System 7 sound select connector 1J8

From Black Knight on, an extra PIA at IC36 on the CPU board drives the sound lines through CPU connector 1J8. Pin 1 commas for displays 3 and 4 (brown-white), pin 2 commas for players 1 and 2 (violet), pin 3 key, pins 4-7 unused, pin 8 sound select 4 (yellow) to 10J3-7, pin 9 select 3 (green) to 10J3-4, pin 10 select 2 (blue) to 10J3-5, pin 11 select 1 (red) to 10J3-2, pin 12 select 0 (red-yellow) to 10J3-3.

Systems

• Williams System 7

Related tips

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Source: Repairing Williams System 3 to System 7 Pinball 1977 to 1984, Part Three, Clay Harrell (pinrepair.com)