DIY home appliance repair school. Self-repair of electronics. What is possible repair of household appliances

Troubleshooting in electronic circuits... In this article, we will look at how to independently find and eliminate simple breakdowns in electronic circuits. Let's say we have a portable cassette recorder that has ceased to show signs of life, does not turn on, does not respond to button presses, and the LED indication does not light up. In this case, the search for the cause of the malfunction should start with the power supply.

Well, if we have an external power supply, in this case we turn on the power supply to the network and measure the voltage on the plug (output from the power supply) with a multimeter. For low power consumer audio equipment, it is usually sufficient to select the 20 volt DCV limit on the multimeter, or in other words, measure the DC voltage.

If you need to repair high-power audio equipment, then the output from the power supply unit may have a voltage significantly exceeding 20 Volts. In this case, you need to select a voltage measurement limit of 200 volts, also DCV. If there is no output voltage, you will have to disassemble the power supply case, or if the power supply is internal, the entire device. In this case, you need to check, first of all, the fuse in the primary circuit of the transformer.

Fuse

Sometimes, as in the diagram below, fuses are installed additionally in the secondary circuit. They need to ring, setting the multimeter in the audible dialing mode, you need to touch at the same time the metal tubes - the contacts at the ends of the fuse. In this case, the fuse does not need to be removed from the metal racks on the board, it is enough to touch them with the probes of the multimeter, if sound signal- this means that the fuse is intact. Otherwise, the fuse has blown and must be replaced with a new one rated for the same current.

Although if the device uses transformer power, first check the integrity of the fuse, and at the same time the cord, you can set the multimeter in the resistance measurement mode to the limit of 2 kiloohms and touch the multimeter probes to the pins of the power cord plug. In this case, we get, as you can see in the figure below, connected in series, the wires of the power cord, the fuse and the primary winding of the transformer.

In this case, readings of the order of 300 ohms should be displayed on the multimeter. This means that the supply wires, fuse and primary winding of the transformer are in good condition. If the device has a power-on button, it must be pressed before this check. You can also “click” the power button during such a check, when the multimeter is turned on, there will be readings of about 300 ohms, when turned off, one or infinite resistance.

Transformer - photo

If, with such a dialing, the cord does not ring through the cord, you will have to disassemble the case and ring the cord and the transformer separately. I think no one will have any difficulties with the continuity of the cord, one probe for the plug, the second for the wires entering the device body, I described the continuity of the cord in detail in the previous article. Those terminals of the transformer, which are connected to the wires, power comes through them, are the primary winding. It can be called by setting the multimeter to the 2 kilo-ohm ohmmeter mode, the resistance should also be about 300 ohms.

It is also possible to distinguish the primary winding from the secondary by the thickness of the wires, the primary is usually wound with a wire of a much smaller section than the secondary, due to the fact that currents flow in the secondary winding that are greater than in the primary. The picture above is a transformer with multiple secondary windings. The resistance of the secondary winding of the transformer when ringing with a multimeter can be close to zero, due to the fact that the number of turns of the secondary winding is much less than in the primary one, and accordingly, during continuity, the resistance will be much less than in the primary one.

If the primary winding does not ring with an ohmmeter, and, accordingly, such a transformer does not work, then do not rush to throw it away, a thermal fuse is usually installed under the insulation near the terminals of the primary winding, as in the figure above. It works when heated above the set temperature and breaks the primary winding circuit. Like a regular fuse, a thermal fuse is used only once, after which it may need to be replaced. You can check it with an ohmmeter or a multimeter in the audible dial mode. Often, after replacing the thermal fuse, if the windings are intact, the transformer can continue to function as before. There are frequent cases when a diode bridge burns out, as you know, a diode bridge is 4 diodes connected to each other by a special bridge circuit.

As you can see in the figure above, the diode bridge has 4 connection points, 2 points are connected alternating current, and going to the load plus and minus. On a real diode bridge, these points are each connected to its own output, these are 2 outputs alternating current and plus and minus.

Photo - diode bridge

This is what we see on the imported diode bridge (+), (AC - alternating current) and (-). In order to check the diode bridge, we conditionally divide it into separate diodes and ring it as if we would have 4 separate diodes. To ring the diode, you need, as everyone knows, to set the multimeter to the diode test mode, on the multimeter it is indicated by the diode icon, often this mode on the multimeter is combined with the sound dial mode.

