Not heating My JEM model GE Spacesaver II is not heating. I hear it turn on normal. Then, less than 5 seconds later it sounds like it is working harder. It makes more noise now than when it was working. When I unplug the magnatron, there is no noise. Diode? How do I test? Magnatron? How do I test? The fan is working. It has been above a stove so it has been working in a higher heat environment than counter top.

Sounds like a bad magnetron tube.

I suggest you have the microwave oven replaced, the prices have dropped considerably for the last several years and you have got your money worth out of the unit.

MOST LIKELY YOU HAVE WHAT IS CALLED A MAGNETRON THAT HAS FAILED... IT IS THE PART THAT DOES ALL THE HEATING ...YOU DO ALSO HAVE A HIGH VOLTAGE TRANSFORMER THAT SEND POWER TO THE MAGNETRON BUT IT SOUNDS LIKE A MAGNETRON.... to be honest with you unless you are servicer it normally cost more to repair and for a few dollars more you can purchase a new one..... good luck to you.....

WHERE THERES SMOKE THERES FIRE LEAVE IT ALONG.
TO REPAIR THE MICROWAVE WILL COAST YOU MORE WHO EVER WORKS ON IT WILL HAVE TO REPLACE BURNT WIRES
AND POSIBLY A SWITCH...TAKE MY ADVICE BUY A NEW ONE
WITH WARRENTY AND YOU WON'T HAVE TO WORRY ABOUT SMOKE IN THE HOME.

Hi,
Here is a tip that will help you to figure out what is wrong with yourMicrowave Oven....

Microwave Oven Basic Troubleshooting Tips

heatman101
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call a pro. these units run at a deadly high voltage. simply not worth your life!

GE Microwave ovens, and Microwave Ovens produced by GE but released under different brand names, have had several power problems for the past 20 years. Because it is so easy to sell parts and charge outrageous rates for repair GE never corrected the problems. They just continued it in the next model. They found that you would most likely purchase a new unit rather than paying $75. for a service charge, and $150. for labor plus parts (if out of warranty period).
Most failures were cold solder connections on the power relay board. These would come completely dis-connected after arcing and burning away the solder. Could be 1 month, could be years, but they knew it would happen. This power relay board feeds 120volts to the LV (low voltage) side of the HV (high voltage) Transformer. No High Voltage,,No cook. Everything seems to run normal, but if you listen carefully you will not hear the low tone from the HV Transformer. Over my thirty years in the business I have re-soldered rather than replace so many I couldn't count.
Next to that, a defective Magnetron.

Sounds like you have a bad transformer. Magnatron should check less than 1 ohm (with wires unplugged). Diode should check resistance one way and open the other. Must have a proper diode checker for this. Check resistance on the capacitor (make sure it is discharged first). Resistance should come up then back to open, reverse and same thing if cap. is good. Check resistance on transformer windings.

Your magnetron, HV diode, Capacitor, or control board maybe bad most of these components run with high voltage and difficult to test without the proper equipment

if you are as lucky as i was...i have a ge spacesaver model jvm130...same problem. first unplug unit and check fuse on the "power control module". if fuse is ok...unscrew the screws holding the "power control module" in place...carefully tilt module and see if a solder joint needs to be re-soldered. my problem was the solder joint under the front plug (5 large wire plug). you may have to unplug the three connectors to the board to get access to bottom. this is the second time i had to re-solder...last one was several years ago though. best of luck tennisrme