CPU board test switches SW1 and SW2
Two buttons on the left edge of the CPU board: the upper one (SW1) runs the sound test, the lower one (SW2, "CPU") reruns the memory chip test performed at power-on. SW2 can be pressed at any time.
Systems
Related tips
- Checking ground and +5 V on the CPU board
- Which System 11 CPU boards fit which games
- Running the CPU board on the bench
- Checking the CPU clock signal
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- Which System 11 CPU boards swap between generations
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Source: Repairing Williams System 11 Pinball 1986 to 1990, Part Two, Clay Harrell (pinrepair.com)