How to Troubleshoot & Replace Ge AP3994062 / WB27X10928 Fuse

Replaced the door switch (had basically shorted and then partially melted). 

My husband is the hero in this story. At this time in our lives we weren't looking to purchase another microwave. After 10 years at my company, due to a workforce reduction, my position was eliminated. He quickly realized it could be the fuse. We searched the microwave and the part on line and appliance part pros came up with the parts for our microwave. We needed the fuse and the fuse holder. For under $20 we were able to get the microwave working again. Thank you appliance part pros for having the parts (our microwave is 13 years old) and for having a solid search campaign as well as an easy to use site. We used screwdriver, wire cutters to cut the zip ties that were hindering our ability to fix the part. 

Originally thought maybe a fuse but first thought to look on the internet. Found this website which was very helpful. Turned out the thermostat on top of the microwave was the problem. Ordered the thermostat and spares for the future. Replaced the thermostat and problem solved. This item is inside so the cover had to be removed. While removing the cover I found a wiring diagram inside the Display Module. It was helpful although I had to trace the wires to locate the thermostat. Turns out microwaves are not that complicated. Thanks AppliancePartsPros.com for your help 

GE SCB2000CWW03 (13 yrs old). Turned off circuit breaker. Removed trim screws into wood. Had to remove GE Advantium Microwave from above the oven & placed on table in front of oven. Long enough pigtail to not have to undo wiring into wall. Removed the top metal cover of the microwave. The fuse was located on the right side of the oven on the side of a circuit board on a vertical. The fuse had blown and melted the fuse holder as well. Looked at all the circuits boards, etc for cracked parts or seepage from parts to indicate they had been damaged too. None were seen. Ordered the fuse and its holder. I broke one of two clips that hold the fuse holder onto the side of circuit board removing the old fuse holder. Replaced the fuse holder and used some hot glue to secure holder to side of board. Placed the fuse into holder and attached wires to fuse holder. Used compressed air and blew out compartment of dust, etc. Replaced top cover. Turned breaker on. Microwave had power. Test heated cup of water - worked. Replaced microwave back above oven. Attached trim screws back into wood. Wife happy again. 

I am a single female and didn't have the money to replace my microwave. My oven was completely dead. The power source was fine. I went on the appliance pro website and chatted with one of the pros. He was able to tell me what the problem might be and sent me the scamatics of the oven. I opened it up and relaxed the fuse and the microwave works perfectly t. Thanks to the pros at AppliancePartsPros! 

Did a little research prior to opening the microwave up. Microwave has to be taken down for repair and then hung back on the wall after repair. Would recommend using 2 people for this job. Checked the 3 thermocouples, one at the top (normally closed) and two at the bottom (one is normally closed and one normally opened). All three checked good. Checked both fuses, found the fuse marked Main Fuse to be blown. Fuses blow because of a problem, did some digging. Prior to the microwave going out there were noises best describe as "baseball card hitting against the spokes of a bicycle wheel". Discarded high voltage capacitor and checked it. Found the capacitor to be bad, used a Fluke digital meter. Capacitance showed "OL" when it should have been around "900", the ohms reading showed bad also. Everything else checked good. Also, keypad is on the door of this model. Keys were very difficult to operate or didn't operate. While doing the repairs for the power issue traced out the wiring for the keypad and found 2 modular connections. Worked these connections (unplug and plug) several times and scraped the pins gently. Microwave is now operating after replacing fuse and capacitor. Keypad is also functioning great. 

Changed fuse and 2 door interlocks now everything now works great. 

Went online with model number to research. Appliance Parts Pro came up, I have used them in past. After checking online, didn't have enough details, so called. Spoke with technician Andrew Shelton, described problem and troubleshooting I had performed; continuity, resistance checks, sequencing, etc. This was a strange, but not unheard of problem! After a brief hold, he came back with questions and recommended part. This interaction took 20-30 minutes, not sure exactly. What was great was no rush, no hassle, direct questions and answers, stayed on the phone while I did some additional diagnostics, . Ordered part on Friday, arrived Tuesday. Installed on Wednesday, Had problems with GE's ribbon connector! My wife treated me to some great cookies that afternoon, mmmmmmm! Thanks Andy. 

Replaced a fuse 

Replaced Fuse