are fastened to the left side of the transformer panel's metal chassis. The problem with this type of ground connection is that the 9-pin female connection becomes loose, and in turn, ground connections become intermittent. One of the common symptoms of poor ground connections is when multiple solenoids are not functioning. If removing the 9-pin Molex plug from the ground board, rotating it 90 degrees, and reconnecting it causes the non-working solenoids to function, the ground connections are bad. Regardless of whether this simple test proves whether or not the ground connections are bad, it is highly recommended to improve the ground connections for future reliability.
The purpose of the ground upgrades is to remove the ground boards, which takes one more potentially failed connection out of the equation. The grounds will then be secured directly to the transformer chassis via solderless eyelet crimp connectors.
It should be noted that 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 Monte Carlo)
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, there earth grounds will not be tied together. 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
If your System 80 or early System 80A game still has the original, orange 12VDC filtering capacitor in the cabinet bottom, you should replace it. It's nearly 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.
4.4.2 Recommended Updates and Repairs for the System 80/80A Power Supply Board
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 trim pot. A quality sealed one like the one pictured is advised.
- 3 inches of 18 gauge wire
- 47uf, 100V axial capacitor
- 680 ohm, 1/2 watt resistor (replacement for R10)
- 12K ohm, 1/2 watt resistor (R3)
- 1N4738 8.2V 1 watt zener diode (CR7)
- 1N4746 18V 1 watt zener diode (CR6)
- LM723 voltage regulator and 14-pin socket (optional if the 5V section is operational)
- 2N6057 or 2N6059 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)
- 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
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: 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.
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 of the resistor and LED. Note the location of the flat side of the 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.
Views of the holes drilled for the LED looking from the front and rear of the System 80 driver board.
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.
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.
View of the holes drilled for the LED as viewed from the front and rear of the board.
Wiring of the resistor and LED on the rear of the board. Notice the location of the flat side of the LED.
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
Views of the drilled holes for the LED's looking from the front and rear of the board.
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 and LED's on the rear of the board. All four LED's installed on front of board.
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 tpoward 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.
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.
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.
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.
Under construction...
- 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
- Check the R/W (read/write) signal at the 6502
- Check the address and data lines to see if 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.
- Check each of the 74XX chips using the procedure "here".
- If original game ROM(s), replacement with 2716 is advised.
4.5.1 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 becomes forgotten, and most cases it does. 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 out that your battery has stepped 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 over 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 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.
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.
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.
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.
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.
4.5.2 Relocating the battery from the MPU board
The first thing you should do to any System 80 MPU is remove the rechargeable NiCad battery from the MPU board. All batteries leak. It's simply a matter of when they will leak. A leaking battery will damaged your (sometimes irreplaceable) board.
There are at least four methods of relocating and/or replacing the battery on your System 80 MPU.
- You can remove the battery completely and not replace it. The 5101 memory will not persist from power-up to power-up and therefore, high scores, replay levels, and credits will be lost.
- You can mount a remote battery pack that uses standard AA batteries (x3) to protect your board. You must also incorporate a blocking diode (1N4001, although a 1N4004 will work just as well) to prevent the game 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.
- You can 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 electrical tape under the cap to ensure that the negative side of the cap doesn't short a trace. 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.
- You may remotely mount a replacement NiCad battery in a location that, should it leak, damage to valuable circuit boards will not occur.
4.5.3 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
4.5.4 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. See the image here for a depiction of what you'll see.
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.
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.
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.
4.5.5 System 80B Daughter Card Solder Joints
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.
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.
4.5.6 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 just to the right of connector J1. Connect the black lead of your logic probe to the negative (bottom) lead of the capacitor. Connect the red lead of your logic probe to the positive (top) lead of the capacitor. Take care to ensure that the clips don't short to adjacent components.
4.5.7 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.
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.
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!
4.6 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.
- 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 spurious resets too. When first trying to get a System 80A or System 80B game to boot properly, it is best to disconnect the reset board. If disconnecting the reset board resolves the issue, the reset board can remain disconnected, provided that someone will always be in the general vicinity of the game to turn it off, should the CPU lock up.
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" 
Trace extending Left from Z10 
PROM2-to-PROM1 Socket Cuts and Jumpers 
Z10, pin 13 to via Jumper
4.8 Using a 2732 at the PROM2 position in a System 80B MPU
As illustrated in the CPU schematics of game manuals, such as "Bad Girls" and "Big House", it is stated 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.
Not to add to the confusion, but PROM2 is actually located at the socket marked "PROM 1" on the PCB. The area on the board marked "PROM 2", which does not have a 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, when using a 2732 EPROM at this position. Should a 2716 EPROM be used for PROM2, do not perform this procedure. Likewise, should a MA-1133 board be used in a game that only uses a 2716 EPROM at PROM2, reverse the following procedure.
