Vincent C Giddings , TX April 07, 2025 Appliance: Samsung Microwave Oven MC12J8035CT/AA-00 Samsung Microwave Mc12j8035ct/Aa-00: It was very noisy and did not heat when using the microwave. How to replace Microwave High Voltage Diode. 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. Do-It-Yourself Rating: Repair Time Estimate: 1-2 hours