Emerson microwave blows fuses

by Charlie

I do some appliance repair, but never really tried to fix a microwave. Someone gave me an Emerson MW8118SL that is about 1 1/2 years old and I figured I'd give it a shot. The main fuse was blown. I replaced it, started to heat a cup of water and it blew again in 1-2 seconds. I found your site and checked the monitor switch. It came apart for me, but when I reassembled it, it tested good. I changed the fuse again in case that was the problem, but it blew it again in 1-2 seconds. Also, I can not find a parts breakdown of it on appliancepartspros.com. Any suggestions would be helpful.

Find your part:


Hi Charlie,

You might find it hard to find exact parts for Emerson parts anywhere but as far as common parts like door switches, diodes or fuses are typically the same on most microwaves. Since you repair appliances I will warn you to take parts availability in account when you take in a microwave like this. What you don’t want to do is take the time to diagnose just to find you can’t get parts because then you may have a hard time collecting anything for the job (especially if they dropped it off at your shop they won’t come back to get it).

If the monitor switch came apart I would strongly recommend replacing it. If you do appliance repair you may have a micro switch that will work just make sure it is rated for at least 15 amps and has the NC terminal (it is ok if it has both NC and NO terminals). If it still blows with the new switch make sure the door latch is hitting all the switches when you closed the door.

If it still blows the fuse you need to narrow the problem down to if the problem is on the low voltage side or the high voltage side so unplug the wires off the relay on the smart board that supplies voltage to the high voltage transformer. If it still blows fuses you know it is in the low voltage side and if it doesn’t you know it is on the high voltage side. Then from their start unplugging devices until you figure out what it is. Make sure when you unplug things you make sure the wires don’t touch anything (it will render the test useless if the wires short out). Make sure you have a few fuses it may take a few to figure this out.

Thank you,

Comments for Emerson microwave blows fuses

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Emerson MW8118SL
by: heapstack

Hey Charlie,

If you didnt fix the Emerson and it ends up "bricked", I need a door for my MW8118SL as the latch is broken and it seems easier t replace the whole door thank to get into the door to replace the latch. Any way you would sell me the door?

emerson high heat only problem
by: Wm

I have a similar problem that it pulls too much power and blows the internal 10 amp fuse. Diagnosing it via the circuitry, and the looks of a couple spade connectors that looked as if they were getting too hot, yielded no problems other than a little easy to clean corrosion. Tested the large capacitor and diodes, nothing.

Replaced the fuse, tried cooking some popcorn on high as preprogrammed with the cover off. At about 1 minute 40, the fuse blew. Checked components for excess temp with an infrared temp probe...everything seemed normal on the low voltage side, except the fuse of course.

The capacitor was normal temp. The transformer was getting warm but nothing more than expected.

Replaced the fuse, tried heating a ceramic cup of water at half power for 2 minutes 30. The power cycled and it was operating normally at 50% power. no problem. Even the fuse stayed cool.

My thinking is the Magnetron is going bad. Am I on target?

by: Shawn/admin

When it is cooking do you hear any electrical arcing? If you there is a strong chance you are right about the magnetron tube. When magnetron tube fail they often burn on the end that can sometimes cause it to arc. Most of the time this does blow the fuse but it can.

If this isn’t the case then I would suggest trying the capacitor first because they cause the fuse to blow a lot more often then the magnetron tube (or anything eles).

Yes They Blow Fuses Because They Are Junk.
by: Buddie

I had the same problem. Long story short, the upper door latch was not depressing the button on the upper primary switch when the door was closed so the microwave safety mechanism defaulted to blowing the fuse. I had to super glue a tiny piece of plastic to the latch where it is intended to depress the button on the switch. Last year I had to glue a piece of plastic to the secondary switch for the same reason. Works now but I'll NEVER buy a piece of Emerson junk again. After 1 1/2 years of use, the switches have all had to be replaced and the whole microwave is getting rusty inside because the enamel (paint) is all peeling away. Good thing I kept my 35 year old Panasonic Micro because it gets used every time the Emerson goes down.

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