How to repair a microwave
yourself Repairing a microwave oven with your own hands can be done if you have basic knowledge of its structure and principle of operation. In the article we will analyze the device of the simplest model of the microwave oven, in which there is a grill and a rotary table.
Let's start the conversation about the microwave device with its visible at first glance details. When you do your own hands to repair the microwave and remove the top cover, be sure to turn off the power beforehand. You will immediately see a transformer with a fuse on it and a high-voltage fuse in the ceramic case next to it. Near the transformer there will be a doubler unit consisting of a diode and a thick capacitor. All this together makes up the power supply circuit of the microwave magnetron.
It is very dangerous to touch the capacitor with your own hands immediately after opening the lid, as it holds a charge for a long time and can hit you with an electric shock.
- 1 The principle of operation of the microwave microwave power supply circuit
- 2 Protection equipment
- 3 Basic malfunctions and repairFirst visually check the integrity of the fuse. If it is blackened or a disconnected hair is visible in the glass case, then a replacement is required. The primary winding of the transformer is located below and visually it can be viewed and measured the incoming voltage at its terminals.
A few more turns of wire can be seen near the primary winding, this is the secondary winding of the cathode heating. It gives a voltage of ~ 6.3v, necessary for the normal operation of the cathode. Above is the secondary winding of the transformer, which produces about 2kv of voltage applied to the doubler. The high voltage winding of the transformer is well insulated with several layers of insulation.
Doubler is a capacitor with a parallel diode. It doubles the incoming voltage of 2kv to 4kv, which is fed to the cathode of the microwave microwave magnetron. The cathode is preheated with an alternating voltage of ~ 6.3v, coming from the secondary winding of the cathode. The anode of the magnetron is connected to earth.
Magnetron is controlled by a relay and a timer using the set parameters on the front panel of the microwave. The parameters of the microwave oven microwave are set by the programmer. The programmer is equipped with a gear or gear, responsible for adjusting the clock. The longer the intervals of operation of the magnetron, the more power is allocated to cooking. Accordingly, the longer the rest intervals, the less power the magnetron produces.
In the new models of microwave ovens, inverter power control of the microwave generator is used. In this case, the cyclical nature of work and rest of the magnetron is managed by a temperature measurement sensor. By its signal, the pulse repetition rate increases or decreases. For high temperature, the pulses go very often, more power is expended and more energy is released for cooking. For a lower temperature, their cyclicity decreases, which allows flexible control over the entire process.
Protective microwave oven relays are responsible for the simultaneous shutdown of all systems when the door is opened while the magnetron is operating. Two protective relays at the same time break the voltage supply in phase and zero. In addition, one of them necessarily controls the correct operation of the second protection element. There is also a third protection relay opening the power contacts when the microwave oven door is open and the warm-up process start button is not turned on.
High-voltage fuse blows, providing protection for the microwave generator from emergency situations:
- hitting metal objects on the pallet.
The secondary mechanisms of the microwave oven:
- fan motor;
- engine pallet;
- backlight lamp;
- lamp grill.
Since all the secondary elements are connected in series, if one of them fails, nothing works except the magnetron and the starting relay.
This makes it easy to repair your own microwave oven.
Major malfunctions and repairs
The list of faults of microwave ovens is not exhaustive, it only reflects the most common breakdowns. You can repair all the listed faults with your own hands.
Problem Possible causes solution not turned to mills Power supply fuse triggered, only replacement After replacing the fuse, the operability of the transformer and transformer safety diode of the transformer turned off.the oven is periodically turned off and on at intervals of several minutes Cooling fan malfunction, relDo not turn on the fan, close the air vents Minor repairs or replacements Sparks are visible and smell like when broken Mica pads are broken due to contamination of Replacing Microwave does not heat low voltage or loss of magnetron emissionApplying an voltage stabilizer Do-it-yourself repair by increasing the number of turns or replacing an magnetron LCD display does not display all segments, highlights and spots The screen or processor is damaged. If the microwave also does not work, then exactly the processor Replacing the Touchpad stopped working conductive paths are damaged Do-it-yourself repair by wiring or replacing The pallet rotates with jerks Roller grooves are not tied, problems and drivers have to work;replacement of the engine The light is on, the pan rotates, the microwave does not heat A strong voltage drop in the network, breakdown in the power supply circuit of the transformer, magnetro is broken Installing a voltage regulator, repairing a transformer supply circuit with a tester, troubleshooting, replacing an microwave generator The buttons on the control panel do not turn on Do it yourself repair by checking a tester, pinning the contacts, or replacing the buttonsbuilding fan, doubler diode or transformer Replacing Microwave works without shutting down Faulty voltage supply relay( contact sticking) Disconnectpower, replace. There may also be a problem in the processor or relay control circuit. Independent repair by checking with an ohmmeter, if the circuits are in order, replacing the processor module
You can repair the microwave oven with your own hands, but you can properly use it and thereby significantly increase the term of impeccable service.Interesting: