How to Fix a Sparking Microwave

If there are sparks inside your microwave while it is running, the high voltage diode may be shorted or opened. The diode working alongside the capacitor and the magneton to provide the heat the microwave needs to work. Before attempting to access the diode, unplug your microwave, remove the cabinet and discharge the high voltage capacitor to avoid getting an electrical shock. You can test the diode for continuity using a multi-meter. There should be low resistance in one direction and high resistance in the other in a working diode. To check the continuity of the diode in the opposite direction you simply reverse the meter leads. If your high voltage diode has is low resistance in both directions or has no continuity, it needs to be replaced.

The stirrer helps ensure there is even heating inside your microwave. The stirrer helps to evenly distribute the energy your appliance is creating. If the stirrer in your microwave is not working properly and energy is concentrating in one area of your microwave, instead of distributing evenly throughout the unit, it can lead to burning and sparking. There are two reasons why your stirrer would not be working: either the drive motor is broken, or the stirrer belt is broken.