to System 7 Pinball 1977 to 1984,
by Cfh@provide.net (with help from Mark & Jerry)
12/22/03. Copyright 2002-2003 all rights reserved.
IMPORTANT: Before you Start!
If you aren't up to repairing pinball circuit boards yourself or need pinball parts or just want to buy a restored game, I recommend seeing the suggested parts & repair sources web page.
Table of Contents
Bibliography and Credit Where Credit is
1a. Getting Started: Experience, Schematics
What Repair Experience Is Expected?
Online schematics are available too:
1b. Getting Started: Necessary Tools
Non-Specialized Tools Required:
Specialized Tools Required:
Cleaning "Tools" Required:
1c. Getting Started: Parts to Have On-Hand
Parts to have:
All parts, schematics and manuals are available from many sources. Please check the parts and repair sources web page for details.
1d. Getting Started: Game List
Williams System 1 (not covered in this manual)
Williams System 2 (not covered in this manual)
Williams System 3
Williams System 4
Williams System 5
Williams System 6
Williams System 7 (seven digit score displays)
Williams System 8 (not covered in this manual)
Williams System 9 (not covered in this manual)
Williams System 10 (not covered in this manual)
* "Wide body" games.
1e. Getting Started: Different System Generations
Williams introduced its first Solid State pinball machine in late 1977, called Hot Tip (was also released in an electro-mechanical version). All Williams Solid State games from the 1977 Hot Tip to the 1984 Star Light shared the same basic board design.
1977 to 1984 Williams Solid State games are referred to by the revision number of their CPU board. The part number in the artwork of the CPU board (usually in a corner of the board on the front) has the "system" number after the dash: -3, -4, -6, -6A. Note System7 CPU boards did not use this convention, but these are easy to tell from system3 to system6 CPUs (because of the extra 6821 PIA chip and 7-segment LED). Along with CPU revisions, other revisions were made to the sound boards, displays, display driver boards, and power supplies. At times it can be confusing to know which board goes with which system, and what parts are interchangeable among systems. The following is a brief time-line in the evolution of the Williams Solid State games.
In 1976 Williams tried their first attempt at a solidstate pinball. Using a converted EM Grand Prix, they made one or two prototype games using their "system 1" boardset. Just after that, Williams went to their system 2 boards, using converted EM Aztec games. About ten prototype Aztec games were produced.
There is also a "System 4-" (as it is often called) CPU board too. This is the same as a "regular" System 4 CPU board, but there are no sockets at IC14 and IC26. The solder pads are there, but no sockets were installed.
Important note about Hyperball: the CPU, power supply, and display board are all standard System7 boards (though the CPU does need the ROM jumpers changed if going into another game). But the Hyperball driver board is unique to this game, and can not be converted to work in any other Williams pinball.
System 8 (not covered in this manual)
System 9 (not covered in this manual)
System 10 (not covered in this manual)
Originally it was thought the term "flipper ROMs" were named so to distinguish them from the "shuffle ROMs", since shuffle alleys used the same CPU/driver board, but alledgedly different operating system ROMs. But according to Larry Demar, this story is untrue, as the shuffle alleys did in fact use the same "flipper ROM" operating system as the pinball games. So the origins of the name "flipper ROMs" is unknown.
The flipper ROMs were identified by color: white, yellow, green and blue. One color for each system of games (more or less as they did overlap, but basically white=system3, yellow=system4, green=system6, and blue=system7). The big exception to this rule was World Cup. This game used a unique flipper ROM 2 at IC17, different than the other four color groups of flipper ROMs. Without this special flipper ROM, World Cup will not boot. There were always two flipper EPROMs on the CPU board at IC17 and IC20 (both 2716 EPROMs or 2316 masked ROMs, except on System7 which had one 2532 EPROM at IC17). Note in many System7 games IC20 was mislabeled (make sure the 2532 EPROM goes in IC17, and the 2716 EPROM in IC20).
What Works with What System?
Williams System 3 through 6 Board Design.
Williams, like the other major pinball manufacturer's of the time, used what is sometimes called a "split board" design. This means the CPU and driver functions are separated onto two different boards. This was done to facilitate the field repair of the machines. The tech would only need to swap out the failing board with a replacement and take it back to the shop for repair. The prevailing thought at the time was that the driver boards were much more likely to fail then the CPU boards. If the boards had been designed as a single unit, then a tech would need to carry ROM chips for each machine on the operator's route and swap them out when replacing the board. However if the driver board were separate from the CPU board, then no ROM swap would be necessary for the majority of repairs.
This philosophy held true, as driver boards have proven much more likely to fail then the CPU. What Williams and the other manufacturers didn't bargain for however was the failure of the connectors between the driver board and CPU board. Gottlieb's had the worst problems due to its use of Personal Computer style edge connectors that relied on the thin coating of copper on the board for the interconnection. Williams boards are far from exempt however due to the decision to extend the CPUs address and data lines across the interboard connection, from the CPU board to the driver board. This requires the connector pins between the driver board and CPU board to provide high speed data transfer. But dirt and loose connectors made this a liability (remember, most connectors have a lifespan of 25 connects!) A bad interboard connection could easily crash the whole game.
All games share the same five major components, the CPU (aka MPU) board, the Driver board, the power supply, the display driver, and the score displays. All games after Lucky Seven also had a sound board, and later System6 games Gorgar and later (Blackout, Firepower, etc.) had speech boards.
All System3 and most System4 games had their sound boards located in the lower cabinet. It was a direct replacement for the chime unit (the sounds were also driven by the solenoid drivers that drove the chime coils). Williams was very paranoid about the change, thinking they might have to change back to chimes if people complained. Plus it meant the volume could be easily adjusted from the front door (no need for a remote volume control). Late System4 and later games had their sound boards located in the back box.
