Watch this microwave oven fan wheel running lights, can not be heated, indicating that K2 is working properly, the door interlock switch contacts are normal, the fault may be heated in microwave circuits, Kl contact coil or VT3, CPU. First, use a multimeter to measure the voltage across the primary winding of the high voltage transformer, found no 220V. After observation, the input Kl pressing the "Start" key does not pull, disconnect the plug and microwave systems related only to the computer control panel AC220V power, short-circuit both ends of the xP5, press the "start" button. Component and pin detection and Kl-related discovery CPU (40) feet can output the main voltage, VT3 collector voltage of about 12V, did not prove VT3 conduction. Disconnect the power supply, power block with a multimeter to measure VT3, found open ce breakdown, resulting in Kl can not pull, after the VT3 with 2SC1815Y replacement, and then simulate the operation, the relay can normally pull, unplug the plug reset the original equipment good test machine, microwave heating can be normal.YQVservice manual download site