Hello! In this review, I will tell you how to convert a monitor up to 24 "to LED backlighting. For this, kits of LED strips and a converter were ordered a long time ago, so the link is to the first seller I found. Look for someone who packs well)
I will redo the Benq q7t4 monitor.


So the monitor stopped turning on. To begin with, we will analyze and externally look at the power supply.
Each monitor is disassembled differently, usually on latches. In my case, screws + latches.


Outwardly, everything is fine, but the fuse burned out. I replaced it in the photo.


The case turned out to be in the transistor on the radiator - because of it there was a short circuit. We change.

I decided to check the high-voltage capacitor and not in vain - it is also under replacement

The monitor began to turn on, but the lamps lit up for a second and the power supply unit went into protection. When all the lamps were turned off, the protection did not work.
Let's change the lighting.
To replace it, you need to disassemble the matrix. The disassembly of many matrices is identical
I take off the chassis. To do this, unscrew the screws on the sides.


I'm removing the main board.


I remove the metal frame that holds the matrix itself. She keeps on the latches around the perimeter

Now carefully remove the board from the seats and leave it hanging on the loops. Be careful not to tear them!


Now turn over, holding the matrix so that it does not fall out. It is still slightly glued to the plastic frame, but this does not prevent its removal.


We remove the matrix and set it aside in a clean place. I put on a4 paper.


Now remove the plastic frame, it is held on by latches. In the corner, she broke me, it's okay


Next come light-diffusing films and plexiglass. Films may or may not be removed. I removed the glass with them.


Removing the lamp housing


Pulling out the lamps


The ruler itself with LEDs is designed for installation in a monitor with a diagonal of up to 24". To install in monitors with a smaller diagonal, you need to shorten it. There are marks on the reverse side for this.

We cut off the excess with wire cutters and glue it on 2-sided tape. I used narrow tape 0.3 mm thick

Now we collect everything in the reverse order. We make sure that dirt does not get under the films. Otherwise, it will be clearly visible on a light background.
Now it remains to connect the converter itself to the power supply.


So, on the right is the contacts for connection.
VIN - backlight power.
ENA - this contact is responsible for turning on / off
DIM - this pin should receive an analog dimming signal from the main board.
GND - common


So, finding food is not at all difficult. You need to find a place where the voltage comes in to power the inverter. I soldered the inverter fuse (indicated by the arrow), thereby completely de-energizing it, and soldered + the converter contact. Well, I dropped out the unnecessary details - they are no longer needed for work anyway.


Now you need to find the power and brightness contacts on the board. To do this, look at the diagram.
They are located on the connector to which the main monitor board is connected.
BRT_ADJ - brightness adjustment
BL_ON - on/off

We find them on the board, find out with the help of a multimeter which side of the connector has 1 contact.
Well, solder the wires to the desired contacts.


Now it remains to connect the LED strips and glue the converter in the free space inside the monitor.
ATTENTION! For good, it was necessary to check the LEDs before installing them in the monitor, but somehow I forgot about it. I was lucky, but you may have several LEDs and not light up. Therefore, we always check before installation.


So, the monitor is assembled, turned on. Everything worked, except that the brightness control was inverted (that is, 0 is the maximum brightness, 100 is the minimum). But this is not critical at all.


There are no highlights / irregularities, although the photo seems to be the opposite. But it's not! Is that the color shade is not warm. But this can be fixed with the settings in the monitor.

It's time to talk about the most common failure of modern LCD TVs. Every day, the call center of our service receives calls with the following content:

• No image on screen
• The screen went blank, but the sound remained
• No picture
• flickering image
• no visibility
• TV blinking red light
• Missing Image

As a rule, two types of backlight are used in LCD panels - lamp and LED:

• Lamp is a small electroluminescent lamp, similar in design to those used in the lighting of industrial and office premises. The TV panels in which they are used are distinguished by a pleasant warm picture.
• The LED represents the strips on which the LEDs are soldered. They differ from lamps in lower power consumption. The image when using this type of solution has a colder and brighter picture.

