Question about Sharp R-1490 Microwave Oven

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Microwave was running fine. Suddenly "running humming sound" dropped to a loud, deeper humming, almost vibrating sound. I opened the door and the oven had a horrible smell. Is it fried and in need of replacement?

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You have a failed high voltage transformer, magnetron, or high rectifier diode, or possibly both of the last two.

A loud buzz, hum, or groan is usually a shorted high voltage rectifier diode, but a sound like gurgling into an empty coffee mug is one symptom of a failed magnetron, and yet the mag can be bad without that sound.

The service manuals you need are here:

http://031d26d.namesecurehost.com/mwd/r1490_r1491_r1492_sm.pdf

http://031d26d.namesecurehost.com/mwd/r1480_r1481_r1482_sm.pdf

Here are some links you or someone you know can use for test help, but read their safety warnings first:

http://www.gallawa.com/microtech/diode.html
http://www.gallawa.com/microtech/mag_test.html
http://www.gallawa.com/microtech/xformer.html

You can order parts from Encompass here or you can call them toll-free at 866-779-5835.

We're happy to help you with free advice and we'd appreciate your thoughtful rating of our answer.

Posted on Oct 02, 2010

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