Checking, repairing and replacing magnetron in the microwave
Microwaves are actively used in every house for cooking and warming up food. However, the owners do not understand exactly how this technique is arranged. Therefore, when the device fails, there are difficulties with the repair. Magnetron for the microwave is source of microwave waves, which, in fact, ensure the heating of food products. The breakdown of this component is one of the most common types of malfunctions. Now we will consider in detail what the microwave magnetron consists of, how it works and ways to restore this part.
The word “magnetis” is literally translated from Greek as “magnet”. The device of the magnetron of the microwave is as follows:
- A copper part in the form of a cylinder is an anode resonator;
- the element inside which is the thread of the intensity. the cathode;
- The ring.shaped components located on the ends of the magnetron for the microwave oven are magnets.
The key principle of the magnetron operation in the microwave is the inhibition of electronic flows that intersect at an angle of 90 degrees. This process occurs in the magnetic and electric field. Ring magnets form a field. The conductor is a special casing equipped with a flange. It is with this element that the part is attached to the waveguide.
Microwave waves appear as a result of the interaction of the electronic flow formed by the emitted cathode and the magnetic field. The wire loop identifies these waves, and then transfers them out with the help of a special antenna. This emitter is located inside the cylinder made of ceramics. Now you know what magnetron is, and how this component works.
How To Test A Microwave Oven Magnetron | How To Repair A Magnetron
As mentioned earlier, an antenna acts as a wave emitter. this is a small pipe, which is commonly called with a pier. The antenna also provides air pumping out of the lamp. A cap made of metal is reliably fixed on this element. In the process of work, the magnetron in the microwave is unusually heated. The probability of overheating is excluded due to the special design.
The component considered is supplemented with a plate radiator. This element is constantly blown by the fan, which significantly reduces the temperature. Additional level of overheat protection is provided by temperature fuses. An integral component is also a high.frequency filter that prevents the penetration of radiation. This part is created using special capacitors and outputs.
Now you know how the magnetron works in the microwave. It is obvious that this is an electronic device with an unusually complex and multi.level design. To make out and not damage the part by the power of only an experienced master. Therefore, after diagnosing the failure of a component, it is more appropriate to contact the service center to exclude the likelihood of aggravation of a malfunction.
However, the presence of special equipment and superficial knowledge in radio electronics allows you to repair the microwave work on your own at home. There is only one condition. adhere to expert recommendations and act clearly in accordance with step.by.step instructions.
The causes of the malfunctions of the magnetron
Experts are customary to distinguish several basic reasons for the breakdown of the magnetron of the microwave furnace:
- The failure of the cap mounted on the vacuum tube. Replace this complete owners of microwaves on their own. Find a similar cap on any other magnetron. Places for installing this part have a standard configuration.
- The heater broke off. The component can overheat and fail. This is due to violation of the rules of operation of the equipment. For example, it is strictly forbidden to include an empty microwave. To check the microwave for performance, namely its incandescent thread, measure the resistance level between the condenser elements. The indicator will indicate about 5 to 7 Ohms about the serviceability of the component.
- The passage capacitor is damaged. Use the tester to diagnose this breakdown. If it shows the infinite value of the resistance of contacts, then immediately change the capacitor.
It is because of these reasons that the magnetron in the microwave stops working. Now we will consider in detail how this malfunction is manifested.
Possible malfunctions of the transformer and their signs
Checking the microwave transformer should be arranged with poor operation of this household appliance, or when it does not function at all. Signs of a malfunction of the transforming device are the following:
- A strongly strong hum (noise) begins to proceed from the technique after turning on;
- The dishes put on the platform do not warm up at all or are subjected to slight heating;
- During operation, there is a smell of burning insulation.
When such signs appear, it is better not to use the device until it is repair. In the latter case, it is necessary to disconnect it from the network immediately to avoid even greater breakdowns.
