This will happen when the microwave starts a heating cycle. Leave the power cable plugged in but turned OFF to maintain a connection to earth.
Microwave Oven Diode CL01-12 and High Voltage Fuse 5kV 800 mA 0.80 A (No heat)
Microwave Oven Diode HV Rectifier 12kV CL01 12 CL04 12 with or without terminals
Microwave Oven Diode CL01-12 and High Voltage Fuse 5kV 800mA 0.8A (No heat)
Microwave Oven Diode CL01-12 and High Voltage Fuse 5kV 650mA 0.65A (No heat)
Microwave Oven Diode CL01-12 and High Voltage Fuse 5kV 700 mA 0.70 A (No heat)
2x Microwave Oven Diode HV Rectifier 12kV CL01 12 CL04 12 with terminals
