How to fix a broken microwave

[skindog]

My cabinet mounted microwave stopped working recently, and after a few searches on Google I figured I would try to fix it myself before calling in the pros.

*Note - Make sure you unplug or kill the circuit breaker for the appliance before attempting to do any work inside. My wall mounted unit's circuit breaker is part of a dual microwave and oven unit, and the circuit breaker ended up being in the panel outside by my meter instead of in the garage. Once inside, make sure you drain the capacitor because it can still have energy stored in it. DO NOT TOUCH THE METAL POSTS ON THE CAPACITOR WITH YOUR BARE HANDS OR BARE METAL, it'll be a shocking experience!*

My microwave started doing weird things like not spinning when I tried to heat something up, but would spin very slowly when I opened the door. Google and YouTube kept telling me to check the fuses and door "micro switches". Most microwaves have 2 to 3 micro switches; One tells the microwave that the door is secured and will allow the magnetron to activate, another turns on the light when you open the door, and a 3rd (if it has 3) is a redundant safety switch.



Micro-switches have 2 modes - Normally Open (NO circuit) and Normally Closed (NC circuit). When the button is not depressed, whichever terminal your wires are connected to determines if it is an open circuit or closed circuit. One door micro switch, for example, would be normally open (NO), because when the door is closed, the button is pressed, turning off the light, and turns it on when you open the door which releases the button the micro switch which turns the light on.

There are numerous examples and videos available online on how to replace the switches so I won't go into a lot of detail. I found out by opening my Kenmore microwave that it's GE components, typical of Kenmore appliances to just re-badge other manufacturers appliances.

Replacing the micro switch took me about 15 minutes the first time after figuring out how to open the front panel of my wall mounted unit. Stand alone units are much easier, as the latches and switches are readily accessible simply by removing the metal cover.

You can order replacement switches from the manufacturer, or other online retailers such as Amazon. I ordered mine from searspartsdirect, and it turned out to be the wrong one (was a NC instead of a NO micro switch), so I went to Amazon and got a 5 pack of universal micro switches that had posts for both NO and NC - https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

You'll need to ensure that the replacement switch can handle the voltage and amperage of the one you're replacing. Some manufacturers will not sell internal parts to "common folk" and/or say that only qualified electricians should replace parts inside the microwave. While I agree you need to be able to read and operate a screwdriver and maybe pliers pliers to do this repair, it's about as hard as replacing a spark plug in a car.