The backlight on the TV does not work

LCD TV backlight repair in Kharkov

Recently, liquid crystal televisions of different brands have gained widespread popularity. However, like any high-tech equipment, liquid crystal TVs in the process of operation can fail. One of the most common breakdowns of this home appliances is a malfunction of the backlight matrix. Therefore, if there was a problem with your TV, replacement of the backlight of the TV screen in Kharkov at our service center will help eliminate it.

Replacing the LED backlight TV cost is low and our master can perform this work quickly and efficiently. There are two reasons why the backlighting of the LED TV does not work, namely:

In order to identify and see for yourself whether you need to repair the backlighting of the TV matrix, you need to direct a lamp or flashlight to the screen of a working TV. Having made an external illumination, you should see on the screen of your TV images.

If the image on the screen is present, you can be absolutely sure that the problem lies in the backlight of the screen matrix. But even in this case, do not get upset, because our service center and there to have a qualified technician inexpensively repaired TV Samsung, Philips, Sony, Sharp, LG, Toshiba, Panasonic, or other brands.

Why you should not repair the backlighting of the TV matrix by yourself? Modern LED TVs are complex electronic devices. To fix it not only requires special knowledge about their circuitry and design, but also the availability of special tools and equipment.

Thus, unqualified intervention in the interior of the TV is dangerous for the TV. In this case, you can hit and break important components, as a result of which the cost of repair will be high or impractical. So it is not worth the risk, because the repair of TV screen backlighting price is low.

Principle of operation of LED / OLED matrices

The principle of operation of matrices in modern TVs is important to know for one reason. the failure of the backlight is not such a serious problem. The very screen of the receiver is made of millions of colored LEDs of low brightness. To be able to see a picture on the TV screen, the matrix is equipped with a bright white LED backlight. It is its light, which is subsequently colored by the LEDs/OLEDs of the matrix, that we see in the TV. The design of the LED screen module of modern television receivers has about the following form:

From the diagram, you can see that the backlight is an auxiliary component of the TV screen module. Failure of this device does not affect the operation of the screen. It’s easy to make sure. Turn on the TV (preferably so that there is no light in the room) and point the light from the flashlight on the screen. In the place where the light from the flashlight falls, the picture currently displayed on the screen will be visible. For example:

You can see in the picture that the TV screen is slightly visible in the place where the rays from the flashlight are falling. If in your case you observe the same picture, it means the TV matrix is working properly, which is good news because its replacement will cost about 70% of the cost of the TV. If you only need to repair the backlighting, the procedure is not that expensive.

What can be the causes of malfunction of the backlighting of the screen?

In fact, there are not many reasons for TV backlight failure, but as practice shows, this breakdown occurs quite often. Due to the fact that with a non-functional backlighting the TV loses the ability to perform its basic function. to display images, to use the device for its intended purpose is no longer possible, it is necessary to repair the TV.

The main causes of screen backlight failure:

High voltage. each of the LEDs in the backlighting system of the screen works under voltage. Without it the operation of diodes is impossible, but also the overvoltage turns out to be destructive for the backlight. Excessively high voltage very quickly puts diodes out of operation, and to stop the backlight completely, it is enough to burn out just one LED.

High load. each TV manufacturer gives the user the opportunity to choose the level of backlighting, its brightness. As a rule, this choice is to select one of the modes, such as “movie”, “dynamic”, “economy” and so on. When selecting the brightest parameter the load of supplied voltage increases on diodes which with time can lead to breakage.

Natural wear and tear. there is nothing everlasting, and if we talk about household appliances and electronics, this statement is especially true. Over the years, the TV backlight loses its original properties and ceases to be as bright as it was originally.

Failure of the LED-driver. a defective driver also provokes the lack of backlighting of the screen. In simple terms, the LED-driver is source of voltage for the LEDs, but a faulty driver is unable to provide the necessary voltage for the backlight.

Problems and repair methods for backlighting of modern LCD TVs

To date, the main problem of failure of LCD TV sets is a faulty backlighting matrix. The problem manifests itself as follows:

2.Backlighting of the matrix is flickering (on and off)

3.Darkening of some area of the screen (middle, top, bottom) and then, as a rule, no backlighting.

