Our microwave oven stopped working one day when the door was closed. The clock stopped showing, the light didn't come on when the door was opened, and the microwave couldn't be started. It acted as if it lost power. So, we did the usual things such as check the plug and the circuit; these were fine. I then removed the cover (need special bits called "Security Bits" which you can buy from Home Depot for $8.00). After removing the cover, be sure to discharge the capacitor (do a Google search to learn how to do this; fortunately, this microwave has a resistive circuit to ground to discharge the capacitor after about 30 minutes of being unplugged). After I discharged the capacitor, I checked the fuse and it was blown. So, I went to the store to buy a new fuse. When I replaced the fuse, and plugged the unit back into an outlet, the circuit blew as soon as I opened the door. This made me realize the faulty components were the "interlock" switches. These are relays (an electric switch) that cause the microwave to shut off when the door is opened and the inside lamp to illuminate when the door is opened. There are two "primary" switches and a "monitor" switch. I checked both primary switches for continuity (do a google switch for "checking interlock switch"). The one interlock switch was bad, meaning, it wasn't opening when it was suppose to. I ordered a replacement and also replaced the Monitor switch too (not sure why, I guess because it was only $6 to buy). After replacing the bad primary interlock switch, I put it all back together and we're working now!
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