Microwave shell open , check the power fuse 6.3A has been blown, and blown more serious degree , and therefore can not replace the fuse and try machine . Check the high-voltage transformers, high voltage rectifiers, high voltage capacitors were normal. When checking bidirectional diode Figure 1 ( referred to as " protection diode ) , I already Breakdown ( normal two-way positive and negative resistance diodes are infinite ) , this two-way diode breakdown , make the transformer secondary short circuit, leading to 6.3A power supply blown fuse . put the same type of ( or remove ) bidirectional diode microwave can work properly.VmCservice manual download site
In the early imports microwave oven, in order to protect the magnetron in the external power grid voltage is too high, charging the capacitor from excessive shock and burn inrush current , high-voltage capacitors are connected in parallel at both ends of a bidirectional diode. Also for some reason the voltage across the capacitor when the pressure is too high , the bidirectional diode breakdown , rapid discharge of the capacitor through the bidirectional diode , thereby effectively protect the magnetron and high voltage capacitors. The high-voltage capacitor connected in parallel so 9MΩ, effect the discharge resistor is stopped when the microwave oven , to provide a high-voltage capacitor discharge path .VmCservice manual download site