System 11 CPU board part numbers and spotting features
System 11: D-10881, a seven-segment LED shows diagnostic codes, sound amplifier on board, an unused opto switch circuit. System 11A: D-11392, three LEDs instead, 1J18 pins 6-7 grounded, zeners ZR3-ZR8 (1N5234, 6.2 V) added, and jumpers W16/W17 added. System 11B: D-11883-xxx (xxx is the game number); the opto circuit and SRC6 were dropped, and a second revision changed the switch circuit and made Q42-Q49 a single row of 2N5550 instead of 2N3904. System 11C: also D-11883-xxx, with no sound section.
Systems
Related tips
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- Special coil stays on even after replacing its driver chain (Rev 3)
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Source: Repairing Williams System 11 Pinball 1986 to 1990, Deel 1, Clay Harrell (pinrepair.com)