Samsung DE91-70063D Microwave High Voltage Diode OEM Part

After dismounting the unit from its wall-hanging bracket, the most tedious part of the repair was removing over a dozen screws holding the cover in place from the top, bottom, and both sides. Fortunately, I had placed the unit on a bench that allowed me to slide the unit allowing access to the screws on the bottom edges of the unit. Always discharge the capacitor before continuing to work on the unit by discharging the capacitor by shorting the contact without the diode to ground. Access to the magnetron is from the right side (behind the control panel) by removing the four (4) retaining nuts from the top, removing the electrical plug and hinging the movable shield out to remove the magnetron through the side. Revere these steps to install the new magnetron. After testing the unit on the workbench, I discovered that the unit still failed to heat, and the louder than normal sound was still evident. By removing the front panel, I disconnected the diode and attempted to check it with a VOM and saw that the readings were inconsistent with the way a diode should work, so I replaced it and retested. This time the microwave worked just fine, and the sound was back to normal. Since most of the work was dismounting and disassembling the unit, and considering that magnetrons do fail, I left the new magnetron installed.

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.