Gottlieb System 1

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1 Introduction

Gottlieb System 1 Board Set

Of the big 4 pinball makers, Gottlieb was slowest converting from EM to Solid State, producing EMs into 1979 while Bally, Stern, and Williams had all abandoned doing so in 1977/early 1978. The Gottlieb system 1 boardset was designed by Rockwell International, to directly replace the EM logic from the earlier machines. Consequently System 1 games play almost exactly like an EM, just with Solid State scoring.

The playfield layouts were solid EM-esque designs, with rock-solid Gottlieb mechanical parts. Unfortunately, the electronics were not as robust in terms of longevity - exhibiting major problems with connectors, battery corrosion issues, and unavailability today of essential system chips.

One of the biggest issues with the System 1 platform was that it had unreliable ground connections. Unlike the other popular manufacturers of the time, Gottlieb relied solely on connectors and daisy-chained wiring to transport the ground lines from board to board. A large ground plane was used behind the boards, but the circuit boards' grounds were not physically secured to it. Gottlieb opted to use plastic standoffs to elevate and secure the boards to the backbox instead. 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.

2 Games

Title	Date of Release	Production#	ROM	Sound	Notes
Cleopatra	11-1977	~7300	A or 409	Chimes	Also produced as a 4-player EM 'Cleopatra' and a 2-player EM 'Pyramid'
Sinbad	05-1978	12950	B	Chimes	Also produced as a 4-player EM 'Sinbad' and a 2-player EM 'Eye of the Tiger'
Joker Poker	08-1978	9280	C	Chimes	Also produced as a 4-player EM 'Joker Poker'
Close Encounters of the Third Kind	10-1978	9950	G	Chime board	Also produced as a 4-player EM 'Close Encounters of the Third Kind'
Dragon	10-1978	6550	D	Chime board	Also produced as a 4-player EM 'Dragon'
Charlie's Angels	11-1978	7950	H	Chime board	Also produced as a 4-player EM 'Charlie's Angels'
Solar Ride	02-1979	8800	E	Chime board	Also produced as a 4-player EM 'Solar Ride'
Count-Down	05-1979	9899	F	Chime board	Also produced as a 2-player EM 'Space Walk'
Pinball Pool	08-1979	7200	I	Chime board
Totem	10-1979	6643	J	Sound board J-SND ROM
The Incredible Hulk	10-1979	6150	K	Sound board K-SND ROM
Genie	11-1979	6800	L	Sound board L-SND ROM
Buck Rogers	01-1980	7410	N	Sound board N-SND ROM
Torch	02-1980	3880	P	Sound board P-SND ROM
Roller Disco	02-1980	2400	R	Sound board R-SND ROM
Asteroid Annie and the Aliens	12-1980	211	S	Sound board S-SND ROM	Only available as a single player game

Conversion kits for system 1 from other manufacturers:

• (circa 1982) Movie (Bell Games, 4p)

• (unknown date) Sky Warrior (IDI, 4p)
• (circa 1982) Tiger Woman (IDI, 4p)

• 1984 Sahara Love (Christian Automatic, 4p, production 150) [conversion of Sinbad]
• 1986 L'Heaxagone (Christian Automatic, 4p, production 150) [original playfield design]

• 1985 Jungle Queen (Pinball Shop, 4p) [playfield based on Gottlieb's Jungle Queen]

3 Technical Info

3.1 The System 1 Board Set

3.2 The Wiring Color Code

Early on, System 1 games up until around Close Encounters used a single-color and two-color wiring code system. Starting around Close Encounters, Gottlieb adopted a three color system. 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. Below is the Gottlieb color chart.

#	Color
0	Black
1	Brown
2	Red
3	Orange
4	Yellow
5	Green
6	Blue
7	Purple
8	Gray
9	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 011. 011 would be a white insulated wire with a black trace and two brown traces, or commonly referred to as a black-brown-brown wire. The ground lines in later System 1 games are code 54. 54 would be a green insulated wire with one yellow trace.