It must be remembered that breakdowns with electrical appliances occur when the voltage of the supply network. If this took place, then when the slightest hint of a malfunction appears, you should proceed to repair, during which production marriage may be discovered.
The above manifestations in most cases are caused by a number of reasons:
- a cliff with the wires of primary or secondary (increasing) windings, in both at the same time (rare case);
- a short circuit between the turns in one of them, or in two at once;
- a cliff or closing in the winding of the glow chain of magnetron.
The transformer magnetic circuit consists of sheets of electrical steel. The noise during the operation of the furnace can also appear as a result of their exfoliation from each other. then it is necessary to change the transformer completely. But this happens very rarely and is easily determined visually.
The vast majority of malfunctions during the work of the transformer are associated with its windings.
Safe verification work procedure
Starting an independent check, it is necessary to stock up on a multimeter (in extreme cases. a two.pole indicator with a built.in power source), screwdrivers with various tips, ohmmeter, pliers.
The general scheme of safe work looks like this:
- turn off the device from power supply;
- Undetting screws, remove the casing;
- discharge the capacitor;
- The terminals are carefully removed from the transformer;
- Check its windings: if the parameters are normal. set in place and look for other reasons;
- When they find a cliff or close, they are replaced by a device;
- The furnace is collected and checked by its performance.
If after assembly the microwave does not function, then you should look for more reasons or resort to a check with a connected voltage.
If after removing the transformer on its windings, traces of melting isolation are visible, a strong burning smell comes from it, then it is no longer suitable for use, and it does not make sense to check. In this case, only replacing the device will help.
Before proceeding with the examination of the transforming device, it is necessary to make sure that it comes to it. To do this, check the availability with a multimeter (after turning on the device to the network and starting the heating program) at the points of connecting the primary winding of alternating voltage with the value of 220 V. This work is carried out extremely carefully in order to avoid electric shock.
Since to check the transformer, you need to disassemble the microwave oven, you can only do this after disconnecting it from the supply network.
The presence of a high.voltage capacitor capable of maintaining an electric charge leads to the need for discharge before conducting verification work. This is done by a simple closure of its contacts with each other (screwdriver, pliers) or on the case when the voltage is turned off.
Signs of a serviceable and faulty capacitor
Initially, signs of problems may be various interruptions in the tension during the work of the microwave, as well as a short circuit.
When checking by a multimeter on the basis of indications on the display during the contact of the probes, you can determine how well the capacitor works and whether there are problems in it.
- If during the check on the display the number one is displayed and the indicators do not change, it means that a cliff occurred in it and it can be safely thrown away. Such details are considered faulty.
- If a constant slight resistance is displayed on the display, then there is a leak, a steamed capacitor also needs to be replaced.
- If the device shows zero resistance and the data will not grow, then the capacitor is punctured, that is, a short circuit occurred in it.
- Finally, if, when the probes contacts, the resistance indicator is minimal, but then it increases smoothly, up to the moment until the unit is displayed on the multimeter, this means that the capacitor is serviceable. It can be safely used in work.
Thus, knowing all of the above nuances when using a multimeter, you can easily determine the part or be replaced.
Timely verification of such responsible parts of the microwave oven will help to save it for good longer.
Observing all the rules, the procedure, as well as having small knowledge in electrical engineering, to determine the problem and eliminate it will not be difficult.
Install a new part
If you have an expensive microwave model, it is still wise to replace the broken part, and not buy a new stove. Of course, it is best to contact the service center, but you can try to replace yourself.
When buying a new magnetron, pay attention to the fact that power matches, contacts and holes for fastening correspond to. Otherwise, you risk acquiring a useless detail.
It is not difficult to connect a new magnetron, since it has only two main contacts. There are detailed information about all designations in the diagram, most importantly, check the compliance of the following parts of the device:
- The antenna must correspond to the diameter of the factory.
- Follow the tight fit of the new device to the waveguide.
- The length of the faulty antenna must correspond to the new.