Caused by a faulty LED backlight matrix, which are soldered to the LED arrays. It often happens that because of one faulty LED the whole backlight does not work. There are several reasons for failure:

Miscalculation of the manufacturers. Very often in repair there are TV sets with the driver of the backlight set to the maximum or even overdriven current, which leads to overheating and failure of the backlight.

The second reason follows from the first. The owners themselves set the backlight of the TV at maximum (100%). And since manufacturers themselves also overestimate the current, operation in this mode greatly reduces the service life of the TV. It is recommended to set the brightness not more than 60-70%. This will significantly extend the life of the backlight.

backlight, does, work

It’s a defect of the LEDs themselves. Repeatedly in the repair there are TVs, in which one LED is defective, but the other diodes are in excellent condition.

What to do with this: how to correctly and reliably repair this malfunction?

The easiest and most reliable way. which does not require special equipment. is the replacement of all the LED bars on the original new (that’s NEW, not used or remanufactured REF from China). And everything would not be bad, but there are some disadvantages. The first minus. the price. The price of these rulers is pretty high, and as it is necessary to change all the rulers at once, the repair is poured into a tidy sum. Second disadvantage is that it is hard to find such new series. Most often you can buy them only for Samsung, LG, Philips, Panasonic, Thomson and not for all models.

The second way is cheap and also does not require any equipment. This is a replacement of faulty ruler(s) on used or reconditioned TV sets. This way is used by the majority of service centers, private individuals and TV owners who want to repair their equipment themselves. The main advantage of this method is the price of repair. Also to the positive sides of this way belongs the fact that you can find ranges with broken TV sets, which expands the possibility of repairing a variety of brands. The disadvantage of this method is the quality of repair. How much will work and what is the remaining life of these linear arrays. is unknown. But as a rule, they work 3-6 months and then get repaired again. If you are lucky then you might get the strip from practically a new TV with minimal wear and tear, then it will work for quite a long time. Accordingly, because of these disadvantages, we do not recommend doing repairs this way.

The third way. The most common and cheapest among TV repairers. is the repair of the light bars themselves. This method consists of replacing/re-soldering only the FAULT LEDs on the strip(s). This method is similar to the second method, but requires soldering equipment, at a minimum you need a soldering iron. The difference from the previous method is that you do not need to look for and buy exactly the same rulers. You can find or buy LEDs, usually from 1 to 5 pieces, which fit the parameters and size, or buy a second-hand line from another TV with these LEDs and remove them from there. The danger of such repairs is as follows: if the re-soldering even of new LEDs is done on cheap equipment with no temperature control (construction, soldering iron, iron, stove, oven, etc.), we will not perform such repairs.), then they overheat when they are removed (if they are removed from the used rulers) and when they are installed, which has an extremely negative effect on their service life. As a result we get overheated LEDs and the remaining, untouched LEDs with questionable life.

Repeatedly we met the repair, when a part of the ruler with defective LEDs cut out and put the same pieces of ruler with working diodes. It turns out a Frankenstein, but this lifetime is not increased, but the subsequent repairs are more complicated. Therefore, we do not carry out such repairs due to the questionable quality and durability of such equipment after repair.

The fourth method. high quality, inexpensive relative to the replacement of new linear arrays, but requires good equipment. This repair of LED arrays, replacement of all the LEDs for new ones: native original LED arrays are left, all the old LEDs are removed from them. New LEDs are selected according to parameters: current, voltage, body, and soldered using special equipment in place of the former.

Our service center uses this method of repair. We use good equipment from Thermopro: chamber furnace LED-580. Such equipment excludes overheating, t.к. Soldering is carried out according to a thermal profile with temperature control. We get the original strip with new LEDs, which are not subjected to overheating. In some cases, if the current in the driver has been overestimated by the manufacturer, it will be underestimated. The result is a cheaper repair, it all works for a very long time, not less than the new original linear arrays and repair a good warranty.

Causes of failure of the LED backlight

Since the backlighting function is provided by a chain of LEDs, failure of individual elements in this chain is not uncommon. If the backlight breaks, there is no picture on the TV, although there is sound and the response to control commands (channel switching, volume control) remains. Looking closely, you can distinguish the contours of the image itself on the matrix. However, the lack of backlighting does not allow the device to reproduce it properly.