3.3 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 A1J6-2. The coin door connection is A6P1 and A6J1 - the connector pin for switch return 0 on the coin door is A6J1-1 / A6P1-1.

The following boards are assigned the same numbers throughout the System 1 games.

• CPU Board - A1
• Power Supply - A2
• Driver Board - A3
• Sound Board - A7

3.4 Switch Matrix

Gottlieb System 1 Switch Matrix

The Gottlieb System 1 switch matrix consists of a maximum of 40 switches. There are a total of 5 switch strobes, (starting with 0, ending with 4), and 8 switch returns, (starting with 0, ending with 7). The first number of every switch is its return number, while the second number is the switch's strobe number. An example would be switch 54. Switch 54 is located on return 5 and strobe 4 of the switch matrix. Not every switch in the matrix is used on every System 1 game.

Connections for the switches originate from the two connectors located at the lower left bottom of the CPU board. Connector A1J6 is used for all the switches on the coin door, the ball roll tilt, (the second slam switch), and in some cases, the pendulum tilt. While connector A1J7 is for all of the switches on the playfield.

	Strobe 0 (A1J7-2 / A1J6-8)	Strobe 1 (A1J6-3 / A1J6-4)	Strobe 2 (A1J7-4 / A1J6-5)	Strobe 3 (A1J7-7 / A1J6-6)	Strobe 4 (A1J7-6)
Return 0 (A1J7-12 / A1J6-3)	00	01	02	03	04
Return 1 (A1J7-13)	10	11	12	13	14
Return 2 (A1J6-14)	20	21	22	23	24
Return 3 (A1J6-17)	30	31	32	33	34
Return 4 (A1J6-16)	40	41	42	43	44
Return 5 (A1J6-15)	50	51	52	53	54
Return 6 (A1J6-11)	60	61	62	63	64
Return 7 (A1J6-10)	70	71	72	73	74

Gottlieb System 1 Diode Board

Unlike most other manufacturers, Gottlieb isolated each switch with a 1N270 Germanium diode versus a 1N4004 or 1N4148 silicon diode. The use of a silicon diode will cause the switch matrix to function incorrectly. Furthermore, Gottlieb attached the diodes to central location diode boards for each switch return versus attaching a diode to the switch itself. In some cases, like shown in the pic, the diode boards are stacked on top of one another. This can make testing the diodes on the lower diode board somewhat difficult. Although, it is not too common for the switch diodes to fail.

It should be noted that the switches on return 0 are always the same for every System 1 game. The following switches have the same designations:

• Switch 00 = Test Switch
• Switch 01 = Coin Switch #1
• Switch 02 = Coin Switch #2
• Switch 03 = Credit (Start) Button
• Switch 04 = Tilt Switches (pendulum tilt on the tilt board and the weighted tilt on the playfield)

Even though the switch matrix is being discussed here, it should also be noted that there are three switches used in System 1 games, which are not on the switch matrix. These three switches are the two slam switches and the outhole switch. Each game has two slam switches. The first is a weighted, normally closed switch on the coin door. The second is a normally closed switch on the ball roll tilt cage. Neither the slam switches nor the outhole switch have a switch number designation.

3.5 Chimes vs. First gen chime board

Gottlieb System 1 Chime Board (Tone Board)

The first three System 1 games: Cleopatra, Sinbad, and Joker Poker all used EM style chimes. Starting with Close Encounters of the Third Kind through Pinball Pool, a first generation chime board was used that generated three tones. The chime board used the same three solenoid drive transistors for input as the chime units, making them interchangeable.

3.5.1 Converting from Chimes to Chime Board

This is a stub.

3.5.2 Converting from Chime Board to Chimes

This is a stub.

3.8 Driver Board

Gottlieb System 1 Driver Board

The System 1 Driver board is responsible for all CPU controlled lamps, relays, and solenoids in the game. The CPU controls the driver board operation via an interface between A1J5 on the CPU and A3J1 on the driver board.

