DIY TV repair: LCD / LCD, plasma, with a tube. Schemes, videos and secrets of repair

At any stage of operation of the TV, a malfunction may occur. In this case, immediate repair is necessary, which can be done on their own. How to do this, we will talk further.

Measuring and repair equipment

To determine how to repair LCD TVs and other models, you first need to establish the cause of the breakdown. To do this, you will need the following equipment:

• tester or multimeter - for determining voltages at special (control) points, measuring the values ​​of resistors and capacitors, continuity of circuits and parts (coils, transformers, diodes, etc.);
• amplifier - to determine where the sound signal disappears;
• oscilloscope - to compare signals at certain points with the circuitry of the TV. It is rarely used at home, because not everyone knows how to work with it.
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Regardless of the malfunction, you will need such devices for repairing TVs:

• screwdrivers of different sizes (straight, cross-shaped, rarely sprockets);
• “Hexagons” are quite rare, but are needed;
• pliers, wire cutters and more;
• soldering iron (25-60 watts) with rosin and tin;
• hairdryer or soldering station - for modern flat-screen models.
• circuit diagram of the TV unit (can be found on the global network). For example, the diagram of the LCD apparatus is as follows:

Start of work - troubleshooting

A special troubleshooting technique for beginners has been developed, which will help to navigate during the repair. The table provides a description of the main malfunctions and instructions on which unit should inspect and repair the TV.

What's happening	Possible reason
The device does not turn on	Power supply, power button, cord
The LCD screen does not light up, there is an image, but hardly noticeable	Lamps or backlight diodes, their power
No sound, TV wheezes	Sound amplifier or harness (microcircuit and parts around it)
The screen lights up, the TV does not show	Receiving unit (tuner and its circuits), video processor

Note that if during a visual review you find blackouts on the board, soot, swelling, or tearing of parts, then damaged elements cannot be changed immediately. A burnt component may be a sign of a circuit, and the cause will be in a completely different direction.

How to repair the TV if it does not turn on

Repairing a TV with a tube

As indicated in the table, the cause of the breakdown can be concluded in the PSU, power button and cord. The wire and the button are easily called by the tester, and the health of the button must be determined in the off and on state. The situation is more complicated with the power supply. If damaged parts are revealed during inspection, it is not a fact that after their replacement everything will work. For example, capacitors can swell from time, overvoltage, or short circuit in a completely different circuit (secondary).

In any case, you need to ring all the details of the PSU. We execute in the following sequence:

1. If the "Conder" swells, the posistor is cracked, or another obvious defect is visible, it is necessary to unsolder this element and clean the carbon deposit or electrolyte.
2. We start the test with fuse 2 and posistor 3. Then we ring the diode bridge, resistors, transistors and a microcircuit (if a high-voltage stabilizer is installed).
3. If everything is in order, install new elements instead of old ones.

When replacing parts, especially transistors and microcircuits, be sure to install gaskets (mica or rubber) if they were installed under the housings of these elements. They serve to isolate components from the chassis.

Repair of LCD / LCD TVs

There are two options for the location of the PSU in such devices:

• Interior. It can be located in such a place that sometimes you need to disassemble the entire television monitor. For example, many Chinese models do not have screws securing the cover. To repair them, it is necessary to pry off the plastic case with a flat tool (screwdriver) and remove the screen with the video driver, followed by a metal casing. Removing (unscrewing) it, you will get to the power supply.
• External. It is more convenient for repair, since there is no need to "climb" into the monitor itself.

All of these PSUs are similar in principle to the power supply unit of a conventional kinescope apparatus, and the method for finding faults is the same. The difference is only in the elemental base and output voltages. Therefore, the repair of plasma TVs and LCD devices for power is no different from the above.

LCD / LCD screen does not light up, plasma - there is an image, but hardly noticeable

This indicates a problem in the backlight circuit. There are two reasons for this:

1. Spoiled fixtures (lamps or LEDs).
2. No power is supplied to the backlight (backlight generator, transformer, transistors).

If the LCD backlight is lamp, then for the rest it is LED.

