How to Test a High Voltage Capacitor in a Microwave

Testing a high voltage capacitor in a microwave.

Note: Before testing any components in a microwave, be sure the unit is unplugged and the high voltage capacitor has been discharged.

The high voltage capacitor in a microwave is rated in microfarads, which is one or less and up to 2100 volts. You’ll see that reading on the tag on the side of the capacitor. With an analog meter set to R times 10K. Again, the 10K setting is required in order to test the capacitor. Calibrate your meter. Place one of the meter leads on top of the capacitor at the terminals, and while looking at your meter, place your other lead inside looking for a jump.

Once you see that jump, flip your meter leads around and you should see a larger jump. If the high voltage capacitor, when the meter jumps, if it stays up, the capacitor is shorted. If you get no movement, the capacitor’s open. It doesn’t hurt to check each terminal to the capacitor itself. Looking for one side to be shorted.