I have a couple mc60’s that I use to power various things. 1 of them is used on a small lathe. I was cutting some H 13 steel, which is really hard. The controller is Powering a 3 hp motor. Admitting Lee, I was probably pushing the motor and board as far as they could go. The circuit breaker blew. The breaker wouldn’t reset unless I unplugged the board. After taking the boat out I did a few checks with the multimeter and there was continuity between both of the AC input leads. I found the diagram that everybody uses for diagnosing the circuit, and figured I would start with R4 which is a 1N4005 diode. I removed r4 And are four was causing the problem, because now there wasn’t continuity between the two 120 V input and R4 was acting like a solid piece of wire, and not a diode. I replaced R4 and as soon as I plugged it in it blew the breaker and the new 1N4005 diode again. So there’s obviously something further back in the circuit that isn’t working correctly that is blowing R4. Any help is appreciated.