Question about Sharp R-520LK Microwave Oven

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Primary intelock switch on a Sharp R-520Lk continues to fail

This microwave is just over 1 year old. I replaced the primary interlock switch in December 08 and now in Feburary 09 it has failed again. When I examined the switch it appears to have melted the case at the NO contact. The switch is an Omron D3V-16G-1C25, which I assume is rated at 16 amps. I looks like the power lead of the fan motor, turntable motor and primary of the power transformer are in series with this switch. The return of the motors and transfomer goes through the cavity temperature fuse and the magnetron temperature fuse. Is this a common failure of the model?

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That switch carries the current of the turntable motor, fan motor, and the high voltage section.

Door switch or mount trouble is usually caused by slamming the door or by opening the door while it's cooking without hitting the Stop pad first.

It causes a spike at opening that eventually arcs and pits the contacts inside, and it can cause melting of the case.

You should check the switch mount for cracks, too.

Sometimes excessive current can make them fail too, but your fuse should blow before the switch.

We have the full service / repair manual for this model and have uploaded it to our site here to help you.

It will give you safety info, step by step help in disassembly, troubleshooting tips, and part numbers.

You will need the
free Acrobat Reader to view or print it in case you don't have it already.

If a switch is all you need, we offer a universal type for only $5 postpaid which you can order here.

We're happy to help you. Once we have all your information and offer a final solution, we'd appreciate your thoughtful rating of our answer.

Posted on Feb 15, 2009

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It sounds like the magnetron may have either failed or is not being supplied with the extremely high voltage required to run it.

YOUR SAFETY IS PARAMOUNT

This is a job for a professional but if you are safety clued up, here's instruction.
Make sure the !!!!any capacitors are discharged!!!!! before attempting any sort of repair.
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Hi,

It sounds like one of the door micro switches is bad. There are three micro switches typically. A primary interlock, a secondary interlock and a monitor switch. It is most likely the primary or secondary interlock switch. You may need to take your switches to a professional appliance shop to determine which one is bad.


Let me know,if needed further assistance.

Hope i helped you.

Thanks for using ' Fixya ' and have a nice day!!

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Make sure the !!!!capacitor is discharged!!!!! before attempting any sort of repair.
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Make sure the !!!!capacitor is discharged!!!!! before attempting any sort of repair.
Check the door interlock switches first then the high voltage diode with either an AVO model 8 on high resistance range for short circuit, the feed fuse on the primary of the high voltage transformer and then finally, the magnetron is best checked by substitution.
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Hope that helps

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Secondary Interlock Switches. If the
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You can get more information about adjuting the interlock switch from this link

http://136.166.4.200/contents/Microwave/LMVM1935xx/LMVM1935xx_Service_Manual.pdf

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