What could be causing the fuse to blow in my Emerson microwave oven?

That would be a problem with a door switch, door switch mount, or hinge.

See my help file on door switches here:
http://www.microwavecontrol.com/doorsw.txt

i had the same problem and did what this fella suggested and worked just fine. There is usually a 125V, 20 AMP line fuse inside the microwave, mounted at the point where the power cord enters the back of the unit. Unfortunately, you will need to uninstall the oven (if this is an over the range model), UNPLUG it and remove the exterior case to access. The case comes off in various ways depending on manufacture and model. If the model number you listed this question under is correct, the line fuse is connected in line with the power cord inside the unit and is listed as part of item 4 in the parts listing (part number STD384200).

If the line fuse is blown, you can usually purchase a box of fuses at a hardware store for just a little more than what the manufacturer charges for a single fuse. 125V, 20AMP Ceramic Slow Blow fuses are recommended.

There is usually a 125V, 20 AMP line fuse inside the microwave, mounted at the point where the power cord enters the back of the unit. Unfortunately, you will need to uninstall the oven (if this is an over the range model), UNPLUG it and remove the exterior case to access. The case comes off in various ways depending on manufacture and model. If the model number you listed this question under is correct, the line fuse is connected in line with the power cord inside the unit and is listed as part of item 4 in the parts listing (part number STD384200).

If the line fuse is blown, you can usually purchase a box of fuses at a hardware store for just a little more than what the manufacturer charges for a single fuse. 125V, 20AMP Ceramic Slow Blow fuses are recommended.

If you have any questions, or need additional assistance troubleshooting, please post back and let me know. I hope you find this information helpful.

NOTE: Make sure you take any resistance readings with the microwave UNPLUGGED and the component under test isolated (removed) from the circuit. These ovens can blow a fuse by simply sitting idle. This can occur from any power fluctuations, brown outs, voltage spikes, etc. Or, it could be the symptom of a component that may have failed. If you find the internal fuse blown and replace it, only to have it blow again, you have a more significant problem than a simple blown fuse.

If it is blowing an internal fuse it could be a lot of things.

-short in the motor
-short in one of the other components
- gunk/dust could be causing a short

If it is your house circuit breaker/fuse then either the microwave draws too much current/amps for the circuit and you should try another circuit or you already have too many things/appliances plugged into the same circuit (not necessarily the same outlet) and need to unplug one or more of them so that the 'fuse' doesn't blow.

Kugellager

hi! first thing first check all the fuses for busted.

In that case the outlet your using is pushing out too much electricity. Try calling your local electric company for help or a professional electric repair man.

You have a shorted high voltage capacitor.

Here is a link you or someone you know can use to test it, but please read the safety info:
http://www.gallawa.com/microtech/cap_test.html

For more help from Emerson visit here or get help using your appliance at 1-800-898-9020. Get help locating a servicer or parts at 1-800-695-0098.

Emerson parts are distributed by Fox International and their number is 800-321-6993. Or you might try e-mailing [email protected]

We're happy to help you with free advice and we'd appreciate your thoughtful rating of our answer.

If it went dead almost immediately after pressing the Start pad, that's usually a shorted high-voltage capacitor.

If it went dead a few seconds after pressing the Start pad, that's usually a failing high-voltage transformer.

If it goes dead or blows the breaker when you plug it in or open or close the door, then there's a problem with a door switch or door switch mount.

That makes it sound like a bad high voltage transformer.

Do you detect any burning smell?

Do the windings of the high voltage transformer seem blued or blackened?

They should be copper colored or maybe a little darker due to the varnish.

It seems that something within the microwave must have fried in the power supply unit. This should not be a very expensive repair, However, get a technician t take a look and give you a rough estimate before you decide to repair.