Kog 6cdbs DIY repair

Details: kog 6cdbs DIY repair from a real master for the site my.housecope.com.

Repairing a microwave oven requires special professional knowledge and skills. But with a little knowledge of the basics of electrical and radio engineering, knowing how to use an electrical installation tool, and you can try to cope with this problem, even if you are a builder, musician or doctor. To make repairs with your own hands, just remember what you were taught at school in labor lessons. In this case, it is necessary to observe the rules of electrical safety: do not make short circuits by connecting the wires, and do not stick your fingers into the outlet. If you are not sure of yourself, then it is better to contact the service center to specialists.

Before we understand the reasons for the breakdown, let's first understand the design of the microwave oven. It is very simple and consists of 4 basic elements:

Magnetron;
Waveguide;
Transformer winding;
Food warming chamber.

It is this set of elements that is the engine of the microwave. And if it is malfunctioning, you should look for the cause in them.

After connecting the microwave to the network, a voltage of 220V is supplied to the first winding of the transformer. The voltage is automatically transferred to the secondary winding. The chamber heating system starts up. Due to the fact that these two windings are isolated from each other, the safe operation of the microwave oven is ensured.
The microwave oven allows food to be heated at high speeds by using twice the voltage. In this circuit, the main role is played by a capacitor, to which a diode is connected in parallel. The duration and magnitude of the temperature regime helps to control the temperature sensor and a regular timer.
For safe use, a power protection relay is built into the oven, the function of which is to stop the microwave operation in case of high voltage drops in the network or when the door is open. If this whole description seems complicated to you, then do not worry: now we will figure it out.

Video (click to play).

Most often, the external signs of a microwave oven failure are the appearance of sparks, puffs of smoke, stopping the rotation of the plate, and the absence of heating food placed in the oven. Or the microwave just won't turn on. In this case, plugging it into the network is dangerous!
There are three main reasons for the failure of an electrical appliance:

Blown fuses;
Defective magnetron;
Burnout of the mica plate.

With this type of breakdown, you can repair the oven if you follow the instructions strictly. First, consider the functional diagram of the microwave oven.

We take a functional diagram because it is easier to understand the principle of operation of the microwave oven, it is universal, regardless of the brand of the oven, it is simpler in comparison with the schematic diagram of the microwave.

And the location of the microwave elements can be seen from this figure:

If the backlight works in the oven, the plate rotates, but the microwave does not heat the food, then, most likely, the cause of the malfunction is a malfunction of the magnetron. In the above diagram, the magnetron is designated "magnetron".
A magnetron is a device that generates microwave radiation. That is why, in the event of a failure of this part, the stove does not heat up.

The magnetron is housed in a small rectangular metal case. First, you need to clean it, and then make a visual inspection. Next, inspect the magnetron unit itself. Namely, the integrity of the wires connecting the terminals and the case. Often the reason for the inoperability of the magnetron is the failure of the bushing capacitor. See below a video on how to repair a microwave oven magnetron with your own hands:

After that, be sure to check the microwave control unit. Again, look out for burnt, smoky, and dirty areas. It is these details that will need to be replaced for the further operation of the microwave.

A sure sign of a broken mica plate is sparks that appear when it is turned on. The reason is improper operation of the oven, that is, heating food with an open lid. With this option, drops of food are sprayed onto the plate. As a result, it gets wet and burns out.

The mica plate is inexpensive and can be purchased at specialized electric stores. If you find a mica plate of other sizes, then you can make a plate of the desired size with your own hands from it.

If you cannot find a replacement for this part, you can reuse the burned-out plate. To do this, it is necessary to remove the plate and carefully clean it from dirt. Then turn it over with the damaged side inward and carefully put it in place. This repair option, of course, can hardly be called ideal, but it will do quite well until the moment when you find a replacement for the damaged part. How to replace the mica plate, watch the video:

Arrangement of elements in the microwave

It is easy to distinguish them, because outwardly the design is not very complex. The magnetron is always installed in the middle, directed towards the food warming unit. The transformer is located under it, representing a massive box with a protruding coil. The capacitor, diode and fuse are located to the right of it, and the control unit is often located near the input panel.