LED backlighting fails easily, even in television brands with worldwide reputation. One of the reasons for this is that the manufacturers set the current transfer to the LED backlight to the maximum level. This provides a crystal clear and bright picture, but the LEDs working under increased voltage burn out rather quickly.

LED backlighting can stop working for two main reasons:

The main disadvantage is that even if one LED burns out, there is a break in the circuit, and the backlight is completely turned off. The TV needs to be disassembled. Repair of LED-backlighting is not so much expensive as a painstaking procedure. The master of the service center should determine what is the fault: the driver does not work or the LED burned out. After that find a damaged LED (or several), replace them with new ones, and check the voltage at all elements of the circuit to avoid a recurrence of faults in the near future.

When you need to replace or repair the backlight

Understand that you need to order the repair of LED-backlighting TV, you can on these signs:

  • The picture is gone (i.e. the device turns on, the channels are switched, the sound works, but there is no picture);
  • You may see dimmed lights on the screen (they may appear both in the center and on the edges);
  • The picture flickers, which quickly begins to tire your eyes.
backlight, does, work

In any of these cases it is worth to contact a specialist. It should be noted that self-repair attempts can lead to complete failure of the matrix and motherboard. So, better to leave everything in the hands of professional craftsmen.

LED TV backlight repair. View from the inside.

Doing the repair of LED TV. decided to share with you photos of how the LED backlighting is set up and why “eternal” LEDs fail faster than Soviet color CRT.

So we have an LG LED TV with a diagonal of 47 inches. 2014 model year. The owner was probably very pleased with the purchase and imagined that for many years, on cold winter evenings he would watch interesting programs and colorful movies. But something went wrong.

In about the fifth year (and that’s not a bad result) the image began to be covered with stains. And then it started to fade at times or flicker. Until it goes out completely. There is sound. And there is no picture. Sadness.

The owner of the TV took his already non-warranty set to the official service. Where he was offered to change 8 (!) of LED strips at 2000 each. And as you can easily guess from the repair with such a cost had to abandon.

But otherwise the repair becomes unprofitable for the customers. It is more profitable for manufacturers to inflate the price of complete ribbons so that customers go to the store for new equipment. So. replace the LEDs. although not ideal, but the best in terms of price and quality.

Also worth noting two important points in this operation.

  • IT IS NECESSARY TO CHANGE ALL THE LEDS IN ALL TAPES. And not just the ones that are burnt out. Because they are all degraded. Just some are holding on by the last breath.
  • MUST modify the inverter circuit to REDUCE the current. Otherwise, the LEDs will burn out again.

Unfortunately, many of our competitors don’t follow these rules. And it ends sadly. And the repair after such repair is much harder, more expensive and the end result can be worse. Not to mention the time, money and nerve.

Well, now the promised photos. Look powerful LEDs with lenses very mesmerizing.

Testing the backlight after replacing the LEDs.

In this TV there are two separate channels of backlighting, so a specialized diagnostic tool lights up only half of it. And then the second one.

Since all is well. proceed to the assembly of the matrix. First, all the LED beauty put on a reflector.

Reflector and a lot of latch-holds.

Once you have clicked a lot of fasteners, go to the next layer. the light diffuser.

Light diffuser

The frame, in which the most important component, the matrix, is inserted, is snapped on. It is made of thin glass. Which is very, very fragile. Any awkward movement and this TV will never please its customer. So you can only trust a trusted professional.

Well then it is necessary to modify the electronic circuit of backlighting so that the LEDs do not work at the limit of their power and do not degrade like this:

backlight, does, work

Why the manufacturer “twists” them so much is a mystery. Conspiracy? And what is interesting. after turning down the current. the difference in brightness level is not visible to the eye. And it becomes easier for the LEDs. DIGNIFICANTLY.

The TV board

In this case, to reduce the current is simple enough. It is necessary to remove two resistors. But in each particular TV, the method is different.

We remove the resistor R836 and a similar one in the second channel.

Then we assemble the entire TV set. Turn on. И.


Do a many-hour test run and give it to the owner. Without a TV as you know life is not the same!

