Cause of this failure reasons: First, the door safety switch is damaged, should be repaired or replaced; Second, the power transformer is damaged, should be repaired or replaced; three high-voltage rectifier components (rectifier diodes or capacitors) damage; net is magnetron damaged and should be replaced. In general, as long as a normal low-voltage winding, high voltage, although no high-voltage, or to disconnect the high voltage is applied between the magnetron and the magnetron, the other line and by examination under normal conditions and can be considered magnetron damage.wEFservice manual download site