It's no secret that a breakdown of a television receiver can ruin the mood of any owner. The question arises, where to look for a good technician, whether it is necessary to take the device to service center? You need to spend your time on this, and most importantly, money. But, before calling a technician, if you have basic knowledge of electrical engineering and know how to hold a screwdriver and a soldering iron in your hands, then in some cases it is still possible to repair the TV yourself.
Modern LCD TVs have become more compact, and their repair has become much easier. Of course, there are breakdowns that are difficult to detect without special diagnostic equipment. But most often there are faults that can be detected even visually, for example, swollen capacitors. In case of 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 design and consist of a power supply unit (PSU), motherboard and module LCD backlight(lamp is used) or LED (LED is used). You shouldn’t repair the motherboard yourself, but the power supply and screen backlights are quite possible.
Power supply repair
No TV signal
When repairing LG, Sharp TVs with an LCD display, Rubin, Horizon with the same screens, a situation often arises when, even though the device is in good working order, it does not turn on. It turns out that the cause may be in the antenna cable. This happens because the noise reduction protection is triggered (in Rubin TVs, they began installing it not so long ago), and the unit goes into standby mode. Therefore, if you find your TV inoperative, you should not panic, but you need to check the presence of a signal from the transmitting station.
In conclusion, we can say - when you make a decision about self-repair television receiver, you should soberly assess your abilities and knowledge in this matter. If you don’t feel confident, then it’s better to entrust this matter to a TV technician, especially since no one has canceled 220 V, and ignorance of basic safety rules can lead to unpleasant consequences.
At any stage of operation of the TV, a breakdown may occur. In this case, immediate repairs are necessary, which can be done on your own. We'll talk further about how to do this.
Measuring equipment and repair tools
To determine how to repair LCD TVs and other models, you first need to determine the cause of the breakdown. To do this you will need the following equipment:
- tester or multimeter – to determine voltages at special (control) points, measure the values of resistors and capacitors, test continuity of circuits and parts (coils, transformers, diodes, etc.);
- amplifier – to determine the location of the loss sound signal;
- oscilloscope – to compare signals at certain points with the TV circuit. It is used quite rarely at home, since not everyone knows how to work with it.
Regardless of the malfunction, you will need the following equipment to repair TVs:
- screwdrivers different sizes(straight, cross-shaped, rarely asterisks);
- “hexagons” – quite rare, but necessary;
- pliers, wire cutters, etc.;
- soldering iron (25-60 watts) with rosin and tin;
- hair dryer or soldering station- For modern models with flat screen.
- circuit diagram TV unit (can be found in global network). For example, the diagram of LCD devices looks like this:
Getting started - troubleshooting
A special troubleshooting technique has been developed for beginners, which will help them navigate when carrying out repairs. The table provides a description of the main faults and instructions in which unit the TV should be inspected and repaired.
Note that if visual overview If you find darkening on the board, carbon deposits, swelling or rupture of parts, then you cannot immediately replace the damaged elements. A burnt component may be a sign of a short circuit, but the cause will be in a completely different direction.
Important! When inspecting, be sure to unplug the TV.
How to repair a TV if it won't turn on
Repairing a TV with a kinescope
As indicated in the table, the cause of the breakdown may be in the power supply, the power button and the cord. The wire and the button can be easily checked by the tester, and the serviceability of the button must be determined in the off and on state. The situation is more complicated with the power supply. If the inspection reveals damaged parts, it is not a fact that everything will work after replacing them. For example, capacitors can swell due to time, overvoltage, or a short circuit in a completely different circuit (secondary).
In any case, you need to call all the details of the power supply. We do it in the following sequence:
- If the “conder” is swollen, the posistor is cracked, or another obvious defect is visible, it is necessary to unsolder this element and clean the carbon deposits or electrolyte.
- We start checking with fuse 2 and posistor 3. Then we call the diode bridge, resistors, transistors and the microcircuit (if a high-voltage stabilizer is installed).
- 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 housing.
Remember! In case of any problems with the power supply, it is better to replace its main element (high-voltage transistor or stabilizer chip).
Repair of LCD/LCD TVs
There are two options for the location of the power supply in such devices:
- Interior . It may be located in such a place that sometimes it is necessary to disassemble the entire television monitor. For example, many Chinese models do not have screws that secure the cover. To repair them, you need to pry off the plastic case with a flat tool (screwdriver) and remove the screen with the video driver, followed by the metal casing. By removing (unscrewing) it, you will get to the power supply.
- External . More convenient for repairs, since you don’t have to “get into” the monitor itself.
All these power supplies are similar in operating principle to the power supply of a conventional CRT device, and the method for finding faults is the same. The only difference is element base and output voltages. Consequently, the repair of plasma TVs and LCD power supply devices is no different from the above.
The LCD/LCD or plasma screen does not light up – there is an image, but it’s barely noticeable
This indicates a problem in the backlight circuit. There are two reasons for this:
- Fixtures (lamps or LEDs) are damaged.
- There is no power supply to the backlight (backlight generator, transformer, transistors).
If the LCD has a lamp backlight, then the rest have LED backlight.
