Williams WPC

Note: This page is a work in progress. Please help get it to a completed state by adding any useful information to it.

1 Introduction

This guide covers Williams WPC, WPC-S, and WPC-95 games.

2 Game List

2.1 WPC (Alphanumeric)

• Funhouse
• Harley-Davidson
• The Machine: Bride of Pin*Bot

2.2 WPC (Dot Matrix)

• Gilligan's Island
• Terminator 2: Judgement Day
• Hurricane
• Party Zone

2.3 WPC Fliptronics I & II

• The Addams Family / Addams Family Gold
• The Getaway: High Speed II
• Black Rose
• Fish Tales
• Doctor Who
• Creature from the Black Lagoon
• White Water
• Bram Stoker's Dracula
• Twilight Zone

2.4 WPC DCS Sound

• Indiana Jones: The Pinball Adventure
• Judge Dredd
• Star Trek: The Next Generation
• Popeye Saves The Earth
• Demolition Man

2.5 WPC-S CPU

• World Cup Soccer
• The Flintstones
• Corvette
• Red & Ted Road Show
• The Shadow
• Dirty Harry
• Theatre of Magic
• No Fear: Dangerous Sports
• Indianapolis 500
• Johnny Mnemonic
• Jack*Bot
• WHO Dunnit

2.6 WPC-95 CPU

• Congo
• Attack from Mars
• Safecracker
• Tales of the Arabian Nights
• Scared Stiff
• Junk Yard
• NBA Fastbreak
• Medieval Madness
• Cirqus Voltaire
• No Good Gofers
• The Championship Pub
• Monster Bash
• Cactus Canyon

3 Technical Info

Motorola 68B09E, running at 2Mhz. It is an 8-bit/16-bit CPU with a 64KB address space. Bank switching is required to address more than 64KB. The game ROM size varies from 128KB to 1MB, depending on the game. 8KB of battery backed RAM is available.

For more information, see The FreeWPC Manual

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3.5 WPC Dot Matrix Controller board

Not much troubleshooting and repair detail here so far. So in the meantime, here is some repair information and links.

3.5.1 Schematic Diagram for WPC and WPC-95 DMD Controller Board

This link explains my experience repairing a Twilight Zone ('93 WPC) DMD Controller Board. Also repaired the actual display PCB, which was damaged from a from a faulty +62v circuit:

TZ DMD Controller Board Repair

Here’s a schematic with a list of the parts needed for WPC and WPC-95. Both board are extremely similar: WPC DMD Controller

Another area which will help with troubleshooting the DMD Controller Board is in the DE area (DE copied the Williams board designs):

Data East/Sega#PS_520-5047-01_-_High_Voltage_Missing_at_the_DMD_display

3.5.2 DMD Repair Warnings

Be careful when repairing the DMD Controller Boards, you are dealing with High Voltages when the boards are running. A good safety measure is to put one hand in a back pocket (or behind your back) when testing voltages.

It's also fairly easy to lift traces on the PCB or ruin the 'through holes' when removing components. If this happens, you may have to check continuity and 'stitch' the component hole with a thin wire strand. It's a good idea to practice on some useless PCB boards first, before taking on the DMD Controller Boards. For details on a stitch see: How to... (solder, desolder, "stitch", test transistors, test ICs, etc)

If you do not have decent soldering and de-soldering skills, DMD HV work should be left to a professional.

HV Repair Kits and advice are available from: Ed at Great Plains Electronics

• WPC-95 HV REPAIR KIT $5.00
• WPC HV REPAIR KIT $5.50
• GPE kits do not contain capacitors, which can be ordered separately as needed.

HV Repair Kits and advice are also available from: Rob Anthony at Pinball Classics

• WPC-95 or WPC HV REPAIR KIT $10
• Indicate in the notes section of the order if you need the WPC or the WPC-95 HV kit, Pinball Classics kits do contain the 150uF 160V capacitors.

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3.8 Miscellaneous WPC Boards

Note: Some of these might best be located in the "Game Specific Problems & Fixes" section. Perhaps the pervasiveness of their use within the WPC game list would drive the decision.

3.8.3 Auxiliary 8-Driver Board

as used in TZ, DM, IJ, etc...

3.8.7 Coin Door Interface Board

If your coin door interface board gets dusty from flipper parts wearing, clean it. That dust conducts electricity and will give you some interesting coinage issues.

4 Problems and Solutions

4.1 MPU boot issues

4.1.1 Relocating the battery from the MPU board

Relocating the 3xAA battery pack from the MPU board is always a good idea. Leaky alkaline batteries are the #1 killer of MPU boards. Simply removing the batteries is not an option with WPC games as you will always receive a "Factory Settings Restored" message when the game boots.