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 Driver Board Issues
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.
4.10 Solenoid problems
4.10.1 Remote Mounted Transistors
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 it's beefier siblings - 2N5883 or 2N5884. An MJE2955 will work also.
The green/yellow wire (Gottlieb® wire color code 54) is always connected to the tip of the transistor (collector) and leads to ground.
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 are not 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.
4.10.1.1 Remote Mounted Transistor Upgrade
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>
The 4.7K resistor is soldered to the base of the remote mounted transistor, and then tied to the 24vdc solenoid bus.
4.11 Lamp problems
Lamp problems are common with most any pinball machine, and Gottlieb® System 80/A/B games are no exception. All 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.
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.
4.11.1 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.
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.
4.11.2 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.
4.11.2.1 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.
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.
4.11.2.2 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.
4.11.3 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.
4.11.4 Controlled Lamp Issues
4.11.4.1 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). See the section How to test a transistor for the procedure. Also, a simple comparison of "diode check" readings between "same type" transistors on the driver board can identify failed transistors.
The System 80/80A/80B architecture does not utilize a lamp matrix. Instead, with the exception of "chase" lamps, all lamps are driven by individual transistors on the driver board, exactly like Gottlieb® System 1 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-U45s available from Great Plains Electronics. A much cheaper MPS-A13 may sometimes be substituted for the less common and more expensive MPS-U45, as was in the pic for Q22. Although this will work, you must ensure that the transistor is driving only a single lamp. This obviously limits the "portability" of this driver board. If Q22 were used to switch anything other than a single lamp on, it will be destroyed. Substitute with caution. 2N6043 transistors are still available but may also 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. The use of a logic probe on the input and output of the associated lamp gate would be a the best test procedure for definitive results. 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 may be 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 right, 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 | Game Over relay, Tilt relay, coin lockout, L3 | ||||
| DS2 | L4-L7 | ||||
| DS3 | L8, sound 16, L10, L11 | ||||
| DS4 | L12-L15 | ||||
| DS5 | L16-L19 | ||||
| DS6 | L20-L23 | ||||
| DS7 | L24-L27 | ||||
| DS8 | L28-L31 | ||||
| DS9 | L32-L35 | ||||
| DS10 | L36-L39 | ||||
| DS11 | L40-L43 | ||||
| DS12 | 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.
4.11.4.2 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.
4.12 Switch problems
4.13 Display Problems
4.13.1 Display Test
Display test is step number 19 for both System 80 and System 80A 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".
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.
4.13.2 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.
4.13.3 Rejuvenating Tired 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 off" the impurities that accumulate on the filaments.
In the picture at left, general illumination power (approximately 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 Sound problems
4.14.1 System 80 Sounds Only Board
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.
If the 6530 is dead, but the 6503 is working (use a logic probe to determine this), it is possible to salvage the board using an aftermarket daughter card called the "MIOT Adapter", found here: http://www.strikesandspares.eu/index.php?lang=en. A review of the MIOT adapter can be found here.
Another option is Pascal Janin's reproduction board. This board is a bit pricier but does not rely on a working 6503. The board can be found here: http://www.flippp.fr/pifx.php?lg=en.
4.14.2 System 80 / 80A Sound and Speech Board
4.14.2.1 Different Revisions of the Sound and Speech Boards
- Revisions of the Gottlieb Sound and Speech board
B20887-1 
B20887-2 
B20887-3
With 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.
4.14.2.2 Sound and Speech Board Operation
In Work - Chris Hibler
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.
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.
Clock signal
6502/6532 operation
The "sound" lane
The "speech" lane
Sound amplification (LM379)
Sound select signals
Sound 1 thru sound 32 are specified at connector A6P1 on the board. Once on board, S1 thru S8 work at TTL levels. S16 and S32 are selected via lamp drive transistors on the driver board. <explain why U24, the lamp driver interface comparator is used>.
SC-01 pinout
| Pin Number(s) | Signal Name | Signal Purpose |
|---|---|---|
| 1 | Input Voltage | |
| 2-3 | Instantaneous pitch adjustment. Will change pitch of phoneme being spoken. | |
| 7 | Strobe to indicate a phoneme code is ready | |
| 8 | Acknowledge receipt of phoneme strobe, indicate completion of phoneme processing | |
| 9-14 | Phoneme number select (from fixed phoneme table) | |
| 15-16 | External Clock Signal (probably used to alter phoneme pronunciation via varying the clock) | |
| 20-22 | Audio Output | |
| 18 | Ground |
4.14.2.3 Speech and Sound board DIP switch settings
The Speech and Sound 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
4.14.2.4 Sound "Locks Up" after certain switch closures
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 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).
