Ge Spacemaker microwave jvm240 wv Micro hood...

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posted by stealthninja on Jan 05, 2008

Blows 20A line fuse upon starting a cook cycle. Checked HV Cap, All interlocks, MGT TCO, Cabinet TCO. Checked for continuity across magnatron filament. HV diode OK. My best guess is a bad HV transformer. Has a slight transformer burn smell when the cook cycle is started. Fuse blows approximately 1 second later.
When microwave is powered up with a new 20A line fuse, everything else works fine, ie: fans, lights, keypad, clock etc. Fuse only blows when starting a cook cycle. Using a mug of water in microwave as test. We have had the microwave since 1996 without a hitch. Is it worth replacing the transformer? I have found them online for $152 + S+H. I am a tech so I will be providing the labor. Thank you for your help.

Comment posted on Jan 06, 2008

Followup to my troubleshooting as of yesterday. The cap reads infinity across each contact to the cap case. Yesterday, before I headed off to work, I disconnected everything from the HV transformer secondary side ie. HV cap, magnatron, etc.. Insulated all connectors thorughly to be sure of no arcing. Installed new line fuse, restored power to microwave. Everything worked fine until I started a cook cycle. Entered 1 min and hit start. Microwave ran for 1-2 seconds then fuse blew. Smelled of typical burnt transformer smell after that. This seemed like a pretty positive sign that the HV transformer is bad. Let me know what you think. Than you for your help.

Comment posted on Jan 10, 2008

UPDATE. REPAIRED. Installed a new HV transformer and the microwave is back in service. My son was elated. He has never known life without a microwave. What a hardship!! Thank you for the help and input. This site is a goldmine for information.

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Posted by danderai1990 on Feb 20, 2008

My GE Spacemaker just did the same thing. It comes on, then a second later it starts to hum, it does not heat up and it smells like electrical burning when the door is opened.

I have not taken any steps to resolve the issue except for looking here.

Posted by Skh0516 on Feb 04, 2008

I have a similar problem with my GE Spacemaker Profile microwave, but I'm not a technician. Symptoms are similar, internal fuse blows a couple seconds into the cook cycle and there's a burnt smell. How hard is it to replace the transformer for a non-technician. I understand there can be some voltage in the microwave even when it's unplugged.

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posted on Jan 06, 2008

vettesrbadas

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Rating: 79%, 15 votes

sounds to me like the magnatron has shorted out. i don't know of a way to test them unless you have some high dollar equipment. a continuity test prob wont tell you anything. what reading did you get on the cap when you tested it?

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