The driver board is actually an extension of the CPU board. The Driver board controls the solenoids and lamps, and reads the switches. The 6802 microprocessor used in these games communicates to the rest of the game through the use of what are known as PIA chips (Peripheral Interface Adapter). These chips have the designation 6821, however early driver boards may have used 6820 chips (which can be replaced with a 6821 chip). In a personal computer, examples of peripherals are the keyboard, disk drive and modem. In a pinball game, peripherals are the displays, switches and solenoids (the switch reading mechanism in a pinball game is identical to that of the keyboard reading mechanism in a personal computer). A PIA chip has an address just like a memory or ROM chip does, and is accessed by the microprocessor in the same fashion. The game's program reads the PIA to see what switches are closed and it writes to the PIA to fire a solenoid or change the score displays.
The driver board used on system3 to system7 are nearly identical, except for the switch matrix resistors. System3 driver boards had 1000 ohm switch matrix resistors R204-R211, a slightly later driver board version had 330 ohm switch matrix resistor, and the last (System7) version had zero ohm switch matrix resistors. The decrease in switch matrix resistor ohms was done to increase the current drive through the switch matrix (so a switch or connector with some resistance that was quickly closed would still be sensed by the CPU board). A System7 driver board can be used in System3 through System6 games (it is downward compatible; the only exception to this rule is Hyperball's driver board, which is unique to that game). However, do not use an unmodified System3 to System6 Driver Board in a System7 game, as the switch matrix may not be read properly. Because of this, it is best to use zero ohm switch matrix resistors in any System3 to System7 driver board, so it can be used in any game.
The PIA chips are easily identifiable, as they are the large 40 pin chips on the board. Don't worry if the chips don't say "6821" or "6800" on them. Williams bought these chips in large quantities which were manufactured specially for them and have a proprietary designation (Bally did this too). Below are the part numbers:
The electrical current used in a pinball game would fry a 6821 PIA in short order. To prevent this, a series of IC (integrated circuit) chips and transistors are used as buffers between the PIAs and the rest of the game. These chips also provide other controls.
All games System3 through System7 have the following power circuits:
Another often confused area is the value of the +12 volt unregulated power circuit. First, Williams calls this the "unregulated 5 volts" (but really it's unregulated 12 volts that gets knocked down to about 5 volts by the CPU board). Since it is not regulated, it will vary depending on the line voltage. It can range anywhere from 10 to 14 volts, and this is normal (some novice repair people will attempt to repair their power supplies because the 12 volts supply is only 11 volts).
Also the last three System7 games (Firepower2, LaserCue, Starlight) had a separate flipper power supply board installed in the backbox. This board took 48 volts AC from the transformer and converted it to 50 volts DC just for the flipper coils.
Games from World Cup (System3) to Pokerino (System 4) used a sound board that would generate a sound when an activity (scoring) occurred (note early World Cup games still had chimes). However when the ball wasn't hitting anything, no sound was produced. Starting with Flash (System 4), a revised sound board was used that would generate constant or continuous background sounds. These usually varied in pitch as scoring increased, giving the player an adrenaline boost when things really got going.
Gorgar (System6) introduced speech to the pinball world. A redesigned sound board featured a connector for the optional add-on speech board module. This sound board was used on all games from Gorgar to the end of System7. But games with speech (Gorgar, Firepower, Blackout, Alien Poker, Jungle Lord and Pharoah) used an additional speech board. System7 games without speech (Solar Fire and later) used the System6 sound board (but the connector to the not-used speech board was missing). These were dark days for Williams pinball, and the added expense of a speech board prohibited their use on many System7 pinballs.
Note the System7 CPU board now had an additional PIA chip just for triggering sound (and for commas in the score displays). This freed up the driver board sound transistors for driving playfield solenoids, making System7 games more complex than earlier games.
Williams used a standard six digit gas filled display in all system3 to System6 games. These are still widely available today. Most replacement displays today have a "nipple" where they were sealed. These will work fine as a replacement, and most display boards already have a hole drilled in them. System7 games (and the last two System6 games, Alien Poker & Algar) use a seven digit display.
Display Driver Board
There were two basic versions of the display driver manufactured (but one version actually had two different designs, so I guess there are really three different versions). All versions are compatible in all games. On version uses integrated circuits (UDN6184A-1/UDN7180A display drivers, with another version that used 22 pin NE584/NE585 display drivers). The other basic version uses "discrete" components (meaning a large number of individual transistors). The reason for the discrete component version was that the UDN6184 and UDN7180 segment driver chips used were at some point in short supply. Williams designed an alternate board that replaced the functionality of these chips with individual transistors (this happened around Flash and up to and including Firepower). The UDN6184A chip continues to be in short supply today, but can be replaced by the plentiful and cheap UDN6118A-1 display driver. The UDN7180A though is still expensive, and averages between $15 and $30 each.
Williams System 7 Board Design.
Later in System7 production, the "backwards compatibility" began to disappear. Williams figured out it was costing them money to be backwards compatible on the CPU board. So the CPU's two LEDs disappeared, along with the SW2 switch and the two banks of DIP switches. This stuff can be easily added back though.
Number of Coils Available in System3 to System7
With the advent of system7, the number of usable coils went up. Where system3 to system6 used coils 9,10,11,12,13 as sound drivers, with system7 coils 9 to 13 were now available for other uses. This happened because the additional sound PIA chip added to the system7 CPU board now handled the "calls" to the sound board, instead of the driver board transistors doing that.