Options:

1. Remotely locate the battery holder somewhere below all other boards. This ensures that even if the remotely located batteries leak, they won't leak onto (or even drip onto) any circuit board. Replace the batteries annually, dating them with a Sharpie! as you do.
2. Replace the 6264 static RAM with a SIMTEK non-volatile RAM (STK12C68). These SIMTEK RAM chips are increasingly hard to find but offer a nice alternative to changing batteries annually. This method requires desoldering/soldering on the MPU and also has the down-side of not maintaining the Real Time Clock (meaningless in some games...nice in games like Twilight Zone that moves the playfield "toy" clock to the current time during attract mode, and Who?Dunnit which has a "Midnight Madness" feature.

4.3 Check fuses F114 and F115 message

This section needs much more info and review - especially with the F115 error and repair

WPC games will sometimes boot but will not enter attract mode. Instead, the message "Check fuses F114 and F115" is displayed. A game cannot be started. The following steps can be taken to identify the cause of this message and repair it.

1. First, actually check fuses F114 and F115 as specified here. If a blown fuse is found, replace it.
2. If the replaced fuse immediately blows this could be due to a shorted bridge rectifier (among other things). Fuse F114 blowing can be caused by a shorting BR1. These bridge rectifiers are covered by a large heat sink which must be removed before replacing. This sink is removed by removing the two screws which are accessed from the solder side of the board.

File:Test-br.jpg

Checking an uninstalled bridge rectifier

To check the bridge rectifiers

1. Set your multimeter to the diode setting.
2. Put the red lead of your DMM to the negative terminal and the black lead of your DMM to one of the other BR lugs (either that is not diagonally across from the negative lug). Your DMM should read between .4 and .6. A reading of 0 indicates a short and the bridge rectifier should be replaced. Keep your red lead on the negative terminal and move your black lead to the other lug. You should still get a reading of between .4 and .6.
3. Now put your black lead of your DMM to the positive terminal and the red lead one one of the BR lugs. Repeat the process above and the settings should be the same.

The heat sink covering BR1 and BR2 on a WPC-board

Take special care when replacing a bridge rectifier. It is easy to lift the traces of the plated through holes when removing these. After removing the heat sink, cut the old bridge rectifier off of the board close to the top leaving as much of the lug as possible. Then add a small amount of solder to the connection on the solder side to improve heat transfer. Finally apply the iron to the solder side to heat the joint and remove the remaining lug with small pliers.

When replacing the new bridge rectifier you should remove the old thermal compound and apply a new thin layer. The old compound can be removed with a little rubbing alcohol. Apply the thermal compound to the top of the bridge rectifiers and reattach the heat sink with the screws. It is much easier to replace the heat sink before resoldering the new bridge rectifier. Make sure that the heatsink is sitting flush with the tops of the bridge rectifiers and that you leave a gap between the bridge rectifier and the board.

It is also recommended not to split the heatsink when replacing the bridge rectifiers.

More info about replacing bridge rectifiers can be found in the section regarding system resets.

Diodes replaced BR1 and BR2 on WPC-95 boards

In WPC-95 games, the bridge rectifiers were replaced by a series of diodes. These are much less prone to failure but can still cause issues.

4.4 Solenoid & Flasher problems

Before proceeding to diagnose solenoid or flasher problems, see this section: How coils and flashers are turned on

4.5 Lamp problems

Lamps (or globes for those of you in the UK) fall into two categories. "General Illumination" and "Controlled Lamps". Your game probably has other lamps which are actually "flashers" that require an 89 or 906 bulb. Flashers are covered elsewhere in this Wiki.

General illumination lamps (GI) provide the ambient lighting for the playfield, backbox, and coin door. These lamps are list most of the time. The only "controllable" aspect of these lamps is their brightness.

Controlled lamps are under complete CPU control via the lamp matrix. These lamps illuminate the various "features" of the game such as mode inserts, pop bumper lamps, inlane/outlane insert lamps, etc.

4.5.1 General Illumination Problems

Background

The WPC power/driver board provides 5 GI circuits under CPU "brightness control". The WPC-95 power/driver board provides 3 GI circuits under CPU "brightness" control and 2 circuits that are always powered. Those two circuits are always connected to the backbox lamps.

GI power is provided by the transformer in the form of 6.3VAC at power/driver board connector J115. Each of the GI circuits is "metered" by a Triac on one side of AC power. AC power is then supplied to the backbox, playfield, and coin door via power driver board connectors J120, J121, and J119 respectively. J119 is a 3-pin header that is always connected to the coin door lamps. J120 and J121 are electrically and physically identical (keyed at pin 4) and therefore can be connected to either the female playfield GI connector or the female backbox GI connector without care.

