Do-it-yourself microwave oven repair does not turn on

In detail: do-it-yourself microwave oven repair is not included from a real wizard for the site my.housecope.com.

You want to reheat lunch but the microwave won't turn on? What to do? You have two options: contact a service center or try to fix the problem yourself. We will tell you how to identify the cause of the problem and fix it without leaving your home.

Microwave ovens of each brand have their own characteristics. Manufacturers can implement additional options in them. However, in microwave ovens manufactured by Samsung, LG, Daewoo, the reasons for the problems are similar. And the principle of operation is the same for all brands and models.

After connecting the device to the network, the current flows to the transformer. It multiplies the voltage to increase heating. Then the magnetron is triggered, which creates radiation, that is, an electromagnetic field. This radiation affects the water in food. Its molecules begin to move, from which friction and heat arise. This is how heating takes place.

Since the operation of the oven is based on electronics, it would be logical to first of all check the corresponding elements if the device stops turning on.

What could have caused the problem:

Lack of voltage in the network or burnout of one of the connection elements;
Blown fuses;
Failure of the transformer;
Breakage of the indicator;
Microswitch malfunction.

What to do if a Panasonic microwave oven or Supra does not start? Can you repair it yourself? In some cases, yes, you can.

First of all, the presence of power in the network is checked. Plug another appliance into the microwave socket. If it does not work either, the malfunction is found, you need to wait for the appearance of electricity. However, if there is light throughout the building and only the outlet is not working, contact an electrician.

Video (click to play).

Now check the power cord and plug. Did you notice insulation melting or damage? Replace the cord or insulate the damaged area. Some models of microwave ovens have a plug with a built-in fuse. In such devices, the cord pins are often loose, or the plug does not fit snugly into the outlet.

Electronics can be damaged after a power surge. Therefore, it is recommended to connect a voltage stabilizer to any advanced technique.

If the microwave turns off 3 seconds after starting work, check the details:

Fuses on the filter... They should not be blackened, swollen or deformed. Is everything outwardly all right? Then diagnose with an ohmmeter.
Magnetron... It can punch to the body. In this case, the part is replaced.
Inverter on board... Most often, a breakdown is associated with a short circuit. A new inverter needs to be installed.
Control module... It is better to entrust its diagnostics to the service center.

Important! Is a microwave oven that turns off immediately after startup is under warranty? Do not rush to open its case, contact the service center. If the master discovers traces of disassembly, he may refuse warranty repair.

Problems in the transformer... Possible cause - primary or secondary winding or thermal fuse burned out. The latter can be replaced. It is located inside the transformer and covered with a cover or electrical tape. If the windings are burned out, then it is necessary to completely replace the transformer.

Indication does not work... When the microwave oven is turned on, the indicator on the panel lights up. If this does not happen, an assumption of a breakdown arises. Therefore, it is better to immediately check the health of the indicator.You can replace it yourself, although the device will work without an indication.

Door not closed tightly or microswitch broken... If the oven door is not closed, heating will not start. But if everything is in order, the door is pressed, then you need to inspect the microswitch, which sends the module a close signal. When it fails, the module, accordingly, does not receive the desired signal. A new switch should be installed.

Now you know what measures should be taken if the microwave turns off or stops starting altogether. Remember that you should not rush to repair the microwave oven yourself with a valid warranty. Better to call a specialist right away.

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.

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.

Read also: DIY 4-stroke scooter repair

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 the microwave microwave. In addition, watch the video on microwave repair, perhaps there is exactly that breakdown that will help you fix your beloved household assistant.

Rice. 1. Microwave device

Legend:

Door latches serve both for fixing the latter and for the system of blocking work in the open position.
A rotating tray on which the dielectric cookware is placed.
Separator equipped with rollers that drives the pallet.
The drive that rotates the separator.
Backlight lamp, turns on depending on the operating mode.
Ventilation (usually forced).
Magnetron - a microwave generator, in fact, is the main structural element. You can find out how it works and how it works by reading an article on our website dedicated to this issue.
Waveguide, provides the movement of microwave waves to the microwave chamber. It is a rectangular hollow metal tube.
High voltage diode.
Capacitor.
Waveguide power supply transformer and control circuits.
Control block.