Above in the picture is the main component of the matrix lamp backlight, and below, respectively, the LED backlight bar.

Currently, lamp backlighting technology is not installed in modern LCD matrices. This is due to the global trend towards energy saving and ecology. Lamps are characterized by high energy consumption and contain mercury. We will talk exclusively about the repair of LED (LED) backlight.

There are two types of LED backlight:

• Direct LED - a design feature of this solution is the location of several horizontal, or vertical rows LED strips on the back of the matrix. The advantages of this design is the uniformity of image illumination and the ability to selectively control the brightness of the backlight in different parts of the screen, which has a positive effect on the quality of the display. Decreasing the brightness in the darker part of the image, or increasing it in the brighter part, makes the colors more contrast. The main disadvantage of this engineering approach is the higher TV thickness.
• EDGE LED - the location of one or two slats on the sides or bottom of the panel allows you to design especially thin TVs. The disadvantages of this technology are small dimming at the corners of the screen.

At the top of the photo is the Direct Led component, at the bottom is the EDGE LED. Pay attention to how the lenses and diodes are located. In the side illumination, they shine to the side, and in the back to the top.

This is what the Direct Led backlight looks like inside the TV panel.

Let's talk a little about the main causes of LED backlight burnout:

• The main reason for the output of LED diodes is that manufacturers force them to work at the peak of their parameters, which leads to accelerated burnout. We won't claim that tech vendors do this on purpose, but some suspicions are hovering in our heads.
• Another terrible enemy of diodes are power surges and thunderstorms. Often after such incidents there is a complete burnout of the backlight. In spring and summer, during thunderstorms, the number of vehicles with such defects coming in for repairs increases significantly.
• Also quite common is a factory marriage. Defective diodes already installed from the factory, or overheated during factory soldering. This is especially true for Chinese brands. We do not want to slander Chinese manufacturers, but often the repair of such radio-electronic equipment makes you sweat. This is due to the lack of such strict unification as that of Korean manufacturers.
• One burned-out LED can often also be the cause of a burned-out backlight. Imagine that there are 18 LEDs with an operating voltage of 6 volts. Accordingly, for normal operation, it is required that 18X6 \u003d 72 (seventy-two volts) come to the LED circuit. When one LED comes out of their system, the backlight, as a rule, does not close due to the zener diode in the LED case. It turns out that 72 volts enter the remaining 17 LEDs, which leads to accelerated burnout, when another LED diode dies, all the same voltage comes to 16 already. And so on until everything burns out, or the current protection of the control driver trips and forcibly turns off the backlight.

There are many types of LED strips. Often, in the same TV model and matrix, several completely different types of brackets can be used. It may depend on several factors:

• Place of production, the same panel model can vary greatly depending on the place of production of the TV. Russian, European and Chinese assembly can vary greatly in the type of components used.
• In the same model, matrices from different manufacturers and, accordingly, different slats can be used.
• Date of production - the manufacturer during the production cycle can change the structural composition. A trite reason for installing different spare parts may be the lack of the required spare part in the factory warehouse (they get out as best they can). In practice, sometimes you have to be very puzzled by suppliers in order to find the necessary spare part. Well, we always try to have in our local warehouse the most extensive range of blocks needed for repair.

Please note that all these brackets are installed in one Samsung TV model. The difference is only in the time and place of assembly (Europe, Russia and China). The strips differ significantly in the type of LEDs used, lenses, length and pitch.

LEDs also do not get tired of pleasing us with their diversity, differing in:

• current strength
• voltage
• Corps
• The location of the anode and cathode sites
• Soldering options
• Service life
• Luminous color temperature

Pay attention to how different the cases are.

Contact pads are also striking in their diversity. In addition, in the same case, the anode and cathode can be in two locations. Often, for craftsmen who are not familiar with such nuances, repairs end in complete burnout of the backlight, when soldering LEDs of the wrong polarity.

