Repair and disassembly guides for GE Microwave ovens.

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Magnetron or Diode or both?

Hey folks, I have a GE Profile microwave and it started arcing. I took it apart and pulled the magnatron. It was arcing between the top of the magnatron tube and the shielding on the microwave. I tested the diode and it is bad for sure. My main question is did the magnatron possibly go bad and arc causing the diode to blow, or would the diode going bad cause the magnatron to arc. I suppose my question boils down to do I just replace the diode or are both parts bad. Oh and I tested the resistance on the Magnatron, the schematic calls for .5ohm and it measure .6-.7

Any help is appreciated.

Thanks,

Brett

Answered! View the answer I have this problem too

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With 240V device i would suggest against replacing parts on things that have failed in this manner, it could be life or death.

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I totally agree on this call.

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Unplugged, the HV capacitor holds 4K-6k volts and has killed many people. Don't attempt to discharge the capacitor or do any repairs if your not certified.

I always replace the diode with the magnitron. Just like I would a belt and pulley on a dryer.

Sparks can be caused by several issues; a bad wave guide, grease build up and more.

The first test I do on every microwave is how many amps it is pulling.

10-14 amps -all components are good.

3-9 amps-transformer is good-problem is in HV circuit

Less than 3 amps problem is in LV circuit

Always test with a glass of water. Finish repairs with a survey test

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LadyTech where do you check for the amp draw? Main power cable?

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Yes. I use a line splitter. The power cord plugs into the splitter and the splitter plugs into the outlet. The splitter has a place to clamp your amp meter.

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Excellent. Thanks.

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[edit: clarification] Your suspicion is correct, that one component going bad can lead to another failure. But your measurement of the magnatron suggests it's sound -- it depends upon the design spec variance allowed in the resistance measurement.

I would try the diode, and power up the microwave with all covers in place. As others have mentioned, these appliances have very high voltage components and you can get hurt trying a DIY repair. Ensure all capacitors are discharged, you have no jewelry on, etc. If you're new to this, leave it to a professional -- the cost of a replacement is far more economical than the potential injury you can incur.

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Good morning Edwin Lebish! The HV capacitor holds 4000-6000 volts, even uplugged. Don't attempt to check voltage on the HV circuit. It's much safer to check the amperage with a line splitter. This amperage test is quick, easy, accurate and safe.

Place a cup of water in the microwave. Attach your amp probe to the line splitter, plug in and run microwave 10-20 seconds.

10-14amps = all is good

3-9 amps = transformer is good. Problem is in HV circuit. The magnetron is more likely to fail than the capacitor.

Under 3 amps the problem is in the LV circuit. There is only 1 diode in a microwave. It's inexpensive and simple to replace. To test the diode, I use a 9 volt diode tester. Honestly, if I'm replacing any part in the HV circuit I replace the diode too.

ALWAYS DISCHARGE THE CAPACITOR BEFORE DOING ANY REPAIRS

Unplug the microwave and once you remove the outer cabinet discharge the capacitor before doing anything else!

Be safe. The capacitor will kill and has killed many technicians.

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What is the value of the high voltage from the transformer going into the magnetron so I can measure it with my HV meter? Oven wattage is 1100. Also, what method can I use to test the HV diode since most meters that have a diode test function can not test such diodes? I assume a HV diode is a diode that actually is several diodes in series in one unit and the average meter does not supply enough voltage to forward bias the diode?

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Brett Houts will be eternally grateful.
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