Testing a high voltage diode from a microwave.
Note: Before testing any component in a microwave, be sure the unit is unplugged and the high voltage capacitor has been discharged.
The high-voltage diode will be connected to the capacitor and to the case itself. Remove the diode from the capacitor and from the microwave case. You’ll need a meter that has a setting of R-times-10K and it must contain a nine-volt battery inside the meter.
Set your meter to R-times-10K and calibrate. Once calibrated, place your meter leads across each side of the diode. Note, do not touch the meter leads with your fingers, as you can pick up your resistance causing a false reading.
You will be looking for deflection in one direction. Our meter has not moved. We will want to go ahead and swap our meter leads around. If we have deflection in one direction, the diode is good. If the diode should deflect in both directions, the diode is shorted. If the diode should not deflect at all, the diode is open.