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)

2.2 WPC (Dot Matrix)

2.3 WPC Fliptronics I & II

2.4 WPC DCS Sound

2.5 WPC-S CPU

2.6 WPC-95 CPU

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

3.1 The WPC Transformer

3.2 The WPC System Boardset and History

3.3 WPC CPU Generations

3.3.1 WPC CPU

3.3.2 WPC-S CPU

3.3.3 WPC-95 CPU

3.4 WPC Power/Driver Board Generations

3.4.1 WPC-089 Power/Driver Board

3.4.2 WPC-95 Power/Driver Board

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.

3.6 WPC Sound Boards

3.6.1 WPC pre-DCS Sound Board

3.6.2 WPC DCS Sound Board

3.6.3 WPC-95 AV Board

3.7 WPC Fliptronics Boards

3.7.1 WPC Fliptronics I board

3.7.2 WPC Fliptronics II board

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.

3.8.1 WPC 7 Opto Board

3.8.2 WPC 10 Opto Board

3.8.3 Auxiliary 8-Driver Board

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

3.8.4 Trough opto boards

3.8.5 WH2O & CFTBL chaser lamp boards

3.8.6 HSII & CFTBL triac board

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:

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.
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.

4.1.2 Repairing Alkaline Corrosion

4.2 Game resets

4.2.1 A disciplined process to eliminate WPC game resets

4.3 Solenoid & Flasher problems

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

4.4 Lamp problems

4.5 Switch problems

Switches in WPC games fall into two categories, those within the switch matrix, and "direct" switches.

Direct switch problems

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 a part of the WPC switch matrix. The MPU senses these switches individually and separate from the switch matrix. They are connected to the MPU at J205. Diodes, which are used in the switch matrix to isolate individual switches, are not used with direct switches.

Normally, the LM339s at U16 and U17 compare 12V tied to the switch (on the MPU) with 5V as a comparison level and signals the 74LS240 at U15 that the switch is open. When the switch closes, this shorts the 12V to ground and the comparison at the LM339 then indicates to U15 that the switch is closed. U15 is "clocked" at pin 48 of the ASIC (SW DIR), making it's data available on the data bus. The 6809/ASIC "debounces" the switch.

Pinout

Left chute Center chute Right chute 4th chute Escape Down Up Enter

Cleaning direct switches

WPC Switch Matrix problems

4.6 Display problems

4.7 Sound problems

4.8 Flipper problems