4.14.2.5 Sound is "garbled" or phonemes appear jumbled
4.14.3 System 80A Sound Only Board
4.14.3.1 Sound Cutting Out / No Sound
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
4.14.4 System 80A / 80B Sound with Piggyback Board
This is a stub
4.14.5 System 80B Sound Board (MA-766)
This is a stub
4.14.6 System 80B Sound Board (MA-886)
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4.15 Flipper problems
All Gottlieb® System 80/80A/80B utilize the traditional flipper design with either an A-17875 or A-20095 coil. The flipper bat is called a "flipper island", Gottlieb® part number A-13150, and uses a 3/8" standard rubber ring.
Gottlieb® System 80 flippers are very well engineered. They are the "Sherman Tanks" of flippers. Very little goes wrong with them.
The general design is a coil with two windings, the "power stroke" and "hold" windings, just like many other flipper coil designs. When initially engaged via the flipper cabinet button switches, both the power stroke and hold windings receive power. As the flipper actuates and opens the "end of stroke" switch, the power is cut to the power stroke winding, leaving only the hold winding with power.
However, when problems do arise, they fall into these categories.
- Flipper "binds" when returning to the "at rest" position. This is a mechanical problem, most often caused by "hogged out" portions of the plastic flipper plunger-to-crank link. The roll pin that connects the plunger/link and crank, eats into the plastic over time, causing an additional cavity to be worn into the plastic, so that it almost becomes kidney bean shaped. The flipper link will then rest in this cavity, with the result being the flipper not returning to the home position.
- Flipper fails to actuate. There are several possibilities that may contribute to a flipper not "flipper".
4.16 Pop bumper problems
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) 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.
4.16.1 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
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)
- Cut to length .156 Molex male header pins with locking ramp (you'll need a 6 pin length)
- 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.
- DMM set to "diode test"
- 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.
***Still in work:***
Steve Charland's LED mod for PBDBs
Replacing the 2N6057 with a TIP-102
4.17 Drop Target Problems
4.17.1 Replacing Drop Target Plastics
4.17.2 Early System 80 / 80A Drop Target Removal
For now, please review the drop target removal guide available at PAPinball.com.
4.17.3 Later System 80B Drop Target Removal
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4.18 Vari-Target Problems
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4.19 Roto Target Problems
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5 Game Specific Problems and Fixes
5.1 Replacing Black Hole Lower Playfield Illumination Lamps with #44 Lamps
This modification developed by Steve Charland.
When Gottlieb designed Black Hole and Haunted House, the designers chose to illuminate the lower playfield with 313 lamps, which are 28 volt lamps. Coil power could be used as a power source, and the lamps are slightly brighter than #44 lamps. However, #313 bulbs are triple the price of #44 lamps and are a unique part to stock.
Converting the power circuit that drives these lamps to 6VDC makes sense and allows the use of the more common #44 lamps.
The big picture...
Here's what the final "hack" will look like, just to get you oriented.
Note the use of red wire to indicate this is an "aftermarket" implementation. You may use black-slate-slate wire to have that "factory" look.
L relay mods...
Remove the orange-slate-slate wires from the switch stack located on the L relay under the lower playfield. Be sure to cap the wires off so they can't short to anything. In the picture at left, heat shrink tubing was used to cap the wires which were twisted together.
Solder a new 16 gauge wire to the vacant solder tab where you removed the orange-slate-slate wires.
Attaching to the power bus...
Solder the other end of the new wire to the black-slate-slate wire that connects to all of the controlled lights on the lower playfield (pictured left).
Use "zip ties" to secure the new wire to the factory wire bundle. You can feed the wire through the factory "tie downs".
Let there be light...
All finished with the mod. The bulbs now will light on 6VDC instead of 24VDC. Swap out all of those #313s with #44s or #47s and never worry about looking for the correct bulb again.
5.2 Replacing the Black Hole "Spinning Disk" Motor
Parts list and this particular motor suggestion provided by Ken Huber
Black Hole back box spinning disk motors, having run continuously since 1981 while the game is powered on, often fail.
Various replacement motor options have been used over the years including the Radio Shack hobby motor and the Granger heavy duty motor.
Another simple and inexpensive option is the DC motor sold by ServoCity at: http://www.servocity.com/
Parts required:
Quantity 1 - RZ12-1000-3RPM geared motor - $24.99
Quantity 1 - 3472H 6mm (the motor shaft size) bore aluminum hub with 5-40 tapped mount holes - $4.99
Quantity 2 - 92005A116 3mm x 6mm pan head phillips screws - $0.15 each, minimum quantity 4 (for mounting the new motor to the original mounting bracket.)
Quantity 2 - 91771A125 5-40 Flat Head Phillips Machine Screws, 5/16" long - $0.23 each, minimum quantity 4 (for mounting the spinning disk to the new hub)
This 3 RPM motor, which is spec'd to run on DC voltages from 3 to 12V, is driven by 6VDC in the game. Since it is not powered at the full 12VDC, it runs slower than the rated 3 RPM at about 1.5 RPM, which looks good and matches the OEM motor speed closely. The shaft of the motor is also the perfect length. When assembled as described below, the spinning disk rides above the #455 flasher bulbs by about 1/4 inch and also about 1/4 inch behind the inner backglass.
