Microwave Oven Repair and Maintenance
Use extreme caution when working on microwave ovens! Even when unplugged, the high voltage capacitor can store up to 2,000 volts just waiting to discharge into your body. Discharge the capacitor before doing anything else inside the box!
Oven Completely Dead
- Circuit breaker tripped.
- Blown fuse. Run continuity check and replace with exact replacement.
- Defective control board. Test for power going to board. If exists, problem lies on board somewhere. On the GE/Hotpoints using the "smartboard," it is sometimes possible to locate a bad soldering connection on the board that can be repaired, restoring function to the board. Otherwise the entire board must be replaced.
Microwave Appears to Work But No Heat
- Defective magnetron. Ohm test between the magnetron terminals, should be less than 3 ohms. Test from magnetron terminal to ground, should be open.
- Defective HV capacitor. Test with capacitor meter or ohm meter.
- Defective control board. Test for power going to board. If exists, problem lies on board somewhere.
- HV Rectifier is shorted or open. Test forward and reverse bias with a megohmmeter. If continuity in both directions, rectifier is shorted, replace. If no continuity in either direction, rectifier is open, replace.
Oven Sparks While in Use
- Grease accumulated on oven cavity ceiling (usually accumulates at waveguide cover) which sparks during use. Clean grease and wash waveguide cover.
- Microwave stirrer inoperative due to either defective stirrer motor, defective fan motor (which drives the stirrer), or broken stirrer belt, depending on how unit is designed. Without the stirrer, microwave energy will concentrate on one part of the oven and cause burning, sparking, etc.
- HV Rectifier is shorted or open. Test forward and reverse bias with a megohmmeter. If continuity in both directions, rectifier is shorted, replace. If no continuity in either direction, rectifier is open, replace.