As a rule, we use original LEDs made in South Korea. For Chinese TVs, we use Chinese LEDs, respectively, except for cases of complete replacement. In such cases, we change Chinese diodes to Korean ones due to the much higher reliability of the latter.

Replacement of LEDs is carried out only if the required strips are missing due to the high labor intensity of the process. Re-soldering a complete backlight consisting of 50 LEDs usually takes one working day, it is much easier to install new strips.

Partial replacement of LEDs (replacing only burned-out ones) is a rather useless task, since after a short time neighboring LEDs begin to die. As a result, everything ends with new repairs every 1 - 2 months.

After the backlight is repaired, we limit the current by about 25 percent to increase the lifespan. This is a recommendation from manufacturers that is sent in the form of bulletins to authorized service centers. Again, bad thoughts arise about manufacturers who set brighter operating modes for factories at the factory, and if such equipment comes under warranty, they recommend forcibly limiting it at the hardware level.

For high-quality repairs, we use only original manufacturer's trims.

The photo above shows original spare parts for Samsung TVs. Having a negative experience with non-original components, we prefer to use only genuine Repair Kits.

Being responsible craftsmen, we are periodically surprised how other service centers perform such repairs. Below we give photographs of such unsuccessful examples. after-sales service by incompetent craftsmen using components of dubious origin.

Instead of a complete replacement of spare parts, the cut-out parts of the used slats were soldered on top of the relatives. Due to poor heat dissipation, they burned out within 3 months. In addition, the lenses were re-glued with Chinese “superglue”, as a result of which terrible spots appeared on the screen. The owner was unpleasantly surprised.

This terrible work was done in one of the "life houses". Not finding the necessary spare parts, the master decided to cut the backlight from other planks. The slats were poorly glued to the body, as a result of which there was a repeated burnout, without having worked even for three months. We made a complete replacement with a one-year warranty. As a token of gratitude, the customers brought us a full bucket of homemade tomatoes.

Another disgusting example of the clumsy work of the masters. Due to the installed non-original spare parts, the backlight burned out, the screen began to shine a little. I had to completely change the backlight. We ask readers to pay attention to the cloudy lens, this is a consequence of the fact that it was glued with cyanoacrylate. As a result of the evaporation of the adhesive, the lens became cloudy, for such work it is required to use epoxy adhesives.

Creativity of a rural radio mechanic. Diodes used to illuminate the premises were installed. The sloppy master also managed to damage the matrix, damaging the cable. Only at the cost of great efforts we managed to bring this TV back to life. The client in a very unforested way recalled a specialist who had made repairs before us.

An example of the work of one well-known Minsk service. After the repair, the TV did not work even for two months. The owners took him under warranty where he stayed for 2 months. Tired of the constant postponement of repairs, the owners took the TV and handed it over to our service center. The next day the TV set was ready, pleasantly surprising the customers. I had to completely change the lighting kit.

Another work of unfortunate masters that did not last even two months. The insert was not properly glued to the pallet, resulting in a very short service life. The client asked us to completely replace the backlight, tired of constant repairs in dubious workshops.

Instead of changing all the LEDs or replacing the slats, the master decided to cut and assemble the slats, which worked for about a month. In an hour and a half, we replaced all the work of the previous specialist and gave the customer a long guarantee, after which he left satisfied.

And this is how some other masters glue lenses. The result is horrible smudges on the screen. Judging by the color of the glue, certain unpleasant associations come to mind. In addition, this glue does not hold the lenses, by the time the TV arrived for repair, most of it had crumbled, exacerbating the already very poor picture.

The guys also managed to put instead of the original LEDs for TV backlighting, the diodes used in the lamps. The funny thing is that to make such a collective farm you need to spend quite a lot of time - to purchase LEDs and glue, to make repairs and diagnostics. And as a result, get low-quality work, spending both your own and the time of the customer. Although it was just necessary to install the original spare part from the manufacturer, which is not so difficult to find in specialized stores.

And here the master could not even glue the insert evenly, which, moreover, was from another TV. It worked for 2 weeks and broke down - when customers began to call a specialist with a request to make warranty repairs, he refused, citing the fact that he did not give a guarantee for his work. Turning to us, the client received a repair within three hours and an honest one-year warranty for all lighting.

