Do-it-yourself repair of breakdowns of LCD, lcd and ice TVs


It’s no secret that a breakdown of a television receiver can spoil the mood of any of its owners. The question arises, where to look for a good master, is it necessary to take the device to a service center? This takes time and, more importantly, money. But, before calling the wizard, if you have basic knowledge of electrical engineering and know how to hold a screwdriver and a soldering iron in your hands, then do-it-yourself TV repair is still possible in some cases.

Common TV problems

Modern LCD TVs have become more compact, and repairing them has become much easier. Of course, there are breakdowns that are difficult to detect without special diagnostic equipment. But most often there are malfunctions that can be detected even visually, for example, swollen capacitors. With such a breakdown, it is enough to unsolder them and replace them with new ones with the same parameters.

All television receivers are identical in their design and consist of a power supply unit (PSU), a motherboard and an LCD backlight module (lamps are used) or LEDs (LEDs are used). You should not repair the motherboard yourself, but the PSU and screen backlight lamps are quite possible.

Can’t turn the TV on or off

If the TV cannot be turned on at all, then most likely the cause of the problem must be sought in the power supply. If the network often experiences voltage drops, then it could simply burn out. It can also cause the device to shut down spontaneously. If the model is equipped with special protection, then during power surges it will work and turn off the equipment.

TV does not turn on

If there is a clear confidence that there are no problems with voltage, then the reason may be in the appearance microcracks on the motherboard.

Read more about why the TV does not turn on.

Poor sound quality

If the sound quality suddenly drops sharply, then this is due to speaker malfunction. It is necessary to carry out diagnostics and check the correctness of their connection. All contacts must be in good condition. If during the inspection no problems were identified, then it is necessary to study in detail the functioning of the radio channels.

See also: what to do if the sound on the TV is gone.

Missing image or poor image quality

One of the most common problems. It consists in the fact that the user hears the sound of a working TV, but there is no image. In this case, you need to contact the help of a repair specialist. There can be many possible causes for this malfunction and a professional is able to quickly determine it. Most often it will be one of the following breakdowns.

  1. There is sound, but there is no image — a breakdown of the video amplifier or matrix.
  2. There is no “picture”, the sound is there, but periodically disappears. In this case, the problem is most likely with the sweep.
  3. There is sound, but the screen just glows. The simplest thing that can be is tuner interference. In the worst case, the video processor is broken.
  4. There is sound and image, but the picture is not stretched to full screen. This indicates that there was a breakdown of the frame scanning module of the matrix. This happens with frequent power surges in the network, or due to a faulty power supply.
  5. There is sound and picture, but a narrow bar appears on the screen. If it is vertical, then this indicates a probable breakdown of the urgent scanning transformer. The horizontal bar indicates a problem in the frame scan itself.
  6. Is there sound. The image is there, but it has become one-color. In this case, it is necessary to consider the breakdown of the video processor or video amplifier as the cause.

stripes on tv screen

See also: why stripes appear on the TV screen.

Matrix malfunction

Matrix failure is one of the most difficult problems. The fact is that it will not be possible to fix it, so you will have to replace it. The matrix is ​​the element on which the image is built. It can break for the following reasons:

  • the TV was dropped, or the screen was hit with something;
  • the matrix contacts have been exposed to liquid;
  • the element was defective;
  • The matrix has been used for a long time and has worn out during this time.

The following signs may indicate that the matrix is ​​damaged:

  • stripes of different colors appear on the screen;
  • black circles in the «picture»;
  • the image freezes or disappears completely.

It is not worth solving the problem of a faulty matrix on your own. A complete diagnosis and replacement of the element should be carried out by an experienced specialist, since this work is quite complicated and requires certain skills.

spot on tv screen

Sweep problem

You can determine that the problem is related to frame scan malfunctions by the following factors:

  • the image is reduced or shifted to the side;
  • the centering was disturbed or lines appeared;
  • frame scanning is completely absent — instead of an image, there is only a white luminous strip on the screen.