Gottlieb did not implement a lamp matrix as some other manufacturers did. Therefore, diodes to isolate each controlled lamp are not necessary. To control the total of 36 lamps, the interface provides device select signals for each of the 9 Quad-D Flip-Flop 74175 chips 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 either an MPS-A13 (32 total) or an MPS-U45 (4 used for lamps) transistor. There are 2 dedicated lamp driven circuits used for the tilt and game over relays on all System 1 games. The transistors for the game over (Q) and tilt (T) relays are always Q1 and Q2 respectively. Equally, there are 2 dedicated lamp circuits for the high game to date and both shoot again lamps,(one in the backbox and one on the playfield). The transistors for these circuits are always Q3 and Q4 respectively.

There is a maximum of 8 solenoids that the driver board can control. Solenoid transistors receive a pulsed signal from the CPU board, which is applied to the associated transistor base. In turn, the solenoid turns on momentarily. 7 of the 8 solenoid transistors used are a 2N6403. TIP102 transistors are a viable, cheaper replacement for the 2N6403. The 8th transistor is a actually a pair of transistors consisting of an MPS-U45 and a 2N3055. There are 5 dedicated controlled solenoids used on all System 1 games. A table of all the solenoids, their associated transistors, and whether or not they are dedicated is listed below.

Sol. #	Sol. Name	Transistor #	Dedicated (Y / N)
1	Outhole	Q32	Y
2	Knocker	Q25	Y
3	10's Chime	Q26	Y
4	100's Chime	Q27	Y
5	1000's Chime	Q28	Y
6	Solenoid 6	Q31	N
7	Solenoid 7	Q30	N
8	Typically drop target reset	Q29 & Q45	N

Remote Transistor Mounted Under Playfield

Starting with Joker Poker, Gottlieb went beyond the threshold of controlled solenoids with 9 total. To accomplish this, they used an MPS-A13 lamp transistor to "pre-drive" a 2N5875 transistor remotely located under the playfield. This practice continued on other System 1 games. See the Remote Mounted Transistorsection for a complete listing of games.

Gottlieb System 1 Driver Board w/ Blocking Diodes

There are two variations of the driver board used in System 1 games. Either board will work in any of the System games. The main difference between the two versions of driver boards is the addition of isolation / blocking diodes. These blocking diodes were added to the transistor signal lines from the CPU board. The change occurred during the run of Close Encounters machines. Games prior to Close Encounters and early runs of the same game will not have the blocking diodes added. Late runs of Close Encounters, and any game after will have the blocking diodes. Keep in mind, it is very common to find a board in a game, which was not originally from that particular game. So, don't rely on your Totem or Genie having a driver board with blocking diodes without actually physically looking at the boards installed first.

3.10 Display Boards

"What's new is blue!", touted the Cleopatra flyer regarding the blue Futaba displays used in Gottlieb's first solid state venture. The System 1 displays are a fairly reliable, long-lasting display. These vacuum fluorescent displays (VFD) have a tendency to outlast the plasma gas displays, which were commonly used by Williams, Bally, and Stern.

File:GTB 6 digit display.JPG

Gottlieb 6 Digit Display

Gottlieb 4 Digit Display

Two different styles of displays were used throughout all System 1 games - four 6 digit displays for the player's score and one 4 digit display for game status. There were two different 6 digit displays used during the System 1 era, however, either style will work in any game, and can be mixed among styles. The display boards and glasses were the same, but the chip sets which were used differed. One style was based on Sprague UDN6118A chips, while the other was based on Dionics DI513 chips.