Read also: DIY gs b210 receiver repair

When the device is turned on, a voltage of 220 V is supplied to the transformer. Passing through the primary and secondary windings, a current of 2 kV is already flowing out of the element. Further, the negative half-wave goes to the diode, and the positive one charges the capacitor, which again leads to a twofold increase in voltage. After that, the generation of microwaves by means of a magnetron begins. The power of the magnetron is regulated by the control unit.

Therefore, in the event of a breakdown, it is worth paying attention to these elements.They carry the greatest load, so they are often the problem.

When disassembling the microwave, be sure to disconnect it from the mains.

Search for breakage in a microwave oven is based on "symptoms". This allows you to gradually eliminate possible causes and find the real one. So, if the oven does not turn on at all, then it is worth checking the following points:

The integrity of the power cord.
Door position and closing system.
Mains fuse and thermal relay status.

In the first case, the situation is elementary - there is no power supply due to damage to the power cord. A similar situation occurs when the outlet is damaged or overloaded. In this case, it is enough to replace this element, everything is in order with the microwave itself.

Next, it is worth checking the operation and position of the door. The fact is that the operation of a microwave oven when the door is open is dangerous for others. Therefore, the design provides for the possibility of operation only when it is completely closed. If a latch, a locking system or a checking element is broken on the door, the protection system will not allow the device to start.

The last points also concern the protective systems of the oven. The fuse prevents damage to the device due to power surges, and the thermal relay provides a complete shutdown of the system when the door is open. Both can fail, it is quite easy to replace them.

It is also worth checking the voltage in the network and the number of devices connected to the outlet. The microwave oven is very demanding on power supply, therefore its slight deviations can interfere with the operation of the appliance.

Procedure if there is no heating

Fuse faults

Most models suffer from common problems and have similar, typical faults. For example, if the microwave works, but does not heat, then this indicates a malfunction of the capacitor, diode or magnetron. To repair a microwave oven yourself, you will need a simple set of tools: pliers, wire cutters, a screwdriver, an adjustable wrench and a five-spanner wrench, as well as a soldering iron with the necessary equipment.

When repairing a microwave microwave yourself, you should remember about safety measures. The two most important hazards in microwave oven repairs are high voltage in oven components and microwave radiation. Do not turn it on if the door is defectively locked or the mesh on the viewing window is damaged. Do not make independent holes in the case and introduce any conductive objects into the units and elements of the furnace. Never touch internal parts and assemblies while the microwave is in operation. Be sure to use a tester or other electrical meter to measure AC and DC current.

If the above reasons are not confirmed, then you need to disassemble the device for troubleshooting. Before that, be sure to turn off the oven from the network and wait a couple of minutes.

Fuse

What should you look for when searching for breakdowns? There are several basic elements that often fail:

Circuit breakers.
Capacitor.
Diode.
Transformer.
Magnetron.

Photo of a microwave condenser

These elements are directly involved in the operation of the device and were mentioned earlier. First you need to check the health of the fuses. Their breakage can be seen immediately, because during combustion, the conductor inside is destroyed. If this did not happen, then it is worth looking further.

For further verification, you need to take a multimeter, because outwardly it is extremely difficult to find a breakdown on the remaining parts. To check the capacitor, you need to switch the device to ohmmeter mode, and then connect it to the part. If there is no resistance, then the part must be replaced.

High voltage diode

It is impossible to check the high-voltage diode with a tester. It is recommended to replace it in case of breakage of other parts, because often the blow falls on it. It can be checked in a slightly different way - by connecting it to the network on the way to the light bulb.If the light is weak or blinking, then the part is working properly. If it burns brightly or does not turn on at all, then the diode must be replaced.