Next, we connect the red probe to the anode or to the positive electrode of the diode, and the black probe to the cathode or negative, or in other words, we connect while observing the polarity. In this case, numbers about 600-900 should appear on the screen. If a beep is heard or a unit is displayed on the screen, this means that such a diode is faulty. When connecting the probes in reverse polarity, there should be a one on the screen.

All that is written above about checking radio components applies only to parts soldered from the board. When checking when the radio components are soldered into the board, it is necessary to take into account the influence on the measurement results of all parts connected in parallel with the measured ones! Let's take a look at troubleshooting with this simple sound probe circuit:

First, you need to conduct a visual inspection of the device, whether there are blackened resistors and similar defects. The fact is that when resistors burn out, this is most often seen by their appearance... Below is a picture of the printed circuit board of this probe:

Printed circuit board for sound probe

If there are suspicious ones;), you need to ring them with a multimeter in ohmmeter mode, determining by schematic diagram their face value. The permissible deviation from the nominal value for imported resistors is 5 - 10%, for domestic type MLT - 20%.

On factory printed circuit boards of various household appliances, a layer of silk-screen printing is applied from the side, reverse printing on a textolite, or, in other words, a designation of where which element and where which terminal is soldered. This helps a lot when repairing, not wasting time tracking along the tracks, every time, where is what part. On printed circuit boards made by radio amateurs, it is also possible to apply a layer of designations using the LUT method with back side boards.

Let's go back to our sound probe board, let's say we decided to ring all 3 transistors soldered into the board. Let's start with VT1, as it is a transistor n-p-n structures, we must install the red probe on the base terminal of the transistor, and the black one alternately on the collector and emitter. In this case, depending on the type of transistor, there will be numbers of the order of 600-900 on the screen. If a sound signal sounds during the check, or there is a unit on the screen, then such a transistor must be replaced. Pinout will help us determine where is which pin of the transistor on the board. Our circuit uses transistors KT315 and KT361. Here is their pinout:

The difference between VT2 and VT1 lies in the structure. In the figure above, it can be seen that the base of the transistor VT2 is n-type, which means that when checking, it is necessary to connect a black probe to it, and alternately red to the collector and emitter. The rest pnp transistors structures are checked in the same way as n-p-n structures. If no conclusions are indicated on the board, you need to look in the transistor manual, or on the page with background information in the Internet. If you need to check non-polar capacitors for a short circuit, they are called with a multimeter in ohmmeter mode. The capacitor leads should not ring among themselves, or, in other words, there should be a unity on the screen.

All modern washing machines are equipped with a control module. The more functionality the SM has, the more delicate the electronics: it is more susceptible to breakdowns, since it is sensitive to voltage surges in the network. Is it possible to repair "brains" washing machines with our own hands, we will find out how to diagnose their breakdown in this article.

The main control box of the washing machine is equipped with two boards. One of them is responsible for the operation of all the details of the washing machine. The other provides the operation of the control panel - buttons, indicators - and has appropriate connectors for wiring.

Is the board not overload protected in any way? Of course, the manufacturer has provided a surge protector for such cases, which takes a hit during a power surge.

How to check the washing machine board and identify a breakdown?

The fact is that most of the signs can indicate a breakdown of both the module and other parts. For example, you notice that the machine stops working, the wash does not start. This may be due to a problem with the module or motor of the washing machine.

What may indicate a malfunction and subsequent repair of the board in the washing machine:

• СМА give an error code on the display.
• The system is "frozen" and does not respond to user manipulations.
• Washes for too long. The machine fills up and then drains the water, after which the system "freezes".
• The drum changes direction abruptly for no apparent reason.
• The spin mode does not turn on.
• The water overheats or does not heat up, which does not correspond to the selected mode.

However, the next time the washer is started, it may work as usual again.

Some models of the CMA have an autotest, which allows you to determine the cause of the breakdown. How to start it is written in the instruction manual of the machine.

1. A short circuit as a result of a voltage drop can lead to burnout of capacitors, thyristors, triggers and other elements on the board.
2. High humidity. If the SM is operated in a bathroom, over time the humidity affects the main unit, which leads to its malfunction.
3. Broken power wire. If the wire is cut abruptly, a power surge may occur, affecting the operation of the module.
4. Frequent abrupt unplugging of the machine over time may cause a malfunction.
5. Factory defects are less common.

Be careful when transporting SM from place to place. Be sure to pull out the powder dispenser as there is some water left in it. During transportation, water gets on the main unit, which leads to its combustion when connected.

