Which -51/-56 sound ROMs respond to the board test button

Test button gives a sound: Silverball Mania, Rolling Stones, Mystic, Viking, Hotdoggin, Frontier, Skateball and Grand Slam. No response: Nitro Ground Shaker, Future Spa, Space Invaders, Xenon and Speakeasy. Unknown: BMX and Gold Ball. A ROM that ignores the button can still work fine in the game.

Systems

• Bally MPU AS-2518-35

Related tips

• Sound module -32 and -50 test points
• Identifying AS-2518-51 and AS-2518-56 sound boards
• Sound Plus -56 and vocalizer test points
• No sound at all: start with the amplifier hiss
• Sound board chip 86L93 can be replaced by a 74LS93
• Spare sound board works on the bench but is silent in the game: no -5 V, bad 7905
• Background sound works in test but not in games: check DIPs 29-30, then reseat connectors
• Odd 43 V coil faults on games with the early AS-2518-32 sound board

Source: Repairing Bally Electronic Pinball Games from 1977 to 1985, Part Three, Clay Harrell (pinrepair.com)