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.
957 views
Usually answered in minutes!
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.
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.
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.
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.
×