Baby Pac-Man
Bally, 1982You're currently viewing posts by Pinsider WOLF.
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Looking at the schematic for this board, TP2 is 11.9v unregulated, so 15v is not a big deal. TP4 is ground, again .01v isn't a big deal. TP3 is supposed to be 21.5v and is part of the zero crossing circuit, which also involves U10- pin 18, so 4.76v is a big deal. I would spend my time diagnosing that circuit. If you look at that circuit, you'll see the voltage changes a few times, so just depending where along there you check it, 4.76v may show up, but not at TP3.
That wire is a gray/no tracer (90) wire that goes to the play field plug for the zero crossing (0A ZXING). If you look at W-1282 and W-1281 and use the wire numbers along with the wire color code chart, you should be able to find which connector it is.
Quoted from ForceFlow:Since I'm getting inconsistent behavior with the boot and reset sequences, and since the voltages seem ok on the U9 CPU, is the U9 CPU itself faulty? Should it be replaced?
I can't safely answer that. I'm not sure how to check U9 reliably, we need someone a little more adept than myself on that subject.
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New Castle, PA