Well and if you have similar or not similar problem with TV. contact us! To the Hard Service Center.

Podskazhi if you understand, gave the TV, just does not work lights, disassembled, thought blown which diode, checked each diode tester, when you check one by one all are lit, where to go next can dig?

Hi. Now check the switching cables, in general, look at the voltage, if it comes out of the power supply on the tape look for where it ends. If it doesn’t work, check the power supply board

Mia, me telamaster for a similar repair said 4-8 kopecks will cost.

I see that you know about it, and what if you just write a normal diode strips on a straight line, will it work.I am a student in the business, just picked up the TV, they thought the matrix is broken, gave me another spotlight in the garage, as a gift for the garage, and that turns out after you started to take apart, and the matrix is alive, but the diodes work, then do not work, then they can turn on and off, from the board where the LCD is wires on a separate board and already it goes on the diodes backlight.So I had a thought, but if this board should be thrown away and the diodes connect directly to the board with a CC, it says 24 volts.Or it’s just a bullshit in my head.

Why is it bullshit, I would call it creative engineering). The more so if you do not want to make the ideal you can do as you please). Tape can also be used, because of its cheapness you can stick a lot of it, just a carpet. If you want to experiment, of course do it. Find the tape as cool white as possible, and glue wisely)

Just think about the amount of tape at your voltage, so you won’t overload it. And it’s preferable to load the tape with 80% of the load. So the diodes wouldn’t light up.

The old ones came back to life, turns out the connectors are all oxidized.I just jiggled a couple at the beginning and they just blinked.Well, I thought that the board that goes with it and directly glue thought kolhoznye.and began to take out these tapes from the TV glued, from the connectors, and there all in such a thick oxide.I cleaned it up, just to check it out, and it’s working.Sprinkled a special liquid that I use in the car for connectors, though now on the screen stripes with fingerprints from this liquid, not much bothers of course, in Sonycu can play, do not stand out.

Just think about the amount of ribbon at your voltage so as not to overpower. And it is desirable to load the tape by 80 percent. So the diodes don’t burn.

Fuckwhy mess up the strip, just re-solder the dead diode to a NEW one and that’s it. I usually remove all the diffusers from the diodes, then examine and measure all the diodes with care. Yes, it’s a pain in the ass to glue all the lenses, but you have to be responsible. The diode darkened. to replace, diode with a crack of the compound. to replace, the diode has lost brightness or voltage higher than normal at the target current. to replace without any discussion. Even if they shine. The hardest part is getting the lenses aligned. For such work take 3000r price diodes (50r each), as a rule, on Chinese TV change every single diode on the original LGE. Repair of Chinese TV diagonal 40 “and above can get out 5000-6000r with diodes, but after changing their brightness increases by 1,5-2 times, improves color rendering, t.к. however after swapping them the brightness goes up 5-2 times the color rendering improves since all the supra-fushenes use shitty LEDs with low output and bad spectrum.

I’m kind of doing this in between, but I’ve already picked up about 30 televisions. The amazing thing is that none of them came back. Preparing to switch from laptop repairs to TV repair, buy LEDs, not a small investment in these LEDs, when you take 1000pcs of ribbons of different kinds (different enclosures, different wattages, different colors).temperature) I’m planning on replacing all the diodes.

Fuckwhy mess up the strip, just re-solder the dead diode to a NEW one and that’s it. I usually take off all the diffusers from the diodes, then examine and measure all the diodes. Yeah, it’s a pain in the ass to glue all the lenses, but you have to take it responsibly. Diode darkened. replace, diode with cracked compound. replace, diode lost brightness or voltage above normal at target current. replace without talk. Even if they glow. The most annoying part is exposing the lenses. For such work takes 3000r price diodes (50r each), usually on Chinese TV changing every single diode on the original LGE. Repair of Chinese TV diagonal 40 “and above can get out 5000-6000r with diodes, but after changing their brightness increases by 1.5-2 times, improved color rendering, t.к. suprafushen use shitty leds with low output and poor spectrum.

there the easier and ultimately cheaper ready-made diode with a diffuser and a piece of tape to cut. all brilliantly simple. Fresh approach, not visible to everyone when it works according to the canons. The main thing is the result, not how beautiful the tape looks or not