Also the added system7 CPU sound PIA gave Williams two more available solenoids, number 23 and number 24. These can be seen in the system7 coil diagnostics, but were never used in any system7 game. These existed because there were two extra unused PIA ports on the new system7 CPU sound PIA, that were set up to be used as coils in the "blue" flipper ROMs (the game's operating system). But unfortunately the system3 to system7 driver board could not use these two new coils, as there were no available driver transistors on the driver board for them. The two new coil PIA outputs also went to a never used and unpopulated ribbon cable connector on the right bottom side of the system7 CPU board. The diagnostic code was added to the blue flipper ROMs most likely because these chips were "masked" ROMs, and adding the code later (when it was actually needed) would have required making new blue flipper ROMs or EPROMs, which would have cost money. Hence we can see these two new system7 coils in the solenoid diagnostics (Williams also added coil #25 to system7 diagnostics, which was the flipper relay). If Williams ever needed these two new coils on a system7 game, they could have populated the ribbon cable connector on the system7 CPU board, and had a mini auxiliary driver board with driver transistors (as was done on some 1990s games like Twilight Zone, Star Trek Next Generation, Demo Man, etc.) Also the use of this new system7 CPU board ribbon cable connector could have eliminated the .156" Molex interconnector, which gave these game reliability problems. But that would have required a new driver board to accept this ribbon cable, and that never happened.
2a. Before Turning the Game On: Game Assembly & the Black/White Connectors.
If the plugs were cross-connected, and the game turned on, there are some likely things that could happen (this example is Black Knight; what blows exactly can be game specific, and may also depend on how long the game was powered on). First the obviously broken stuff was:
In this Black Knight example, here's what fried, and what survived:
So the moral of the story is, "don't cross-connect the connectors"!
Loose/Broken Wires in the Connectors.
Don't Forget the Grounding Strap.
2b. Before Turning the Game On: the Power Supply (Explaination, Testing, Fuses, Bridges, Test Points, Modifications, Repair).
IMPORTANT! Before Turning the Game On!
For example, when the CPU board does not work, and the game is powered on, often all the coils will energize and all the lamps will lock on. This can burn the coils and lamps at minimum. The same thing can happen if the game is turned on with the CPU board missing, or if the "blanking" signal (pin 37 of the interconnector) stays low.
What if the game Locks-Up or "Resets"?
What Voltages does the Power Supply Output?
The power supply board takes in 18.6 volts AC (9.3 volts AC times two) from the transformer, and outputs +12 volts DC, and +5 volts DC. In addition it takes in 90 volts AC from the transformer and outputs +/- 100 volts DC. The unregulated 28 volts DC for the solenoids and the 18 volts DC for the lamp matrix power actually does not use the power supply board (this is handled by the backbox mounted bridge rectifiers and filter capacitor). But these two voltages do go through the power supply board for fusing, but neither is manipulated or altered. On System7 power supplies, 6.3 volts AC also comes into the power supply board, but only to provide a fuse and a G.I relay to the circuit (there are three additional connectors on a system7 power supply for GI input and output, and for control of the GI relay). Also note that the Sound Board has its own dedicated power supply. So if the sound is not working, don't mess with the game's main power supply.
Early power supplies (first two system3 games, Hot Tip and Lucky Seven) also routed the G.I. through the power supply board, and contained a 300 volt feed for the display driver that was later dropped. All power supplies boards from System3 to System7 are interchangeable (except for maybe the first two system3 game power supplies which used the 300 volt feed and GI power supply connector).
Transformers on earlier games also used slightly different plug arrangements. Hot Tip/Lucky Seven and System7 games routed the GI power through the power supply board. System3 (World Cup and later) to System6 games had direct connections to the fuse card for the GI circuit. If swapping transformers, make sure the GI power is routed properly through the fuse card or power supply, as dictated by the game in question. Also the last three System7 games (Firepower2, LaserCue, Starlight) used 50 volt flipper coils (compared to the rest of the 28 volt game coils), so these trasformers are different too.
System3 and 4 games (all games through Flash) do not have the fuse for the Flipper power on the power supply. Instead the fuse is located under the playfield near the flippers. Fuse holder F4 is present on the power supply on these games, but the circuit isn't used on games from World Cup through Flash, so fuse F4 can be removed. Likewise on the last three System7 games (Firepower2, LaserCue, Starlight); these games used 50 volt flipper coils, and had a separate 50 volt power supply board for the flippers. The F4 power supply fuse is therefore not used (instead the 50 volt flipper power supply board has a F2 fuse 5amp slow blow).
The first two System3 games from Williams (Hot Tip and Lucky Seven) use F4 as the GI fuse. These games routed the GI power through Power Supply board and the .156" connectors. The photo below shows the GI connector from a Hot Tip and the associated burn marks on the connector. Williams smartly removed the GI from the Power Supply board by World Cup, but had a lapse of judgment and put it back onto the Power Supply board in System7 games (because the power supply board also got a G.I. relay), albeit with a larger Molex connector, but the same burnt connector results.
Main fuse: All system3 to system7 games use a main fuse of 7.5 amp fast blow in the front of the cabinet (accessed through the coin door).
System 3 Fuses.
Sound Board Fuses (except Hot Tip & Lucky Seven):
Backbox Panel Fuses (located below power supply board):
Playfield Fuse (located under playfield):
Power Supply Bridges (located on power supply board):
Backbox Bridges (located below power supply board, 35 amp, 400 volts):
Sound Board Fuses:
Backbox Panel Fuses (located below power supply board):
Playfield Fuse (located under playfield):
Power Supply Bridges (located on power supply board):
Backbox Bridges (located below power supply board, 35 amp, 00 volts):
Sound Board Fuses:
Backbox Panel Fuses (located below power supply board on a fuse card):
No playfield fuses, as the fuse F4 on the power supply board is now used for the flippers.