It is best to unscrew the old part and go to the service with it so that the specialists pick you up the right.
Signs of breakdowns
You can identify a breakdown at home according to the following signs:
- Food is poorly heated. If food does not heat up even with high power, the reason may be in the magnetron.
- Smoke appeared. Together with it, the melted parts inside the camera are indicated for breakdown.
- Extraneous sounds while warming up food. It looks like a buzz and ringing. over, a faulty microwave can make a sound even at the end of cooking. This continues for several minutes.
If any of these signs is detected, it is better to hand over the microwave for repair. If you do not diagnose in time and not eliminate the problem, other details may suffer.
How to check the magnetron for serviceability
Without a magnetron, the microwave cannot work. Therefore, if this part is broken, many buy new equipment. But first it is worth making sure that the cause of the breakdown is in the magnetron.
It is necessary to turn off the microwave from the network. Then you need to see if there are external signs of a breakdown of magnetron. In the internal compartment, you can notice melted areas, deformed parts. If they are present, the case is in a broken magnetron.
You can also use a tester or multimeter. You need to connect it to an element of electromagnetic radiation. If the intensity becomes increased, an infinity sign will be displayed on the tester.
Checking the magnetron
The service life of the magnetron can be significantly increased if you constantly maintain the cleanliness of the mica gasket that protects the waveguide from the ingress of particles of fat and/or food into it. Otherwise, food fragments on the lining are charred and become electrical wire, which leads to the appearance of sparking in the chamber. You can also protect the magnetron from breakdowns by connecting a microwave to the mains through a stabilizer, which will eliminate fluctuations in the size of the network voltage, causing accelerated wear of the thread threads.
Violation of the work capacity of the magnetron may occur for the following reasons:
- The protective cap burned out and therefore sparkles during work. Replaced by any whole, since they are the same for all magnetron.
- Figure of the thread of the intensity.
- Depressurization of magnetron due to overheating.
- The breakdown of the high.voltage diode.
- The high.voltage fuse burned.
- No contact in the heat.subject.
- A high.voltage capacitor is broken.
With all the malfunctions, except depressurization, it is possible to repair with your own hands.
Determination of a malfunction
To find out why the oven does not work, you need to turn it off from the outlet and remove the lid.
- The inside is carefully examined for the melting, burning, soldered wires. The condition of the high.voltage fuse is visible to the naked eye. The fuse with a tattered thread changes to the whole and if, when testing the furnace, it blocks again, then the search continues.
- For further diagnosis, a multimeter or tester will be required. The check begins with a printed circuit board, which collects a power supply circuit for magnetron, consisting of resistors, diodes, capacitors, varistors. Details can be nicknamed in place, without falling out.
- After which the thermal subject is checked by the tester. With normal contacts, the resistance is zero.
- Checking a high.voltage capacitor by a multimeter is possible only on a breakdown. If the device shows a short circuit. the part is replaced. Since some types of capacitors have built.in discharge resistors, a working capacity will show a resistance of 1 MOM, instead of infinity.
- The tester is not suitable for checking the high.voltage diode, since it has a small range of resistance measurement. To correctly assess the state of the diode, a megammeter with a scale of up to 200 MOM is required. But he is unlikely to be found in a home workshop. Therefore, the diagnostic method is used using a two.wire home power grid with mandatory compliance with safety rules. One diode output is connected to the network wire. Between the second and other conductor of the network, a multimeter is turned on for measuring a constant voltage in the range up to 250 V. If the diode is intact, the device will show the presence of a straightened voltage. With a breakdown or cliff, the arrow will remain at zero. Any high.voltage diode with a working voltage of 5 kV and current 0.7 A is suitable for replacing.
- Magantron check starts with a filament call. For this, the resistance between its terminals is measured, which is a few Ohms at good intensity. If the tester shows infinity, this does not mean that the thread has burned out. For complete confidence, it is checked, after removing the cover, the integrity of the joints of the throttle with the terminals of the magnetron.
