87790 LG Range

Over the stove microwave installed in top cabinet row.
1. Unplug device.
2. Two people to remove from wall/cabinet (remove two, large, top mounting screws and rotate entire microwave down and off the wall mount). Should be some wood spacers between top of device and bottom of cabinet.
3. Remove screws from sheet metal cover ... Read more .
4. Remove one screw holding blowers in place and rotate out of the way, in order to gain access to 2 of 5 screws that hold the magnetron in place.
5. Unplug magnetron and remove the 5 screws.
6. Drop in new magnetron and re-assemble microwave in reverse order (steps 5-3).
7. Two people restore micro to wall/cabinet. Replace wood spacers, re-install two, large mounting screws (finger-tight). Test device. Secure the two large screws.

Unplug the microwave. Remove the Philips head and safety Torx head screws along the bottom of the sides and rear of the microwave which hold the black cover on. Lift the cover up at the rear and slide it backwards to disengage the tabs on the front top. Remove the cover. Discharge the capacitor by shorting the terminals to each other ... Read more and then ground. Do this with a well insulated object and be aware there may be a pop when you do this. Keep hands, etc. on the insulated part of the object (screwdriver handle, etc). There's a lot of stored energy in that capacitor. I'd advise first checking the diode to make sure its not bad. Replace it if it is. The Magnatron is held in with a couple of screws on the top and sides. Unplug the connector and remove the screws. Remove the Magnatron. Installation is the reverse of removal.

I looked up my problem on the internet and found a very helpful video. Microwave on video was different brand but the internals and methods were very much the same. The video made it simple and easy to fix. Found the replacement switch on the LG parts site and ordered. Two different switch types. One with red switch, the other green. ... Read more Part was $7.28. Saved a bundle in service costs. Here is the repair video.

https://www.youtube.com/watch?reload=9&v=_AglBJoHgDs