Power Supply Bridges (located on power supply board):
Backbox Bridges (located below power supply board, 35 amp, 400 volts):
Flipper Power Supply (Firepower2, LaserCue, Starlight ONLY):
Sound Board Fuses:
Backbox Panel Fuses:
No playfield fuses, as the flipper fuse F4 is now on the power supply board or the flipper power supply board.
Power Supply Bridges (located on power supply board, 35 amp, 400 volts):
Backbox Bridges (located below power supply board, 35 amp, 400 volts):
Adding Two Fuses to a System3 to System7
The two bridge rectifiers mounted to the backbox are the lamp matrix and solenoid bridge rectifiers. If either of these bridges shorts, or the large backbox mounted 30,000 mfd lamp matrix capacitor shorts, the main power fuse *should* blow. But if this single fuse was "over fused", a fire could result!
The Varistor and AC Line Filter.
Cracked Header Pins.
The best way to fix this is to resolder the header pins. NOTE: it is *highly* recommended that the old solder be removed, before adding new solder! This can be done using a solder removal tool, as documented in the document at marvin3m.com/begin. Also look for any damaged or burnt header pins. Replace them now if any are found!
(Component #3 in the "key" picture.)
This is the +12 and +5 volt logic filter capacitor. Electrolytic capacitors have a working life of about 10 years. So if this capacitor is original, chances are nearly 100% that this capacitor needs to be replaced! On System3 to System6 games, this is a 12,000 mfd 20 volt electrolytic capacitor. On System7 games, this is a 18,000 mfd 20 volt electrolytic cap.
Failure to replace this +5 volt filter cap will can cause all sorts of unpredictable game behavior and problems. Game resets and lock ups are most common. THIS CAPACITOR MUST BE REPLACED ON ALL SYSTEM3 TO SYSTEM7 GAMES!
Note all newer capacitors (of the same value) are smaller than the original capacitor. Original style 12,000 or 18,000 mfd axial electrolytic capacitors are not easy to find. An easier to find replacement, currently available from many sources, are radial "Snap Caps". To install one, the snap cap will need to be siliconed (and if possible nylon tie wrapped) to the power supply board, and have wires going from its terminals to the power supply board. Not the cleanest look, but it does work well. Be sure to mount the cap "flat" to the power supply board, with the cap leads facing *down*. DO NOT MOUNT THE CAP WITH THE LEADS FACING OUT (away from the power supply board). Due to the vibration in pinball machines, the silicone used to secure the cap will eventually fail if the "tall" cap is mounted with the leads facing "out".
Another method is to use a snap cap and drill a hole in the board for the second cap lead. This method is NOT recommended! Again, due to vibration, the solder leads will crack, removing the capacitor from the circuit.
Adding these fuse can is a good idea, and could prevent a fire. This applies to all System3 to System7 games. Please see above for this information.
Upgrade 3: Replace Connector at 3J6.
(Component #4 in the "key" picture.)
On System3 to System6 power supplies only, the diodes at D7 and D8 need to be replaced. These two diodes rectify the AC voltage to DC, which is ultimately used for the +12 volts and +5 volts logic. The MR500 diodes are 3 amp diodes, but should be replaced with 6A4 (6 amp, 400 volts) diodes, or 6A2 (6 amp, 200 volts), or even 6A50 (6 amp, 50 volts). Radio Shack sells 6A50 diodes, part number 276-1661. Note on System7 power supplies the AC to DC conversion circuit was beefed up. Diodes D7 and D8 were eliminated, and replaced with a bridge rectifier BR1. A bridge rectifier is essentially a grouped set of four diodes.
(Components #1 in the "key" picture.)
Power supply zener diodes Z2 and Z4 are 1N4764 diodes, which are 100 volt diodes. These should be replaced with 1N4763 diodes, which are 91 volt diodes on all System3 to System7 power supplies. The reason for this is simple; the 91 volt diodes increase score display life. This decreases the score display voltage from 100 volts to 91 volts, making the score display last a lot longer. Since score diplays are now only made by one manufacturer, it is important to make them last as long as possible. The downside to this modification is the score displays will be a bit dimmer. But the added life of the displays is worth it.
(Components #1 in the "key" picture.)
Williams recommend upgrading resistors R2 and R5 from 680 ohms to 1.2K ohm 1/2 watt resistors for better reliability of the high voltage section. Also it's a good idea to at least check resistors R1 and R4, 39k ohms. Replace as needed with new 39k ohm 1 watt flameproof resistors. This applies to all System3 to System7 power supplies.
Upgrade 7: Check Connector 3J3.
Upgrade 8: (System7) Replace the G.I. Connectors.
To do this, disconnect *all* the connectors from the power supply, except for 3J1 and 3J2 (these are the two square connectors). J1 is a rectangle 12 pin connector, which feeds all the input voltages to the power supply. J2 is a rectangle 6 pin connector, which feeds ground from the external bridge rectifiers. All the other .156" straight line connectors are output connectors, and should be removed.
With all the connectors removed except for J1 and J2, turn the game on. Measure the +12 volts DC with a DMM at 3J6 pin 6 (pins 11 to 15 of J6 are ground). This is unregulated 12 volts, so it should be in the 10 volts to 14 volts DC range. If the voltage is outside that range, most likely it is the filter capacitor (C15 12,000 mfd at 20 volts for system3 to system6, or C10 18,000 at 20 volts mfd for system7). This capacitor commonly fails on these power supplies. There is more information on this capacitor below (see the +5 Volt Logic Filter Capacitor.)
Beyond the capacitor, on system3 to system6 games, it could be either diodes D7 or D8 (MR500, which should have been replaced with 6A4 diodes, as discussed above). These diodes commonly fail due to heat. These diodes can be easily tested using a DMM set to the diode function. Put the DMM leads on each lead of the diode, and a reading of .4 to .6 volts should be seen in one direction, and no voltage in the other. On system7 games, the BR1 bridge rectifier (35 amps 400 volts) could be faulty. Lastly the problem could be the transformer (but that is unlikely). Testing this bridge rectifier is described below in the +5 volts section.
