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Posted on Dec 07, 2007
Answered by a Fixya Expert

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Fuse blows immediately when start button is pressed

Thank you for your help. My wife tells me yesterday that the microwave made a loud buzz, right as she was opening the door to take something out. Later when I tried it, I got a very loud startup buzz and then nothing. I removed the unit from the wall and replaced the fuse. Same thing happened again, dies immediately after pushing start button. The unit is a Kitchenaid KHMS105ESB-0 made in 1998.
I am very electronically inclined and have read enough on this site to speculate that it is the High Voltage Capacitor that is bad. I wanted to email you for other possibilities before I dig deeper into the unit and buy a $100 part.

  • Ragtop78 Dec 07, 2007

    I pulled the HVC last night without any fireworks and followed the testing instructions from http://www.gallawa.com/microtech/cap_tes.... I get a reading of zero ohms when bridging the contacts and a reading of infinity when bridging each contact to the metal case. Model number on the microwave is KHMS105ESB-0.

  • NONuke Apr 15, 2008

    I have a KitchenAid Microwave - model KHMS145JBL-0. The clock works, the timer works, but ... if I try and "nuke" something, it blows the fuse a few seconds after it starts.



    I read your post for someone else (another model) and the problem was a High Voltage Capacitor (you suggested also a High Voltage Transformer). I believe it turned out to be the capacitor. How can I determine if mine has either and, if so, how to diagnose the problem part.



    Thanks in advance for your suggestion.

×

1 Answer

William Miller

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  • KitchenAid Master 9,179 Answers
  • Posted on Dec 07, 2007
William Miller
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It sounds like the high voltage capacitor.

You first need to be sure the unit is unplugged from the wall.

Assuming the HV cap is shorted, there wouldn't be any need to discharge it (*grin*) but it's good practice. Once you do that, you can remove the leads and ohm it out. That will tell the tale.

If that's not it, then it may be a bad high voltage transformer. *

You can usually find helpful exploded view diagrams and order parts by entering your full model number here: http://tinyurl.com/gv383

We have critical safety, disassembly, and troubleshooting info at our site, and our link is at our listing here on FixYa: http://tinyurl.com/yzjozk

* If yours is not a Kitchenaid KHMS105E then please post back with your correct info so we can best guide you.

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

  • William Miller
    William Miller Dec 08, 2007

    .

    Great job! So my solution was a FixYa! *grin*



    It is the capacitor.



    You can find one by entering model KHMS105ESB0 (no dash) here. It's on diagram # 7, ref # 4: http://tinyurl.com/gv383



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

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[double post]

If it went dead almost immediately after pressing the Start pad, that's usually a shorted high-voltage capacitor.

If it went dead a few seconds after pressing the Start pad, that's usually a failing high-voltage transformer.

You can usually find helpful exploded view diagrams and order parts by entering your full model number here: http://tinyurl.com/gv383

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But I would wait until the authorized servicer gets there (or take it to them) to maintain your warranty.

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

If it goes dead or blows the breaker when you plug it in or open or close the door, then there's a problem with a door switch or door switch mount.

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If it went dead a few seconds after pressing the Start pad, that's usually a failing high-voltage transformer.

Guest

If it went dead almost immediately after pressing the Start pad, that's usually a shorted high-voltage capacitor.

If it went dead a few seconds after pressing the Start pad, that's usually a failing high-voltage transformer.

We're happy to help and we appreciate your thoughtful rating of our answer.
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You can usually find helpful exploded view diagrams and order parts by
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Please write back with your brand and model number if you need further help.



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