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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
ANSWERS:
"LadyTech
@ladytech
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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."
"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"
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?
"Edwin,
The only difference between this microwave diode and other diodes is the voltage it is rated at. This diode is rated for thousands of volts, which is what the magnetron circuitry produces. It is not many diodes in series, as you suggest. Testing the diode is done just like any lower voltage diode, infinite resistance in one direction, low resistance when you reverse the ohmmeter test leads (less than 10 ohms)."
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