Check the +5 Volt Logic Voltage.
To check the +5 volts, use a DMM and measure the +5 volts DC at power supply connector 3J6 pins 7 to 10 (remember J6 pins 11 to 15 are ground). The +5 volts should measure between 4.9 and 5.2 volts DC.
If the +5 volts is low at the power supply, either the connectors are in bad shape, or the regulation circuit is probably damaged. If the voltage is Ok at the power supply, but is later tested at the CPU board and found to be less than 4.9 volts, the CPU board could also have some problems that are "dragging down" the power supply. There could also be a problem on the power supply +5 volt regulation circuit, which fails "under load". But first check and replace the connectors on the power supply (3J6) and the CPU board (1J2) before doing anything else.
Fixing a bad +5 volt circuit is pretty straight forward. On System3 to System6 games, this involves the large heat sinked X3 (LM323, 3 amp, 5 volts) voltage regulator on the power supply board, and two diodes at D7 and D8. The voltage regulator itself is pretty well protected and doesn't usually fail. As described above, diodes D7/D8 do often fail though. A shorted D7/D8 diode should blow a fuse, an open diode causes +5V voltage to drop and prevent the game from starting. These can be easily tested using a DMM set to the diode function. Put the DMM leads on each lead of the diode, and a reading of .4 to .6 volts should be seen in one direction, and no voltage in the other.
On System7 power supplies, low or no +5 volts is either the bridge rectifier BR1, chip IC1 (723PC), or transistor Q5 (2N6057, which should be replaced with an easier to get 2N6059). The bridge rectifier BR1 (35 amps 400 volts, which is really four diodes in a metal case) is used to convert AC to DC volts, and replaces the D7/D8 diodes on older System3-6 power supplies.
The System7 BR1 bridge can be tested. Note the positive side of the bridge is "offset" from the other three leads, with the lug facing a different direction than the other three lugs. The negative lug is diagonial to the positive lug. And the two AC lugs are the two remaining lugs.
Check the High Voltage +/-100 volts.
With the connectors on, if the score displays are dead, before repairing the High Voltage supply, look for a small orange glow in the corner of the score displays. If that is present, then the proper voltages are probably getting to the displays, and the problem lies elsewhere, other than the high voltage section.
If the score displays light up, but then go dim or flicker, try replacing the two 100 mfd 150 volt electrolytic filter capacitors in the high voltage section (C7/C11 on System3-6, C1/C3 on System7). When those capacitors dry up and get old, the displays can look like they are dying.
Also part of the high voltage section on the first two System3 games (Hot Tip and Lucky Seven) is a 300 volt supply circuit. The original design used this voltage to provide an extra "kick" to get the score displays gas to ionize. Hot Tip and Lucky Seven used this extra voltage, but it was deemed unnecessary after that and dropped. If a System3 power supply has some extra capacitors and diodes that aren't on the schematic, this is part of the 300 volt supply. The 300 volts was produced using two diodes and two capacitors to triple the incoming AC voltage. If a System3 power supply has a failed 300 volt supply, there is no need to repair it. The two extra diodes and capacitor can be removed, and this will not affect the score displays.
Check the Lamp Voltage.
Check the Solenoid Voltage.
The flipper voltage has a slight deviation. On System3 and System4 games, +28 volts goes directly to the flippers from the solenoid bridge rectifier (there is a fuse located under the playfield). On System6 and System7 games, the flipper voltage is goes through the Power Supply board (but is not manipulated), with fuse F4 protecting the flipper circuit (the under playfield fuse is now gone). On the last three System7 games (Firepower2, LaserCue, Starlight), flipper power comes from a separate 50 volt flipper power supply board.
The +5 Volt Logic Filter Capacitor - Replace it
Filter caps are largely a mechanical device. Because of this, they wear out! The normal life span for a filter cap is about 10 years. Since these games are well past that age, I would highly recommend replacing this capacitor! On system3 to system6 power supplies, it is really important to replace it because of the lower value Williams used. System7 power supplies have less problems with this cap, but it is still a good idea to replace it.
The capacitor can be tested, with the game on using a DMM set to AC voltage. Put the red lead of the DMM on the positive lead of the filter capacitor, and the black lead on the negative lead of the cap. If an AC voltage of .3 volts or more is seen, the capacitor is not smoothing the DC voltage enough, and definately needs to be replaced!
Problems with the Backbox Mounted Bridge Rectifiers Wire
Williams CPU Board System 6 Test Points and their
A Revision System6 board has a part number on the lower right corner ending in a 6 or 6A, or something similar. If the board in question does not match the location of the test points, or if the part number differs, it may be a system7 CPU board, as the test point location differs (see below).
Williams CPU Board System 7 Test Points and their Location. The system7 test points are the same as system6, but their location is different.
Remember some early Black Knight games (first system7 game) used the early System6 power supply. This is easy to identify; if the transformer is in the lower cabinet, it's a system7 power supply. If the transformer is in the backbox, it's a system6 power supply. A System7 CPU board has identical test point values to a System6 board, but the test points are in different locations.
The first two system3 games (Hot Tip and Lucky Seven) had two additional capacitors and diodes compared to the later system3 to system6 power supplies. These were used for the 300 volt feed for the display driver. These parts were dropped starting with World Cup (the third System3 game). Unless there is a specific problem with the display drive on these two games, the two 1N4001 diodes and two .22 mfd capacitors do not need to be replaced or checked (the capacitors are actually not electrolytics, but are "MKP" caps). They can even be removed entirely from the power supply if used in later system3 to system6 games.
