10 replies to this topic

[Todd Norris]

GE Spacesaver JVM1441BH04

My daughter slammed the door to the microwave, but not much harder than the kids usually do. Then it would not come on at all. I did some research on the forum and found the fuse and replaced it. The lights came on and all seemed well. I could open the door and the inside light came on. But when I put something in it and started to microwave it the fuse blows in just a few seconds. I checked what I could of the board the fuse is on and the switches (seems to be three) where the door connects. I don't see anything odd, but I don't really know what I am looking for.

I am expecting a switch or two needs to be replaced. But I am not that great with a volt/ohm meter and am not sure how to even check them. I don't want to order all the switches if I only need one... or if that is not really the problem.

Is there a chance this is something else? Can you give easy directions on how to test the switches to determine which one(s) are shot? Are there other things I should look for?

Thanks for the help.

[KurtiusInterupptus]

More than likely it is the monitor switch...try to id it by the wiring diagram.
Otherwise, simply remove the door switch holder asm. and feast your eyes and ears on the switches.
Pay attention to the switch plungers...and any of them stuck? When you depress one, does it spring back cleanly,with a knowing click?
Also look for melting or discoloration of the contact spades where they enter the switch housing.
Hopefully, the offender will become apparent to ya this way, although sometimes I find a switch that looks and feels OK, but fails to test good with a meter.
To prolong the repeat of this issue, coach the family to pause/cancel the microwave before opening the door while it is running...

[Todd Norris]

I checked all three switches with an ohm meter. The top one showed 0 when I was not pressing and 1 when I pressed the plunger down. The other two were opposite. They all seemed to switch fine. No sign of anything burnt. Put it all back together and fuse new a soon as I started to cook something.

Thoughts? Appreciate any help.

[RegUS_PatOff]

... the fuse blows in just a few seconds..

I think if the Door Switches were bad, it would blow the Fuse right away.
It may be a shorted High-Voltage Diode,
a shorted High-Voltage Capacitor
OR may be a bad Magnetron
High voltage is stored in the Capacitor even with power removed.

[Todd Norris]

So I wonder what to do next? Is there a way to check which it is? Would these parts be practical to replace? Is this something I can do myself?

Thanks

[RegUS_PatOff]

... Is there a way to check which it is?
... Would these parts be practical to replace?
... Is this something I can do myself?

1) if you have a test meter
2) yes, Capacitor and Diode, maybe Magnetron
3) The Capacitor stores high voltage,, even with the Microwave turned OFF and disconnected from power.

[KurtiusInterupptus]

I am not ready to rule out the doorswitches yet...been burned on this several times...
Very possible for them to fail under load...yet test good on continuity.

Most often ,when one of these HV components (diode,mag,transformer and cap) fail, it is accompanied by a loud buzzing or grinding noise.

I say ,get one of the door switches and, starting with the monitor switch, try it in different locations till you have tried all 3.
Very easy and inexpensive...

[Todd Norris]

So I have done a little more testing and have a few more questions.

Question 1 - the fuse blows when I hit start. I hear one noise for the first second or so, then a lower pitched hmm starts and the fuse blows. This all takes about 2 seconds. However, it does not matter how long I have the microwaveplugged in, can open and close the door, etc and nothing blows. Would the fuse blow before I even started the microwave cooking if it was the door switches?

More info - I discharged the capacitor. Nothing really popped or anything regardless of how much a shorted the posts. Then I took the ohm meter set to 20k. When I touched the two terminals it went to maybe 1300 on the meter and then goes back to 1. This number seemed to vary each time though. Then I tried to test the diode. On one side I just got infinity (1) and when I swap the probes the number runs up to around 1500, but I did have tomwiggle the leads in the diode around a bit to get it off of 1.

I am not sure if I am testing these right. I may be over my head a it, but by the time I get an electrician to come in and fix it I would be close to buying a new one.

On the suggestion that I get one switch and rotate it around,does that mean all three switches are the same so I can get one and try it in different places (there are three) until I find the one that was not working?

Sorry for all the silly questions. Any help is appreciated. I may just be better off tomreplace the unit, but it is only 6 years old and I was hoping to get a few more years out of it.

Thanks

[RegUS_PatOff]

For testing purposes, you could disconnect the Monitor Switch
(center switch, one wire is white)
The Microwave should work, but if the other Door Switches fail,
the microwave oven could operate with the Door open.

[Budget Appliance Repair]

I really doubt it's the door switches from everything that you have described.

One way to test this is to remove the ?black (L1) power wire from the high voltage transformer, or both wires going to the the primary 110 volt side of the high voltage transformer if you can't figure out which is the line and which is neutral, (be sure to tape them safely away from touching anything).

Then turn the microwave on and it should startup and count down and cooling fan should run, just won't do any heating, (by disconnecting the high voltage transformer you have completely eliminated the high voltage system from the picture). If this works OK then you know the switches and complete control circuit is OK.

From what you say about hearing it sound like it's powering up then in 2 seconds it blow the fuse, it sure sounds like a shorted mag tube, (2 to 3 seconds is the time it takes for the filiment in the mag to heat up and it to start operating).

If the test with the high voltage system disabled above works, next reconnect the transformer and disconnect the two wires going to the mag tube, (make sure to mark the terminals they come off of), and make sure they are safely away from everything and give it another try. If again it works without blowing the fuse you can be pretty sure you have a bad mag tube, even if it doesn't show as a directly shorted mag tube when checking continuity from the terminals to the mag tube case.

[Samurai Appliance Repair Man]

Magnetron part link ==> http://www.repaircli...ber=JVM1441BH04