How to Troubleshoot & Replace Lg AP5203812 / 6851W1A002E Microwave High Voltage Diode Assembly

LG Help-line said probably a failed magnetron, but since out of warranty,referred me to an authorized LG repair service. They wanted $79.95 service call to come out & diagnose problem. I ordered replacement magnetron for less than cost of a service call, Plus the part was delivered next day! Works like new again. Happy wife = happy life! Notes for DYI-ers: 1.Be careful removing over the stove microwaves--get help,they are heavier than you think. 2.Unplug microwave for 48 hrs, carefully disconnect capacitor leads, and CONFIRM capacitor is discharged before doing any electrical repairs in a microwave~!! 

The high-voltage capacitor shorted and it blew the main fuse (20A) causing a loud popping sound. I replaced the capacitor the fuse and the related high-voltage diode (I think the diode was stressed during the short condition). During troubleshooting and prior to the repair I checked all the switches, the high voltage-transformer, the diode and the capacitor which had a dead short of less than 1 ohm. Thanks ApplianceParsPros.com for having these parts handy. 

I ordered this part and it arrived the next day and now the microwave is back up and running! Happy wife....happy life! 

Dismantle and replace 

I ordered an replaced the Diode and the thermostat; Fuse was ok .This was a Kenmore, I had to remove it and open the case to be able to access these parts. 

After checking all of the high voltage components and having them check ok, I figured the magnetron likely was bad even though it checked good with electrically. After replacing it, the microwave worked great. I'm returning the unused parts. 

Microwave made a loud noise at first then a strong electrical burning odor. so I uninstalled unit from hood and took unit apart.the easiest part of job is removing screws from outer metal case to expose all components. During inspection I found that the magnatron had burn marks on unit and the high voltage diode had a a bubble on the rubber part and it smelled like burn rubber. So I order a new diode and a magnatron a week later I installed new parts and reassembled unit and tested unit now its like new again. total parts were about 70 bucks. for a microwave combo that was 350 bucks from kenmore 

I replaced the magnetron. While I was in there, I decided to go ahead and replace the capacitor and the diode. 

Replaced hi capacitor and rectifier diode 

First I checked the diode and suspected it was bad but could not confirm it with my meter. Small price to pay to test. Received the part in 2 days from my order and installed the diode. No help. Finally I removed the Magnetron and found a cracked magnet. Ordered the magnetron and received it the next day. Installed it and problem solved. Spent less than $100 to repair a $300 microwave. I have used AppliancePartsPro many times and have never been dissatisfied. Always the correct part and always a fast delivery. Prices good. Service Great.