Rebuilding the +/- 100 volt High Voltage
Commonly Defective System3 to System6 High Voltage Parts:
* Note that the original style SDS201/SDS202 transistors at Q1/Q3 are no longer available in any flavor or form. These two transistors must be replaced with the newer MJE15030/MJE15031 transistors. BUT NOTE: the MJE transistors had a different pinout than the original SDS transistors, so they must be installed differently on the board!!
2c. Before Turning the Game On: Batteries, the Battery Holder, Battery Corrosion, and the 5101 RAM.
How old are those batteries in that game? If an answer can not be determined, it's time to change them! Besides dead batteries, CPU board battery corrosion and/or a bad IC19 CMOS 5101 RAM can cause some problems too. This section talks about these problems.
The problem with old batteries is leakage. If the batteries leak, they will leak corrosive material over the CPU and driver board! Also the corrosive fumes from the batteries alone can corrode the ROM sockets and the 40 pin inter-board connector. This is cause random game lock ups and resets, game boots into audit mode, or make the game not work at all.
Isn't Battery Corrosion Obvious?
If there is any battery corrosion on the CPU board, it needs to be removed immediately. If it is not properely removed, the corrosion will return, and you'll be chasing your tail! It's not worth fixing any circuit board if the battery corrosion is not removed first.
Here's the procedure for removing corrosion:
Game Comes up in Audit Mode.
On system4 to system7 pinballs all the game's options and audits are stored in CMOS memory (system3 is a bit different, and is explained below). If the batteries are dead, or the battery holder is damaged, or the blocking diode D17 has failed, or there's a bad IC19 RAM 5101 chip, or battery corrosion has damaged the CPU board, the game will power up into "audit mode". Audit mode is shown in the picture above, and is saying that the game has lost its CMOS memory, and there's a problem. It's a big red flag when the game is turned on, since the game goes into audit mode instead of attract mode (game over mode). Operator assistance required!
These software identification numbers made it easy to see if the wrong Game and/or Flipper ROM software was installed in the machine.
Note the lack of a code above for White flipper ROMs (system3). This is because the boot-up "software revision" mode was not implemented until System4 and the Yellow flipper ROMs, when adjustment were also stored in memory (system3 used DIP switches for the adjustments, which are read by the CPU board at boot up). Williams did the audit mode routine to show instantly upon power-on that the game's adjustments/audits were lost, and that the batteries needed to be replaced. The main reason this was done was to protect the game from having garbage in an adjustment that may put the game into free play (or some other equally accidental bad mode), since now all the game's adjustments were stored in memory instead of being "hardcoded" with DIP switches. With system6 and its memory protection circuit/coin door switch, it also keep miscreants from drilling through the bottom of the game and activating the switches to change the settings (like one quarter equals 25 credits!), since the coin door now had to be open to change an adjustment/audits.
On system3 games, a dead battery or failed CMOS memory still comes up in audit mode, but there is no indication of software revisions. The audits in system3's white flipper ROMs looks a bit different too, with the audit number in the credit window, and the "04" (to signify audits) in the ball-in-play/match window (this was reverse of system4 to system7), and the audit value in the player1 score display. If the manual-down/auto-up switch is in the auto-up position, the game rotates through all the audit numbers automatically also. Because of this, system3's audit mode has a different look and feel then its later system4 to system7 cousins.
Battery Holder Woes.
Always Check Diode D17: Checking the Battery Voltage and D17
After the battery holder is replaced, install new good quality batteries. Using a DMM, then measure the voltage right at the RAM chip IC19 (5101 CMOS RAM), pin 22 (and pin 8, which is ground). This should show about 3.9 to 4.3 volts DC. On System6 and System7 CPU board, this voltage is also at test point 7. If there is not 4 volts at IC19 pin 22, check the voltage at the blocking diode D17.
If there is no voltage on the banded side of D17, but there is voltage on the non-banded side, replace this diode with a new 1N4148 or 1N914 diode. If there is no voltage on the non-banded side of diode D17, then the batteries or battery holder is at fault.
Also check for voltage at the CPU chip IC1 pin 8 (+5 volts pin) with the game off. If voltage is found, the D17 diode is shorted allowing the battery to power the entire CPU when the game is off. This will drain batteries in a few days. Also if this happens, the CPU board will try to charge the batteries when the game is turned on. Alkaline batteries are obviously not designed for this, and will get hot, and probably leak.
If batteries are not installed in the CPU board, diode D17 can also be tested with a DMM on the diode setting. Put the black DMM lead on the banded side of the diode D17, and the red lead on the non-banded side. The DMM should read .4 to .6 volts. Reverse the DMM leads, and a null reading should be seen.
Batteries Ok but Still Powers-up in Audit Mode - Bad 5101
On all System3 to System7 games, if the game boots into "audit" mode, try this: Turn the game on, allowing it to boot into audits. Then flick the power switch off/on quickly. This should put the game into game-over "attract" mode (the coin door may need to be open on System6 and System7 games for this to work). This won't fix the dead 5101 chip, but it may allow the game to be played in the short run. If the game still won't come up in attract mode with this trick, the 5101 RAM at IC19 is *really* dead.
Another trick on System7 games (only) if the game boots into audit mode, is to try advancing through the audits/adjustments with the Advance button inside coin door. After the audits get to number 50 or so, it will pause, and reset the game to "game over" (attract) mode. If it doesn't come back to attract mode, but goes to audits ("04") again, try the Advance button again to move the audits past number 50 or so. If it can't get into attract (game over) mode, then there may be a bad resistor DIP network in the memory protect circuitry, in addition to a bad 5101 RAM. Note System3 to System6 did not use DIP resistor networks, and the audit would never go into attract mode (they just wrap around, back to zero, except on World Cup).