Three distinct voltages are needed for either the 6 digit or 4 digit displays to function properly.
6 Digit Display

• +60vdc
• +8vdc
• 5vac

4 Digit Display

• +42vdc
• +4vdc
• 3vac

3.11 Solenoids and Relays

All System 1 solenoids and relays are powered by a +24VDC solenoid bus. Each game has CPU controlled solenoids and "non-controlled" solenoids consisting of the same types of solenoids:

• flippers
• pop bumpers
• kicking rubbers (slingshots)

The CPU controlled solenoids are ultimately driven via the driver board, while the non-controlled solenoids are essentially "live" at the start of a game. The conditions which make them live are a normally closed switch on the tilt relay and a normally open switch on the game over relay. Once the game over relay locks in, all that is necessary for these solenoids to activate is an associated playfield switch to close, or in the case of the flippers, pressing the appropriate flipper button. All of the non-controlled solenoids have switches with tungsten contacts, which supply power to the solenoids. It is safe to file or burnish these types of switches. However, there are secondary "gold flashed" scoring switches on the pop bumpers and slingshots, which should not be filed or burnished.

Gottlieb System 1 Game Over and Tilt Relays

System 1 games employ the use of "open cage" relays. Relays relevant to every game are the tilt relay, game over relay, and coin lockout relay. There are seldom used extra relays on some games such as the vari-target reset too. The tilt, game over, and var-target relays are all controlled by the driver board. But, the coin lockout relay is energized as soon as the game is turned on.

Whether or not a solenoid or relay is controlled by the CPU board, all solenoids and relays should have 1N4004 diodes installed.

Below is a list of solenoids / coils used in System 1 games.

Sol. #	Common Usage	Wire Gauge	Windings	Resistance
A-1496	Pop bumper	23	635	2.95
A-5194	Kicker (Slingshot), Pop Bumper	24	780	4.5
A-5195	Outhole (early), Knocker, Kickout Hole	26	1305	12.3
A-16570	Outhole (later), Kickout Hole	27	1450	15.5
A-16890	Game over relay, Tilt relay, coin lock out	35	4000	231.0
A-17564	Vari-Target Reset
A-17875	Flipper	24 / 31	560 / 1100	2.8 / 40.0
A-17876	Chimes	28	1750	24
A-18102	3 or 7 (2 used) bank drop target reset	24	1430	9.0
A-18318	4 bank drop target reset	24	1130	6.7
A-17891	5 bank drop target reset, Roto	22	850	3.35

3.12 Setting up a Game for Free Play

Early Gottileb 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-White or Brown-Yellow-Yellow

1st coin switch wire - Orange-White or Brown-Red-Red

2nd coin switch wire - Brown-White or Brown-Orange-Orange

Gottlieb System 1 Transformer Board

Solder a small lead wire from the credit button wire to any of the coin switch wires. 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.

4 Problems and Solutions

4.2 Ground Updates

Gottlieb System 1 games are notorious for having poor ground connections. As mentioned at the introduction of this System 1 guide, ground problems are one of the biggest issues with the System 1 platform. Unlike the other popular manufacturers of the time, Gottlieb relied solely on connectors and daisy-chained wiring to transport the ground lines from board to board. A large ground plane was used behind the boards, but the circuit boards' grounds were not physically secured to it. Gottlieb opted to use plastic standoffs to elevate and secure the boards to the backbox instead. 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 erratic behavior with locked on coils, relays, and / or controlled lamps. In turn, transistors and chips would fail.

Chiefly due to age and / or alkaline battery damage, the connectors carrying the ground lines would fail. Connectors become fatigued losing their tensile strength against the edge finger surface of the board. Thus, the ground connections would become compromised. Equally, if battery damage was present due to an aged, leaky battery, the connectors would corrode, and either have too much resistance, or completely break. Replacing the failed connectors is always a great start, and highly recommended. However, there are additional procedures to keep from the ground being lost at each board. Once the ground lines are added to the circuit boards, Gottlieb System 1 games are one step closer to being as reliable or more reliable than the other pinball manufactures' games from the same era.

