• ** REMEMBER! **The microwave can still shock you even unplugged!!

    ALWAYS discharge the high-voltage capacitor first if you even think your hands will come close to any HIGH VOLTAGE components.

    Jeff mentions this: Anything in the high voltage ( magnetron, capacitor, diode, wires to and from ):
    ...Use a metal ( not the shiny chrome type ) screw driver with a insulated handle to short across ( touch both at the same time ) the terminals of the high voltage capacitor to discharge it.

    From Jeff's site: http://www.applianceaid.com/component-testing.php

    Jake

FIXED Nice Kenmore convection microwave that works great but produces no microwaves

tsmith35

Premium Member
Joined
Mar 17, 2011
Messages
6
Location
TN
Model Number
721.80823500
Brand
Sears Kenmore
Age
6-10 years
Hi, guys. I have a Kenmore under-counter microwave MN 721-80823500. The microwave appears to work fine: clock works, light works, door switch turns the light on and off, fan works, convection heating works, and turntable turns. But in microwave mode, it won't heat anything at all. It worked like a champ up until it suddenly stopped heating.

I've read that it could be a door safety switch, a fuse, the HV capacitor, HV transformer or the magnetron. I have a good meter (1000V Cat 3, 600V Cat 4), but I'm not sure where to start.

I do have a copy of the service manual for this microwave, so that should help.

Any suggestions for where to start? I have access to soldering/desoldering equipment, meters, scopes and whatnot. As an aside, my daughter went to heat a bowl of soup (she didn't know the microwave wasn't working and the soup had no metal in it) and saw a flash of light from the inside of the heating compartment. She immediately stopped the microwave and took her soup out when she found that it was still cold.

Thank to anyone willing to answer. :)
 

jeff1

Appliance Tech - Moderator
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Messages
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tsmith35

Premium Member
Joined
Mar 17, 2011
Messages
6
Location
TN
Jeff, thanks for the reply. I guess I'll follow the directions on your link and narrow it down to find the problem. Thanks again!

Tom
 

tsmith35

Premium Member
Joined
Mar 17, 2011
Messages
6
Location
TN
Jeff, I got the diode, capacitor and magnetron here, pulled the microwave, opened it up, tested everything per the manual and found that the HV diode was shorted. Everything else tested good, but since the microwave is 7 years old, I went ahead and replaced the capacitor and magnetron. I'll save the old ones as spares.

Interestingly, I found out that whoever installed the microwave managed to push the hinge side top mounting bracket loose from the cover, causing it to go right through the airbox. Shattered plastic everywhere inside... :/ So I have a replacement on order for that. It'll be nice to have the microwave back in service.

Thanks again for your help!
 

jeff1

Appliance Tech - Moderator
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Thankx for the update :)

jeff.
 

tsmith35

Premium Member
Joined
Mar 17, 2011
Messages
6
Location
TN
By the way, the HV diode is fairly common. It bears the generic PN "CL01-12" and is rated at 12kV, 350mA. They're all over eBay. The only difference between the stock diode and the OEM diode is that the OEM part has a 22-16 ga. ring terminal for a 4mm stud crimped on one end and a 22-16 ga. 0.250" receptacle terminal (tab type) on the other end. End-to-end length is 3-9/16".

I'm waiting for Sears to ship the airbox (backordered, but nearly impossible to find in-stock anywhere), so we're getting by with my daughter's old college microwave. The little microwave can just about fit inside of the big microwave... :)
 

jeff1

Appliance Tech - Moderator
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Messages
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Location
Ontario, Canada
The little microwave can just about fit inside of the big microwave
LOL!! :D

jeff.
 
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