But we saw such work - having dismantled the device, which visited one infamous service, which periodically becomes the hero of an article known to the Onliner site. This sheet is a reflector from Chinese TV. A feature of Chinese engineering is that, unlike the Koreans, the sheets are not fastened with latches, but are glued to double-sided tape. Masters with “hands from their shoulders”, instead of carefully cutting off the sheet, began to pull it completely tearing it. Not having a similar one, they decided to combine from what was available, as a result, having received such a miracle.

Let's summarize our article:

• Z It makes sense to replace LEDs completely, replacing only burnt ones leads to a short service life of the product.
• It is best to change the backlight components immediately with strips.
• Only original accessories should be installed. Savings negatively affect performance.
• You need to carefully approach the choice of workshops that carry out repairs. The wrong choice can lead to financial and time costs.

If the backlight on the TV works partially, for a short time or does not work at all, then straight arms, a set of screwdrivers, a soldering iron and several meters of LED strip will save the family pet.

Apparently, a few backlights are not working. Over time, they will all rest and the TV can only be used in radio mode. Let's fix the broken lighting. More precisely, change the old CCFL backlight to a modern LED.

Why change CCFL to LED?

In my understanding, CCFL backlighting is a monstrous but fragile monster, which consists of inverters (which give out dangerous voltage), backlights (thin and fragile), powerful metal shields for safety and a bunch of wires. And what exactly broke there - I have no idea. Perhaps the lamps need to be replaced (150 rubles apiece, and there are 16 of them). Maybe the inverter is faulty (it’s hard to find the same one in stock, and the price is more than 1000 rubles apiece). Basically a lottery.

And the LED backlight consists of an LED strip (1000 rubles for five meters), connecting wires (we will find in stocks) and any power source that produces harmless 12V (we will find it on the spot).

Advice for the Thrifty: if you are willing to wait a bit, then buy led strip on aliexpress. It's twice as profitable.

Preparing to replace the backlight

First of all, stock up on screwdrivers of all types and sizes. You will also need a soldering iron and soldering accessories. And it will also take several hours of free time (it took me 6 hours at a leisurely pace). And very, VERY much free space to expand all the insides of the TV and not lose anything.

If you are ready, there is nowhere to retreat, read on!

LED Strip for TV Lighting

I bought the most ordinary LED strip in a local store, without bothering with the characteristics, the warmth of the color and other things. I just didn't have any options. More precisely, there were two: either a tape for 60 LEDs (three diodes per 5cm segment), or a tape for 120 LEDs (three diodes for 25mm) - this is one meter. I chose the second one: the gap between the diodes is smaller, and the tape can be cut more accurately in place.

Connected all five meters of the tape to the power source. I found out that the current consumption does not exceed 1A.

Of course, the tape from the store will have all the certificates and parameters carefully indicated on the instructions. The tape will even have a tail for connecting to a power source, it will come in handy.

We disassemble the TV Philips Flat Tv 30pf9975

The back cover is fastened with 16 screws around the perimeter, 6 more are recessed in rather deep wells, 2 more above the main connector block and 1 on the side connector block. A total of 25 star screws.

After removing the cover, we will see this picture.

Here, two massive TV mount beams stand out clearly, they also need to be removed. Near the left beam, a pair of backlight inverters is hidden under a metal cover. Remove the cover, it is on the usual "plus" screws.

We release the inverters from all connectors and carefully remove both boards. I believe the inverters do not heat up sour during operation, so their boards are installed on a thermal pad. The gasket is not adhesive, but voluminous, so the board must be picked up and slowly peeled off from the thermal pad. You can try to poke the gasket with a knife, it will be faster, but it will turn out like this.

It is most convenient to hook the inverter board from the side of the contacts to the backlights, there is no thermal pad there.

