Question about Sharp R-630D Microwave Oven

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No heat, loud noise or buzz, everything else works.

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Re: No heat, loud noise or buzz, everything else works.

I would suspect the high-voltage rectifier diode (shorted) or the magnetron, in that order.
Here are some helpful links for testing & safety.

We have the entire service manual for the R-630-series ovens at our site:

You can order Sharp parts from Tritronics at

We\'re happy to help and we appreciate your thoughtful rating of our answer.

Posted on Jan 21, 2008

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SOURCE: Loud and not heating

If it's less than a year old, it's still under warranty. If it's just over a year old, GE will still cover parts, but you'd have to pay for labor.

Contact them at

The most likely causes are a shorted high-voltage diode or a bad magnetron.

If you or a friend decide to look into it, we have critical information on safety, disassembly and door switches at our site, linked here on Fixya:

You can find helpful exploded view diagrams and order parts by entering your full model number here:

Posted on Nov 18, 2007

  • 5911 Answers

SOURCE: Microwave won't heat/Makes buzzing noise.

The symptoms you are describing are typical of a magnetron that has gone bad. Continuing to attempt to use the oven in its current condition can cause further damage. So, I would recommend not using it. Microwave ovens are considered dangerous and repairs should not be attempted by anyone that is not electronic saavy. The High Voltage Network inside the oven has voltage potentials of 14,000 volts and higher. If you feel this is something you wish to attempt, the Magnetron part number is 1156751 and costs approx. $158. Keep in mind, if the magnetron has been arcing and making a burning smell you may have burned the protective coating that lines the walls of the waveguide. If the waveguide is damaged it is not repairable. I do not know if this is a replaceable item on your model microwave. Double check your warranty information and/or owner's manual. In many cases the magnetron is warranted for several years beyond the limited warranty that comes with most appliances. Post back with comments and let me know if you want me to assist you further. In addition, if you provide me with your EXACT model number (located along the door opening) I can narrow down parts a little better. I know this all sounds discouraging, but I do hope I have been able to help you.

Posted on Jan 15, 2008

  • 117 Answers

SOURCE: loud buzzing noise with Whirpool microwave oven

The loud buzzing you hear is the sound of the magnatron tube.That is what emits the microwave radiation and buzzing should be normal. The mag tube may be nearing its end at witch time you will hear no buzzing and hence no heating of foods. Replacement can be costly depending on the model so most people just opt for a new one. Hope this helps

Posted on Jul 30, 2009

  • 14 Answers

SOURCE: Microwave making loud noise behind control pad and won't heat

Sounds like the magnatron (the bit that creates microwaves) could be goosed. Remove outer cover ( Isolate from the electric supply then remove screws at bottom on the sides).

Find big lump that says on magnatron with model nos etc on, any good electrical supply shop ( Maplins etc) should stock new one.

It is easy to change. It took me about half an hour having never done one before.

Buyer beware the price of the parts could be in excess of a new microwave.

Shop around

Posted on Sep 15, 2009

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microwave_diode.jpg Power Diode

A diode is an electronic component that readily passes current in one direction only and blocks the flow of current in the opposing direction. If your microwave's diode has become defective, your microwave will not heat and you will hear a buzzing noise. Test the diode to determine if this is the cause of your problem. Replace it if it is defective.

picturena.gif High Voltage Capacitor

A capacitor is an electrical device which stores electricity. A defective capacitor may be why your microwave is not heating but you are hearing a buzzing or humming noise. The capacitor will have to be tested to determine if this is the cause of your problem. A defective capacitor will have to be replaced before your microwave will work again. Make sure you discharge the capacitor before you test it, though.

microwave_magnetron.jpg Magnetron

A defective magnetron is the third possible cause of why your microwave is not heating, but you can hear a buzzing noise. Test your microwave's magnetron. Replace it if it is defective.

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1 Answer

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It could be an issue with the diode, high-voltage capacitor or the magnetron itself.

Please try following the steps from this article:

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