No sound at all, or sound that cuts in and out (sometimes when coils fire).

No sound or sound cutting out

Cause: A broken or disconnected cabinet speaker (which silences the others), intermittent speaker wire connectors, dirty ribbon cables, sound EPROMs with bent pins or fitted backwards, or blown speakers.

Checks

• Check the cabinet speaker and its connectors.
• Reseat all sound board ribbons.
• Inspect the socketed EPROMs for pins bent under or outside the socket and for the notch matching the socket.
• Test each speaker with the game off by touching a 9 V battery briefly across its leads: a good cone moves.

Fix

• Repair the wiring, straighten pins, replace blown speakers. An EPROM fitted backwards is ruined and must be replaced.

Systems

• WPC Alpha-Numeric
• WPC Dot Matrix
• WPC Fliptronics
• WPC DCS
• WPC-Security (WPC-S)
• WPC-95

Related tips

• Sound board RAM error at U9, wrong call-outs or no sound: replace the U9 RAM
• DCS or WPC-95 sound faults: amps and op-amps
• WPC sound board versions
• WPC-89 sound board layout
• The WPC sound board runs on its own
• Sound board beep codes before DCS
• Pre-DCS sound board A-12738
• Adding a line out to the A-12738 sound board

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