I've been reading all about MWs recently, as my GE Spacesaver XL1400 decided to die over the weekend. I had noticed an occasional arcing sound, and a mild electrical odor prior to it failing. At this point everything works (lights, turntable, clock) but it does not heat. MW was working fine up until about a week prior, when I first noticed the arcing sound and electrical odor.

I checked the Diode and the Capacitor, and it appears from what I've been reading that the Diode resistance (12 ohm) is way too low, and the Diode may be shorted. The only thing I've checked on the Magnetron is the resistance across the filament connectors (continuity seems good) and am not sure what else to check. Any ideas? I'd hate to replace the Diode only to have it get fried again due to faulty other component (magnetron, transformer, etc.). Thanks for your suggestions.

pennstatejeff

Gene: Thanks for your timely response. I decided to start slow (and less expensive) and replaced the HV diode first (I bought 2 just in case). I placed a small glass of water in the oven and ran if for 30 seconds. No real indication of any heat added to the water. I ran for another 30 seconds but cut it short when I heard a crackling sound. Not sure whether I partially damaged the new HV diode, since I was still able to get a resistance reading on it with the ohmmeter. I tried to measure resistance on the HV capacitor and had to switch the range on the meter to Rx10K to get any movement. The needle moved about 1/8 across the scale and decayed right back to infinity. This occured with the meter leads switched on the capacitor as well. One thing that strikes me as odd, and I didn't really think about it until now - I've tried to be extremely cautious in making sure I discharged the capacitor before I do anaything else, but I have never heard a pop or seen any spark or arcing when attempting to discharge the capacitor, even after I had just run the oven. Is this an indication tha tthe capacitor is the likely culprit? I'm learning as I go, but I'm more familiar with traditional household wiring issues than heavy duty electronics. What do you think?

Thanks again for all your help.

PennStateJeff

You can check an HV diode for resistance only with a good ohmmeter set to the highest range. It should read infinity in one way and very high resistance in another way.

If you can get a resistance reading on the HV diode that means the diode is probably shorted out. Thats why you did not see any sparks when you tried to discharge the capacitor.

The cause of it could be a wrong diode you installed or a bad magnetron.

What is the part number of the diode you installed?

Gene.

If your magnetron was arcing to the waveguide, your waveguide is pitted and can't be fixed, your new magnetron will fail also.