GE Profile Microwave Oven - Won't Heat

I have a GE Profile built-in microwave oven, model JE2160SF01. It appears to work but will not cook food. If I set it for 50% power, I can hear it change sound when it cycles on and off every 15 seconds, but heating is not happening.

This microwave was working fine when my wife touched up some paint to repair a chip that started to rust beneath the door. The door was left open for several hours before I opened the circuit breaker so the microwave oven light would not remain on over night. After being off for about 24 hours, I turned the breaker back on, set the clock, and figured all was well. The first time we tried to heat something, it didn't heat.

I suspect that the light being on for several hours may have tripped a thermal fuse somewhere. From the parts list for this model, I find a cavity thermostat and a magnetron thermostat. Are these really thermostats that will self-reset once they cool back down? Or are they thermal fuses that must be replaced once they are tripped?

I will be pulling it out and opening it up shortly, but would like to understand how these components work so I can test them.

UPDATE:

I pulled out the microwave and removed the cover. Following the documentation and schematic conveniently located inside, I found the non-resettable thermal cut out components are normally closed and both tested about zero ohms. I now suspect the high voltage diode. This diode measures over 1 megohm in either direction. I will be researching further to learn how to properly test the high voltage diode.

UPDATE 2:

I found a good way to test the high voltage diode here:
How to Test a Microwave Oven High-Voltage Rectifier

Using a 9V battery, I was able to determine that the diode is not bad.

Any ideas on what else might have failed?

 

If you can hear the high voltage supply cycling when set at 50% then it sounds like the magnetron may have gone bad. There's only four parts.... the HV transformer, diode, capacitor and magnetron.

I use a special high voltage probe to check for high voltage.

Be advised... I don't consider microwave servicing a DIY project. Be aware that the high voltage present can kill you.

Here are some helpful testing links.
How to Test The High Voltage Capacitor Used In Microwave Ovens
How to Test The High-Voltage Diode (Rectifier) Used In Microwave Ovens
How To Test The Magnetron Used In Microwave Ovens
The Purpose and testing of the Typical High Voltage Transformer

 

Thanks for the useful information on testing the high-voltage components. I am an electrical engineer so I can appreciate the note of caution.

After fully discharging the capacitor with no pop or spark (it was likely already discharged), I performed the tests in the links you provided using my Fluke 23 digital multimeter.

The high voltage diode did not test as bad.

The magnetron resistance across the terminals was 0.1 ohm or less. Touching the meter leads to each other reads 0.1 ohms so the magnetron leads could have been a dead short.

The capacitor also did not test as being bad.

The transformer read 0.1 ohms across the primary and filament coils and open to chassis. The high voltage tap read 79.2 ohms to chassis. This doesn't indicate a bad transformer.

Based on other things I've read and based on the symptoms observed, I suspect the magnetron filament is shorted. I may pick up a used magnetron to see if that fixes it. It's not worth buying a new one for a speculative repair.

Thanks for your help.

 

Magnetrons can be hard to check. The filament is under an ohm so without using a milliohmmeter it's tough to know if it's actually shorted. Did you check for leakage from the filament leads to ground.... using a high ohms scale there should be no continuity.

 

I did check the filaments to chassis and they are open. I ordered a used magnetron on Ebay for $15 shipped. If that fixes it, great. If not, it's no big loss.

I installed a new microwave today so my wife is happy. When I learned that a new GE model would bolt right into the cabinet using the existing trim kit, I bought it. (model PEB7226SFSS)

 

Ahhhh..... a built-in. You're lucky the trim kit was the same.

They been known to change models and the old trim doesn't fit. It's real high on the list of things people like about GE.

 

GE will tell you a new kit is required, but several Amazon reviews confirmed that this PEB7226SFSS will install as a direct replacement for this specific old model, JE2160SF01. It was an exact fit down to the last screw.

 

Well, I received my $15 magnetron and installed it. A 20 second test confirms that the microwave now heats, but this magnetron makes snapping and arcing sounds with associated electrical arcing smell. The installation was very straight forward, so I don't think I did anything to cause this issue.

I think I only confirmed that the transformer, capacitor, and diode are all working and I still will need a good magnetron to repair this unit. I don't think I want to spend the money at this point.

 

I recently fixed my microwave for about £25. A new one to the same spec would be about £200, so it's worth fixing if you do it yourself. Just note the safety guidelines.
See the video guide I made:
https://youtu.be/WAf18e8sW4E

 

Welcome to the forums.

Thanks Jon. Your video is very well done and easy to follow.