How to Repair a Micowave Oven

Unplug the microwave from the outlet before performing any troubleshooting. Check to make sure that the electrical cord is not frayed or damaged in any way.

Look to see if the microwave fuse is not blown. Take off the microwave cabinet by removing all of the screws on the bottom and on the back of the appliance. Slide the cabinet off the base of the microwave.

Locate the fuse. Most microwave fuses will be found near the electrical cord. Refer to your owner's manual for the exact location. Remove the fuse with a fuse puller or screwdriver.

Test the fuse with a multimeter. Replace the fuse if the meter does not find a charge.

Examine the microwave's capacitor and diode if fuses continue to blow. The capacitor and diode make it possible to change household AC power to the high-voltage DC power needed by the magnetron that powers the appliance. Locate the capacitor and diode at the back of the microwave. Use the owner's manual for the exact location. Do not touch the capacitor with your hands.

Remove the leads connected to the capacitor with a screwdriver. Set the multimeter to its highest resistance scale. Connect the probes on the multimeter to one terminal on the capacitor. You should receive an infinity reading or a value. Switch the probes to the other terminal. The other terminal should have an infinity reading. If not, the capacitor should be replaced.

Disconnect the diode from the capacitor. Attach the positive meter probe to the anode terminal on the diode and the negative probe to the cathode terminal. The normal reading should be between 50,000 and 200,000 ohms depending on the microwave models. Switch the probes to the opposite terminals to get an infinity reading. If you do not get these readings, the diode must be replaced.