How to Troubleshoot & Replace Samsung AP4236698 / DE91-70063D Microwave High Voltage Diode

I took the microwave apart and visually inspected it, which yielded nothing. I discharged the capacitor with insulated screwdrivers and needle nose pliers. I then unplugged the wires to all the larger components. My microwave had a schematic diagram inside the case so I was able to test with my multimeter all the individual parts against the expected results. I tested the transformer, magnetron, capacitor, and the diode. All parts passed which left me a little discouraged. I removed the magnetron for a closer visual inspection. On inspection I found a hairline crack in the top magnet. My theory was that under electrical load, that crack expanded, which would explain the failure to create heat (and the favorable multimeter tests when cool). I decided to replace the magnetron. I did the diode too since it is only a couple bucks and I already had the case open. I was unable to find the original OM75P10ESGN magnetron so I purchased the substitution, OM75P10ESHL. I put the new magnetron and diode in, cleaned and reassembled all the case pieces, and tested with a glass of water. Water was hot… success! 

After checking, I found the capacitor was bad. Not too sure about the HV diode, so I replaced that as well. Worked like a champ. 

I first began troubleshooting by checking the diode. The high-voltage diode unfortunately does require a ohmmeter that has the capability of utilizing more than 9 V. The trick is to put another 9 V battery in line of the leads. But just to be sure I ordered a diode just in case I was wrong. I also ordered hey capacitor and high-voltage transformer just in case I was wrong as well. My first suspect was the Megatron and that is the first item I replaced when I receive my parts and bingo that was it. Interestingly enough, the magnetron looked absolutely in good shape when I pulled it out but I guess since it is a tube it can fail. Ohm meter measurements revealed no issues at all. 

Replaced the magnetron using replacement part OM75P-21-ESGN. And the microwave started heating food again. The most challenging part of the repair was taking out and putting back all of the screws in the cover. 

Removed and replaced old magnetron and diode with exact replacement parts. Hardest part was so many screws in the microwave cover and lifting microwave back into position over the stove. Caution required when working around capacitor. See YouTube procedure. 

Replaced magnetron and diode. Followed video directions. Magnetron cheaper by its own model number rather than the one listed for my microwave (same part). Still purchased at Appliance Parts, but saved some cash. Disassemble first before ordering. 

I replaced the diode after checking out videos on YouTube I went to AppliancePartsPros.com and saw my diode. No heat- replace the diode. Now it works perfectly. 

Replaced diode in Samsung microwave that quit heating (only 3 yrs old). Can’t believe how easy it was. Literally bought another microwave because I thought it would be too hard/too expensive to repair. New microwave handle did not match the rest of the Samsung appliances and could not be swapped out (way to go Samsung). So I thought, what the heck, let’s try. So glad I did! Hardest part was taking it off the wall to take off the million screws holding the “skin” of the unit (again, way to go Samsung). Anyway, easy and best of all CHEAP repair. Thank you!!! 

Replaced high voltage capacitor which was shorted internally. Also replaced high voltage rectifier as a precaution. 

I got Samsungs repair manual and started testing the components and found the magnetron was shorted internally, 107 ohm to ground. Also found low resistance on both the primary and secondary side of the transformer, according to the manual. THE MANUAL IS INCORRECT, THE REPLACEMENT TRANSFORMER HAD THE SAME RESISTANCE. Using the diode test function on the test meter indicated the diode was open. found the same on the replacement diode, I wound up using a 9v battery and measured the voltage drop across the diode because the meter does not supply enough voltage to measure across the diode. replaced the magnetron and is it working properly.