Now that the high-voltage dangerous inverters have been removed, we connect the TV to the network, pick up a multimeter and poke into all the contacts in search of the coveted 12V line. It is important that this line only works when the TV is on and does not work in stand-by mode. First, let's check the power outputs of the inverters, of course.

Inverters operate from 24V, that's a bummer. But the sound amplifier board, among other things, receives 12V. We ask from her.

12V is taken from the sound amplifier board. Ground on the black wire (rightmost), +12V on the leftmost pin, or pin 4 from ground. The fourth is easier to solder. Therefore, let's take the connector that was carefully attached to our tape and solder it to the amplifier board. The wire can be clamped between the capacitors on the board.

Before we go all out, let's connect the tape and check if there is enough current from the amplifier to power the entire tape. And is the backlight working properly?

Hooray! The ribbon glows when the TV is on. And it does not glow when it is in stand-by mode. Now it's time to disassemble the TV to the end and replace the CCFL backlight with an LED strip.

We take everything we can. We remove the main fee.

We remove the power supply and the additional power supply board, remove the sound amplifier board.

An additional matrix cable will be found under the power supply. We take it off. The adhesive tape is only there because I already dismantled the TV. We pick up the dark brown holder up and pull out the train.

After that, you can remove the metal casing, under which there is a response backlight board. This board and the connecting cable to the inverters can be thrown away. The casing too.

We continue to disassemble and unscrew until we can pull out the central part with the screen from the TV.

Here we unscrew 14 screws along the edges of the metal frame and remove it.

Now unscrew the screws from the plastic frame. Then we carefully release the matrix loops (having previously removed the metal casing with the board from the back side, it can be seen in the photo in the upper left corner) and remove it.

Be careful with the matrix!

The matrix cannot be bent, so be extremely careful and set it aside on a flat surface.

Under the matrix there will be two thin matte films (do not confuse their order), a plexiglass substrate and ... Backlight!

On the sides, the backlight is in rubber bands, I bit out the wires of the lamps and pulled them out of the rubber bands (because otherwise it’s just soldering). It turned out like this.

Let's try our tape at the installation site.

It turned out 625mm of tape, that is, five meters is enough for exactly 8 segments. Therefore, the segments will be where the plastic holders of the CCFL lamps are now. Take a knife and remove the holders. We also bite out plastic spikes.

Now let's move to the lab. We cut the tape into 8 segments of 625 mm each, lay it with a snake and solder it sequentially. Remember to observe polarity!

After soldering, we carefully check our snake, check the polarity, and only after that we glue the tape in place old backlight.

It turned out pretty crooked. However, if you choose between not working at all and working at least somehow, then “it will do.” Now we collect everything in the reverse order. Extra parts will remain from the old backlight: inverters, cables, protective metal casings and fastening screws. And inside the TV will become more spacious, like this.

Please note: I did not shorten the wire going to the backlight. In the future, it will be possible to make a variable resistor on the case and control the brightness. And now the cable is laid in the old fasteners of the inverter loops.

In the near future, a smart-tv board or some kind of raspberry pi can be placed in the place of the inverters, there is enough space here.

We finally assemble the TV, hang it on the wall, connect all the cables and watch. Unlike CCFL lamps, which shine in all directions, the LED strip gives a fairly directional light, so it is not weakly visible against a plain background.

If I bought an LED strip on aliexpress, I could buy two five-meter skeins for the same 1000 rubles and make 16, not 8 segments. I would have had a more even illumination. But, as I said before, it will do. Just compare with what it was.

LED backlighting is almost invisible against a heterogeneous background, that is, watching TV shows is quite comfortable.

Now about shortcomings. The backlight brightness is not adjustable. But eight segments give an average level of brightness. I plan to add another 5 meters of backlighting to make it more uniform, but ... To be honest, repeating a complete many hours of disassembling the TV is very lazy. Perhaps someday...

And now to the benefits: the TV has lost 1100 grams. Here are all the extra details on the scales.

I successfully sold all these parts at auction. And he saved 10 rubles. But I learned from the buyer that 90% of the problems are in the backlights, that is, it was enough to replace them ... If I knew where to get just such, I would have done so.