First option
LCD devices have from 1 to 10 lamps. Rarely do all the lamps burn out at once. In the first case, the lamp itself may be faulty. As a rule, television cameras with other technologies have LED strips. In many models they are located in series, and the combustion of one of the LEDs leads to the extinguishing of the entire screen.
Repair of LCD and other TVs is performed as follows:
Step 1 . Open the case.
Step 2 . Remove the driver and power supply boards (they can be located in a metal casing).
Step 3 . Disassemble the screen part. To do this, you need to remove one or two metal casings and (if any) protective film.
Step 4 . Find backlights or LED strips.
Step 5 . Replace those that do not light up. It doesn’t hurt to check the contacts in the lamps or diode strip to the cliff.
Second option
If you have the second case, and all the lights do not light, most likely the problem is in the backlight power supply. LCD equipment uses a high-voltage converter made according to a transformer circuit. Faulty parts (microcircuit or transistors) in its trigger circuit are easily determined by the tester. To do this, measure the voltage on their legs, checking the diagram. If a discrepancy is found, the element is replaced.
But the transformer is difficult to check. 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 this is a hassle, and the quality of such winding will again lead to failure. It’s better to buy a new one (get a working one from a TV workshop) and install it.
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 are supplied to the transformer. To do this, it is better to remove it. If everything is normal, change the transformer; if not, use a tester to check the remaining elements of the converter.
No sound or wheezing
In this case, there is a breakdown in the sound path. Check the supply and output voltages on the pins of the microcircuit audio amplifier(tester according to the diagram). If they are normal, the piping and input capacitors are to blame.
If nutrition is low or absent, there are two reasons:
- It doesn't come with the PSU. . In this case, all elements going from the power supply to the charger are called and the ones that are faulty are replaced.
- The microcircuit is unusable . This can be easily checked by unsoldering the microcircuit. If after this the voltage appears and is normal, it needs to be changed.
The screen lights up, but there is no image
This happens for many reasons. Here are some of them:
The video amplifier input does not receive a signal from the receiving unit (tuner and its circuits). To check, you need to connect some video signal source (computer, VCR, set-top box) to the “Video” sockets on the TV body. For example, HDMI, VGA, tulips (yellow) and others.
If the image appears, the tuner, microcontroller and their circuits are to blame. The microcontroller can be checked quickly. It is responsible for the operation of buttons, input, sound and video signals. If when you press the buttons you can enter the menu and it is displayed on the screen, then the microcontroller is not at fault. Check the potentials on its legs with a tester. If they all match the diagram, change the tuner.
The video processor is to blame. If nothing happens after connecting to the tuners, then check the microcircuit (video processor). Check all supply and output circuits for compliance with the required potentials. If there is a discrepancy, the processor is 70% faulty.
- When checking the power supply, turn off the secondary circuits, and instead turn on ordinary light bulbs at the appropriate voltage.
- If you suspect that the “electrolyte” has lost capacity, warm it up with a soldering iron. The electrolyte inside will boil and the capacity will be restored for a short time. The method helps with frame scanning malfunctions, 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 noise can be heard. Turn off the lights. In the dark you can tell where the sparks are coming from.
Video tutorials on troubleshooting
The video explains in detail how to replace LEDs on an LED matrix:
And about how to completely replace the matrix on a TV.
Sometimes there are atypical malfunctions 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 equipment to use when searching for them, and how to repair some problems with your video equipment. To fix more serious damage, you will have to contact a teleworkshop.
Hi all!
This article will talk about the simplest, but at the same time the most common, malfunctions of LG CRT TVs with a diagonal of 29 inches (72 cm).
Such malfunctions can be dealt with by having the skills to work with a soldering iron, as well as having normal vision. In this case, no more skills other than holding a screwdriver are required.
We will develop this topic on specific example, i.e. we will produce TV repair LG with your own hands .
So, I entered TV repair LG, model 29FS4RN, chassis MC-05HA.
According to the client, the TV periodically went into standby mode while watching (it turned off, but the indicator on the front panel glowed red). Then, one fine evening, the TV was turned off by the remote control, and the next day it did not turn on. Only after this did the client realize that there was something wrong with the device, and thus this television receiver ended up in my possession.
I’ll say right away that the malfunctions that will be discussed below are very typical for CRT TVs with a large screen diagonal, so the tips for eliminating them will be relevant for any brand of TV.
I tested this device and, indeed, the standby mode indicator glowed red, but the TV did not turn on in operating mode.
Next, I proceeded to disassemble the faulty device, namely, I unscrewed the back cover.
Then I removed the chassis (board) from the case.
Attention! Be careful when disconnecting the chassis from the picture tube! In any picture tube there is always a large current charge remaining. Therefore, disconnecting the high-voltage wire coming fromTDKSto the anode terminal of the kinescope (suction cup), use a well-insulated screwdriver (or something similar, non-conductive electric current). Slide a screwdriver under the suction cup, press the contacts under it and carefully, without touching the metal part of the screwdriver and the contacts with your hands, pull the rubber part of the suction cup to disconnect it from the kinescope. Remember, the current going to the anode of the kinescope has a voltage of 25 kV (25,000 volts).