- Some craftsmen recommend removing the throttle. This is never done in any case, since the transformer mode is violated, which is why a fire is possible.
- After measuring the resistance between the conclusions and the case, it is possible to judge the state of the passage capacitors. At infinity. everything is fine, at zero. punched, and in the presence of resistance. with current leakage. Faulty capacitors are bitten off by nippers and new ones are soldered in their place with a capacity of at least 2000 pf.
- If all the elements are intact, but magnetron radiation is not enough for a complete warming of food, then the cathode has lost the emission. This malfunction is eliminated only by replacement. When replacing the capacitors, you cannot use the usual solder, refractory brands or a compact apparatus for contact welding are required.
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Appointment and device
Heating and cooking in the microwave is carried out due to the radiation that the magnetron selects.
Reference. Magnetron is an electronic lamp that generates microwaves using a magnetic field and electrons.
The speed of cooking depends on the power that this lamp can be released. The higher its power, the higher the speed will increase. In other words, the magnetron is the main element, the serviceability of which ensures the functionality of the entire microwave oven.
How the device works
In the design of the important part of the microwave, the following components are distinguished.
- Antenna for radiation of microwaves.
- Antenna isolation cylinder.
- Magnetic circuit distributing a magnetic field.
- Stream distribution magnets.
- Radiator that protects the element from overheating.
Like any detail, magnetron due to frequent use can periodically fail. We’ll talk about the main factors of stopping work and popular verification methods below.
Signs of a malfunction
The failure of the microwave oven becomes a real problem for every housewife. After all, the microwave has long become an indispensable assistant in the process of cooking and heating dishes.
The main signs of the malfunction of the part
- Termination of heating. The microwave oven works, but does not warm or heating is carried out periodically.
- The appearance of smoke and the occurrence of sparking inside the housing of the household appliance.
- The occurrence of melted areas on the internal walls of the microwave.
- The appearance of extraneous noise (buzz or buzz) when the mode is on.
The manifestation of any of these factors indicates the occurrence of malfunctions among the details of the microwave oven. Proper diagnosis and timely repair will help to quickly solve the problem.
Cooling and protection of magnetron
During operation, the magnetron emits a large amount of heat, so the radiator is installed on its case. Since overheating is the main reason for the failure of the magnetron, other methods are used to protect it:
- Thermorelele. This device is used to protect the magnetron, as well as the grill, if it is in the model. The heat.guide is equipped with a bimetallic plate, which can be configured at a certain temperature. When this value exceeds this value, it bends and opens the power chain.
- Fan. It not only blews the magnetron radiator with cool air, but also performs a number of other useful functions, such as cooling the electronic components of the device, air circulation inside the chamber during the grill operation, as well as the removal of hot steam through special holes.
- Blocking system. Several microwavens control the position of the microwave door, not allowing the magnetron to turn on when it is open.
The principle of operation of the microwave oven
To deal with this, you need some introductory data. Most foods in their composition contain the following substances: salts, fats, sugar, water. So that the microwaves “work”, that is, heated food, there must be dipole molecules in the products. On the one hand, they have a positive electric charge, on the other. negative. There are enough of these molecules in the food. these are fats and sugar, but the main dipole is a water molecule.
Vegetables, meat, fruits and fish contain a large number of dipole molecules, the number of which reaches millions. If there is no electric field, the molecules are located in chaotic order. In the microwave, microwaves have a frequency of 2450 MHz.
In the presence of an electromagnetic field, they begin to “line up”: “plus” is directed in one direction, “minus” to the other. When the field changes polarity, the molecules “unfold” 180 degrees.
In the microwave, microwaves have a frequency of 2450 MHz. 1 Hertz = 1 oscillation per second. Megaers. a million fluctuations. Polarity changes twice in one period of the wave.