4.2.3 Additional Ground - Driver Board

Ground Added to System 1 Driver Board

The best place to add an additional ground on the driver board is the negative side of capacitor C1. The capacitor is marked with a "+" on the top side. Using 18ga stranded wire, the new line must be soldered to the bottom of C1, which is the negative side. This coincidentally happens to be the same place the driver board receives ground from the CPU board via the interconnect harness (A1J5 pin 24 to A3J1 pin 22). On the other side of the newly added ground wire, either a solderless crimp eyelet or solderless crimp fork should be added. Once the driver board is reinstalled into the game, mechanically secure the eyelet or fork with one of the screws which hold the metal board rails. Just ensure the screw used to hold the added ground line has continuity to ground.

4.6 Solenoid problems

4.6.1 Remote Mounted Transistor

Remote Transistor Mounted Under Playfield

Some System 1 games went beyond the threshold of 8 controlled solenoids total. The first game to do as such was Joker Poker. There are 4 drop target banks on the game, but only 3 solenoid drivers are available. To overcome this issue, a remote mounted 2N5875 transistor was added under the playfield, and an MPS-A13 lamp transistor was used to pre-drive the remote mounted transistor.

In other cases, Gottlieb didn't run out controlled solenoid transistors. Instead, they chose to "beef up" the solenoid drive by using a 2N6043 as a pre-drive transistor. System 1 games which use remote mounted transistors are listed in the table below.

Game Name	Sol. Name	Solenoid or Lamp Designation	Pre-Driver Transistor #	Transistor Type	Notes
Joker Poker	Kings Drop Target Bank Reset	Lamp 17	Q17	MPS-A13
Close Encounters	Roto Target	Solenoid 7	Q30	2N6043
Count-Down	Yellow Target Bank Reset	Lamp 17	Q17	MPS-A13
Count-Down	Blue Target Bank Reset	Lamp 18	Q18	MPS-A13
Pinball Pool	Left (1-7) Drop Target Bank Reset	Lamp 17	Q17	MPS-A13
Hulk	Left ("A") Shooter	Solenoid 6	Q31	2N6043
Hulk	Right ("B") Shooter	Solenoid 7	Q30	2N6043
Buck Rogers	Vari-Target Reset	Lamp 17	Q17	MPS-A13	Remote mounted TIP-115
Roller Disco	Left Drop Target Bank Reset	Solenoid 7	Q30	2N6043
Torch	Left Drop Target Bank Reset	Solenoid 6	Q31	2N6043
Torch	Right Drop Target Bank Reset	Solenoid 7	Q30	2N6043
Asteroid Annie	Left Drop Target Bank Reset	Solenoid 7	Q30	2N6043

Shortly after the release of the System 80 game Black Hole, Gottlieb realized that it was necessary to add pull up resistors to remote mounted transistors. Otherwise, the transistor could potentially lock its associated solenoid on, and burn the transistor.

4.7 Lamp Problems

Lamp problems are common with most any pinball machine, and Gottlieb System 1 games are no exception. All Gottlieb System 1 games use either a #44 or #47 lamp. The choice of which lamp to use is the preference of the game owner. An occasional #455 blinker bulb is used in the backbox in a specific socket, and will only be powered when the game is in the game over state. Of course, #455s can be used elsewhere in the backbox for effect purposes.

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

1. 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.
2. 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 1 games have three separate lamp circuits. The circuits are comprised of:

• General illumination for the backbox
• General illumination for the playfield
• Controlled lamps for primarily the playfield, although, there are four controlled lamps located in the backbox (shoot again, high score game to date, tilt, and game over)

Just one note about controlled lamps. It’s unfortunate, but System 1 games do not strobe the lamps, (turn the controlled lamps on / off), during attract mode. Being at the mercy of the game’s lamp test mode, (self test step 13), is not the greatest option for testing lamps either. During lamp test, the lamps are only powered on solidly for 5 seconds. 5 seconds isn’t nearly enough time to troubleshoot a non-functioning lamp. So, it is best to start a game, and figure out what events it takes to turn the lamp on.