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Hello!

Sometimes when refurbishing LCD illumination , there are difficulties in acquiring the necessary fluorescent (CCFL ) lamps . In such cases, you can convert the lamp backlight to LED. Such an alteration is not so complicated, and there are no special problems with spare parts.

In this article, I offer you the principle of such a reorganization in the form of some instructions.

Replacement steps LCD illumination to LED:

Disassemble the monitor or TV. After removing the plastic case, carefully disconnect the wires from the board, remove the metal frame from the LCD module and remove the matrix. With the matrix, you need to be especially careful not to damage the fragile connecting cables. If everything is done correctly, then full access to the electronic board, power inverter and backlight elements will be open.

2. Remove the canisters with lamps from the matrix or the lamps themselves, if they are installed without canisters.

3. Disconnect the old lamps and dispose of them. With elements CCFL You also need to be extremely careful, because they contain mercury.

4. We proceed to the replacement stage. First you need to purchase an LED strip, preferably with a margin so that it is enough to replace all the lamps (measure the length of the lamp and multiply by their number). It should be as narrow as possible and with at least 120 LEDs per meter. To make the backlight more pleasing to the eye, it is better to take LEDs with a white glow.

5. Tape with LEDs must be glued to double-sided tape where the lamps were. Next, wires from old lamps are soldered to the contact leads of the tapes and insulated with hot glue. You can immediately check the performance of this design by connecting the wires to an external power source.

6. Now you need to connect the backlight on the power board of the monitor or TV. To do this, you need to find the jumpers marked with the inscription "12 V" and solder the backlight wires there, respectively, observing the polarity. Assemble the monitor in reverse order and enjoy your invention.

Backlight in this case, it will work when the device is connected to the network.

To control the backlight, and bring it to normal operation, you will have to work harder. The wires leading to the LEDs must be powered in such a way that it is possible to turn on the backlight when the on / off buttons are pressed and adjust its brightness. There are 2 options for this:

1. We independently create a power supply circuit and adjust the brightness of the backlight:

• On the monitor or TV power supply chip, we are looking for a plastic box (connector) with wires pulled out of it, where each socket is signed on the board.

• Here we are interested in the output of "DIM". He will be responsible for signaling on / off and adjusting the brightness by changing the duty cycle in the PWM controller. The duty cycle of the pulses changes until the desired brightness level is set, and the limit values ​​​​just correspond to turning on and off.

• Now we need any N-channel field effect transistor (field worker). Wires from the LED strip with a minus are soldered to its drain (Drain), a common wire from the backlight is also connected to the source (source), and the gate (gate) through a 100-200Ω resistor and any wire is connected to the “DIM” output.

• We still have wires from the backlight with a plus, we output them to the + 12V power source on the microcircuit and solder them.

• Now we set the backlight to its rightful place and assemble the monitor in reverse order. Do not forget about caution and accuracy in handling the matrix and filters, so that dust does not get in and the cables are not damaged. Everything can be used.

1. The second way, more expensive, but convenient, is to buy ready-made LED backlight with own inverter :

• Again, pay attention to the plastic connector and the DIM (brightness) pin and the on/of pin (better to use the pinout).

• Using a multimeter, the places on the control unit of the old lamps are determined, from which the signal goes to brightness and on / of.

• Now soldered to the found places of the wire inverter new LED backlight .

• Still, it is better to unsolder the jumpers from the inverter power supply of the old lamps so that the backlight is regulated by the new inverter.

• If, after turning on the LCD TV panel, the user hears sound, but there is no image on the screen, this may indicate a failure of the LED backlight. To diagnose and troubleshoot, you can call a representative of the service center, but, knowing the procedure, having spare parts and the necessary tools, you can repair the TV's LED backlight with your own hands. The rules and algorithm of actions of this process are later in the material.

