There are more and more appliances in our homes, which makes life more comfortable. But any equipment breaks at some point, including microwave ovens. If the microwave warranty has already expired, you can either call a repairman or try to repair it yourself. Some breakdowns are easy enough to eliminate with your own hands, without spending money on specialists. Do-it-yourself repair of a microwave oven basically boils down to identifying the affected unit and replacing it with a serviceable one. Sometimes it is necessary to replace parts.
Do-it-yourself repair of a microwave oven will be easier if you have at least a little idea of its structure and the functions of the elements. Knowing the work algorithm and which part is responsible for what, it is easier to determine the causes of the breakdown.
Magnetron power supply
To begin with, let’s consider the algorithm of operation of a microwave oven. The main working element is a magnetron. It is he who produces the waves from which the food is heated. But it needs to be supplied with high voltage, so power (220 V) is first supplied to a high-voltage transformer, the output of which is already 2000 W. After the transformer, there is a diode and a capacitor, which double the voltage. About 4 kW is supplied to the magnetron. This is where the microwave generation begins. In order to ensure that the magnetron does not burn out during power supply problems, a fuse is installed in the power supply circuit. If it burns out, the microwave oven will not start.
The waves emitted by the magnetron enter the working chamber, where, reflecting off the walls, they are concentrated in the area where the dishes with food are placed. Since the magnetron heats up a lot during operation, it is blown by a fan. Warm air also enters the chamber, which accelerates heating.
To avoid overheating of the magnetron, which in this case may fail, there is a thermal fuse in its power supply circuit. In the event of a violation of the operating mode (the fan does not work or does not cope with cooling), this fuse blows. Then a situation arises when the microwave oven works but does not heat. In this case, the plate rotates, the light is on, but the food is not heated.
Waves emitted by a magnetron can “heat up” everything that happens to be in their path. Therefore, the microwave oven should not work with the door open. All waves must remain inside the chamber. That is why blocking buttons are installed in the power supply circuit of the transformer. They close only when the door is closed, the door latches close the contacts, the power is supplied to the transformer.
Sometimes the microwave does not turn on precisely because the door lock does not work. It can be a foreign object that got into the holes for the door handles, burnt or loose contacts. In this case, repairing a microwave oven with your own hands consists in replacing the contact group. You can handle this yourself.
To ensure that food in the microwave oven is heated evenly, a movable glass table is installed in it. In the lower part of the camera there is a guide roller, on which the glass tabletop-plate is installed. On the bottom of the table top there are protrusions of a certain shape that cling to the protrusions of the guide roller. Since the plate-tabletop has large dimensions, so that it does not tilt, a plastic ring with small wheels is installed under it. It facilitates the movement of the table.
The roller is moved by a motor that receives power when the door is closed. Sometimes the microwave oven works, but heats the food unevenly because the table has stopped rotating. It can be seen through the closed door. The reason is failure of the motor or breakage of the ring with rollers. In this case, repair of the microwave oven with your own hands is to replace the motor or the guide ring.
Rear view with the cover removed
Knowing how a microwave oven works for self-repair is not enough. You still need to have an idea of what the details look like and where they are located. You will have to start repairing the microwave oven with your own hands by removing the casing. All elements are below it.
There are many models of microwave ovens, but the layout is usually the same. The magnetron and power circuit is on the right side (when viewed from behind). There is also a fan here. On the left is the control unit, there are also locks and door devices. Actually, that’s all.
Independent repair of a microwave oven
Now that you have an idea about the device of the microwave oven, the algorithm of its operation, you can start troubleshooting. Several rules must be followed when working:
- Work should be carried out only after the cord has been removed from the outlet. After that, you need to discharge the high-voltage capacitor. Capacitor discharge is a mandatory procedure after each connection to the network. Even if the microwave is not working.
- Do not turn on the magnetron with the door open, especially if it is removed from its place.
- During repairs, replace parts with similar ones. Even small deviations can lead to serious changes in work.
- After repair, carefully remove all excess from the camera, waveguide, elements.
- When turning on the microwave oven, be sure to put something inside for checking. Even a glass of water or an empty plate. Starting the microwave oven without a load leads to its failure.
The rules are simple, but they must be followed. Otherwise, either the equipment will be damaged or your health will be seriously damaged.
And one more tip. During the disassembly process, photograph the area BEFORE starting work. Then it is easier to restore.