First option

LCD devices have from 1 to 10 lamps. All lamps rarely burn out at once. In the first case, the lamp itself may be malfunctioning. Typically, cameras with other technology have LED strips. In many models, they stand in series, and the combustion of one of the LEDs leads to the extinction of the entire screen.

Repair LCD and other TVs are as follows:

Step 1. Open the case.

Step 2. Remove the driver board and PSU (they can be located in a metal casing).

Step 3. Disassemble the screen part. To do this, remove one or two metal casing and (if any) a protective film.

Step 4. Find backlight or LED strip.

Step 5. Replace those that do not burn. It does not interfere with a visual check and a tester to check the contacts in the lamps or the diode tape for an open.

Second option

If you have a second case, and all the lights do not light up, most likely the matter is in powering the backlight. In LCD equipment, a high-voltage converter is used, made according to a transformer circuit. Defective parts (microcircuit or transistors) in its start-up circuit are easily detected by the tester. To do this, measure the voltage on their legs, referring to the circuit. Having found a discrepancy, the element is changed.

But the transformer is difficult to verify. Check all voltages (according to the diagram) on the elements of this converter. If everything is normal - the transformer is to blame.

It can be rewound, but it is a hassle, and the quality of such a winding will again lead to failure. It’s better to buy a new one (get a worker in the teleworkshops) and install.

In the LED backlight transformer, the potential difference is only 50-100 V. If it is not on the connector, you need to check how many volts come to the transformer. For this, it is better to remove it. If everything is normal - they change the transformer, if not - the tester checks the remaining elements of the converter.

Read also:

• Why the TV turns on and off immediately: overview of causes and repair methods
• How to connect a tablet to a TV through such interfaces: USB, HDMI, Wi-Fi, RCA?
• How to hang a TV on the wall: with and without bracket?

There is no sound or it wheezes

In this case, a breakdown in the sound path. Check the supply and output voltages on the legs of the sound amplifier microcircuit (tester according to the scheme). If they are normal - strapping capacitors and input ones are to blame.

If the power is underestimated or is absent - there are two reasons:

1. It does not go with BP. In this case, all the elements going from the power supply to the memory are called up, and the failed ones are changed.
2. Bad chip. This is easy to verify by evaporating the chip. If after this the voltage appears and is normal, it must be changed.

The screen is lit, but there is no image

This happens for many reasons. Here are some of them:

The signal from the receiver unit (tuner and its circuits) does not go to the input of the video amplifier. To check, you need to connect some source of video signal (computer, VCR, set-top box) to the "Video" jacks on the TV. For example, HDMI, VGA, tulips (yellow) and others.

If the image appears, the tuner, the microcontroller and their circuits are to blame. The microcontroller can be checked quickly. He is responsible for the operation of buttons, input, audio and video signals. If, when you click on the buttons, you can enter the menu, and it is displayed on the screen, then the microcontroller is not to blame. Check the tester for potentials on its legs. If all of them coincide with the scheme - change the tuner.

The video processor is to blame. If after connecting to the tuners nothing happened, then check the chip (video processor). Check all supply and output circuits for matching potentials. If there is a mismatch, the processor is 70% defective.

Tips and secrets of the masters

• When checking the power supply, turn off the secondary circuits, and instead turn on the usual bulbs for the appropriate voltage.
• If you suspect that the "electrolyte" has lost capacity, warm it with a soldering iron. The electrolyte inside will boil, and the capacity will recover for a short time. The method helps with malfunctions of a frame scan, when you can visually see how the screen opens as a result of heating.
• If the high-voltage part is faulty, a slight hissing and crackling is heard. Turn off the lights. In the dark, you can determine where the sparks come from.

Troubleshooting Tutorials

The video explains in detail how to replace the LEDs on the LED matrix:

And about how to replace the matrix completely on the TV - read here.

Atypical malfunctions are sometimes found, due to which the backlight may not start. You will learn how to eliminate one of them in this video:

You can learn more about the combustion of transistors and microcircuits in the following lesson:

The video will tell you how to find and replace swollen capacitors in a power supply:

As you can see, not all TV malfunctions can be repaired at home. We told you how to find typical breakdowns, what devices to use when searching for them, and how to repair some problems with your video equipment. To eliminate more serious breakdowns, you will have to contact a telemaster.