Hi,
Following Samuel Goldwasser's Great(!) Notes on the Troubleshooting and Rep air of Microwave Ovens I tested:
* Defective interlock switches or misaligned door. There are four switches, three use only the two terminals to make a contact. The fourth uses all th ree terminals, to break and make contact. Switch 4 was a bit dodgy so I swa pped it with Switch 1: o Switch 1: 1-2 closed: 0.0 ohm, open: infinite (swapped with Switch 4) 1-4 closed: 0.0 ohm, open: infinite o Switch 2: 1-2 closed: 0.0 ohm, open: infinite 1-4 closed: 0.0 ohm, open: infinite o Switch 3: 1-2 closed: 0.0 ohm, open: infinite 1-4 closed: 0.0 ohm, open: infinite o Switch 4: 1-2 closed: 0.2 ohm, open: infinite (swapped with Switch 1) 1-4 closed: 0.0 ohm, open: infinite o The door is not visibly misaligned.* Shorted HV capacitor. o Tested: ~10M ohm, but not open -> good?
* Shorted HV diode o Tested: 6.5V -> good.* Defective HV transformer. o Primary: 2.5 ohm -> good enough??? (should be 0.2 to 0.5 ohm, 0.2 typical ) o White to frame: ~ 100 ohm -> if this is HV, then OK o Red to red: ~0 ohm -> if this is filament, then OK
Would the 2.5 ohm of the primary winding definitely be way too high and cau se the fuse to blow when I start the cook cycle? I would expect the opposit e to be true, however:
After putting everything back together but leaving the transformer primary winding disconnected I switched it on. The conventional oven worked, and he ated. When I pressed the microwave button the fan worked and the fuse didn' t blow . So I assumed the transformer was faulty. I then reconnected the tr ansformer and tested the microwave function. It worked for three seconds an d then blew the fuse, 'confirming'(?) that the transformer was faulty. I re placed the fuse, disconnected the transformer again and tested again. The c onventional oven worked again, and when I pressed the microwave button the fan worked, but the fuse didn't blow. 'Confirming'(?) again that the transf ormer was faulty. Then I put the microwave oven back in the kitchen cabinet and demonstrated that it worked, partially, but the fuse blew...... sugges ting again that the switches are (may be) faulty.
Am I overlooking something still?
Regards,
Rouke