Next, the transformer is checked.

Photo of a microwave transformer

It is important to observe safety precautions, because

Photo of microwave magnetron

this element is able to hold a charge for a long time. It will take several minutes to discharge a serviceable transformer, and if the discharge resistor breaks down, it will take much longer. It is worth discharging it on the case or not touching it at all if there is no experience with such a technique.

Next, the transformer windings are checked. It is necessary to remove the terminals and check the terminals of the device one by one with an ohmmeter. First, the primary winding is checked, for which the rate varies from 2 to 4.5 ohms. For the secondary winding, the limits are 140 and 350 ohms. It is also worth checking the filament winding by connecting the terminals leading to the magnetron to the multimeter. The norm here varies from 3.5 to 8 ohms.

All previous tests have failed, then the problem may lie in the magnetron.

To test the magnetron, just connect the tester to its power terminals. The tester switches to ohmmeter mode. If the resistance is 2-3 ohms, then this means a breakdown of the device. The situation is the same if the tester reads infinity. In both cases, the device must be replaced.

These items are the most common culprits in microwave oven breakdowns. However, the failure of the device is often associated with other malfunctions, such as problems with the electronic control unit, timer and other electronic parts. Here, simple checks with a multimeter will not help; the help of a qualified technician is needed. Although it is much easier to simply replace a part if you are sure that it is broken.

There are frequent cases of breakage associated with the destruction of the cap on the magnetron. The thin aluminum body simply cannot withstand stress and is destroyed by microwave waves. This problem often occurs in older devices that are more than a few years old. The obvious symptoms in this case are noise and sparks during the operation of the device.

To check, it is enough to remove the transformer, because the cap is located towards the food chamber. If the cap is destroyed, then there are 2 options:

Cap replacement.
Flip the cap.

The first option is a priority, it is enough to order a replacement or return the magnetron for repair. The second option is considered a temporary alternative that allows you to extend the life of the device indefinitely. It is enough just to rotate the cap 180 degrees around the axis, because the load falls on only one half.

Repairing a microwave oven is a feasible task for a novice electrician. If the problem lies in the breakdown of one of the constituent elements of the furnace, then the simplest and correct solution is to replace it. The bottom line is that most of the parts of this device cannot be repaired, but only completely replaced with a new one. This especially applies to fuses, diodes and capacitors - the main reasons for the failure of the device.

Parts replacement is carried out in several steps:

The microwave is disconnected from the network.
The transformer is discharged (5 minutes).
The terminals are disconnected from the defective part, it is removed.
A workable part is connected to the same place.

There are two important factors to consider when replacing a part. The first is schema compliance. It is important to remember that each part has its own characteristics, selected for the performance of the entire electrical circuit. If, after replacement, this nuance is not taken into account, then this leads to new breakdowns. This is especially true for the transformer and capacitor.

The second important factor is the connection of the part. It is necessary to connect the replacement correctly, keeping the previous arrangement of the terminals.Reconnecting the device in reverse order can damage it, as well as several other parts in the system.

This will restore your microwave in most cases. If the breakdown is related to the electronic part of the device, then you should contact the professionals. This will ensure quality repairs and prolong the operation of the device for a long time.

The most common malfunction is the failure of the waveguide cover in the microwave oven chamber. This is caused by splashes from cooking. This starts sparking between the magnetron antenna and the protective cover. Untimely removal of burnt products leads to local burnout of the lid and to complete destruction.

Local burnout of the lid mica plate can be removed with alcohol or solvent 646. It is enough to gently wipe the burnout area.

Burning out mica

If the mica plate of the lid is clearly in poor condition, is greasy or begins to paint, then it should be replaced. Removing the diffuser plate is a snap. This can be done using an ordinary sharpened knife. Usually, the mica plate is attached with a self-tapping screw or rivets. Carefully place the old plate on the new template and cut out a new one. The best way to do this is with a knife - you can break the mica with scissors. We make holes in the new plate with a sharp screwdriver and process the edges of the fields of the plate with sandpaper. We install the new plate in place of the old one.

