Question about Whirlpool MH7140XF Microwave Oven
Here are some links you can use for test help, but read the safety warnings first:
http://www.gallawa.com/microtech/cap_test.html (if it is NOT shorted, it's probably fine)
http://www.gallawa.com/microtech/diode.html (if it is NOT shorted, it's probably fine)
The average DMM doesn't have a high enough voltage to bias a high voltage diode, which is several diodes is series.
If the diode was not shorted, it was probably okay. They almost always short when they go bad.
I don't advise people on measuring a microwave's high voltage. The voltages can be instantly lethal.
The tech sheet should show you how to measure the resistance of the windings of the high voltage transformer. You know you're getting 120V on the primary.
The capacitor is probably okay because they usually short when they fail, and that would blow the fuse when you hit Start.
Look for corrosion or signs of melting on the FA terminal of the magnetron (and on the other temrinal if someone reversed the wires). Look fro a loose connection at the magnetron.
If these connections are fine, then you probably have a bad magnetron.
Probably the best prices on Whirlpool parts can be had here.
We're happy to help you with free advice and we'd appreciate your thoughtful rating of our answer.
Posted on Oct 23, 2008
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