#1 Son brought over his RCA microwave, symptom: Dead.
Fuse found blown, replaced and worked OK for several operations, found after a couple more blown fuses that it occurred intermittently when heating cycle had finished and then the door was opened, a study of the schematic and the 3 door switches activated when door open/closed found one to be stuck in, this caused a intermittent dead short across the AC in, one switch is supposed to open as another closes, if both closed (fault) result = blown fuse.
Max.

 

Nice. Can you post the model number in the thread title?

 

Done!
Nice that they also have the schematic on the inside cover.
Max.

 

Most microwave ovens have the circuit diagram on the inside now..