The question often arises, how to replace mica for microwave ovens? For these purposes, any dielectric with a similar dielectric constant is suitable. For example, PTFE or Teflon.

Common breakdowns in a microwave oven are also malfunctions associated with other elements of the oven. For example, such as the keyboard of the oven control unit, the microwave oven electronic control unit and the dissector. Less often, the high-voltage capacitor and transformer, the microwave waveguide plug and the rotating pan fail. The power supply and magnetron of the microwave oven are subject to wear and tear.

Knowing how to troubleshoot microwave ovens can save you significant repair costs. However, if you do not know how to repair the microwave yourself, then it is best to contact a specialist. Specialized service centers will help you to repair a microwave microwave oven. In addition, watch the video on microwave repair, perhaps there is exactly that breakdown that will help you fix your beloved household assistant.

Is your TV, radio, mobile phone or kettle broken? And you want to create a new topic about this in this forum?

First of all, think about this: imagine that your father / son / brother has an appendicitis pain and you know from the symptoms that it is just appendicitis, but there is no experience of cutting it out, as well as the tool. And you turn on your computer, access the Internet on a medical site with the question: "Help to cut out appendicitis." Do you understand the absurdity of the whole situation? Even if they answer you, it is worth considering factors such as the patient's diabetes, allergies to anesthesia and other medical nuances. I think no one does this in real life and will risk trusting the life of their loved ones with advice from the Internet.

The same is in the repair of radio equipment, although of course these are all the material benefits of modern civilization and in case of unsuccessful repairs, you can always buy a new LCD TV, cell phone, iPAD or computer. And for the repair of such equipment, at least it is necessary to have the appropriate measuring (oscilloscope, multimeter, generator, etc.) and soldering equipment (hairdryer, SMD-hot tweezers, etc.), a schematic diagram, not to mention the necessary knowledge and repair experience.

Let's consider a situation if you are a beginner / advanced radio amateur soldering all sorts of electronic gizmos and having some of the necessary tools.You create an appropriate thread on the repair forum with a short description of “patient symptoms”, ie. for example “Samsung LE40R81B TV does not turn on”. So what? Yes, there can be a lot of reasons for not switching on - from malfunctions in the power system, problems with the processor or flashing firmware in the EEPROM memory.
More advanced users can find the blackened element on the board and attach a photo to the post. However, keep in mind that you are replacing this radio element with the same one - it is not yet a fact that your equipment will work. As a rule, something caused the combustion of this element and it could “pull” a couple of other elements along with it, not to mention the fact that it is quite difficult for a non-professional to find a burned-out m / s. Plus, in modern equipment, SMD radio elements are almost universally used, soldering which with an ESPN-40 soldering iron or a Chinese 60-Watt soldering iron you risk overheating the board, peeling tracks, etc. The subsequent restoration of which will be very, very problematic.

The purpose of this post is not any PR of repair shops, but I want to convey to you that sometimes self-repair can be more expensive than taking it to a professional workshop. Although, of course, this is your money and what is better or more risky is up to you.

Read also: DIY alpina trimmer repair

If you nevertheless decide that you are able to independently repair the radio equipment, then when creating a post, be sure to indicate the full name of the device, modification, year of manufacture, country of origin and other detailed information. If there is a diagram, then attach it to the post or give a link to the source. Write down how long the symptoms have been manifesting, whether there were surges in the supply voltage network, whether there was a repair before that, what was done, what was checked, voltage measurements, oscillograms, etc. From a photo of a motherboard, as a rule, there is little sense, from a photo of a motherboard taken on a mobile phone there is no sense at all. Telepaths live in other forums.
Before creating a post, be sure to use the search on the forum and on the Internet. Read the relevant topics in the subsections, perhaps your problem is typical and has already been discussed. Be sure to read the article Repair strategy