The other side of the AC GI circuit on the power/driver board is fused by F106 through F110 which are all 5ASB fuses.

Each Triac is switched on/off by a 2N5401 transistor which is controlled by U1, a 74LS374, an octal D-Type Flip-Flop with three state outputs (a fancy way of saying that the device is an 8-bit data buffer).

Wire colors to J115 during the early WPC games were always yellow (AC) and yellow-white (AC return). Pin 1 of J115 provides the "ground reference". Later WPC games used different wire colors at J115 and instead of "looping" power through the connector at J115, connected two wires to the same pin at the 9-pin connector between the transformer secondary and J115.

J119 is always keyed at pin2, with a white-Violet wire at pin 1 and a Violet wire at pin 3

J120 and J121 are 11 pin connectors. Wire color/positions (when used) are identical for all WPC games and are shown in the table.

Pin	Wire color at J120/J121
1	Brown
2	Orange
3	Yellow
4	Key
5	Green
6	Violet
7	White-Brown
8	White-Orange
9	White-Yellow
10	White-Green
11	White-Violet

Common GI Problem Causes (listed by probability/ease of testing and correction)

1. Blown fuses. This is also the easiest problem to fix. Check each fuse following this procedure. Don't trust your eyes.
2. All lamps blown. Don't laugh. Just for giggles, put a known working lamp into one of the lamp sockets of the suspected GI string. I've seen it more than once. Usually the result of operators never changing a bulb, or somehow connecting higher voltage to the circuit.
3. Burned connectors. <need a picture> Over long periods of time, both the male and female GI connectors at J115, J120, and J121 often burn. This was especially prevalent in early WPC games like Terminator 2. Numerous "hacks" have been employed over the years by well meaning repairmen but the only real way to fix burned connectors is to replace both the male header pins and the female housings/pins. "Trifurcon" pins are recommended to provide a better connection. There is also a 9-pin (3x3) connector between the transformer secondary and J115. This connector/pins sometimes burn also and may require replacement.
4. Burned traces. Usually, this is a secondary problem created after the connectors burn. Visual inspection of the traces might uncover the problem, but "buzzing" them for continuity is the best practice.
5. Failed 2N5401. These don't fail very often, but are easy to test following this procedure.
6. Failed resistors. Again, these don't fail very often but are easy to test with your DMM. Keep in mind that "in-circuit" measurements may not be reliable.
7. Failed 74LS374. This is rare too but easy to test following this [[ | procedure]].
8. Failed Triac. These rarely fail. But, if you've gotten to this step in the procedure, it's time to replace the Triac.

4.6 Switch problems

"Switch Matrix" switches section under construction...
Switches in WPC games fall into two categories, those within the switch matrix, and "direct" switches.

Direct switch operation

Direct switches include:

• Left coin chute
• Center coin chute
• Right coin chute
• 4th coin chute
• Service Credits/Escape (referred to as "escape" here)
• Volume down/Down
• Volume up/Up
• Begin Test/Enter

Direct switches are not part of the WPC switch matrix. All of the direct switches are located on the coin door, and connect to the MPU at J205. The MPU senses these switches individually, and apart from the switch matrix. Therefore, isolation diodes are not used with direct switches.

Normally, with the switch open, the LM339s at U16 and U17 compare 12V supplied on the MPU to both the switch and to the LM339 with 5V (as a comparison level) and signals the 74LS240 at U15 that the switch is open. When the switch closes, it shorts the 12V to ground and the comparison at the LM339 then indicates to U15 that the switch is closed. U15 is "clocked" by pin 48 of the ASIC (SW DIR), causing U15 to make its data available on the data bus. The 6809/ASIC "debounces" the switch. Debouncing is not a factor to be considered here and doesn't factor in switch testing.

Direct Switch Pinout at J205 for both WPC and WPC-S MPUs
Notes:

J205, pin 5 is the "key" pin.

J205, pin 10 provides ground (black wire)

J205, pin 11 is unused

J205, pin 12 is an "enable" back to the coin door interface board

Signal	Wire color at J205	MPU pin	Diode	LM339 & input pin	U15 input pin
Left chute	orange/brown	J205-1	D15	U17-5	11
Center chute	orange/red	J205-2	D16	U17-7	13
Right chute	orange/black	J205-3	D17	U17-11	15
4th chute	orange/yellow	J205-4	D18	U17-9	17
Escape	orange/green	J205-6	D11	U16-9	2
Down	orange/blue	J205-7	D12	U16-11	4
Up	orange/violet	J205-8	D13	U16-7	6
Enter	orange/gray	J205-9	D14	U16-5	8

Debugging direct switch problems

Some techs will start at the end of the signal path and work back to the switch. This article works from the switch signal source to U15 on the MPU. This allows you to test the easiest, yet high probability failure points, first. If your MPU has obvious alkaline damage at U15, U16, or U17, address the alkaline damage first.

