Symptom Description microwave front-end circuit is normal, not heating may be normally open relay contacts K4-1 (see figure) cause poor contact or contact with 220V AC power is not applied to the high voltage transformer T1, or damage caused by high-voltage circuit-related components the. T1 pulled across the primary connector XT1 and XT2, detection T1, C, R, VD2, VD1, MT normal. The multimeter in AC 250V block. Table rods connected to Jian-stage circuit XT1, XT2, press the start button after power multimeter undetectable AC voltage, and the normally open relay contacts K4-1 without closing sound estimate of the control circuit has a problem, so check IC1 15 feet, R14, VT10, K4, VDl3 other components found VT10's be very open relay K4 can not pull caused due to the fault. Replace the VT10, troubleshooting.U7rservice manual download site