Question about Sharp R-1405 / R-140 Microwave Oven

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Fuses keep blowing out

My microwave oven suddenly just started popping fuses. The fuse is 250v 20 amp. when i put in a new fuse and turn the oven on it sounds like it is going to start for about 2 seconds then the fuse blows. I have killed 5 fuses so far so I believe it is time for a diffrent approach. Any suggestions?

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  • Anonymous Feb 05, 2009

    I have a similar problem Except our first fuse blew after 25 years. When we opened up the micro we found a spare fuse inside. We replaced the blown fuse and it worked fine....but only for a few days. It blew again this morning. Should I just go buy a couple more fuses? Is it time for a new Microwave? Could the spare old fuse inside have gone bad after all these years? Any suggestions would be helpul. Thank you.



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In case it's still helpful, I'll inject a little sanity into the replies.

If the fuse blows as soon as you hit Start, it's probably a shorted high-voltage capacitor. That's usually economical to repair.

If the fuse blows a few seconds after you hit Start, it's probably a shorting high-voltage transformer. That's usually not economical to repair.

It's not radiation (non-ionizing RF by the way) that's the hazard, it's the voltages.

Posted on Nov 05, 2007

  • William Miller
    William Miller Nov 05, 2007


    We have critical safety information, info on door switch diagnosis and replacement, and disassembly information at our site, linked here on Fixya:


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I have the same experience in replacing five microwave fuses within two days and cost me almost ten dollars. They are expensive. True somewhere inside the circuit had a short. But I could not find any lead in locating the faults, nothing burnt or smell inside the microwave. However I noticed that this blowing fuse acts happened after I cleaning the inside of the microwave oven with grease removal solution. At last I found a thick grease (over ten years history) covered those switches that behind the door notches. So I disconnected all the connection wires from those switches (make sure to draw a trace map of all wire connection before disconnected them, so you can put them back in order), pull out the switches from the cradle and immersed them in the diluted organic grease removal solution for overnight. Gave them a good clean water bath and dry them good before installed them back to the cradles and connected all wires back. I have been using the microwave for more than two months now, no more blown fuse. Please be aware I am not an expert but just share this with you. The greasy switches might be one of the causes. One final warning, please make sure you have the proper skill and knowledge to do this, otherwise find some friend to help you. Hope this help!

Posted on Mar 08, 2009

  • nty Young Oct 22, 2010

    Here is ntyfixer again. Just recap what happened to my microwave. Good Lord! It is running like new and no more blown fuse since I cleaned the switches over a year ago.


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Yes a fuse blows because there is an internal short in the unit. The more you replace the fuse and hopes it will fix it, the more damage you may cause and maybe even cause a fire. A fuse blows in a piece of equipment as a safety feature. most fuses do not blow because they simply go bad, they blow because of a problem. First thing would be to check the door switch alighnment. next would be to check the Hi voltage diode and the capacitor, next test should be the magnatron for a short. If you do not have any knowledge on microwaves, call in a pro to assist you in this repair ans there is alot of high voltage inside this puppy. Good Luck

Posted on Apr 08, 2007

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Throw the darn Microwave out before you kill yourself with Radiation. Blown Fuse is a sign of Sorted circuit to ground. With a microwave they are cheap now a days and does not warrant the risk.

Posted on Apr 18, 2007

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For more help from Emerson visit here or get help using your appliance at 1-800-898-9020. Get help locating a servicer or parts at 1-800-695-0098.

Emerson parts are distributed by Fox International and their number is 800-321-6993. Or you might try e-mailing [email protected]

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