The format of your post should be as follows:

Topics with the title “Help fix the Sony TV” with the content “broken” and a couple of blurred photos of the unscrewed back cover, taken with the 7th iPhone, at night, with a resolution of 8000x6000 pixels are immediately deleted. The more information you post about the breakdown, the more chances you will get a competent answer. Understand that the forum is a system of gratuitous mutual assistance in solving problems and if you are dismissive of writing your post and do not follow the above tips, then the answers to it will be appropriate, if anyone wants to answer at all. Also note that no one should answer instantly or within a day, say, no need to write after 2 hours “That no one can help”, etc. In this case, the topic will be deleted immediately.
You should make every effort to find a breakdown on your own before you get stumped and decide to go to the forum. If you outline the entire process of finding a breakdown in your topic, then the chance of getting help from a highly qualified specialist will be very great.

If you decide to take your broken equipment to the nearest workshop, but do not know where, then perhaps our online cartographic service will help you: workshops on the map (on the left, press all buttons except “Workshops”). You can leave and view user reviews for workshops.

For repairmen and workshops: you can add your services to the map. Find your object on the map from the satellite and click on it with the left mouse button. In the field “Object type:” do not forget to change to “Equipment repair”. Adding is absolutely free! All objects are checked and moderated. A discussion of the service is here.

The main detail in any microwave oven is the magnetron.A magnetron is a special vacuum tube that generates microwave radiation. Microwave radiation has a very interesting effect on ordinary water, which is found in any food.

When irradiated with 2.45 GHz electromagnetic waves, water molecules begin to vibrate. Friction arises as a result of these vibrations. Yes, normal friction between molecules. Heat is generated by friction. It then heats up the food from the inside. This is how you can briefly explain the principle of the microwave oven.

Structurally, a microwave oven consists of a metal chamber in which food is cooked. The chamber is equipped with a door that prevents radiation from escaping. For uniform heating of food, a rotating table is installed inside the chamber, which is driven by a motor-reducer (motor), which is abbreviated as T.T.Motor (Turntable motor).

Microwave radiation is generated by a magnetron and fed into the chamber through a rectangular waveguide. A fan is used to cool the magnetron during operation. F.M (Fan motor), which drives cold air through the magnetron. Then the heated air from the magnetron is directed to the chamber through the air duct and is also used to heat food. Part of the heated air and water vapor is discharged outside through special non-radiating openings.

In some models of microwave ovens, a dissector is used to form an even heating of food, which is installed at the top of the microwave chamber. Outwardly, the dissector resembles a fan, but it is designed to create a certain type of microwave wave in the chamber so that uniform heating of food is carried out.

Let's take a look at a simplified electrical diagram of an ordinary microwave (click to enlarge).

As you can see, the circuit consists of a control part and an executive part. The control part, as a rule, consists of a microcontroller, a display, a push-button or touch panel, electromagnetic relays, and a buzzer. These are the “brains” of the microwave. On the diagram, all this is shown as a separate board with the inscription Power and Control Curcuit Board... A small step-down transformer is used to power the control part of the microwave. It is labeled L.V.Transformer in the schematic (only primary shown).

The microcontroller controls electromagnetic relays through buffer elements (transistors): RELAY1, RELAY2, RELAY3... They turn on / off the executive elements of the microwave oven in accordance with the specified operation algorithm.

Actuators and circuits are a magnetron (Magnetron), a stage gear motor T.T.Motor (Turntable motor), a cooling fan F.M (Fan Motor), Grill heating element (Grill heater), backlight O.L (Oven lamp).

We especially note the executive circuit, which is a microwave radiation generator.

This circuit begins with a high-voltage transformer (H.V.Transformer). He is the healthiest in the microwave. Actually, this is not surprising, because through it you need to pump the power of 1500 - 2000 W (1.5 - 2 kW) required for the magnetron. The output (useful) power of the magnetron is 500 - 850 W.

