The game has no sound. The unregulated supplies arriving at the sound board read about +10 V and -16 V.

No sound though sound board voltages are fine: unreadable sound ROM

Cause: The supplies were within range; the sound program ROM had failed and could not be read.

Checks

• The +12 V feeds the amplifier chips directly (8 to 16 V is fine), and the -12 V is regulated down to -5 V; check for -5 V at the regulator output.
• Check the amplifiers, then read each sound and voice ROM in a programmer and compare them with good images.

Fix

• Program a replacement for the failed sound ROM and fit it.

Systems

• Data East CPU Version 1/2

Games

• Laser War

Related tips

• No sound with all voltages present: the PALs
• No sound, only amplifier hiss with the volume up
• Check the sound board's regulated -5 V and +5 V
• Sound board versions are not interchangeable
• Data East and Sega sound boards by game
• No sound at all: check the -5 V regulator
• Loud hum from the speakers
• Sound board power input connector CN2

Source: Pinball Repair help group!! (Facebook group)