power but no heat
My Kenmore microwave model 721.66339011 runs like normal, the light works and the carousel goes around, but there is no heat and it doesn't cook. Can it be fixed? Replace a part?
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You couldn't pay me to repair one of these, just to dangerous. I'd buy a new one. But here's what needs to be done:
Cause 1
Diode
The diode converts the A/C power output of the transformer to D/C, doubling the voltage to nearly 5,000 volts. This high voltage powers the magnetron to heat the food. If the diode burns out, the magnetron won’t receive enough voltage to operate, preventing the microwave from heating. When the diode fails, it is often visibly burned out. Inspect the diode and if the diode is burned out, replace it. If inspecting the diode proves inconclusive, test it with a multimeter that uses a 9-volt battery or put a 9-volt battery in series with the diode. When the leads are reversed, the diode should only have continuity in one direction. (Warning: The microwave oven can store a lethal amount of electricity in its high voltage capacitor, even after the microwave oven has been unplugged. Due to the high running voltage and the potential for electric shock, it is extremely dangerous to replace the electronic components in a microwave. Only a licensed technician should replace the diode.)
Cause 2
Door Switch
Most microwaves have three or four door switches. When the microwave door closes, the door switches actuate in sequence to ensure that the door is closed properly. If any of the door switches fails, the microwave will not start or heat. To determine if any of the door switches are defective, use a multimeter to test each of the switches for continuity. If any of the door switches does not have continuity, replace it. (Caution: The microwave oven can store thousands of volts of electricity in its high voltage capacitor, even after the microwave oven has been unplugged. Due to the potential for electric shock, it is extremely dangerous to replace the electronic components in a microwave. Only a licensed technician should replace a door switch.)
Cause 3
Magnetron
The magnetron uses high voltage, high current DC power to generate the microwave frequency that cooks the food. If the magnetron burns out, the microwave won’t heat. The magnetron is not repairable—if the magnetron is burned out, you must replace it. (Warning: The microwave oven can store a lethal amount of electricity in its high voltage capacitor, even after the microwave oven has been unplugged. Due to the high running voltage and the potential for electric shock, it is extremely dangerous to replace the electronic components in a microwave. Only a licensed technician should replace the magnetron.)
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I’ve exactly this issue with my Kenwood microwave model K23MSW16E that also burns the 5 kVolt 0,7 A fuse. Now I know how to test the diode.
How can I test the magnetron?
@janrou most microwaves only have 1x 20A fuse. Are you sure it is a fuse or is it the HV diode? If it is the HV diode, and you replaced it and it burned again, it is likely a shorted cap or magnetron.
@ruggb Thank you! It's a fuse between the transformator and condensator. On the fuse is written 5 kVolt, 700 mA. I've replaced it, because it was burned. After replacement the microvawe didn't heat a littel cup of water for a 30 second test. After a longer test run the fuse was burned again. I believe, it's the magnetron. This is an European model for 240 V and 50 Hz. Thanks again for the quick answer!
@janrou That isn't a fuse, it is the HV diode. If it burned again, ASSUMING you replaced it with a HV diode and not a fuse, try testing the HV cap. If not, then it is probably the Mag and not worth fixing.
If you replaced it with a fuse, that is your problem.
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A Kenmore and a Whirlpool are both made by White, so I am assuming they are very similar since I can't find your Kenmore service manual.
The switch that activates the magnetron is the secondary switch, which is the bottom door switch on my Whirlpool.
The other common item would be the Diode, then maybe the capacitor, but I have not replaced any caps.
I have repaired many MWs with no issue, so I wouldn't go as far as Mayer because most fixes are cheap. BUT unless you discharge the capacitor several times, you could burn you finger off, or worse. So read about how to do that first.
Then figure out how to open it up, discharge it, and find those parts. The diode would be the first thing to look at since it usually burns and would be obvious. It is also easier to get at and test. The switch is more cumbersome to test.
Oh, did I mention to unplug it first?
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3 件のコメント
What kind of fuse do you buy foe microwave
gizdal2000 さんによる
Microwave me more 97086182
gizdal2000 さんによる
Kenmore microwave 97086182 doesn't heat what do I look for ,what kind of fuse
gizdal2000 さんによる