An alternating voltage of 220V is supplied to the primary winding of the transformer. An alternating heating voltage of 3.15V is removed from one of the secondary windings. It is fed to the filament winding of the magnetron. Filament winding is necessary for the generation (emission) of electrons. It is worth noting that the current consumed by this winding can be up to 10A.

Another secondary winding of the high-voltage transformer, as well as the voltage doubling circuit on the high-voltage capacitor (H.V. Capacitor) and diode (H.V. Diode) creates a constant voltage in 4kV for feeding the anode of the magnetron. The anode current is small and is somewhere around 300 mA (0.3A).

As a result, the electrons emitted by the filament winding begin to move in a vacuum.

The special trajectory of the movement of electrons inside the magnetron creates microwave radiation, which we need to heat food. Microwave radiation is removed from the magnetron using an antenna and enters the chamber through a section of a rectangular waveguide.

Here is such a simple, but very sophisticated circuit is a kind of microwave heater. Do not forget that the microwave oven chamber itself is an element of this microwave heater, since it is, in fact, a resonator in which electromagnetic radiation occurs.

In addition to these elements, there are many protective elements in the microwave oven circuit (see KSD thermal switches and analogs.). For example, a thermal switch monitors the temperature of the magnetron. Its nominal temperature during operation is somewhere between 80 0 - 100 0 C. This thermal switch is attached to the magnetron. By default, it is not shown in the simplified diagram.

Other protective thermal switches are labeled on the diagram as OVEN THERMAL CUT-OUT (installed on the duct), GRILL THERMAL CUT-OUT (controls the grill temperature).

In the event of an abnormal situation and overheating of the magnetron, the thermal switch opens the circuit, and the magnetron stops working. In this case, the thermal switch is selected with a small margin - for a shutdown temperature of 120 - 145 0 С.

Very important elements of the microwave oven are three switches, which are built into the right end of the microwave oven chamber. When the front door is closed, the two switches close their contacts (PRIMARY SWITCH - main switch, SECONDARY SWITCH- secondary switch). Third - MONITOR SWITCH (control switch) - opens its contacts when the door is closed.

Failure of at least one of these switches will cause the microwave to malfunction and trip the fuse (Fuse).

To reduce the interference that enters the power grid when the microwave oven is operating, there is a power filter - NOISE FILTER.

In addition to the basic structural elements, the microwave oven can be equipped with a grill and convector. The grill can be made in the form of a heating element (heating element) or infrared quartz lamps. These microwave elements are very reliable and rarely fail.

Grill heating elements: metal-ceramic (left) and infrared (right).

The infrared heater consists of 2 infrared quartz lamps connected in series at 115V (500 - 600W).

Unlike microwave heating, which comes from the inside, the grill creates heat radiation that heats the food from the outside to the inside. The grill reheats food more slowly, but without it, it is impossible to cook roasted chicken.

A convector is nothing more than a fan inside the chamber, which works in tandem with a heater (heating element). The rotation of the fan circulates hot air in the chamber, which contributes to uniform heating of food.

Elements in the magnetron power circuit have interesting properties that must be taken into account when repairing a microwave.

So, by default, the high-voltage capacitor (H.V. Capacitor) has a built-in resistor.

It serves to discharge the capacitor. The fact is that the capacitor is under high voltage (2 kV), and therefore, after turning off the microwave oven, its discharge is required. This is a precautionary measure... It also happens that the resistor inside the capacitor burns out and the capacitor does not discharge. Therefore, before repairing the microwave, it is recommended to forcibly discharge the capacitor onto the case.

Appearance of high voltage capacitor 1.0µF * 2100V AC.