Does not turn on at all
It is very annoying if the microwave does not turn on. But usually this problem is easily solved. There are not so many complex breakdowns. So, here’s what could be causing it:
- Power supply problems. The magnetron is demanding on power supply. If the voltage is too low, it may not turn on. The solution is to install a voltage stabilizer.
- Problems with the cord. It is necessary to call it for integrity, check the connection, tighten the contacts if necessary.
- Check the presence of voltage in the outlet.
- The fuse in the power circuit has blown. It is easy to find. It is usually located next to the transformer.
The fuse is blown
The fuse is a glass tube with metal caps. An elastic wire is stretched between the caps, one end of which is soldered to the cap. When there are problems with the power supply, the wiring heats up, the solder softens. If the power does not return to normal for too long, the wiring is unsoldered.
The fuse is a fragile thing that is easily damaged, and is hidden in a plastic case. It can have a different shape and appearance, but inside is a glass tube with a wire inside.
The problem is usually visible visually – the wire dangles. But there are cases that the contact is broken, but this is not visible visually. Therefore, it is better to take a multimeter and ring the fuse or check it on the cliff by measuring the resistance.
If the microwave does not turn on because of a blown fuse, it must be replaced or repaired. With the replacement, everything is simple – it is removed from its place, then a similar one is inserted. Another thing is that the same one is hard to find. And it must be of the same denomination (exactly) and size. Therefore, you will have to take the burnt one with you to the store. And it is better to buy several pieces at once. Because fuses usually blow for some reason. And until you find it and eliminate it, they can often burn.
The fuse can also be reset. To do this, carefully remove the metal cap from the side where the wire was unsoldered. Using tweezers and a soldering iron, solder it in place, put the cap back. A similar repair of a microwave oven with your own hands is possible if you know how to handle a soldering iron. If not, it’s easier to buy a fuse.
The light is on, the table turns, but the food does not heat up
What to do if the microwave oven is working, the lamp is on, the table is moving, but the food is not heated? The reason may be in the power circuit of the magnetron, or the emitter itself may have failed. But the same picture will be if the mica plate that closes the output of the magnetron is damaged, or there are enamel chips in the chamber. If the metal is exposed, it can cause the microwave oven to fail. Therefore, we inspect the camera, paint over all chips with white enamel, remove stains. If all this did not help, and there is damage on the plate, then we start the repair from it.
Problems with the mica plate
The mica plate has a gray-brown color and looks very similar to metal. It closes the output of the magnetron and is in the chamber on the right. We take a flashlight and carefully examine it. It should not have damage or heavy pollution.
If there is no damage, clean it thoroughly using dishwashing detergent (non-abrasive). After drying, you can try to turn on the microwave oven.
If there is damage, we unscrew it. It is fixed on screws or plastic latches. If the hole is through, it is advisable to replace the plate. If there are only traces of soot and the damage is not so serious, by removing the plate, we remove soot, soot, and greasy stains. If possible, we restore it to its original state. We put it in place, we try to start it.
If there is a hole in the mica plate, and there is nowhere to get a new piece, it can be turned over for emergency repairs. We turn it upside down so that the hole is in a different place. Do-it-yourself repair of a microwave oven like this is only a temporary measure. But for some time, working capacity is restored.
Problems with the magnetron
If everything is fine with the mica plate and the camera, but the microwave still does not work, the problem is most likely in the magnetron. But first you need to check the power supply circuit. It consists of a high-voltage transformer, a capacitor, a high-voltage and a safety diode.
First of all, we check the protective diode. He is the first to “take off”. It is located in a plastic case near the magnetron. If there are traces of soot, then it has burned out. It should be replaced with the same one.
The next step is the ringing of the transformer windings. First, turn off the power, discharge the capacitor, remove the terminals of the primary winding from the contact plates. Now you can measure the resistance of the transformer windings. The values should be:
- primary winding – 1.5 Ohm;
- secondary – 110-120 Ohm;
- the secondary winding of the filament is 0.1 Ohm or less.
If there is a deviation, then we change the transformer. We select the same parameters.
If everything is fine with the transformer, put it in place, connect the terminals. Next, check the network filter. To do this, remove the terminals with which the magnetron is connected to the transformer. One by one, we measure the resistance between the removed terminals and the body. If the resistance of at least one of them is less than 50 ohms, it means that the capacitors on the network filter are broken. In this case, you can repair the microwave oven with your own hands by completely replacing the entire circuit board or replacing broken capacitors. Once again, we pay attention that the denominations must be the same.
