Missing, distorted or intermittent sound, sometimes only certain kinds of sound.

DCS or WPC-95 sound faults: amps and op-amps

Cause: Failed TDA2030A amplifiers (U27 and U28 on DCS, U5 and U6 on WPC-95) or TL084 op-amps (U7 and U8 pre-DCS, U21 and U29 on DCS, U1 and U2 on WPC-95). Leaky sound board rectifier diodes cause intermittent faults before failing short.

Checks

• Test the amps, op-amps and the rectifier diodes.

Fix

• Replace the failed parts.

Systems

• WPC DCS
• WPC-Security (WPC-S)
• WPC-95

Related tips

• Sound board beep codes, WPC-DCS and WPC-S
• Early WPC-95 games: static or thin, tinny sound
• Loud foghorn noise at power-on after recapping the DCS sound board: broken through-hole
• WPC-95 won't boot with the A/V board plugged in after a -125 V short
• Deafening hum at power-on: cracked ground trace at the DCS sound board filter caps
• WPC-95 audio/visual board LED and beep codes
• Sound cuts out or a rising shriek after a few minutes
• Line out on DCS and WPC-95 sound boards

Source: Repairing Williams/Bally WPC Pinball Games from 1990 to 1999, Part Three, Clay Harrell (pinrepair.com)