The microwave does not heat

Do you have a microwave, but it does not work? If you have problems with the microwave oven, use the repair recommendations to fix the problem yourself. So, the microwave does not heat, but it works: what to do?

The microwave does not heat well, but it works: what to do?

Who still does not know that the electric current is killing? There are two basic rules to avoid lethal electric shock or prolonged treatment in the burn unit:

1. Before you begin technical intervention in the microwave, disconnect it from the source of electricity, that is, unplug the plug from the outlet.
2. When repairing high-voltage systems equipped with elements that accumulate energy, it is necessary to be extremely careful and to discharge the capacitor only with tools with well-insulated handles.

If you decide to protect yourself with surgical gloves, then they will not save you from electric shock. Dielectric gloves made of thick rubber are invented for personal protection.

We find out the causes of failure

The microwave "Samsung" does not heat, but it works - what to do? Immediately I must say that the model of your oven absolutely does not matter, since almost all microwaves are arranged the same way. As practice shows, if the microwave works, but does not heat, this is the reason:

• most likely the problem is with the high voltage circuit;
• faults in the circuit board.

Troubleshooting stages:

• To find a fault, after you have disconnected the microwave from the network, you need to remove the back panel by unscrewing the fixing screws. This will give you access to the various elements of the home appliance. In some models, this may not be the back panel, but a side panel or both.
• Do not forget that inside the oven you may encounter high voltages that accumulate in the capacitor, therefore, before starting the diagnosis, discharge it in a safe way.
• Next, visually assess the degree of possible damage: the presence of burnt elements, melted wires or insulation, and the like. If visible destruction is not detected, move on.
• Go through the high voltage circuit, start from the stove. If it does not heat up, and this process is provided by microwaves, most likely, the generator - magnetron does not work. But this does not mean that it has failed, because before it there are a number of elements in the high-voltage circuit.
• For normal operation of the magnetron, a voltage of 5000 V is needed. It is supplied to it through a transformer, the secondary winding of which relieves 2500 V and is doubled with a capacitor. At the outlet of the capacitor, a high-voltage diode is installed to rectify the AC voltage. A high-voltage fuse is installed in the circuit between the transformer and the capacitor, which is equipped with a return-closing spring.

• Disconnect the high voltage transformer primary terminals. Using a multimeter with set limits from 100 to 200 Ohms, measure the state of the primary winding. Normal values ​​are in the range of 1-3.5 ohms. To measure the secondary winding, set limits for an ohmmeter of 1-2 KΩ. The resistance between the output of the secondary winding and the grounding point of the power cable must be between 50-230 ohms.
• Make the next measurement between the output points of the secondary winding and the connection of the capacitor at the limit of 2 KΩ. If the device shows infinity, then the fuse is open and turns on when the voltage is applied after all the checks. The readings of the multimeter, if the fuse is OK, when measuring the resistance between its output and the input at the limit of 100-200 Ohms will be in the range of 0.1-2 Ohms.
• Disconnect the input terminals of the magnetron. Measure between the power terminals, setting the multimeter limit to 100-200 ohms. With a working magnetron, the readings will be between 0.1-0.3 ohms. Infinity will mean the break of the microwaves.
• The next measurement is the resistance between the terminals of the magnetron and its body. At the measurement limit of 1–20 kΩ, the device should show isolation, that is, infinity. If the value is displayed, you will need to replace the magnetron.
• The integrity of the capacitor is checked by measuring the resistance between its terminal and the housing. If the capacitor is in good condition at the maximum measurement limit, the multimeter should indicate isolation. Between the terminals of the capacitor should also be infinity.

It remains to check the high voltage diode. To do this, we use a diode tester with a DC voltage of 20 V through a universal controller. The diode must pass current only in the forward direction. If, when the tester is connected to the diode, the indicator lights in both directions, then it is in a “punched” state and can be safely disposed of. The same expects the diode, if the tester indicator does not glow when connected both in the forward and in the opposite direction, it means that it is in the "open".

If the indicator lights up only in the forward direction - this is already good. In parallel with the tester, observing the polarity, we connect the multimeter, having preliminarily set the limits for measuring the DC voltage up to 20 V.

General recommendations

We, as we could, told what to do when the microwave stopped heating. At the end of the topic are a few helpful tips:

1. If you had to change the high-voltage fuse more than twice, then you need to think about replacing the magnetron.
2. Make sure that the permeable screen of the emitter from mica is always clean. A dirty screen misses microwaves poorly and can cause a plasma arc.
3. Keep the inside of the furnace clean so that chips and rust stains do not appear on the protective polymer coating.

And more about safety: you should never turn on the device with the panel removed! Be careful!