I'll need to look at this tomorrow. It is too late tonight to continue. I'll look at the board and let you know what I see.
The board is OK. After getting it apart, and all looked OK, it occured to me that the problem could be caused by a heavy load on that breaker and running the microwave just adds enough current to trip it. I checked this hooking the electronics back up and running an extension cord to the microwave and put it on a different circuit. It ran the microwave without blowing that fuse.
Unfortunately, after I put it all back together, it no longer works at all. No clock, no lights, nothing. I double checked and all the connections are back where they are supposed to be. What do you think can be causing this?
If one of the internal thermal fuses has tripped or opened that could cause that problem as it would be just dead
The main fuse was removed to pull apart the interior to get to the inverter. For some reason when I re-inserted the fuse, it was not making contact to the fuse holder. I thought it was a blown fuse, but tested it and it was OK. When I reinserted it, I had power. In the meantime, I busted the relay that powers the inverter by pulling on the cable that attaches to the transformer board. I've go to order a replacement relay and solder that onto the card.
I still don't know what is on the house circuit that is tripping the breaker.
I'm not sure how to rate this service. I've not used it before, and am a skeptic concerning internet diagnostics of this type. The tripped breaker was the evidence I presented, but rather than have me check the house circuit load first, which seams like the obvious first step now, you had me pull apart the microwave to check the inverter. The microwave turns out to be fine, so that effort was a waste of time, plus the assembly and disassembly caused me to damage the relay, so now I have to pull the power supply card out and desolder and replace the relay. Your guidance on the thermal fuses was also misguided and would not have resolved the power loss issue I fixed last night.
Still, I suspect the only true mistake you made was not having me check the circuit load before tearing into the microwave. How should I rate this?
I don't know what is on it yet. I know the stovetop and exhaust fan both stopped working when the breaker tripped, but there could be more things. I've been using the same stove/exhaust with the microwave for several years without an issue, so something must have changed recently.
I'm waiting on a relay that needs to be replaced before I can get the microwave back together again. After that I'll check the breaker as you suggest.
It is back together with the new relay and when I plugged it in the clock came back on, lights worked, etc. I pressed the start button and now the fuse is blowing (not the breaker). I replaced the fuse and that fuse blew immediately as soon as I plugged the microwave into 120v. Ideas?