AS-2518-51/-56 sound board jumpers

CPU: a 6802 needs jumper A in, B out and no 6810 RAM at U10; a 6808 needs B in, A out and a 6810 at U10. -51 ROM: 9316/2716 uses jumper C (D out); 9332/2532 uses D (C out). -56 ROM: 2732 uses C and E (D, F out); 2532 uses D and F (C, E out). Without a vocalizer fit jumper G, remove C27 and jumper J; with one, fit J and C27. Jumper H makes a -56 act as a -51. Most -56 boards are set B, C, E, G, H (6808, 2732, no vocalizer).

Systems

• Bally MPU AS-2518-35

Related tips

• Sound module -32 and -50 test points
• Bench-test a -51/-56 sound board with a test EPROM
• Sound Plus -56 and vocalizer test points
• No sound at all: start with the amplifier hiss
• Odd 43 V coil faults on games with the early AS-2518-32 sound board
• Sound board chip 86L93 can be replaced by a 74LS93
• Background sound works in test but not in games: check DIPs 29-30, then reseat connectors
• Faulty sound board blanks the displays and confuses the lamps

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