If the microwave still does not turn on, check the magnetron itself. It must be removed from its place, inspected. If the antenna cap is burnt out, it must be replaced. But the cost of a magnetron can be compared to the cost of a new microwave oven. So if the equipment is old, it is easier and smarter to buy a new one.
We check the door lock
If after all manipulations the microwave oven still does not work, you need to check the door locks. First, check how tightly they fit. We take a sheet of paper and clamp it between the case and the door so that the edge sticks out. We try to pull out a sheet of paper behind this edge with the door closed. With normally working blockers, this is impossible or very difficult.
If the sheet is pulled out, adjust the pressure of the door. There are adjustment screws in the area of the hinges. By twisting them, we achieve a tight and uniform pressure.
Next, you need to check the electrical part of the blockers. When viewed from behind, they are on the left. We take a multimeter and check their resistance in the open and closed state. If even one of them is faulty, it is better to replace everything. They have almost the same degree of wear and tear. If you replace only the one that failed, another one will fly out after a short period of time. You will have to disassemble the microwave again and go through everything step by step.
The microwave oven sparks: what are the reasons and what to do
If sparks often fly in the microwave chamber during operation, the mica screen is most likely damaged. Fat and food particles fall on it during operation, which gradually burn into coals. Sparks appear between these coals and the wall of the microwave due to the potential difference. They are similar to an arc discharge during welding. Occur under certain conditions and can cause significant damage. Therefore, it is desirable to solve the problem immediately.
The first way is to remove the mica screen and clean it thoroughly, removing all traces of soot and soot. The second option is to replace it with a new one. You can buy the desired piece of mica at the service center. This is pressed mica. A piece of the desired size and shape is cut out of it, a hole is made in it with the help of a screwdriver, the edges are sanded with fine-grained sandpaper.
But if you are already going to change the mica screen, it is better to put a special plastic one. Such screens are also available in service centers, and they last longer because they do not absorb grease and are easy to clean.
There are microwave ovens that already have a plastic screen. His paint burns at the exit point of the waves. This soot also causes sparks. The plastic screen is fixed on two clamps, it is easy to remove it – hook it with a screwdriver and squeeze it. To repair the microwave oven with your own hands in this case, we clean the soot with fine-grained sandpaper. It is removed together with the paint. Clean well so that no traces remain. We paint over the stain with white paint (enamel). You can use nail polish.
Replacing the magnetron cap
Sometimes the sparking of the furnace is caused by the burnout of the magnetron cap. And here we remove the magnetron from its place, inspect the cap. If there is damage, repairing a microwave oven with your own hands consists in replacing this cap.
Carefully remove the cap, inspect the antenna. If the metal is intact, the device may be working. Then we find a replacement cap of the appropriate size, install it in place. It is not easy to find a cap on sale – it costs a penny, no one contacts it. But it can be made from an old-style capacitor. It is important to find the appropriate diameter. Then a piece of the required length is cut, a hole is drilled in the center, the edges and the entire surface are treated with sandpaper with a very fine grain. Then it is polished to a mirror shine. The effectiveness of the microwave oven depends on how well the cap will reflect the waves.
Causes of breakdowns
Most often, the cause of microwave oven breakdowns is non-observance of operating rules. The first rule to remember is that metal objects should not enter the camera. Even a metal rim on a plate — painted with metal-based paint — can cause a violent spark to start in the microwave. A spark often “flashes” the magnetron, which then fails. In addition, it is when the microwave oven sparks that the protective plate is damaged, and the elements of the power circuit can fail.
The second common cause is the use of dishes not intended for microwave ovens. If you heat food in a regular closed container, it may burst. At the same time, the contents fly in all directions, clog the waveguide, and the microwave oven does not work again. Turning it on in this state will again lead to the burnout of the magnetron.
The last unacceptable mode is no load. If you turn on the microwave oven with an empty chamber, it is almost guaranteed to fail. And in this case, the magnetron will also burn.
There are not many technical reasons for the breakdown of microwave ovens. First, there are power outages. This problem can be eliminated by installing a voltage stabilizer. Secondly, it is physical wear and tear of parts. This is true for equipment that has been in operation for more than 7 years. Thirdly, the use of low-quality parts. This is the problem of cheap equipment. And fourthly, production shortage. And again, brands that have been on the market for more than one year have better quality control than unknown brands. The good news is that the manufacturing defect is usually fixed during the warranty period, and it will be easy for you to replace the equipment by contacting the service center.