Check the sound board's regulated -5 V and +5 V

Steps

• Check +5, +12 and -12 V at CN2.
• Measure across C49 (red on the leg toward VR1, black on ground): -5 V. This applies to every board from Laser War to Batman Forever.
• On boards from Batman on (all except 520-5002), also measure across the 0.1 µF capacitor C47 (red on the leg toward VR2, black on ground): +5 V from the 7805C regulator VR2.

Systems

• Data East CPU Version 1/2
• Data East CPU Version 3
• Data East/Sega CPU Version 3b

Related tips

• Sound board versions are not interchangeable
• The 520-5050-00 sound board variant
• Data East and Sega sound boards by game
• No sound at all: check the -5 V regulator
• Loud hum from the speakers
• No sound with all voltages present: the PALs
• No sound though sound board voltages are fine: unreadable sound ROM
• Sounds suddenly come out wrong even with new ROMs: bad ribbon cable

Source: Repairing DataEast 1987 (Laser War) to Sega 1995 (Batman Forever), Part Three, Clay Harrell (pinrepair.com)