  Causes and symptoms of faulty backlight

  The TV screen consists of many dots - pixels located close to each other, and in order for the user to see the image, light must be supplied to them, then they “come to life” and form a picture. LED technology in LCD TVs is a new way of backlighting the screen using LEDs, which has replaced CCFL fluorescent lamps. LED-backlit devices are characterized by excellent color reproduction, high contrast, incredible clarity and realism of the image, low power consumption and small thickness.

  Backlight types

  Depending on how the LEDs are arranged, there are two types of LED backlight:

  • edge (end, side) illumination involves the location of the LEDs on the left and right edges, top and bottom, or around the entire perimeter;
  • direct (matrix) illumination means the distribution of LEDs over the entire area of ​​\u200b\u200bthe matrix.

  With the first type of LED arrangement, it is impossible to achieve uniform illumination of the screens. In the second case, the diodes are located along the entire matrix, which ensures uniform illumination of the entire display, as well as the highest contrast and rich black light.

  Causes of failure

  If the user turns on the TV and finds that there is no picture or video, but the sound is played, this may indicate a breakdown of the backlight.

  Important! To make sure that the backlight is malfunctioning, it is enough to direct a burning lantern at the screen. If a picture appears, this confirms the assumption.

  

  There are several reasons why LED lighting fails. First, maybe diode strip damaged. The LEDs are connected in series, which means that if at least one stops working, the entire strip will go out. In this case, the voltage will continue to be applied. Secondly, maybe brokenLED-driver. In this case, the lamps do not receive an image, so they do not light up.

  Sometimes the TV comes with a marriage even from the factory. After all, just one faulty LED is enough for the TV screen to not work. In other situations, the lamps burn out due to the fault of the user, who sets the maximum brightness of the screen - the voltage rises, the LEDs cannot cope with it and burn out. The store may also be to blame for the problem, in which the sellers are trying to attract the attention of customers with a bright image on the TV panel screen.

  

  Troubleshooting

  To fix the problem, you need to understand whether the LED strip is really the cause. For this purpose, you need to disassemble the TV receiver and inspect its components.

  Advice! If the user is not sure that he will be able to correctly perform all the necessary actions, he should contact the specialists in order not to risk the device and prevent the situation from worsening.

  For diagnostics, you need to partial disassembly TV panel and a number of measurements. So, the TV needs to be placed face down on a hard surface, for example, a table covered with a blanket or sheet, in order to prevent damage to the matrix. Next, remove the leg, and then unscrew all the fasteners holding the back cover, and remove the latter to the side. If it is not removed, you need to find the bolt that is not unscrewed and remove it.

  

  Now measurements. First you need to check the voltage on the driver. If the output value is 220 volts, this means that the part is working and is supplying power to the tape. Next, you need to diagnose the backlight in the same way. If it is faulty, the value will be 100 volts. For repair, the user will need to remove the matrix.

  On a note! Typically, LCD TVs use special LED strips with lenses that provide even and clear illumination of the matrix.

  What you need to fix the breakdown

  To fix the problem, the user will need a tool, as well as new LEDs. Buy LED strip in service center it will not work - they are not ordered and sold there. It is possible to order such a product from the manufacturer, but the delivery will take a very long time, and the price will be too high. The best way out change faulty LEDs.

  Advice! Work lamps can be found in markets, repair shops, services, etc. The main thing is that they are in good order, so you can even buy soldered ones (from non-working TV receivers).

  

  On different models the same company can have a different number of LEDs. For example, if on a 32-inch LG TV 32LN540V-ZA there are only 21 LEDs (3 rows of 7 lamps), then on 32LB522U this figure may be different. In addition, the larger the diagonal, the more LEDs are used to illuminate the matrix. For example, on Samsung TV UE40ES5507K has 112 bulbs installed. Therefore, you can determine the number of elements in your television receiver, just sorting out his.

  Disassembly of the TV receiver

  The LED replacement steps are the same on all TV panels, be it LG, Samsung, Philips, Toshiba or another brand of equipment. Before starting work, you should prepare: next to the table on which the TV lies, put a second one to put the details (matrix, LED strip, panel). Then you need wash your hands thoroughly so as not to leave dirt on the matrix or filters, which, after assembling the TV receiver, can have a deplorable effect on the quality of the picture.

