Early System 11 CPU in a later game gives meaningless LED codes
A first-generation board with the seven-segment LED, fitted in an 11A, 11B or 11C game, shows garbage on that digit, because later game software drives the LED lamps instead. Do not read those codes as faults.
Systems
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Source: Repairing Williams System 11 Pinball 1986 to 1990, Part Two, Clay Harrell (pinrepair.com)