Using the Internal Diagnostics to Test the 5101
2d. Before Turning the Game On: 40 Pin Interboard Connector (Dead Game or Random Lockups & Resets)
If the user of the System3 to System7 game in question wants a good, dependable, working pinball, ALL of these following connector issues must be addressed!
Inter-Board Connector Woes.
The inter-board connector worked well for the first few years of a machine's life, but after years of service, connectors would start to fail. Besides getting dirty, the solder joints on both boards would develop microscopic cracks due to vibration, heat and humidity changes. If this caused one micro-second of a disconnect in a data or address line, that would be enough to lock the machine.
To make matters worse, on system3 to System7 games, the batteries are located right above the 40 pin inter-board connector! If the batteries leak they will damage this connector for certain.
Another little known fact is these .156" Molex connectors have a lifespan of only 25 cycles! That means after a connector has been installed and removed a number of times, the female and male connector pins are essentially worn out. Add to this time (again, these games are 20+ years old), environment and vibration, and the cycle life is probably well below the 25 cycle spec. This compromises the "gas tight" seal between the female and male pins, allowing corrosion, and hence intermittent connections. Between the female pins loosing tension and the plating on the male pins wearing from inserting and removing the connectors, they are just worn out. Now the only solution is to replace the connector pins to regain reliability.
Frankly connector replacement is the ONLY solution to a reliable game. Before even turning on one of these 20 year old machines, replace BOTH the male and female sides of the 40 pin inter-board connectors. These are cheap parts, and replacement ensures the machine will operate reliably. Some repair people will recommend just resoldering the header pins or reseating the boards. This is not the long term solution! The tension on the female pins is gone as is the tin plating on the male pins after 20 years of use, and replacement of both the header pins and the female pins is the only choice. Also male header pins are now square, replacing the old style round male header pins. This increases male-to-female pin surface area, resulting in a better, more reliable connection.
If re-seating this 40 pin connector causes a game to "work", this is a BIG RED FLAG that there's a problem. Re-seating is NOT a fix. It just identifies a problem. The only way to fix the problem is to replace the interboard connector. If after re-seating the game works, this means the gas tight seal provided by the socket or connector is gone. And the only way to fix this is to replace the connector. Trust me, this connector needs to be replaced!
Inter-Board Connector Replacements.
.156" male Molex Connector Pins and Female bottom entry connectors. These are used for the 40 pin inter-board connectors. I am suggesting (four) 10 pin sections, because economically it is cheaper (the factory used five 8 pin connectors). However some retailers may only sell the 8 pin version.
Removing (Desoldering) the Old Female and Male Connector
But aside from that, there are a couple tricks and cautions that should be mentioned. First, use a good quality (de)soldering station or Soldapullt tool. There are a total of 80 pin to be removed (assuming both the CPU and Driver board connectors are replaced), so don't mess around with solder wick. Also the two outside pins on each board (pins 1,2 and pins 39,40) will be the most difficult to desolder. This happens because these pairs of pins are connected together (they are ground and +5 volts lines), and hence they have larger solder pads and more solder on them. This will dissipate the (de)soldering iron's heat very easily, making them more difficult to get to a high enough temperature to desolder. Just keep that in mind, as more heat may be needed for desoldering these pins.
2e. Before Turning the Game On: Power Connectors (Dead Game or Random Lockups & Resets)
If 95% of the connector problems lie with the interboard connector, the other 5% lie in the power connectors! The logic bus connectors supply +5 volts, ground, and unregulated 12 volts (called "unregulated 5 volts" by Williams once it hits the CPU board) from the power supply to the CPU/driver board. This includes two .156" Molex single line connectors, one on the CPU board (1J2), and one on the power supply board (3J6). Both of these connectors male headers MUST be replaced, along with it associated connector housing pins (be sure to replace with "trifurcon" terminal pins).
Again, like the 40 pin inter-board connector, there really is no exception to this rule. The 1J2 CPU connector and 3J6 power supply connector supplies the logic current that runs the game. The most common problem is the 12 volt unregulated power (unregulated 5 volts after a zener diode on the CPU board). There is only ONE pin per connector handling this voltage (unlike the +5 volts and ground, which have a minimum of three pins each). If this single 12 volt pin fails (and it will fail!), the game can lock up randomly, or not run at all.
The CPU board connector 1J2 is a nine pin .156" header male connector. The originals use round pins. Be sure to replace with the newer square pin variety. In the plastic housing use new .156" Trifurcon terminal pins. This applies to all System3 to System7 games. On Firepower and later games, replace the original IDC connector terminal pins and housing with new crimp-on trifurcon connector pins and plastic housing.
Replace the header pins at connector 3J6 on the power supply. The power supply board connector 3J6 is a 15 pin .156" header style. This applies to all System3 to System7 games. This is the +5 volt connector, and it needs to be in perfect condition. So just replace this with new .156" header pins before even powering the game on for the first time. In the plastic housing use new .156" Trifurcon terminal pins. Again on Firepower and later games, replace the original IDC connector terminal pins and housing with new crimp-on trifurcon connector pins and plastic housing.
Always replace the connector pins with a crimp-on style pin. Never use IDC (Insulation Displacement Connector) pins. Be sure to buy a hand crimping tool like the Molex WHT-1921 (part# 11-01-0015), Molex part# 63811-1000, Amp 725, or Radio Shack #64-410.
Most System3 to System6 games used crimp-on connectors. But with Firepower, Williams changed to IDC (Insulation Displacement Connector) style connectors. These connectors are excellent for production, but are *terrible* in the long run. If replacing connectors on a Firepower or later game, always replace these with crimp-on Trifurcon connector terminal pins (a new plastic connector housing will also be required to replace the IDC connector housing).