In this situation, the cause of the malfunction is the frame generator block. It contains many electronic elements. Therefore, it is necessary to call a specialist who can accurately determine which one needs to be replaced and carry out repairs.

Power supply repair

As already mentioned, the design and principle of operation of LED and LCD TVs, regardless of the manufacturer, are the same. Of course, there are some differences, but they do not play a significant role in troubleshooting. Often, if there is a problem with the PSU, the LCD TV does not turn on at all, while there is no indication, or it turns on for a while, and turns off spontaneously. The example considers the repair of the power supply unit of the DAEWOO LCD device (can also be applied to plasma), which is not much different from the repair of an LG TV, as well as Toshiba, Sony, Rubin, Horizon and similar models.

  1. First of all, before repairing the TV, you need to remove the back panel of the device with a screwdriver by unscrewing the screws. On some models, there may be latches installedwhich must be handled carefully so as not to break them.
  2. After removing the cover, you will see on the left the power supply, consisting of several modules, and on the right — the motherboard.
  3. Power supply and motherboard
  4. On the PSU board you can see 3 transformers: the bottom is the mains rectifier choke, the top left (large) feeds the inverter, and the standby power supply transformer is on the right. You need to start checking with him, since he turns on the standby mode of the TV receiver.
  5. duty transformer when the device is connected to the network, it must produce a voltage of 5 V. In order to correctly find the wire on which you want to measure the voltage, you can use the diagram, or you can look at the markings on the case. In this case, opposite the desired contact is written — 5 V.
  6. First, a measurement is taken to break the chain, by connecting one probe to the found contact, and the other to the cathode of the diode standing on the radiator. In this case, there is no break.
  7. Next, one tester probe can be attached to the body of the device, the other to the previously selected contact, and measure the voltage, after connecting the telly to the network. In this case, the device shows 1.5 V, instead of the required 5 V. Such transformer readings indicate that it is working, but not at full strength. The reason may be dry condenserlocated below, or swollen — above the transformer.
  8. To unsolder the parts that have become unusable, it is necessary to remove the power supply board. To do this, first disconnect all wires and the matrix cable coming from the inverter and the system board. So that in the future, after repairing the power supply, not to get confused where what is connected, you can take a picture of them before disconnecting the wires and cables.
  9. Now you can remove the entire LCD TV power supply by unscrewing the 4 screws. After removing it, it is very important discharge all capacitorsto avoid electric shock.
  10. We solder defective capacitors and change them to new ones, observing the polarity.
  11. The device is assembled in the reverse order: the board is screwed into place, all connectors and cables are connected, the rear panel of the unit is closed.
  12. Again we measure the voltage on the transformer of the TV power supply (the device should turn on) and see that it has become 5v. Having deployed the repaired TV receiver, you will see that it works.
    Voltage measurements

As you can see from the review above, repairing TV power supplies with your own hands is not such an impossible task. Following this description, you can also repair plasma TVs.

Power supply in a kinescope TV

Do-it-yourself TV repair with a kinescope, for example, such as: Rubin, Horizon, Sharp 2002sc, LG TVs, as well as Vityaz TV repair, begins with checking the PSU for operability (this is done if the unit does not turn on). It is checked with incandescent bulbs for 220 V and a power of 60-100 watts. But before that, be sure to turn off the load, namely the line scan output stage (SR) — connect the lamp instead. The voltage of the SR ranges from 110 to 150 V, depending on the size of the kinescope. Must be found in the secondary circuit SR filter capacitor (its values ​​​​can be from 47 to 220 microfarads and 160 — 200 V), behind the power supply rectifier СР.

To simulate the load, you need to connect a lamp in parallel to it. To remove the load, for example, in the widespread Sharp 2002sc model, it is necessary to find and unsolder the inductor (located after the capacitor), fuse and limiting resistance through which the CP cascade receives power.