We will not give a complete schematic diagram of the device, since they can be very different in different models of microwave ovens. In our case, the supply circuit of the magnetron will suffice. As a rule, it has a typical structure.

Typical diagram of a magnetron power supply circuit

Let us briefly describe the principle of operation of the above circuit. Power to the primary winding of the transformer (I) comes from an external control circuit that regulates the power and duration of microwave radiation. One of the secondary windings (II) supplies voltage to the magnetron filament. Winding II is made of 2-4 turns of a thick wire, since the current in the heating circuit can reach 10.0 A at a voltage of about 3 volts.

Another secondary winding (III), which supplies a high voltage level (up to 3.0 kV), is called anode winding. As can be seen from the figure, in this circuit, a rectifier and a voltage multiplier are built on the basis of a high-voltage diode (VD1) and a capacitor (C1). In this case, VD1 is turned on so that the opening occurs with a positive half-cycle, as a result, the capacitor begins to charge. When the negative half-cycle begins, the diode VD1 closes and the voltage is supplied to the magnetron M1 together with the charge accumulated on the capacitor. This leads to a doubling of the voltage and the formation of an electric field of the required intensity in the magnetron.

Resistance R1 in this case is necessary for C1 discharge. Typically, this resistor is located in the capacitor case. As for VD2, it provides protection in the event of an increase in voltage across the capacitor C1 or the occurrence of a short circuit in the magnetron M1.

Before proceeding with the repair, it is necessary to collect as much information as possible about the failed device. Ideally, this is a model-specific service manual. In this document, the manufacturer provides all the necessary data, starting from the assembly drawing (exploded view, literally from the English explosion-diagram) and ending with the troubleshooting algorithm.

Fragment of microwave explosion diagram

Unfortunately, manufacturers are in no hurry to share this information, distributing it only among the networks of certified service centers. If you manage to find the technical documentation for the repair, be prepared for it to be in English.

If the documentation could not be found, and this will happen in most cases, do not worry, typical microwave oven malfunctions can be determined without a schematic diagram. It is enough to know what the main elements look like and where they can be located. A photo of the microwave oven with the cover removed will help you with this.

The appearance and location of the main elements in the microwave case

The intuitiveness of the process in most cases allows you to remove the casing and get to the main structural elements without an assembly drawing. But in this case it is necessary to remember the sequence of actions and try not to leave “unnecessary” parts after the reassembly.

In most cases, you can get by with a Phillips screwdriver and a multimeter. In some cases, you may also need a soldering iron. Accordingly, spare parts will also be needed, which ones will be clear after diagnostics.

As we promised, here is a list of common faults:

No response to the power button.
The device does not turn off after working out the mode.
Weak heating.
No heating.
Sparking is observed.
The pallet does not rotate.
No response to the control panel.
When turned on, the scoreboard does not work.
The fuse blows when the door is closed.

Before considering in detail the elimination of the listed malfunctions, we consider it necessary to warn that before diagnostics and repairs, it is necessary to physically disconnect the device from the power supply, that is, pull the plug from the outlet.

In this case, diagnostics and repairs should be subject to the following algorithm of actions:

We check the presence of voltage in the power supply. If it is not there, we solve the problem with the power supply, otherwise go to the next step.
We check the power supply unit of the control module. We start with the fuse. If it is burnt out, we will replace it. After that, we turn on the device and try to heat, for example, a glass of water. If everything works, the repair is complete. If the fuse blows, the problem is in the control module, it should be repaired or replaced.

In order to independently repair the control module, you must have certain skills in radio electronics; without them, it is not recommended to start self-repairing the control module.

Example of fuse location on a control module

In most cases, this problem indicates a faulty door position microswitch. To eliminate the problem, we find, check and, if necessary, replace the switch.