Also, do not touch the contacts of the power capacitor with your hands (located in the primary power circuit, it is also called a “jar” because it is the largest) while it retains a charge. Under no circumstances discharge it in the board itself by shorting the contacts - this can lead to failure of the power chip. It needs to be carefully removed from the board, and then, at arm's length, bridge the contacts with an insulated screwdriver, thereby discharging it. And after that, solder it into place, observing the polarity.
In order not to forget the location of the various cables and wires that are disconnected from the board when removing the chassis from the case, you can take several photos so as not to get confused when connecting.
I will announce the composition of the LG TV on the MC-05HA chassis:
UOC - VCT6743G B3 080 (processor)
EEPROM - AT24C16A (memory)
SMPS - STR-F6458
TR Chopper - 6170VMCB16P
STBY - STR-A6151
Multistandard TV Digital - STV2310SD
Vertical - LA4876N (frame)
Sound - TDA7297 (sound)
Tuner - TAUD-S210D / 6700SP0001A
TV/AV - LA7222
FBT - 6174917003A BSC30-N2570 (TDKS)
HOT - 2SC5858 (line transistor)
RGB Amp. - LM2423TE
Remote control: - 6710V00145J, 6710V00112V
Entering service mode: Turn on the TV in operating mode and press MENU on the TV and MENU on the remote control simultaneously.
Output - OK.
Download TV circuit LG, chassis MC-05HA, as well as TV firmware , you can from "» of this site.
After removing the chassis, I began a visual inspection of the board.
First of all, I looked for swollen capacitors. If you suddenly find capacitors on the board that have even the slightest swelling, feel free to replace them with known good ones, or better yet, with new ones.
When replacing capacitors, keep in mind that they are polar, i.e. have “+” and “minus” pins, and are installed on the board accordingly.
So, no faulty capacitors were found during visual inspection.
Then I turned the chassis over printed circuit board up, took a magnifying glass and with the “armed” eye began to inspect the board for microcracks and missing solders.
During such an inspection, I discovered several cracks in the area where the TDKS contacts were attached (a diode-cascade line transformer), as well as peeling of some reinforced contacts in the same area.
A reinforced contact is a contact that is attached to the board not only with solder, but also with a metal washer.
After that, I soldered the cracks in the board with wires. During this procedure, I found another crack in the primary power circuit, which I also soldered with wire.
I also soldered all the reinforced contacts that are on this chassis. I soldered everything because there were cases when such a contact peeled off from the board and it was very difficult to notice.
After carrying out all the activities outlined above, it was necessary to install the chassis back into the body, which I did.
Well, it’s time to turn on the device for the first time after repair. What I got, look at the photo below:
As you can see, the TV is functioning.
That's it. It took me about 40 minutes to do everything.
Agree that there is nothing particularly complicated in this repair.
If, having examined your TV in this way, you did not find anything like this, and if at the same time you do not have certain knowledge about repairing radio equipment, then it is better to contact a professional so as not to aggravate the problem with your actions.
Few people can imagine a full-fledged home without video and audio equipment, and it is precisely because of regular and intensive use that this type of equipment is most often subject to breakdowns. TV repair can be done at home, if you call a specialist, or you can do all the work yourself.
Diagnostics
Before starting repair work, you should determine what exactly is broken in the TV. In any case, this will greatly facilitate both the independent repair process and explaining the essence of the problem to the TV technician.
Photo – Samsung designMain types of faults:
Of all the listed troubles, screen breakdowns are the most difficult to fix. For example, if light reflections appear on the monitor after an impact or water got on the matrix, it is better to immediately take the device to a service center, where it can be repaired under warranty.
Photo - details LCD and LED repair
But most repairs can be easily done by yourself. Let's consider in order how to implement urgent repairs home LCD and LED TVs Thomson (Thomson), Sharp (Sharp), Samsung, Panasonic (Panasonic) and other models:
In addition, a certain area of the backlight may burn out.
IN different models In television equipment, lamp replacement is done in different ways. For example, on many Daewoo, Akai and Hitachi TVs, in order to dismantle a burnt out lamp, you will need to remove the matrix from the panel and reinstall the element on it. At the same time, for some Rolsen (Rolsen) and Funai it will be possible to change a burning light bulb or diode without dismantling it. Depending on the design, you will need to bend (unsolder) the contacts, remove the gasket and carefully remove the burnt element from the housing. A completely similar lamp, both in parameters and in size, is installed in its place.
Photo – LCD monitor device Many Chinese models of television equipment - CTV, VAO, BBK - when disassembling you can see light stripes on the matrix. They indicate a breakdown of this particular element. Because of some external factors the part stopped working and oxidized. In this case, you need to select an element that is identical in terms of performance and install it in place of the faulty one.
Unlike old stationary CRT or portable models, plasma and ED options are very rarely repairable if the screen breaks. This is a very labor-intensive process, so not even all professional workshops undertake such work. In most cases, if the monitor is cracked, it will be cheaper and easier to buy a new TV than to repair the old one.
Video: PHILIPS TV repair
CRT repair
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