Williams System 8

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1 Introduction

Williams System 8 Board Set

The Williams System 8 boardset was used in 1984 with only two games, the pitch and bat Pennant Fever and Still Crazy, a novelty game. Combining the driver board, sound board, and cpu directly onto one board eliminated several design deficiencies of the earlier System 3-7 boardsets; mainly the 40 pin interconnector, and extra wiring harness interboard connectors.

System 8 is very similar to its successor (System 9), but it is more of a "slimmed down" version. There are a total of 8 controlled solenoids versus the 16 used with the system 9 boardset. Another distinct difference is system 8 hardware does not utilize special solenoids. System 8 also lacks the connector for a speech daughterboard.

Although system 8 is capable of driving four 7-digit displays and one 4 digit display, only two 7-digit displays are used with Pennant Fever and one 7-digit display is used with Still Crazy. Therefore, master display boards are not used on either game. Both the lamp and switch matrices are 8 x 8 in size, but neither Pennant Fever nor Still Crazy use many switches in their matrices.

2 Games

Title	Date of Release	Model #	Other Boards	Notes
Pennant Fever	05-1984	526	CPU rev A	Pitch and Bat
Still Crazy	06-1984	534	CPU rev X1	Novelty Vertical Pinball

3 Technical Info

3.1 CPU Driver Board

System 8 CPU rev A (Pennant Fever)

System 8 CPU rev X1 (Still Crazy)

3.2 Power Supply

System 8 Power Supply

4 Problems and Solutions

4.2 MPU boot issues

4.2.2 Repairing Alkaline Corrosion

Remove the battery holder entirely from the MPU board and wash the board's affected areas with a 50/50 mix of vinegar and water. Scrub the corrosion with a soft toothbrush, rinse with water, then rinse with 91% or 99% isopropyl alcohol to displace the water.

4.2.3 Connecting a logic probe to the MPU

Connect the +5V lead of your logic probe to the top of C6.

The System 8 MPU lacks test points. Argh!

To connect a logic probe, pick up +5V at the top lead of capacitor C6 (a trace extends down from the larger electrolytic cap at C5).
Pick up ground at pin 9 of 1J5.

4.2.4 Using a PC Power Supply For Bench Testing

Powering the System 8 MPU on the bench with an old PC power supply.

The System 8 MPU requires 5/12/-12VDC and ground to fully operate on the test bench. +/-12VDC is used by the sound amplifier.

Connect...

• Ground to pin 1, 2, or 3
• +5VDC to pin 4, 5,or 6
• -12VDC to pin 8
• +12VDC to pin 9

4.4 Solenoid problems

this is a stub

4.7 Display problems

WARNING: This circuit uses high voltages. Don't continue, unless you are confident in your diagnostic abilities.

4.8 Sound problems

The sound generation section of the System 8 MPU.

The System 8 MPU creates sound on the MPU itself, much like the baseline version of the System 11 MPU.

General System 8 Sound Subsystem Theory of Operation

• The sound subsystem consists of a 6808/2 processor, 6821 PIA, 1408 DAC, and finally a TDA2002 amplifier.
• Sounds are conveyed to the sound subsystem by the main processor via the input ports of the 6821 PIA at IC13.
• The 6808 at IC11 reads the PIA input port then pulls the appropriate sound file from the sound ROM at IC49.
• The 6808 sends the sound data back to the 6821s second set of output ports, which are attached to the 1408 digital-to-analog converter.
• A remotely located volume pot may be used to adjust volume levels.
• The analog audio is then presented to the TDA2002 for final amplification.

Note that the sound subsystem can be configured to use either a 6808 or a 6802 microprocessor.
To use a 6808, jumper W1 should be in, W2 out.
To use a 6802, jumper W1 should be out, W2 in.

5 Repair Logs

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