If the microswitches are OK, the problem may be with the relay supplying voltage to the power transformer in the magnetron supply circuit. We "call" the relay contacts with a multimeter, if they are "stuck", we change the electrical switch to a new one.

When no problems are found with the relay, it means that the malfunction is associated with the control unit, we change or repair it.

Most often, this malfunction is associated with a voltage drop in the household power supply. If it falls below 205.0-210.0 V, a sharp decrease in the intensity of the microwave flow occurs. This problem is typical for private houses in rural areas, where power grid overvoltage occurs regularly, and, as a result, voltage drops.

If the multimeter shows the permissible voltage level of the household network, then the power circuit of the magnetron should be checked, as we will describe how to do this in the next section.

When the diagnostics of the magnetron circuit did not give results, then everything indicates a problem with the control module.

Such a malfunction clearly indicates a malfunction in the magnetron power supply circuit. Diagnostics is performed as follows:

Important! The magnetron must be changed to the same type. This is due to the fact that the parameters of the high-voltage transformer and the control circuit are calculated based on the specific model of the microwave generator.

Such a malfunction can be caused by the following reasons:

Burnout of the mica plate, which insulates the waveguide from splashes and food pieces... The plate is located inside the chamber on the side of the magnetron. The condition is determined visually. If the problem is with the plate, it is sufficient to replace it.
During operation, the cover of the coupler burned out... This is a kind of plastic cap that rotates the pallet. In this case, only replacement will help. Naturally, it is necessary to install a coupler from the same type of model, since the design of such a cover may be different even from one manufacturer.
The "wrong" dishes are installed in the chamber... We remind you that metal appliances, as well as those on which metallized dyes are applied, cannot be used in microwave ovens.

First of all, it is necessary to check that the pallet is not blocked by any foreign object, it is correctly installed or the separator. If everything is normal, then the reason lies in the drive. This may be due to the following reasons:

Jammed engine (determined tactilely) or breaking one (dialing is carried out) of the windings. In these cases, a replacement of the drive is required.
Gearbox problem... In this case, it all depends on the design. In some cases, the gearbox can be repaired. But, as practice shows, it will be easier and cheaper to replace it.

In modern electronic models, such a malfunction indicates a problem with the control module. In products with an electromechanical control system, it makes sense to check the mechanical relays and / or switches, if necessary, replace defective parts.

If, when turned on, the power indicator lights up, but the digital display does not work, then everything indicates problems with the control module. It needs to be repaired or replaced.

A characteristic indicator of faulty microswitches for door position. One of them is "stuck" and does not switch; as a result, a short circuit occurs in the control circuit. The repair consists in replacing or cleaning the microswitches.

Of course, any hostess and owner will be offended if the microwave oven suddenly stops turning on or malfunctions. The first thing you want to do is take your favorite device and go to the nearest workshop or service center. If the microwave is under warranty, this is exactly what you should do, and if not, then you will have to pay for the repair.

But as practice shows, most faults have very simple reasons and a person who knows how to use the tool and has it can make simple repairs on his own. But for this you need to know the principles of microwave operation. Let's see why this useful device may not work?

The main malfunctions of a microwave oven are the result of improper use or neglect of the appliance. Factory defects most often appear during the warranty period and therefore are eliminated by service centers free of charge.

Never and under no circumstances should you run the microwave oven magnetron with the door open, if the chamber or waveguide is damaged.
You should never, under any circumstances, even try to connect a magnetron removed from its original place. It is life threatening!
It is forbidden to start the microwave oven with the fan off. This could damage the magnetron.
It is possible to make any manipulations with the parts of the furnace only after disconnecting from the network and forcibly discharging the high-voltage capacitor.
All elements must be replaced only with similar ones.
After completing all the work, you need to remove all, even the smallest, objects from the waveguide.
Do not start the microwave oven without load. A non-metallic container with water must be placed in the chamber.

When disassembling the microwave, it is best to take pictures of each step, so that later you can easily restore the original position and attachment of all parts.Digital cameras and mobile phones will be of help here.