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

4.7.1 Bad Bulbs

The first thing when troubleshooting lamp problems, and this may seem blatantly obvious, but determine whether the lamp is good or not. 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 1 game are powered by ~6 volts. 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 putting out 7v - 7.5v. 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.

4.7.2 Lamp Power Issues

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

4.7.2.1 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 backbox GI and playfield GI 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 1 game is always on when the game is turned on. If the backbox GI fuse is good, the connection at A6J3 / A6P3 (pins 12 and 13) which feeds the GI could possibly be bad. 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 under the right top of the playfield. These switches can sometimes get bent or misaligned due to the nature of the location of the relay and stack. If the playfield GI fuse is good and the tilt relay switches are good, the connections at A6J5-1 / A6P5-1 and A6J4-7 / A6P4-7 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 lamp insert shorts. Pop bumper lamps are not CPU controlled, and are included in the playfield GI string. 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 to something else.

4.7.2.2 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. System 1 game 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.

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 connection at A6J4-6 / A6P4-6.

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.

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.

4.7.3 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 keep a string of bulbs lit for too long. The lamp may only glow very dimly, but that is enough to determine if the socket is good or not.

If testing a controlled lamp socket, remove the A3-J3 and A3-J5 connector housings from the bottom of the driver board first. 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 lamps lights to determine whether the lamp socket is good or not.

4.7.4 Controlled Lamp Issues

4.7.4.1 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. 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. See the “How to test a transistor” portion of the PinWiki guide. 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.

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 common related issue is that the clock signal for a particular 74175 is lost between the CPU and driver board. Below is a chart of lamp clock signal path.

Clock Signal	CPU Connector	Driver Input	Driver Quad Flip-Flop	Transistor #s	Lamp #s
DS1	A1J5-21	A3J1-5	Z1	Q1-Q4	L1-L4
DS2	A1J5-20	A3J1-6	Z2	Q5-Q8	L5-L8
DS3	A1J5-19	A3J1-7	Z3	Q9-Q12	L9-L12
DS4	A1J5-18	A3J1-10	Z4	Q13-Q16	L13-L16
DS5	A1J5-17	A3J1-13	Z5	Q17-Q20	L17-L20
DS6	A1J5-16	A3J1-14	Z6	Q21-Q24	L21-L24
DS7	A1J5-14	A3J1-15	Z7	Q33-Q36	L25-L28
DS8	A1J5-15	A3J1-16	Z8	Q37-Q40	L29-L32
DS9	A1J5-13	A3J1-17	Z9	Q41-Q44	L33-L36

4.7.4.2 Lamp(s) Will Not Turn Off

If only one lamp is involved, or only a handful of lamps with different lamp clock 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. If numerous lamps will not turn off, suspect the associated 7404 on the CPU board, either Z24 for DS1-DS5 clock signals or Z25 for DS6-DS9 clock signals. If the lamps involved originate from both groups of clock signals, suspect the 74154 4:16 decoder chip, Z30, on the CPU board, or possibly the U3 10696EE spider chip on the CPU.

4.9 Display Problems

{WIP}

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

Display problems can be classified into the following categories:

1. Power problems
2. Display glass failure
3. Data problems
   

4.9.1 Power Problems

Before even attempting to work on System 1 displays, there are two caveats to heed. First and foremost, the displays function due to the necessity of several voltages, including high voltage. IF YOU ARE UNCOMFORTABLE WORKING ON HIGH VOLTAGE CIRCUITS, THEN DO NOT WORK ON SYSTEM 1 DISPLAYS! High voltage can hurt or even kill you. If you don't feel comfortable working around this type of scenario, then hire a professional to do the work. Secondly, any time a display connector needs to be disconnected, DO NOT REMOVE ANY DISPLAY RELATED CONNECTOR WITH THE POWER ON! This goes for the connectors located directly at the display, connectors A1J2 and A1J3 on the CPU board, A2J3 on the power supply board, and A6J3 / A6P3 from the transformer. Removing connectors with the power on can damage the display, the CPU board, and / or you. Sorry to "yell", but it is extremely important to stress the above two statements. Now that this is out of the way, let's move on.

