The microwave oven cannot heat and makes abnormal sounds after starting, which may be caused by a variety of reasons. First, check the two-door interlock switch. If frequent operation leads to poor contact or electric shock damage, the 220-volt voltage may not be transmitted normally. At this time, a new interlock switch needs to be replaced. Secondly, if the light is on but the turntable does not move, it may be that the high-voltage transformer is faulty, and replacing it directly can solve the problem. Aging of the magnetron or broken filament will also cause similar symptoms. Test the filament winding by cutting off the power. If the resistance value is abnormal, the magnetron needs to be replaced. Finally, if the turntable rotates but does not heat, the high-voltage diode may be damaged. The filament winding and diode need to be measured. If both are infinite, it indicates that the diode is broken and needs to be replaced with a new one.

In short, in order to solve the problem of the microwave oven not heating up and making loud noises when starting, it is necessary to check these possible fault points one by one, find out the specific reasons and take corresponding maintenance measures. Remember to ensure safety during operation to avoid the risk of electric shock and seek help from professional technicians when necessary.