• ** 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

KB6524PS Sharp drawer Microwave won't heat food, but magnetron gets hot.

wigglytoes

Premium Member
Joined
Sep 27, 2015
Messages
7
Location
Colorado
Model Number
KB6524PS
Brand
Sharp
Age
Less than 1 year
Hi:
Kind of a science question here. You might not know the answer, but your knowledge of how microwaves work could put me on the right path.

My Sharp microwave is basically brand new. (Unfortunately it's also out of warranty because it sat for a year waiting it's turn to be installed in a kitchen remodel)
I used it 4-10 times and it worked fine.
Then it broke. It won't heat food.
Everything powers on. The unit powers up, the display works perfectly, I can start a cook cycle, it will go through that normally, the light will come on, the unit will hum, but anything inside the MW does not heat up.

Additional details.
I've taken it apart, a little. (I even built a nice resistor wire with alligator clips to drain the capacitor)
Everything checks out visibly. The magnets in the magnetron don't look cracked.
The magnetron checks out. In that I get close to a 0.0 ohm reading when I connect a multimeter to the two prongs. (My multimeter is analog, pretty old, and I would have a hard time seeing a small reading. Like 0.1 ohm or 0.2 ohm.) In fact it looks like it's exactly 0.0 ohm (But the accuracy of the multimeter is questionable) Perhaps that's a clue. What would cause a 0.0 ohm reading? I know the reading is supposed to be tiny, like 0.3 or so, but 0.0 seems too much.
Also the magnetron shows an open circuit when I measure resistance between either prong and the body of the magnetron. As it's supposed to.

Here's the big clues.
1) If I run the microwave for a couple minutes, the magnetron gets very hot.
So the magnetron is heating up, but the food is not. It's like it's creating microwaves, but they aren't being moved into the food compartment of the microwave.
The stirrer is turning, when the unit is running.
2) The fan that is supposed to cool the magnetron wasn't working, until today. So the magnetron could have gotten quite hot in the couple weeks that I used it. However, I never ran a cycle over 2 minutes. No baked potatoes, or anything else which took a long time. But the magnetron was definitely on, without a fan blowing any cooling air on it.
3) During the short time that the unit worked, I hadn't tried any of the fancy settings. Just time and Start. The unit failed the first time when I tried the 'Sensor Reheat' button. It was at this point that I pulled out the directions. Sensor reheat is supposed to measure the steam coming off the food, and heat it accordingly. It didn't heat it at all, and eventually I canceled the cycle. It hasn't worked since.

To me, the fact that the magnetron heats up but food doesn't probably tells us what's going wrong.
 

wigglytoes

Premium Member
Joined
Sep 27, 2015
Messages
7
Location
Colorado
Solution: I replaced the magnetron and it solved the problem. I viewed a lot of YouTube video's on how to test a microwave, and tested as much as I could. everything checked out. The one authorized repair company in denver wanted $150 just to make a house call. (They don't have a store front where I could take it, and maybe save some money) A magnetron cost $40 online. I decided to just replace the magnetron. If that was the problem - great. If it wasn't, then I was only out $40 So I ordered a new magnetron, and it works now. One other note- Most online posts and messages about bad microwaves say that it's usually the magnetron.
 
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