High voltage diode (H.V. Diode) is a combined element and consists of a whole string of diodes connected in series. This allows the composite diode to operate at high voltage. But this is the catch. The fact is that it will not be possible to test such a diode with a standard test method. The multimeter simply cannot “open” such a diode due to the fact that the threshold (forward) triggering voltage (V_F) diodes are added. As a result, the high voltage diode will have high resistance in forward and reverse connection.

So, for example, for the HVR-1X3 diode, the maximum forward voltage (V_F) is 11V. Considering that usually the voltage drop at the junction in direct connection (V_F) for silicon diodes is 1 - 1.1V, it turns out that 10 diodes connected in series are approximately mounted in the HVR-1X3 diode.

The maximum constant reverse voltage of such a diode is 12kV!

In some microwave ovens, parallel to the high-voltage capacitor is installed fuse diode (protective diode). Basically, a fuse diode is a bi-directional high voltage suppressor. It serves to protect the capacitor from an overestimated operating voltage, which is fraught with the failure of the latter. But in practice, it often happens that he himself fails. In such a case, the repairmen simply remove it from the chain like an unnecessary appendix. In fact, it turned out that microwaves work fine without such a diode.

For those who wish to understand in more detail the structure of microwave ovens, an archive with service instructions for microwave ovens has been prepared (Daewoo, SANYO, Samsung, LG). The instructions contain schematic diagrams, disassembly diagrams, recommendations for checking elements, a list of components.

We also recommend that you read the book "Microwave Oven Repair".

To repair a microwave oven, you need to have a general idea of how it works. Microwave oven repair begins with removing the top cover. Before that, you should take care of completely disconnecting the device from the power supply, only then proceed with the elimination of breakdowns with your own hands.

When these steps are successfully completed, a transformer with two fuses will open for access: one is located directly on the part itself, it is fusible, the second is located nearby on the very body of the microwave oven, made of ceramics. Also next to the transformer is a doubler block consisting of a thick capacitor and a diode. The whole set of these elements is the power supply circuit of the microwave oven magnetron.

Carefully! Do not touch the condenser immediately after removing the top cover. This element is capable of holding voltage for a long time, which can easily lead to an electric shock. When repairing a microwave oven with your own hands, this factor should be taken into account.

The peculiarity of microwave ovens is that all parts are connected in series. First, you should pay attention to the above magnetron and its power supply circuit. After removing the protective housing, a transformer with a large capacitor located next to it becomes accessible. There will also be a ceramic, low-melting fuse, a diode. The magnetron operates according to this high voltage circuit. Under no circumstances should you get into it with your hands, tools. After a complete de-energization, the capacitor will lose its residual voltage, the likelihood of an electric shock will decrease.

The primary winding of the micro-transformer takes over 220V. As a rule, its location is at the bottom. You can recognize it by the coils of copper wire, which will be bare in appearance. However, it is not. It is covered with a transparent insulating film. The location of this coil is under the secondary winding.
The microwave oven has two secondary windings. On one of them, several turns of a simple wire are usually not neatly wound. This heats up the cathode. Here the AC voltage is only 6.2V so that the electrons can be lifted from the surface. But where there is good insulation, there is a high voltage winding. About two kV directed towards the exit.
A capacitor shunted by a diode is located at the output of the circuit. The action of the negative half-wave falls on the cathode, the action of the positive half-wave charges the capacitance. Further, the electrode is subjected to double voltage, which is removed from the capacitor and the micro-transformer. As a result, approximately 3.5-4 kV is created. This power is enough to start the generation process.

You should be extremely careful, the output winding is always parallel to the magnetron, which has two output options. But the grounding of the anode is done in a separate way.

Thus, this is what happens:

the heating coil has 6.3V;
at the cathode stays up to 4.2 kV, grounded by the anode.

All microwave ovens have an electrical connection for the cathode, heating coil. Each microwave oven is equipped with a timer that controls the magnetron power. The use of a start relay is used in order to avoid the occurrence of a spark. Next, you should pay attention to the front panel.

