The main reason that caused the failure is poor ventilation or fan motor M1 microwave burned, causing the furnace temperature is too high, the magnetron self-resetting thermal breaker (thermostat) S4 protection due to disconnection.F7qservice manual download site

First remove dust from vents, this does not work, then check the fan blades without slippage and deformation stuck phenomenon measured with a multimeter barrier (normal resistance of about 23012) M1 ends of the fan motor has burned out. Using the same model (after SP-6309-230V) shaded pole motor replacement, troubleshooting.F7qservice manual download site