The crimp-on plastic connector housings can be reused when replacing the terminal pins. Unfortunately the IDC plastic housings can not be adapted to use crimp-on pins, and the IDC housings must be replaced with crimp-on housings.
To remove the old connector terminal pins, on the sides of the connectors are slots with small metal "tabs". Press these down with a small screw driver, and the wires/pins should pull out easily from the housing. Do one pin at a time, and replace the pin with a brand new Trifurcon crimp-on .156" terminal pin. Do *not* replace with the Insulation Displacement Connector (IDC) style terminal pin! Only use crimp-on Trifurcon pins, as documented below.
More info on pinball connectors, how to crimp, why IDC is bad, and other pinball related connector information is avaialble at marvin3m.com/connect.
Check the Other Connectors.
.156" Male Molex Connector Pins and Housing. These are used for the non-interboard connectors (such as the power, lamp and switch matrix, and solenoid plugs), and can be cut to the number of pins needed. I buy the header pins and white plastic housings in a single long length, and cut it to size. Below are the exact part numbers for the number of pins needed.
Burnt General Illumination Power Supply Plugs.
Resoldering Board Header Pins.
As described above, insertion, vibration, temperature and humidity can cause microscopic cracks in the header pin's solder joints. This can cause the CPU board to lock up randomly. A quick solution is to resolder the header pins.
The first trick in doing a proper resolder job is to REMOVE THE OLD SOLDER! Now this may sound really anal, but it must be done. The old solder is often flawed with corrosion, dirt and other crud. If the old solder is just reflowed, often a solder "donut" will appear around the connector pin, where the old solder (or even newly added solder) just will not stick to the pin.
Because of this, use the desoldering method of your choice (see marvin3m.com/begin), and remove the old solder. Then solder with fresh new solder. The rosin flux in the new solder is often the added ingredient needed to make the new solder really stick to the old header pins. Be careful when soldering so adjacent pins are not "bridged" and shorted together.
Sometimes the two square plug power supply connectors 3J1 and 3J2 get damaged also. These connectors were used on Williams power supplies system3 to system7 (and also system 11b and DataEast/Sega power supply until 1995). The six pin 3J2 is a ground connector, and usually does not get damaged. But the twelve pin 3J1 handles all the input voltages from the transformer to the power supply, so sometimes it gets burned. Finding the part numbers for these connectors was difficult, as they were designed in 1971! So here are the part numbers for these wafer style, mixed pin connectors.
Removing the Boards from the Backbox.
The CPU board sits in a tray, which somewhat locks it into place. Make sure the CPU board is still in the tray when peeling apart the CPU and Driver boards. Also notice when taking the boards apart, how much the driver board flexes during this operation. The more times the boards are separated, the more chances that a small break will occur in the connector solder joints.
Installing the Boards.
Once the boards are back together, reattach the boards to the backbox with at least two screws each. Then reconnect all of the header connectors on both boards.
2f. Before Turning the Game On: Circuit Board Sockets (Dead Game or Random Lockups & Resets)
The CPU board has the bulk of the sockets: One 40 pin socket for the CPU chip, and usually three to seven 24 pin sockets for the game's EPROM and RAM chips. Most of the time the driver board has no factory installed sockets (but if there are any, be sure to replace them!)
There really is NO EXCEPTION to this rule. Even if the CPU board in question does not have Scanbe sockets, chances are good they are dead. There are only so many insertion/removals a socket will take before it is worn out. And on these Williams system3 to system7 games, worn out sockets can cause serious problems, locking on coils and ruining other circuit board components in the process.
The sound (and speech board, if the game has one) will also have sockets, for the EPROMs (24 pin) and CPU (40 pin) chips. Again, if these are the closed frame (Scanbe) variety, they will need to be replaced too. Though the sound board sockets are not as critical as the CPU board sockets, it's still a good idea to replace them.
Do I really Have to Replace All those Sockets?
"I Re-Seated the Chips, and My Game Now Works..."
Check out marvin3m.com/begin for the recommended soldering and desoldering tools and techniques. But for most of these old sockets, the plastic frame on the component side of the circuit board can be pried up with a small screw driver. After getting the black plastic frame up, the sockets legs should be exposed on the circuit board (be sure to check that the screw driver did not damage/cut any circuit board traces).
After the circuit board's solder hole is clear of the old socket leg, a Soldapult solder-sucker can be used to clear the the solder from the circuit board hole. Sometimes removing the socket's leg with pliers can be skipped, using the Soldapult to remove both the old solder and the old socket leg (do this from the component side of the board).
After all the socket legs are removed, and the circuit board holes are clear, sand the area with some 220 grit sand paper. Now carefully examine the area. Are any traces lifted or broken? Use a DMM set to continuity and double check. Remember nearly all the personality ROM chips legs "daisy chain" together, so testing is easy between ROM sockets with the DMM's continuity feature.
Always install a new socket! Don't solder chips directly into the circuit board. The best socket to use are SIP (Single Inline Package) machine pin sockets. These allow access to all the traces around the new socket. The sockets can even be soldered from the top side of the board, if needed. But conventially open frame mid-priced sockets also work well (AMP is a good socket brand). Just make sure the new sockets grip the chips leg on *two* sides (not just one!)
Socket Installation Tip.
Solder Flux Removal.
The easiest way to remove the solder flux is to use an old toothbrush and some 90% (or better) Isopropyl alcohol. Just put the alcohol on the board and use the toothbrush to scrub the flux off. It only takes a minute, and the alcohol dries quickly leaving a nice clean board.
* Return to the Pin Fix-It Index
* Go to Part Two System3-7 Repair Guide
* Go to Part Three System3-7 Repair Guide
* Return to Marvin's Marvelous Mechanical Museum