My microwave is making a loud buzzing noise and there was some charred areas inside on side wall

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Aug 12, 2011 - 10 posts - ‎2 authors
My Whirlpool MT4155SPS-2 microwave oven has recently started to buzz loudlywhen operated. The sound is getting louder and more frequent ...

Whirlpool making intermittent loud buzzing noise Microwave ...

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If your microwave buzzes loudly and produces no heat you probably have a defective power .... I have a whirlpool oven range and it's less than a year old. .... Humming sound stops when I open door to remove food, but when door is closed, ...

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Check the circuit board.

Unit uses a Magnetron and likely a power board called an inverter to run it. Someone would have to open the unit in a way where they might pinpoint where the sound is coming from and then take action--does not of course sound normal or good to me.

see this causes and proceed. God bless you
Magnetron If the microwave is loud or noisy only when cooking, the magnetron tube might be defective. The magnetron uses high voltage, high current DC power to generate the microwave frequency that cooks the food. Under normal circumstances the magnetron is nearly silent. However if it is damaged or nearly burned out it can begin emitting high pitched or growling noises. It's not normally dangerous to use a microwave oven when it makes these noises, but they are an indication that the magnetron is almost dead and will need to be replaced.

Exhaust Fan Motor If the microwave is loud when running the fan motor might be
Stirrer Motor If the microwave is loud or noisy the stirrer motor might be worn out. The stirrer is a metal blade which slowly turns around, deflecting the microwave energy in a random pattern inside the microwave oven. As the motor nears the end of its useful life it begins to make grinding noises. The microwave will not heat food evenly without this stirrer, the motor should be replaced.

Turntable Motor If the microwave is loud or noisy the turntable motor might be worn out. This is a common problem and relatively easy to replace.

see this causes and fix it. God bless you
Magnetron If the microwave is loud or noisy only when cooking, the magnetron tube might be defective. The magnetron uses high voltage, high current DC power to generate the microwave frequency that cooks the food. Under normal circumstances the magnetron is nearly silent. However if it is damaged or nearly burned out it can begin emitting high pitched or growling noises. It's not normally dangerous to use a microwave oven when it makes these noises, but they are an indication that the magnetron is almost dead and will need to be replaced.
Exhaust Fan Motor If the microwave is loud when running the fan motor might be
Stirrer Motor If the microwave is loud or noisy the stirrer motor might be worn out. The stirrer is a metal blade which slowly turns around, deflecting the microwave energy in a random pattern inside the microwave oven. As the motor nears the end of its useful life it begins to make grinding noises. The microwave will not heat food evenly without this stirrer, the motor should be replaced.
Turntable Motor If the microwave is loud or noisy the turntable motor might be worn out. This is a common problem and relatively easy to replace.

THe buzzing noise is most likely coming from the magneton. The magnetron is the main component of the unit (it generates the microwaves). Replaceing it can be very expensive. You may be better off getting a new oven. Prices for new microwave ovens have dropped significantly.

You should have no arcing within the unit. Assuming you have adequate food/water in the cavity, it should not arc. You NEVER run the unit without something to be heated in it!!!

You might check the stirrer fan which is often in the roof of the unit to see if contamination might be in the area causing arcing. The electric fields in th area are very high and arcs can jump.

If the insulating window is charred or has charred grease, it should bbe replaced.

I would recommend changing the diodes as well. This will usually take care of the problem.

My microwave was totally dead. Things I discovered: 1) There is an easily replacable fuse accessed by taking off the top front vent cover (two screws on top, gently massage off) and then the inside plastic grill. UNPLUG before doing this! 2) Pop off two wires on either end of fuse holder for safety. Then pop out fuse and replace. For more extensive help, there is an evelope with a wiring diagram inside the case on the inside wall! Very helpful when diagnosing the surface lamp problem (I forgot to plug the ballast back in when I closed up the bottom).

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?