Legacy K4 possible blown board

The pinouts of the RCMC were diagramed by Bruk here on page 5.  You are correct that unplugging that plug takes the power off the board.  I assume the short occurs even with the shell off.  After carefully inspecting for pinched wires, I would start with unplugging the smoke unit and see if that clears the short since it was in the vicinity of the stack.  Hopefully, you can narrow down the problem by pulling plugs.

Bob

If you unplug the 4-pin motor/power plug, there is no power to anything else plugged into the board.  At that point, it's pointing to the pickups and associated wiring, something is shorted to the frame.

John

I think he said that it did NOT blow the breaker when he disconnected the power connector (grey, black, yellow, blue) from the board. So the pickups and associated power leads should be ok.

Bob

@RRDOC posted:

I think he said that it did NOT blow the breaker when he disconnected the power connector (grey, black, yellow, blue) from the board. So the pickups and associated power leads should be ok.

You're right, I mis-read his reply!    In that case, I'd be looking for grounds/shorts in all the other wiring.

Looks like a board failure. Unplugged everything from the board, applied power, and immediately blew the breaker. Guess I’m buying a board!🤨 thanks to everyone for your input. Much appreciated!

Bob

Wait a minute?  You unplugged EVERYTHING from the board and it still trips the breaker?  If so, it's not the board that has the short.

Everything except the power input. Left that hooked up, unplugged everything else. Unplug the stripped board from the power, short goes away.