The microwave oven is one of the most commonly used electrical appliances in the kitchen. Once again, you put food on heating - the microwave hums as usual, the lighting works inside, the plate of food is spinning, but after the time set on the timer the food remains cold. What to do in this case? The failure of a microwave oven causes a number of inconveniences, so many people prefer to try to repair the microwave oven on their own, saving not only time, but also money.
Why does the microwave not heat food? Let's consider the possible causes of malfunction of mechanically controlled microwave ovens.
If the microwave oven works, but does not heat food, then first of all, you need to make sure that the voltage in the network is not too low. It is often mistakenly concluded that the microwave is malfunctioning, but in fact, the reason lies in the excessively low voltage. Even if the voltage in the electrical network is reduced by 20 V, the microwave oven noticeably loses its power and instead of the usual two minutes it will take 5 or more minutes to heat up food.
If the voltage in the network does not deviate from the permissible limits, then it is necessary to look for a fault in the household itself. electrical appliance.
Safety precautions when troubleshooting
A common mistake is that people start looking for a problem without even knowing the danger of electric shock, mistakenly believing that if the microwave oven is disconnected from the mains, the danger of electric shock will be excluded.
Remember that the microwave oven is one of the most dangerous household electrical appliances. Even after disconnecting it from the mains, there is a danger of electric shock of several thousand volts, which remains in the high-voltage capacitor for a long time. If you do not have the appropriate knowledge and skills to repair electrical appliances, it is better to contact the service of a qualified specialist.
If you nevertheless decide to carry out the repair yourself, then when performing troubleshooting work, you should follow all safety measures.
Before start removing the lid of the microwave oven, you should make sure that the electrical appliance is disconnected from the electrical network.
A dangerous discharge remains in high-voltage circuits, so you should not rush to check high-voltage elements - as practice shows, most microwave oven faults are in the primary circuits 220 V.
Only if a fault in the primary circuits could not be found, then it is necessary to proceed to checking the step-up transformer of the microwave and high-voltage elements.
Checking the electrical circuits before the step-up transformer of the microwave oven
The first step in troubleshooting the microwave oven is checking the electrical circuits and various devices through which voltage is applied to the primary winding of the step-up transformer.
It should be noted that structurally microwave ovens from different manufacturers have some differences, but in general, the described troubleshooting principle allows you to determine a faulty element in a microwave oven, regardless of its type.
To find a malfunction, you must remove the microwave housing cover by unscrewing the screws (or screws) on the back of the microwave and on two sides.
You can check the continuity of the circuits by dialing them with a tester or a multimeter in continuous mode.
If, when the microwave was turned on, the lighting was on, the plate of food was spinning, and the usual noise was heard when the microwave was operating, then the voltage was supplied to the microwave - the power cord is integral, the fuses are not blown, the lighting lamp, the plate rotation motor and the cooling fan are powered.
In this case, the first step is to make sure that the mains voltage is applied to the step-up transformer. To do this, remove the terminals from the primary winding of the transformer and start checking the circuits.
Before dialing, turn on the microwave heating mode (the grill mode switches the power to the heating elements, while the transformer is de-energized), the microwave oven timer and close the microwave door to close door interlock limit switches.
In the absence of an open circuit and faults in other elements of continuity, the continuity of the circuit between the phase terminal at the input from the power cord and one of the removed terminals of the step-down transformer, as well as the continuity between the zero input from the power cord to the second terminal supplying the transformer.
If the device shows an open circuit, then you need to find out where it is. To do this, it is necessary to ring all the elements and circuits that go to the terminals of the primary winding of the transformer.
On the case or in the operating instructions for the microwave oven, a circuit diagram of this electrical device can be given. The presence of the circuit simplifies the troubleshooting process. In the absence of a circuit, it is necessary to carry out a continuity, visually tracing the path of current flow to each element, starting from the very beginning - from the mains filter board, where the phase and neutral conductors of the microwave oven power cord are connected. If you need help with emergency microwave repair, call us right now!