Microwave starts and turns on but does not heat anything. sometimes you hear the buzz and it does heat but most of the time it doesnt. Took the cover off and checked the switches all ok. Moved the wires a little on the capicator and it seem to make it work for a bit but same thing again.

If the magnetron was making louder noises prior then replace the magnetron. While the cabinet is open make sure to look for burned wires, check the continuity of thermal cutoffs, and check the main circuit-board for burned traces or components. The relays in most electronics are known for arcing (spot welding) and staying in the wrong position. Tap them hard with the back end of a screwdriver.
You may have to replace the capacitor too. During all of this use safe electrical practices by having the power cord unplugged. The capacitor could still have a high charge on it so be careful.

hELLO THERE
when a microwave quits heating but every thing else is ok normally
investigate these 4 areas

Investigate these three areas if your microwave won't heat but you hear a loud buzzing or humming noise:
Power Diode

A diode is an electronic component that readily passes current in one direction only and blocks the flow of current in the opposing direction. If your microwave's diode has become defective, your microwave will not heat and you will hear a buzzing noise. Test the diode to determine if this is the cause of your problem. Replace it if it is defective.

• How to test a microwave diode.
• How to replace a microwave diode.



• 
  

High Voltage Capacitor

A capacitor is an electrical device which stores electricity. A defective capacitor may be why your microwave is not heating but you are hearing a buzzing or humming noise. The capacitor will have to be tested to determine if this is the cause of your problem. A defective capacitor will have to be replaced before your microwave will work again. Make sure you discharge the capacitor before you test it, though.

• How to test a microwave capacitor.
• How to replace a microwave capacitor.



• 
  

Magnetron

A defective magnetron is the third possible cause of why your microwave is not heating, but you can hear a buzzing noise. Test your microwave's magnetron. Replace it if it is defective.

• How to test a microwave magnetron.
• How to replace a microwave magnetron.

Sounds like the magnatron (the bit that creates microwaves) could be goosed. Remove outer cover ( Isolate from the electric supply then remove screws at bottom on the sides).

Find big lump that says on magnatron with model nos etc on, any good electrical supply shop ( Maplins etc) should stock new one.

It is easy to change. It took me about half an hour having never done one before.

Buyer beware the price of the parts could be in excess of a new microwave.

Shop around

The loud buzzing you hear is the sound of the magnatron tube.That is what emits the microwave radiation and buzzing should be normal. The mag tube may be nearing its end at witch time you will hear no buzzing and hence no heating of foods. Replacement can be costly depending on the model so most people just opt for a new one. Hope this helps

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 - 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.

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 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 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.

You may have a control board issue. Thank God for safety switches.
This is a problem that an integrated circuit tech. can repair, but it may be costly.
Decide how much you want to put into this oven vs. buying a new one.

Contact me once you decide and I can help you find a service center.

Thank you,

Dave E. (Illeagle)

I have a GE counter top microwave oven. When the oven starts cooking (the magnetron turns on) the oven makes a harsh buzzing noise. What is wrong and what should be done?

it is the door problem it seems to be known issue per target sales guy he advise to call emerson since it is past 90 days for target to return

Check this website:

http://www.partselect.com/microwave+no-heat+repair.htm

It sounds like it is either the power diode, the high voltage capacitor or the magnetron. If it is the magnetron, it may not be worth fixing as these can cost well over $100.

Do you hear a buzzing sound?