Here at work our little Samsung microwave was cooking away and then just quit. Upon investigating it, I find the fuse blown. Ok, then check the door switches - all 3 ok. I have put a copy of the schematic at
If I replace the 15A fuse with a little larger one, it will come on but with an abnormally loud hum. If I unplug the magnetron by pulling the wire from the FA terminal, the excessive hum is still there, which to me means that the magnetron isn't the cause of the problem here. If I lift the rectifier ground, then the hum stops. The rectifier isn't shorted, but I also can't test it with my Fluke meter as it reads open both directions. But the spec sheet on the rectifier says it needs 14 volts to pass through it, and my meter only has a 9 v battery. When I measure the cap, I get .2 ohms across it, which tells me it is shorted unless there's something special about it that I don't understand.
Sound reasonable?
WT