Begin testing with the game OFF.

Test the direct switch's path to ground

1. DMM set to continuity
2. Red lead on the solder joint between the switch and the black wire that provides ground.
3. Black lead on any game ground, like the lockdown bar.
4. You should hear "tone". If not, further diagnose the break in the black wire between the solder joint and game ground.

Test the direct switch itself

1. Clip the black lead of your DMM to game ground
2. Red lead on the solder joint opposite the black wire (or bare wire jumper) on the switch under test
3. Depress the switch. You should hear "tone". If not, the switch is defective and not "making". See the section below that describes cleaning these switches.

Test the signal path to the MPU

1. Clip the black lead of your DMM on the solder joint opposite the black wire (or bare wire jumper) for the switch under test.
2. Remove the connector plug at J205 from the MPU.
3. Red lead on the appropriate pin of J205 for the switch under test. See the table above. It's easiest to access the pin through the rectangular hole in the back of the connector where the pin's "tang" snaps in.
4. You should hear "tone". If not, there is a discontinuity in the wire between the direct switch and J205. Note that the coin door interface board is between these two points. The coin door interface board is a "pass-through" for these signals and rarely causes a problem. Still, reseating connectors J1, J3, and J4 on the coin door interface board might uncover the problem. More likely, the wire between J1 on the coin door interface board and J205 has a break in it.

Test the signal path through J205 and onto the MPU
J205 is right below the battery holder and as such, sometimes receives the unwanted gift of dripping alkaline from depleted batteries. Carefully examine both the male and female connections of J205 for alkaline "greenies". Assuming no alkaline damage...

1. Connect J205 to the MPU.
2. The black lead of your DMM should still be clipped to the solder joint opposite the black wire (or bare wire jumper) for the switch under test.
3. Red lead on the banded end of the appropriate diode shown in the table above.
4. You should hear "tone". If not, there is either a problem with the physical connection at J205 or the alkaline "greenies" are sneakier than you gave them credit for. Re-examine J205 and the surrounding area of the board for alkaline damage. The traces from the switch connectors are very small and it takes very little alkaline damage to compromise them. You may also re-pin the female side of J205.

At this point, a logic probe would be the best tool to use. You can pick up 5V power for your probe across the electrolytic cap at C31 which is immediately to the right of the battery holder. Black lead on the negative side (top of the cap). Red lead on positive side (bottom). The board is silkscreened with polarity markings. Set the logic probe to "CMOS" test mode, as you will be measuring 12VDC.

If you don't already have a logic probe, you should. Although for this test, you can still get by with your trusty DMM. Clip the black lead of your DMM to game ground. The ground braid in the head is a good place to pickup ground at this point. Set your DMM to DC volts.

You now need to turn the game ON.

Test the LM339 inputs

1. Again, set your logic probe to "CMOS"
2. Measure the signal at the appropriate LM339's appropriate pin. Either place your logic probe on the pin or place the Red lead of your DMM on the pin. The signal should measure high (or about 12VDC with your DMM).
3. Have someone close the switch under test and hold it closed as you observe the results.
4. You should see the signal transition to low. If you still measure high, then the pin isn't being grounded correctly. Candidates are a failed diode/resistor in the circuit, the board trace between the diode and the LM339 is compromised, or a badly failed LM339.
5. Note that if the signal transitions to low but not "crisply", then the switch is marginal and should be cleaned or replaced to ensure proper future operation. That is, the signal should transition directly from high to low and stay there without flip-flopping much at all while transitioning or when held down.

Test the LM339 outputs/74LS240 (U15) inputs

1. Set your logic probe back to TTL as you will be measuring 0 - 5V signals
2. Measure the signal at the appropriate pin (see table) of U15. The signal should measure high (or about 5VDC with your DMM).
3. Have someone close the switch under test and hold it closed as you observe the results.
4. You should see the signal transition to low. If you still measure high with the button pressed, then either the LM339 outputs have failed, the board trace between the LM339 and U15 is compromised, or the 74LS240 has failed and is corrupting the signal. You can test U15 using the procedure in the "How to..." section of PinWiki, here.

The output side of U15 can't be tested effectively since that is the processor/ASIC data bus and should be constantly and irregularly changing states.

If you've followed this process step-by-step (or even in reverse step-by-step), you should have identified the problem with the signal and will be able to effectively perform the appropriate repair.

Cleaning direct switches

Coming soon...will describe disassembly and cleaning... Sometimes, several rigorous open/close cycles will "clean" corrosion from the switch.

WPC Switch Matrix problems

Coming soon...