Well, as usual, you can't trust ANY documentation to get it right!
I have a CSM84, model PA1306/20, the last model with DC brush motors. I have the service manual for the machine, it has schematics of much of the machine, but skips the servo amps and CPU board. I have M5841-03 drives for the DC brush servos. The CPU-3 section consists of a single page pictorial of the CPU board, and that's IT! No schematic.
If anyone has schematics for these boards, (or a Yamaha YM84 or machine from that series under their brand should have the same boards) I would very much like to complete my set, for "just in case"....
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