To start repairs, you need a circuit board for the washing machine, as shown in the example of the Indesit washing machine.

We can advise you to superficially inspect the module to find burnouts and damage. There are other ways to check, but they can only be carried out by an experienced specialist. If faults are identified, you will have to replace the "brains" for the washing machine.

To conduct a visual inspection, we will figure out how to remove the washing machine board. First unplug the washing machine, then proceed as follows:

• Pull out the detergent dispenser drawer. To do this, pull it towards you while pressing the latch in the center.
• Now remove all screws holding the control panel.

• Use a screwdriver to release the plastic clips. Remove the panel from the case.

• The main unit is located behind the panel. Take a photo or mark the location of the wires with a marker. Then disconnect them and remove the unit.
• You may need to release the block latches to get to the board.

Once the board is in front of you, carefully examine it. Did you notice some burnt areas? Then you need to repair the control unit of the washing machine.

We will show you how you can replace some of the elements. To do this, you will need a soldering iron and a new part.

• Capacitor. On the control board, it serves as a kind of stabilizer. To replace it, you need to solder the new part to the positive electrode. Use a tester to find out where which electrode is.

• Resistor. A tester is used to check the operation of the resistor. 1st order resistors should show a result of 8 ohms and an overload of 2A. Second-order resistors show 3-5A, while the resistance indicators depend on the frequency of the module. If the indicators do not correspond to the norm, the elements are replaced by soldering.
• Thyristor block. You can check the thyristor unit by measuring the negative resistance. Indicators should be no higher than 20V. The filter of the block could also burn out. You can repair it by cleaning the cathode.
• Trigger. The trigger test is to measure the voltage of the input contacts. Their readings should not exceed 12 V. The resistance of the trigger filter should be 20 ohms. Replacement of the element is also carried out by soldering.

The soldering of the board components can be disturbed by strong vibrations from the machine. Therefore, you need to monitor the correct and stable installation of the washing machine.

The master knows how to properly repair the control board. Think before starting your own repair, because the electronic unit is quite expensive. If you do not have the skills to work with a soldering iron, and the verification indicators do not give specific results, contact the service center.

For those who nevertheless decided on self-repair, video

Repair of household appliances is quite possible with your own hands, but it is not always possible to do this, since modern devices very complex in terms of technical parameters and finding a fault is not as easy as it might seem at first glance. It is worth noting that household appliances are an important component of every home, and it is simply impossible to do without it. It is hardly possible to imagine a person who washes clothes on his own, cooks food over a fire, or heats water using an iron cup, not a kettle.

Advantages of professional equipment repair by specialists

It is quite difficult to repair electrical appliances, since there is an incredible number of models, brands and types of products. Each device has a certain electrical circuit, which a beginner is not always able to deal with.

To restore the work of a gadget, so necessary for the home, experts recommend contacting an organization such as an electronics workshop.

In cooperation with experienced people, there are a number of advantages that you should familiarize yourself with before the equipment breaks down even more during self-repair. In service centers, technicians offer comprehensive diagnostics, through which even the smallest malfunction can be detected.

Advantages:

1. Detailed advice is provided regarding the breakdown, the method and cost of elimination, as well as how to avoid such a situation and properly operate the product.
2. In service centers, they provide installation of exclusively original spare parts, and the use of budgetary parts is possible only with the permission of the client and when drafting papers.
3. V service center professional service is carried out, as only qualified specialists are hired, which emphasizes the prestige of the center.
4. After the repair of any household appliances, the device is set up, adjusted and calibrated so that the customer can receive the installation completely serviceable and suitable for use.

Service in the service center provides an opportunity to obtain a warranty and repeat free repair if a breakdown occurs precisely because of the master's oversight. Carrying out repairs by the master will be much faster than independently looking for devices for diagnostics, as well as parts to resume work.

Reasons for repairing electrical appliances

What to do if the electrical equipment breaks down, and is it possible to carry out an independent repair? If the outlet does not visually raise any suspicions, then you need to connect any other device to this connector. As soon as there is evidence that it is in good working order, you need to look for the cause in the equipment.

You should not immediately go to the service, as it is advisable to check a number of commonplace points, for example:

• Serviceability of the outlet;
• Availability of food;
• Correct connection.

Due to the fact that in this case a washing machine is considered, then you need to check the water access or simply whether the water supply tap is open. Due to its overlap, the device will block operation.

Maintenance and repair of household appliances may require some training, work experience and, of course, devices for diagnostics, which only specialists in service centers have.

