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fastss396man

Microwave oven KitchenAid KHMS155LWH1

16 posts in this topic

I am repairing my mom and dads microwave (they are in their 70's and I am 55 - just making sure you don't think I'm a 13 year old kid messing with the guts of a microwave oven). Dad said microwave was not heating up and made a loud buzzing noise. Same thing happened several years ago and a repairman replaced the magnatron and charged big bucks to do it. I removed the cabinet, located and discharged the capicitor (Unit has been sitting for several months so no drama with pops and sparks here) I have tested the Magnatron - seams to test good, (less than one ohm one way and infifity the other) tested the capacitor reads infinity both ways???, tested HV diode and it tests infinity both ways. This should indicate a bad diode. I ordered a HV diode since it is the cheapest part to start with. My question is once I replace the diode do I have to completely reinstall the cabinet before turning on and testing to see if the oven is now working? And secondly the readings of infinity of the Capicitor both ways is that unusual to not see some resistance momentarily one way?

Thanks,

SSMan

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Need appliance parts? Call 877-803-7957 now!

Hi SSMan,

If you are using an inexpensive multimeter you may not be able to properly check the diode or the capacitor. You should also check the magnatron magnates for cracks.

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Check diode with a 9 volt battery and a DC volt-meter. DC voltage in one direction, but not the other...

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Thanks guys, I replaced the diode and no different results, I guess the next step is to go ahead and replace the manetron.

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This magi tested good.

gallery_66469_17_70123.jpg

Edited by RussTech

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LOL - I was just trying to meld some of my Gold Boullion bricks together"

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Yes, no physical signs of problems with capacitor. Did seem to test differently in circuit (discharged and no power applied). I guess no harm no foul with replacing the diode as I read that it is a good idea to go ahead and replace the diode when replacing the magnetron.

Now that I have an extra diode I will try testing with the 9 volt battery just for my own education.

Thanks again.

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Ok, just tested the old diode with a 9 volt battery and yes about 4.8 volts one way and zero the other. Finally some readable results! Mag is on order...

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What's the model number of this unit?

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Model Number: #KHMS155LWH1

Thanks

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For others coming along later and reading this topic, some other repair goodies:

The Willie Method™ for testing a magnetron ==> http://appliantology.org/blog/1/entry-236-the-willie-method™-for-testing-a-microwave-oven-magnetron-tube/

Magnetron part link ==> http://www.repairclinic.com/PartDetail/Magnetron/W10245183/1489083?modelNumber=KHMS155LWH1

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.. readings of infinity of the Capicitor both ways is that unusual to not see some resistance momentarily one way?

should see some resistance increasing or decreasing ..

may depend on your meter and which OHM scale you are using.

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Fermented Grand Master,

Thanks for the link to the "Willie" method Mag test... This test seemed to prove out a bad Mag. With Mag connected I had a loud buzz/hum, with Mag disconnected loud buzz/hum was gone. However no abnormal smells of any kind. Tests run for 30 seconds each.

The amp test was a bit different... Amp meter placed around the power cord... With Mag connected and unit turned on Amp meter set to 20, the amp reading was .20 after 3 seconds and did not increase after 15 to 20 seconds. With the Mag disconnected and unit turned on the amp reading was .03 after 3 seconds and did not increase after 15 to 20 seconds. Again no abnormal smells detected.

Mag still on order, scheduled delivery Mar 2nd.

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Mag arrived the other day, installed and all working fine once again.

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