Installation:
- Remove the spinning disk face and the old motor assembly.
- Remove the 3 screws that attach the OEM motor to the mounting bracket.
- Use one of the new 3mm x 6mm screws to mount the new motor to the mounting bracket. Optionally, you may "elongate" one of the holes in the mounting bracket so that another screw may be used, but one screw is probably enough since the motor center protrudes through the bracket.
- Mount the new hub to the motor shaft so that it is flush with the end of the shaft. Tighten the set screw with a 3/32" Allen wrench (hex key).
- Mount the motor and bracket assembly to the lamp insert board using the two original flat blade screws.
- Ensure that only #455 blinking lamps are used in the area behind the spinning disk. #44/47 lamps protrude too far and will scratch the back of the spinning disk.
- Mount the spinning disk to the hub using two 5-40 Flat Head Phillips Machine screws.
- Solder the power wires to the solder tabs on the motor. Connecting the Green/Yellow wire to the positive side of the motor causes it to spin counter-clockwise. Connecting the Green/Yellow wire to the negative side of the motor causes it to spin clockwise. You be the judge of the age-old debate as to which direction is correct.
- Optional: but recommended, insert a 2-pin molex connector inline with the power connections (as shown in the picture below) to provide a quick way to disconnect the motor.
- Optional: paint the two flat head screws used to mount the spinning disk black.
- Optional: If you need more clearance because your disc is warped, replace the 455 bulbs with LED blinkers from Marco or Cointaker. The LED blinkers allow an additional 3/8" clearance behind the disc. To mount the disc farther back, either cut the shaft shorter, or secure the motor to the mount with washers (use 3mm X 8mm screws).
Note: The 2 RPM ServoCity motor may also be used . The mounting holes on the motor face are slightly wider apart, allowing two additional screws with washers to "clamp" the motor to the mounting bracket without elongating holes. The motor will, of course, turn 1/3 slower than the 3 RPM motor.
- Black Hole Spinning Disk Motor Replacement
Front view of the motor assembly. Note the single screw attaching the motor to the bracket. 
Rear view of the motor assembly. Note the inline 2-pin molex connector. 
455 Lamp Clearance. Nice... 
The Completed Job 
The OEM Motor Assembly after detaching the mounting bracket 
Replacement Parts Acquired from ServoCity. Note: 5-40 Flat Head Screws not shown
5.3 Black Hole Auto Spin Disc Circuit
Parts needed for project
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5.4 Black Hole Ball Lift Kicker Mod
This modification developed by Steve Charland.
From an engineering standpoint, the upkicker for BH is a simple and direct design but it does have its faults. The first being that there is no way to adjust the power of the "kick" from the lower playfield to the upper playfield. The second is the problem of the ball lift coil getting fried. This happens all too often due to shorted transistors, or failing transistors that provide "trickle" power to the coil, heating it up over time and eventually causing it to short.
The solution(s)
The first problem was to be able to control the speed that the ball would travel up the tube. The simple solution is to add an end of stroke switch and use a flipper coil. Since the switch can be adjusted to open at various "throw" points of the coil plunger, you can control the force of the plunger strike to the ball. Open the switch early, and the ball travel will be slower. Open the switch later and the ball travel is faster. Making the end of stroke switch bracket isn't too difficult to do. Contact Cliffy at Passion for Pinball, and hopefully he'll have them for sale soon.
Now, on to the A-4893 coil getting fried. There is something to note here. The schematic calls for a 6 1/4 amp Slo-Blo fuse for F17. A 6 1/4 amp Slo-Blo passes way too much current to protect the ball lift coil should either the pre-drive transistor or the under-playfield drive transistor short on. No wonder it cooks so often. This coil needs to be protected with a 2.5 amp Slo-Blo fuse, just like the pop bumper coils (so in theory the fuse will blow before the coil cooks).
For this mod, I used a A-20095 flipper coil instead of the stock coil, and an end of stroke switch to turn off the power-stroke winding of the flipper coil. By using an end of stroke switch, if either drive transistors short on, only the hold portion of the flipper coil will be energized, in exactly the same way as a flipper operates.
- Black Hole Upkicker Modification.
Measuring for hole placement on the new bracket. 
Trial fitting some sheet steel to the new holes. This sheet steel will eventually become the EOS bracket. 
The new bracket and switch. 
Another view of the new bracket and switch. 
The bracket and switch in place. 
Completed work, flipper coil installed.
5.5 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.
5.6 Haunted House Upkicker Plastic Tube Mounting Bracket
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).
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 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 ?!