Now you need to connect the power to the PSU, and measure the voltage under load. The voltage should be from 110 to 130 V if the kinescope has a diagonal of 21 to 25 inches (as in the 2002sc model). With a diagonal of 25-29 inches — 130-150 V, respectively. If values ​​are too highthen a check of the feedback circuit and the power supply circuit (primary) will be required.

It should be taken into account that electrolytes dry out and lose capacity during prolonged operation, which, in turn, affects the stability of the module and contributes to an increase in voltage.

When undervoltage it is necessary to test the secondary circuits to exclude leaks and short circuits. After that, the CP power protection diodes and vertical scan power diodes are checked. If you are convinced that the PSU is working, then you need to disconnect the lamp and solder all the parts back. Such a check can also come in handy when repairing a Philips TV yourself.

Backlight Replacement

Another common telly breakdown that can be fixed is the burnout of the screen backlight lamp. In this case, the TV receiver, after turning on, blinks with the indicator several times and does not turn on. This means that after self-diagnosis, the device notices a malfunction, after which the protection is triggered. That is why there is no image on the screen.

For example, a Sharp LSD TV receiver with this malfunction was taken, although in this way it is possible to repair a Samsung TV, Sony Trinitron, Rubin, Horizon, etc.

  1. To repair the TV, you need to remove the back panel from it. To do this, you need a screwdriver or screwdriver.
    Back panel
  2. Next, be careful disconnect cables from matrix.
    Loop disconnect
  3. The next step is to detach the control panel from the case. You do not need to remove it, you will still need it to turn on the device.
    Panel detachment
  4. The remaining loops also need to be disconnected. Then you need to remove the case on which the electronic boards are fixed.
    Case detachment
  5. Before removing the matrix, unscrew front frame. We remove the matrix itself and the filters, snap off the side mounts.
    front frame
  6. We connect the power and hold down a few keys to enter service menu. This will turn on the lamps for a while.
  7. The figure below shows that after turning on the lamps, the 5th one from the top turned out to be non-working. Disconnect it and replace it with a new one — now all the lamps are on when checking.
    Checking lamps
  8. Assembly takes place in the reverse order.
  9. After that, you need to turn on the TV receiver and enter the service menu to reset lamp error counter. If this is not done, the device will not work. Entering the menu, you need to find the corresponding line and reset by selecting ok. Now the repair of the LCD TV receiver is completed. Tests show that the unit is working properly.

Thus, you can repair Philips and LG TVs with your own hands, and other LCD panels, as well as devices with LED backlight (LED). Owners of the latter type of devices should read the article on LED backlight repair, where the whole process is described in detail using the LG TV as an example.

Other causes of TV failure

Among the typical and simple reasons that the TV does not turn on may be the remote control or the lack of a signal from the antenna cable.

Remote control malfunction

If the TV does not turn on with the remote control, first you need to make sure that the batteries are good. If they are worn out, replace them. Often the TV receiver cannot turn on due to contact contamination below the buttons. To do this, you can disassemble it yourself, and clean the contacts with a soft cloth from accumulated dirt. If your remote has been dropped, it’s possible damage to the quartz emitter. In this case, it must be replaced. Well, if you filled the remote control with water or some other liquid, and it didn’t work after disassembly and drying, then it will have to be replaced with a new one.

You can learn more about repairing the remote control from the following video or article.

No TV signal

When repairing LG, Sharp TVs with an LCD display, Rubin, Horizon with the same screens, a situation often arises when, with a fully functional device, it does not turn on. It turns out that the reason may be no TV signal in the antenna cable. This happens due to the operation of the noise reduction protection (in Rubin TV sets, they began to install it not so long ago), and the unit goes into standby mode. Therefore, if you find your TV in a non-working state, you should not panic, but you need to check for a signal from the transmitting station.

In conclusion, we can say — when you decide to repair the TV set yourself, you should soberly assess your abilities and knowledge in this matter. If you do not feel confident, then it is better to entrust this matter to the telemaster, especially since no one has canceled 220 V, and ignorance of elementary safety rules can lead to unpleasant consequences.


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