My microwave is making a constant loud noise (constant hum I suppose), it is not heating anything through, but the turntable still turns. I tried unplugging but the problem persists.

make this test and fix it. God bless you

1. MagnetronIf your microwave is emanating high pitched or growling noises during operation, the magnetron could be going bad. Normally a nearly silent part, the magnetron uses high voltage and induces the frequency required to cook food. Although normally not a safety hazard to operate, this is a sign that the magnetron is failing and will need to be replaced as soon as possible.
   
2. Exhaust fan motorIf your microwave is making a very loud humming noise during operation, it could possibly be the exhaust fan motor. If defective the part will need to be replaced to silence the appliance once more.
   
3. Stirrer motorAnother leading cause of a noisy microwave is an expired stirrer motor. With use this part becomes worn and makes a loud grinding noise, which is usually a leading indicator that the part needs to be replaced. The stirrer is a metal blade that is slowly turned by the motor. This action disperses the microwave energy in a random pattern, which heats the food evenly. If the stirrer motor is determined to be nearing expiration, it should be replaced to halt the grinding noise.
   
4. Turntable motorA very common cause for a noisy microwave is a worn out turntable motor. This is a relatively easy repair and will put an end to the noise once replaced.
   

make this test and fix it. God bless you

1. MagnetronIf your microwave is emanating high pitched or growling noises during operation, the magnetron could be going bad. Normally a nearly silent part, the magnetron uses high voltage and induces the frequency required to cook food. Although normally not a safety hazard to operate, this is a sign that the magnetron is failing and will need to be replaced as soon as possible.
   
2. Exhaust fan motorIf your microwave is making a very loud humming noise during operation, it could possibly be the exhaust fan motor. If defective the part will need to be replaced to silence the appliance once more.
   
3. Stirrer motorAnother leading cause of a noisy microwave is an expired stirrer motor. With use this part becomes worn and makes a loud grinding noise, which is usually a leading indicator that the part needs to be replaced. The stirrer is a metal blade that is slowly turned by the motor. This action disperses the microwave energy in a random pattern, which heats the food evenly. If the stirrer motor is determined to be nearing expiration, it should be replaced to halt the grinding noise.
   
4. Turntable motorA very common cause for a noisy microwave is a worn out turntable motor. This is a relatively easy repair and will put an end to the noise once replaced.
   

follow this steps and use the VOM , and fix it. God bless you

1. MagnetronIf your microwave is emanating high pitched or growling noises during operation, the magnetron could be going bad. Normally a nearly silent part, the magnetron uses high voltage and induces the frequency required to cook food. Although normally not a safety hazard to operate, this is a sign that the magnetron is failing and will need to be replaced as soon as possible.
   
2. Exhaust fan motorIf your microwave is making a very loud humming noise during operation, it could possibly be the exhaust fan motor. If defective the part will need to be replaced to silence the appliance once more.
   
3. Stirrer motorAnother leading cause of a noisy microwave is an expired stirrer motor. With use this part becomes worn and makes a loud grinding noise, which is usually a leading indicator that the part needs to be replaced. The stirrer is a metal blade that is slowly turned by the motor. This action disperses the microwave energy in a random pattern, which heats the food evenly. If the stirrer motor is determined to be nearing expiration, it should be replaced to halt the grinding noise.
   
4. Turntable motorA very common cause for a noisy microwave is a worn out turntable motor. This is a relatively easy repair and will put an end to the noise once replaced.
   

This clearly indicates a bad magnetron, "heats food" in most cases it is cheaper to replace the microwave oven than have it repaired, since the magnetron is the heart of the unit.

you either have a bad magnatron, that is trying to heat but won't or you could have a capacitor or diode (rectifier) that is bad. if you order a magnatron replace capacitor and diode (rectifier)

The diode that connects to the capacitor needs to be replaced. Once its replaced microwave will begin to heat again. (If it wasn't heating and wasn't making a humming noise, then your magnetron would need to be replaced). If you are thinking of doing it yourself and need instructions, i'll be glad to help.

Hi,

Here is a tip that will help you to figure out what is wrong with your Microwave Oven....

Basic Microwave Oven Troubleshooting Tips

heatman101

From your description it sounds like the magnetron has failed in this oven. That's the part the makes the microwaves to heat the food. It typically fails by shorting out and making a loud hum noise. It not usually worth fixing since the price of a replacement magnetron is almost as much as a new oven.

If all of your door switches check out, replace the magnatron, capacitor, and diodes.

check turntable motor or bush, this very easy problem, you can use oven no problem..