The most likely breakages occur in the area of the mica plate. Energy is supplied from the magnetron to the waveguide along the rod. The latter is highly sensitive to the presence of various food debris. All these contaminants begin to ignite, emit sparks, thereby disrupting the stable operation of microwave ovens. To avoid unforeseen situations, the developers decided to close the waveguide with a mica plate. It has soft, flexible properties, relatively affordable pricing. It will not be difficult to fix such a breakdown with your own hands. You can buy material of any size, cut the corresponding segment. The peculiarity of the mica plate is that it transmits a frequency level of 2.45 GHz without obstacles. It is at this frequency that the microwave oven operates.

Also, mica plates do not get wet. This is a very important factor if liquid is heated inside microwave ovens. After all, water very quickly absorbs the radiating frequency of 2.45 GHz, there is a danger of serious damage. If the water reaches the waveguide, a big accident is created, which will not be easy to repair with your own hands. The high-voltage fuse will blow instantly. If things get worse, the magnetron itself burns out, other electronics that power the microwave oven.

What factors influence the destruction of the mica plate? Most reheated food contains a lot of fats, oils, and other such ingredients. They differ in that instead of the usual boil, they shoot out greasy drops. Once such a drop hits the mica plate, a small wire bridge is created. An electric arc is formed: from the waveguide to the mica plate, then from it to the body of the microwave oven. As soon as pops and sparks, uncharacteristic for the operation of stoves, appear, this is a sure sign that the stove will soon need to be repaired.

Anyone who has tried to fix the microwave with their own hands wondered about the high-voltage fuse. The mechanism of microwave ovens of this kind triggers at least two fuses:

If you look at the electronic board of the microwave, this part appears as a small white or transparent cylinder. Its task is to protect integrated, wall-mounted microwave oven components. This small cylinder is also part of the power supply circuit. Its burnout occurs in the event of a capacitor breakdown, a resistor short circuit.
The circuit that forms the power supply of the magnetron includes a diode, a transformer, and a capacitor. Through them, about two or three kilovolts approaches the cathode. These details are not difficult to find. It is difficult to confuse the appearance of the capacitor with anything else. This is a huge detail in the form of a jar weighing up to one hundred grams. One diode leg is attached to it, the other is fixed to the body. Nearby is also a small barrel, often ceramic, painted in brown. It is this barrel that contains a high-voltage fuse inside it. Its task is to prevent overheating of the magnetron. When a mica plate breaks through or a metal spoon is placed in the microwave oven, the high-voltage fuse immediately burns out.

It is best not to try to assemble the high voltage fuse with your own hands or remove it from the electronic board. This practice is extremely dangerous for people. The microwave oven may stop working and there is a high risk of fire and electric shock.Before you start talking about repairing a fan that cools a magnetron, grills or an illuminating lamp in a microwave oven chamber, you should also pay attention to the protective relay.Their task is to turn off all operating systems at the moment when the chamber door is in the open position. Two relays usually break the power supply circuit. And one relay will be controlled by the functionality of the second. The work is carried out as follows:

If the oven door is open, the relay trigger is released.

In this operation, the power supply circuit has two breaks.

The second relay closes the ground on the phase.

When the first relay is energized, nothing bad will happen as the power supply circuit is in the open position.

When the first relay sticks, the fuse is blown out. This is due to the fact that the ground was short-circuited by a phase.

Video (click to play).

The fuse is not meant to be on top of the magnetron or inside the case, but on the board. To fix a microwave oven with your own hands, you should check the operation of the protective relay. Without this functionality, access to the power supply to the magnetron is practically impossible. The task of the power fuse is to take into account the movement of current in the magnetron. In the event of a dangerous situation, the protective element burns out, the generator breakdown is excluded. A similar situation occurs when the microwave oven is idle or there is some kind of metal thing in its chamber.

Rate the article:

Grade 3.2 who voted: 85