  

  Advice! When disassembling the TV panel, you need to be very careful with the decoders - any careless action can tear off the cable.

  Every TV, regardless of the receiver, has three key boards:main, T- conand power adapter. They are easily found immediately after removing the back panel.

  To disassemble the TV receiver, you need:

  • remove and pull out the T-con board, after unscrewing the fasteners and disconnecting the cables;

  

  • remove the metal protection from the decoders by disconnecting the side fasteners and removing the bolts, after which only rubber fasteners will hold them;

  

  • unscrew the bolts holding the front frame, turn the TV receiver on the back side and remove the frame;

  

  • carefully turn the TV over, holding the matrix;
  • disconnect the rubber clips holding the decoders;

  

  • remove the matrix and set aside.

  Debugg

  To gain access to the LED strip, you need to remove the plastic frame, after removing the fasteners. You also need to remove the films that scatter light. In television receivers with LED backlighting, the LEDs are connected in series, which means that if one of them is damaged, the rest will not light up. To fix the breakdown, you need to replace the LED with a new one. If there are no signs of burning, you will need check each one separately.

  Plank testing

  In order not to test all the LEDs, you can apply voltage separately to each bar. If the lamps on it are intact, it will glow. Otherwise, you need to ring each LED on the bar. Usually it has contacts for connecting a multimeter. Probes should be connected polarity. When connected correctly, the entire LED lights up. If the multimeter is connected correctly, and the lamp does not light or shows a short circuit, this indicates that it is faulty.

  

  Replacement

  To eliminate the damaged element, you need to remove the reflective lens from it. The bar is fixed with double-sided tape, so to dismantle it, you need to warm it up with a hair dryer. Next, you should securely fix the part and heat it with a soldering dryer from below near the LED until the tin melts and the lamp can not be disconnected. A new LED is soldered in the same way or with a very thin soldering iron.

  Important! It is necessary to act very carefully so as not to melt the diode during heating. If the LED does not fit, then the negative pad (usually it is larger than the positive one) must be carefully cut and then the lamp soldered.

  
  If lenses are removed during operation, it must be borne in mind that they are fixed with a compound - a polymer resin that acts as a protection and insulator. They should be disconnected very carefully, and reinstalled in their original place - with superglue and in the same position so as not to disturb the focus.

  Exist another way to replace, which is relevant when it is almost impossible to melt a damaged LED. It is necessary to cut out a faulty lamp with a hacksaw along with parts of the bar on both sides. The same steps must be performed with a new part. After that, it is necessary to remove the paint from the tracks on the piece with the LED and on the bar and carefully solder them.

  

  Completion of the repair

  Having completed the work on replacing the LEDs, before fully assembling the TV panel, you need to connect the voltage to the strips and check whether the ribbon is lit. If all the lamps are functioning properly, it is necessary to restore the TV receiver in the reverse order, performing all the steps as carefully as possible.

  Advice! If the user took photographs during the disassembly of the TV panel, it is recommended to refer to them during assembly before each action.

  After the equipment is assembled, you need to install it in its original place, connect it to the network and turn it on. If the image is good, there are no light or dark spots on the matrix, as well as any spots, this indicates that the work has been done correctly and the LED backlight repair operation has been successfully completed.

  

  Prevention

  In order to prevent the repetition of the malfunction, you need to open the TV receiver menu, find the brightness of the backlight in it (not to be confused with the brightness of the screen) and set this indicator to 75%. In this case, the lamps will function normally, and they will receive normal (rather than increased) voltage, which will significantly extend their service life.

  So, if the TV does not display an image, but there is sound, very often the reason lies in a faulty LED backlight. To repair it, you can resort to the help of a specialist, but, knowing the correct procedure and buying new parts, you can fix the TV yourself at home. However, if there is no self-confidence and experience in fine electronic work, then it is better to use the services of a professional master so as not to aggravate the situation.

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