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  by Bill Degnan - 02/05/2021 10:47
Click image to view PDF.


Howie Zwik's original repair notes.

Closeup of the 4040 and 4201 chips (see Zwik's notes). Click image to see entire CPU board/zoom out.


I replaced the 4201 chip to follow up on Howie's troubleshooting conclusions, but doing so did not resolve any issues. The system is still DOA.

NEXT - Circle back to the RAM and then the power supply. Get a better understanding of what's doing what here. I have schematics. The goal is to repair so I have something to program 2708 ePROMs



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