Rough Shelf Handling Bent Pins Cause System 11A MPU to Not Boot
Video
Summary
Hibler repairs a Williams System 11A MPU board with bent pins, a shorted Q9, and a missing Q50 for a Taxi machine.
Chris Hibler walks through repairing a Williams System 11A MPU board for a Taxi pinball machine that wouldn't boot. Causes included bent connector pins touching adjacent pins, a shorted Q9 transistor, a missing Q50 part, a mismatched 74HC08 replacement chip, and an unsafe 7408 substitution. He documents in-circuit diode-check testing of transistors and the bring-up sequence through coil, lamp, and switch tests.
Bent pins from rough shelf handling cause System 11A MPU to Not Boot A hangar queen is an airplane that has been in the hangar for a long time and usually becomes cannibalized for parts. 
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