I have a "continuous" humming sounding when units are heating. The sound is very loud

Hi and welcome to FixYa, I am Kelly

When everything but the heat works there are 2 common components that fail. The high voltge capacitor or the high voltage diode. In rare cases the magnetron fails because the oscillator in the top of the magnetron sticks. When the oscillator sticks the magnetron makes a LOUD humming sound and you do not get heat. However.... a open diode or shorted capacitor will make the exact same sound briefly before the main in line / internal fuse fails.

The capacitor and diode are items 4 and 9 this link:
http://www.appliancepartspros.com/partsearch/model.aspx?model_id=504310&diagram_id=28243249#d28243249

NOTE: Before doing ANY maintenence you must hold an plastic handle screwdriver back on the handle and ground the capacitor terminals at least 3 times. (Just in case it has not failed.)
Failure to do so will ruin your day and pass along one heck of a shock.

To check the diode you must disconnect one terminal first. The read it with a meter. Reverse the leads and check continuity again. It should read continuity in ONE direction / polarity only. Id should NOT read open both ways or shorted both ways.

To check the capacitor you have to remove all the terminals from ONE side of the capacitor terminals. With the meter on R X 10,000 probe the 2 terminals. You should see a brief jump in resistaqnce and then the meter drifts to infinty. Reverse the leads and do this again. You must get the same jump in resistance and then the meter drifts to infinity. If it does not do this it has failed and must be replaced.

If both the diode and the capacitor pass the checks above the next step is to check the magnetron for continuity across the 2 terminals. It must read continuity. Even if this test passes the oscillator can be stuck and it will not heat. (Again if it is stuck it will make a LOUD humming noise.) It is not repairable.

I suspect you either have a bad diode (most probable cause) or bad capacitor (2nd most probable cause).

Thanks for choosing FixYa,
Kelly

A loud buzz, hum, or groan is usually a shorted high voltage rectifier diode, but a sound like gurgling into an empty coffee mug is one symptom of a failed magnetron, and yet the mag can be bad without that sound.

At our Web site, we have a video available showing how to remove a typical over the range control panel assembly in under 5 minutes.

Here are some links you or someone you know can use (in order given) for test help, but read the safety warnings first:

http://www.gallawa.com/microtech/diode.html
(if it is NOT shorted or burned looking, it's probably fine)

http://www.gallawa.com/microtech/mag_test.html
(continuity can be good even though mag is bad!)

You can find helpful exploded view diagrams and order parts by entering your full model number from the tag on the oven here.

There should also be a "mini-manual" hidden inside the unit behind the control panel or hidden on the left side behind the grille, which is very helpful when troubleshooting, & testing.



We're happy to help you with free advice and we'd appreciate your thoughtful rating of our answer.

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

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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 it's an arcing sound, there may be grease or food particles on or behind the waveguide cover or in the area of the turntable motor.

Otherwise, it's likely to be a failing high voltage part:

- A sound like gurgling into an empty coffee mug is one symptom of a failed magnetron, and yet the mag can be bad without that sound. Usually it will not heat is this is the case.

- A loud buzz, hum, or groan is usually a shorted high voltage rectifier diode, but if this were the case, it would not heat.

- Sometimes a high voltage transformer will cause a loud hum and burning smell, too.

Please note that FixYa is not currently notifying us Experts when Clarification Requests are answered.

To allow us to help you effectively (at no charge), please post a NEW problem to FixYa, and please include your brand name and the full model number from the tag in or on the unit, and your specific symptoms.

Let us know which of the examples we gave seems to be closest to the sound you're experiencing.

With the details you described, the high voltage diode might be shorted( usually HVR 1X). It is connected from the Capacitor and the chassis, or else the capacitor is the one at fault,but not common .

humming sound is your magneto going out Dont have any idea of the cost for replacement however it may be cheaper to purchase another microwave than to repair this one. Good Luck

Dave

est the high voltage capacitor,the rectifier diode.or the magnetron. If all this are fine, test the control board.

Thediode and capacitors can br tested. The capacitor must bealloweddischarge before testing, or you risk to get electrocuted, evenifpower is off. Capacitors can get discharged by shorting theirtwocontacts.
Before replacing the magnetron test also the control board.
Replace the magnetron if the checks and all of the high voltage component tests are good, but the unit still does not heat.



All locations, and description of this parts can be located using the diagram here: Counter top.

Parts must be tested to find out what is wrong.

Remember that microwaves are potentially dangerous devices if not repaired properly, the job must be done by a competent person.
A microwave energy leakage test must always be performed when the oven is serviced for any reason.

Regarding parts, contact the seller here to purchase parts.

If your magnetron was shorted, the unit would not heat at all.

The sound of a shorted magnetron is usually a loud hum-- but no or very little smell and no smoke.

Components in the High Voltage section -capacitor, diode- give problems if they short out.

As long as the door latches correctly there should be no danger. Some items will cause loud "explosions" in a microwave, such as whole potatoes when the skin has not been pierced. If the food contains pickling spices for example, the seeds will explode with a very loud sound like a gun.

As long as the oven continues to heat, there may be no other problem. But I suggest you stay near the unit when using it. Watch for smoke and be alert for strange odors. You don't mention the age of your oven but if it is new you can call GE customer care at 800 432 2737.

Ray