As stated above, the displays need several sources of voltage to function properly. These voltages include +5VDC for all displays. As far as the other voltages, they are broken down by the type of display: +60VDC, +8VDC offset, and 5VAC are used for the 6-digit displays; +42VDC, +4VDC offset, and 3VAC are used for the 4-digit status display. If any of these voltages are missing, the display will never light.

The best place to start checking voltages is simple - the fuse for the high voltage display source. In most every System 1 game, there is a 1/4 amp slo-blo fuse used for the display voltage. This fuse is located on the transformer board in the bottom of the cabinet. The first thing to do is to unplug the game from the wall outlet. Then, remove the fuse from its fuse holder. When checking fuses, never "eyeball" the fuse. Your eyes may tell you that the fuse is good, but your eyes can fool you. Use a digital multi-meter (DMM) or a continuity tester to check fuses. Put each lead of DMM on opposite ends of the fuse. A tone should be heard. If not, the fuse is bad, and should be replaced with the same value. Fuses are used to protect equipment, the surroundings, and you. Installing fuse values with higher ratings is very dangerous. DO NOT USE A FUSE RATED AT A HIGHER RECOMMENDED VALUE!

4.9.2 Display Glass Failure

Display with a good display glass

The simplest and easiest problem to identify is display glass failure. All of the 6 digit displays used by Gottlieb System 1 games will have a black "blotch", for lack of a better term, in the upper left and lower right corner of the glass. The 4-digit status display typically has only one black blotch. The evidence of a black blotch or blotches is good.

Display with Broken Nipple on Back

However, if there is a muted white blotch visible at the corners of the display, it means the display's "vacuum" has been compromised, either due to a cracked glass or broken nipple. If this is the case, the display glass can not be repaired and is useless.

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

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

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

4.9.3 Data Problems

4.11 Flipper problems

Gottlieb System 1 Flipper Assy.

The System 1 "fat boy" flipper mechanism appeared on the earliest System 1 games and was carried all the way through System 80 except for the last game. Operators loved it because it rarely breaks. Players were harder on it, leading Gottlieb to finally move the the System 3 ("thin boy") mechanism. Unlike the System 1 mechanism, players AND operators dislike the System 3 mechanism.

The mechanism itself is a serial-wound flipper coil with an EOS switch, activated by a cabinet switch. Operation is broadly similar to other manufacturers.

The System 1 flipper mechanism is a little wimpy, compared to some (that is, Williams). The heavy flipper bat and super-durable mechanisms also tend to add a bit of weight.

The System 1 flipper mechanism is incredibly hardy. If it is clean and assembled correctly, it will work reliably for a long time.

The major weakness is the EOS switch. The EOS switch is actuated by the crank assembly, and it's a metal-on-metal contact point. After a time, the crank may wear a hole in the EOS switch. At one time (late '80s), Gottlieb offered a kit that added a roller, making the flipper mechanism even better. But in home use, even that modification is overkill.

The flipper plunger is attached to a squarish nylon link that does wear out—that is, the hole may enlarge. Alternatively, the nylon can break. In these cases, the link must be replaced. A punch is very helpful in removing the roll pin that holds the link into the crank.

Coil stops and plungers do occasionally show wear, and can be replaced, but it's not really necessary often to do so.

Steve Young sells a nice kit to do a flipper rebuild, but unlike a Williams flipper, it is better to replace parts as needed. They simply don't self-destruct the way late-model Williams flippers do.

5 Game Specific Problems

For the "kings" drop target bank reset coil locking on at start up, see the Remote Mounted Transistorsection.

6 Repair Logs

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