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. 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...

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 Solenoid & Flasher problems

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

4.5 Switch problems

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.

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 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.
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 give them credit for. Re-examine J205 and the surrounding area of the board for alkaline damage. 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 right of the battery holder. Black lead on the negative side (top of the cap), and Red lead on positive side (bottom). 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, 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.

Test the LM339 outputs/74LS240 (U15) inputs

1. Set your logic probe back to TTL
2. Measure the signal at the appropriate pin 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 the 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...

WPC Switch Matrix problems

Coming soon...