Depending on the type of equipment, in particular its dimensions, it is possible to carry out diagnostics and repairs at home, if the breakdown is not too complicated. It is important to note that if household appliances were purchased very recently and malfunctions began to occur, then it is strictly forbidden to independently penetrate into the case and carry out any actions, as this automatically removes the manufacturer's warranty. It is best to contact the store where the device was purchased and request a warranty diagnosis, which is carried out free of charge.

Do-it-yourself preparation for the repair of household appliances

Modern progressive technologies are what creates new generation household appliances, but even such devices can fail. Some problems can be attributed to the main reasons for the malfunction of electrical appliances.

Namely:

• Overload voltage;
• Power surges;
• High room temperature;
• There is vibration or shock when using the product.

If a malfunction occurs and the object refuses to work, then you need to look for the cause in the electronics after a series of preliminary actions. Testing of items such as lamps, fuses, switches and the like is required.

The power supply unit and the power supply unit are checked by using a voltmeter, through which the voltage at the input and output is examined.

It is advisable to additionally check the serviceability of the sensor, signaling device, limit switch, monitor, kinescope and speaker system if the TV or speakers are checked.

Household electrical appliances: causes of breakdowns

To repair any kind of home appliances, it is not enough to learn to understand the details, as you need to familiarize yourself with the most common malfunctions. Some of them can be attributed.

Namely:

• Open circuit;
• Increased resistance for no reason;
• Significant decrease in resistance;
• The presence of a short circuit.

There is common reasons over which they arise. An open circuit can be due to the old age of the elements through which an increased current flows, as well as shock, vibration and corrosion. Resistance increases in the electricity network also due to the aging of the elements or simply the loss of their proper form.

This contributes to the deterioration of the contact connections and to deviations from the required parameters.

Reducing resistance in electrical circuit can occur due to increased surface leakage and aging of parts. A short circuit occurs due to breakdowns in insulation, as well as when a wire, an element is short-circuited and the integrity of its body is violated.

In Moscow, you can find various companies, websites and even such a service as a private master, through which it is possible to repair household appliances. However, in order to save money, you should try to find the malfunction yourself, which can be done by following a number of recommendations presented below.

1. An intermediate voltage measurement is carried out, due to which it is possible to track the presence of the correct signal passage to different channels in system.
2. It is required to exclude those parts of the device that are working properly, which will reduce the number of breakdown options, and provide the master with specific data. This helps reduce diagnostic costs.
3. If you replace a block in which there may be a malfunction, then the probability of eliminating the breakdown increases to 80%.
4. It is necessary to assess the serviceability of a serviceable circuit and a faulty circuit in order to determine which parameter requires intervention and maintenance. This requires special diagnostic equipment.

The troubleshooting process consists of specific steps, the sequence of which must not be disrupted. The fact of a breakdown of the device is established. This is not difficult to do, since the device will refuse to fulfill its direct duties. It is required to analyze the problems that arise and compare them with the possible problems described in the instructions from the manufacturer.

A full-fledged diagnosis of the device is desirable, since the cause of an external breakdown may lie inside, and it is simply impossible to determine it without special equipment.

It is required to determine the degree of breakdown and decide that the maintenance will be carried out independently or with the help of a master. Sequential tests are performed on each element connected to the control module. An overall assessment of the device malfunction is made. Problems are being eliminated.

How to repair an electric waffle iron and other appliances with your own hands

It is quite possible to repair an electric waffle iron or electric samovars with your own hands, but an electrical household appliance requires accuracy, clarity, and maximum care. The most important thing is to examine the device only after disconnecting from the mains. First you need to familiarize yourself with the principle of operation of the device.

When diagnosing, one should study the most complex details of the device, and only then proceed to diagnose smaller components. An analysis of the malfunction is carried out, during which it is necessary to decide on the type of repair and its benefits. To ensure the accuracy of the results obtained, it is best to double-check each part of the device for serviceability. Experts recommend visually dividing the equipment into several parts, and checking each module separately, which will reduce the time to find a breakdown. If the malfunction is not too big and self-repair is possible, then you should do it yourself.

Repair of household appliances (video)

In some cases, breakdowns can be of this kind that it is easier to purchase a new device than to repair an old one. Such recommendations can only be given by experienced specialists after a thorough diagnosis. If you do not have the skills to work with electrical appliances, then it is better to entrust it to professionals in order to avoid even bigger problems.

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