The game is silent, or quieter than it should be.

No sound, or weak sound

Cause: F10 and F11 both blown kills all sound; one blown usually leaves sound working but quieter. A5 parts can also fail: the TDA2040 amps, MC3403 op-amp and LM340T regulator.

Checks

• Check F10 and F11 (3 A slow-blow).
• Listen for the two-tone screech at power-on: if present, the sound boards are working.
• Make sure the CPU board's A1P4 plug is in place.

Fix

• Replace blown fuses and any failed A5 parts.

Systems

• Gottlieb System 3

Related tips

• No sound after the 12 V plug went on the speaker lead
• Parts on the A5 auxiliary supply
• No sound at all: check the -5 V regulator
• Both sound board LEDs dark
• The A6 sound board
• A5, A6, A8 and A20 plug identification
• The A20 auxiliary sound board
• Gottlieb System 3: loud screeching from the speakers: replace the sound board capacitors

Source: Repairing Gottlieb System 3 Electronic Pinball Games from 1989 to 1996, Clay Harrell (pinrepair.com)