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Always remember Electricity is dangerous and should be treated with respect.
Microwaves are very dangerous, they can still shock you even unplugged!! These pages are to help give you indications of what might be wrong and some safe "how to check" and repair helps.
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. With the microwave unplugged.
This is a common way to do this....
Q - My microwave seems to shut off every once in a while, what might be wrong?
A - Make sure you hear the fan is still operating in your microwave. Next is to make sure the air intake grill on your microwave is not plugged up with air borne dust and dirt.
Use an old tooth brush to help clean off the grille area.
Q - The microwave makes a loud "hum or buzz" noise but will not heat up the food?
A - 9 times out of 10 this is usually this is a bad magnetron, the other time is sometimes a bad high voltage diode. See components section.
Q - My microwave is running and sounds like it is working but will not heat up anything.
A - Many thing can do this but, common things are....loose high voltage wire.....poor solder joint on board.....magnetron.....power relay.....
Q - The microwave display counts down and the inside light is on, but nothing is heating and the fan is not running.
A - This most commonly is a bad door switch, other possible problems are a faulty relay or solder joint on the power module, but a bad door switch is most common.
Q - My microwave went dead when I opened the door ( same problem as closed the door ).
A - This often is a stuck or faulty door switch and it has blown the interior microwave fuse.v
Q - My microwave is completely dead.
A - House fuse has blown or interior fuse inside the microwave has blown ( usually a part inside the microwave makes this fuse blow ) Sometimes a bad fuse holder inside the microwave cannot hold the fuse tight enough and the fuse will blow as well.
Q - The fan in my microwave oven is not running will this hurt my microwave?
A - YES, the fan cools the magnetron and electronics, take the microwave in for service, most fans are not too expensive to replace.
Q - My microwave blows the fuse inside itself as soon as I push the start button.
A - Usually a shorted high voltage capacitor...see components section.
Description of problem (Maytag CMV1100Q):
Microwave stopped working while cooking. Replaced a 20AMP fuse.
When the cook cycle starts, microwave makes a groaning noise and stops. It loses power since the fuse is blown.
Solution: High-voltage capacitor shorted. Replaced it and microwave works fine.
Its located behind the fan underneath the high-voltage transformer.
Microwave works great now.
Q - I burnt something in my microwave and now it is dead...help!
A - The fuse inside the microwave may have blown, but more commonly the flame/oven thermostat has sensed the over cooked food and the flame/oven/cavity thermostat has opened up - Info on that.