When microwave radiation acts on the products, molecules in them begin to rotate more often, literally erased about each other. In this case, heat is released, which serves as source of heating of products.
Heating by microwaves can be compared with how the palms are heated if they rub them one about another. “Waves” act only on the surface layer of food, penetrating no deeper than 1. 3 cm. But, the heat “goes” further. the thermal conductivity is turned on. Hence the advice: if you need to warm up a large piece of meat, it is better to put the microwave oven for average power. So it will warm up better, even though it will take more time. Heat from the outer layers will begin to penetrate inside.
Similarly, things are with soups: it is better to periodically remove them from the furnace and mix, helping heat to break inward.
In the current models of the furnaces, there may be a “double radiation” function. this indicates a bifurcated source of radiation. Due to this separation, the products warm up more uniformly, and the microwave of the patch has increased efficiency.
What equipment will be needed
To check the magnetron in the microwave, you will need special equipment. multimeter or tester.
A multimeter is a combined electrical measuring device that determines the characteristics of the electrical signal:
In addition, in some multimeters there are functions of measuring the power of alternating current, calling (determining the electrical resistance with sound or light alarm), testing diodes and transistors, etc.
Reference. Functionally multimeter combines the capabilities of several measuring devices: ammeter, ohmmeter, voltmeter.
Checking the Magnetron of the microwave oven by a tester for a hidden breakdown is carried out in several stages:
- The microwave is disconnected from the network.
- Remove the side and top panels of the case, thereby providing access to the block.
- Check the thread of the intensity. To do this, connect the tester probes to the magnetron terminals to measure the resistance between them. If the multimeter displays a value of several ohms, then the thread is in good. If the tester shows infinity, the thread burned out.
- Check the printed circuit board. the power supply circuit, including resistors, diodes, capacitors, varistors. All details are tested by multimeter on the spot, without falling out from the board.
- Determine the condition of the heat.subject. If it is working, the tester will show the resistance equal to 0.
- Check the high.voltage capacitor for breakdown. If it is in working condition, the multimeter will show infinity, if it is faulty. a value close to 0.
It is advisable to test the high.voltage diode. The internal resistance level is high, so the tester with a small range of resistance measurement for this is not suitable. To properly assess the condition of the part, a mega.reprimrum is required. an electro.measuring device (ohmmeter) with a scale of more than 100 MOM. However, such a device is not always found at hand.
There is another method of diagnosis using a two.wire household electrical network. For this:
- One diode output is connected to the network wire.
- Between the second and other conductor of the network include a multimeter for measuring a constant voltage.
- If the diode is a whole, the measuring device will show the straightened voltage. If the diode is damaged, the indicator will remain zero.
Almost any malfunction can be eliminated by replacing the failed part. Only upon depressurization, the block cannot be repaired. it is replaced with a new.
Attention! During your work, observe safety precautions.
What is the magnetron in the microwave
The device of the magnetron of the microwave oven is very complicated. Basic structural elements:
- metal cap on the antenna of the magnetron;
- flange with fasteners;
- Ring constant magnets (2 pcs.) that are required for the distribution of the magnetic field;
- radiator providing the cooling of the magnetron;
- the body of the magnetron in the form of a cylinder;
- the outer body of the block;
- filter formed from transitional capacitors and throttle (protects against penetration of radiation from magnetron);
- Contacts and insulator.
The body of the magnetron is an isolation ceramic cylinder, inside of which there are:
- Anode. copper cylinder consisting of several compartments. It contains resonators with a wire loop. The latter is connected to the cathode and is displayed to the antenna.
- Cathode. a cylinder with a thread of intensity responsible for creating an electron flow.
The principle of operation of the magnetron is the formation of microwave radiation as a result of the interaction of the electric field created by the cathode when the high voltage is supplied to it, and the magnetic field created by ring magnets. The wire loop picks up the radiation and sends it along the waveguide to the camera to the antenna. This is how the food is heated.