How to repair the LED backlight of an LG TV with your own hands

Even the best quality equipment experiences various glitches and malfunctions. Therefore, every user should be prepared for the fact that they will have to repair the equipment with their own hands, because paying for the services of service centers can go broke.

Today we will talk about the most popular failure - a malfunction of the LED backlight on LG TVs. It is with this problem that ordinary users most often turn to service centers. Few people know that you can normalize the operation of the device on your own. No special skills are required, the main thing is to follow the instructions.

Before you start repairing the LG TV backlight, you should first understand how this component works, what are its functions and why is it even needed?

What is LED backlighting?

The abbreviation LED stands for Light Emitting Diode, which is translated from English as a diode that emits light. Speaking specifically in the context of the television equipment manufacturing industry, this abbreviation denotes the type of liquid crystal matrix and backlighting with light-emitting diodes.

After a new type of backlight for LCD monitors was introduced, manufacturers began to replace the abbreviation LCD in model names with the designation LED. Of course, LG TVs are no exception to this rule.

In fact, the motive for such changes was more likely to be marketing objectives than real necessity. The fact is that LED backlighting of matrices is not a fundamentally new technology for manufacturing screens for television equipment. It's just an updated way of lighting. However, the trend has harmoniously taken root, so the term Light Emitting Diode is still actively used today.

The most common TV matrices are based on the use of a cold cathode lamp, essentially the same as fluorescent lamps. As for LCD and LED models, they are characterized by light-emitting diodes.

It's no secret that LCD screens consist of liquid crystal pixels. The position of the crystal in a pixel determines whether the cell allows light to pass through. This is actually how the screen glows.

The quality of the screen matrix is ​​determined by a huge number of parameters, in particular: the level of dark shades, viewing angle, static contrast, image refresh rate and even response time. Liquid crystal matrices are produced using several technologies. Let's list the most popular: TN, IPS, PLS.

As for the backlight itself, it affects brightness, color reproduction, coverage, and dynamic contrast. However, it is still worth evaluating the parameters as a whole, taking into account the type of matrix and backlight.

Thus, when buying a TV with LED backlighting, the user receives:

• balanced contrast;
• rich brightness;
• high picture clarity;
• color palette.

In addition, LEDs consume much less electricity, about 40%, than their counterparts. Fluorescent lamps, which are also used in the production of television equipment, contain mercury, which has a negative impact on the environment. In this regard, the advantages of LED are obvious.

There is no point in arguing; modern TV devices with backlighting consisting of LEDs ensure the transmission of the brightest image possible. Dynamic contrast appears - adjusting the brightness of the diodes for different areas of the monitor. The image becomes more realistic.

Regulating the glow of the diodes directly while watching TV also has a positive effect on the black level. When dark shades appear, the backlight level decreases, resulting in the screen becoming darker.

More possible problems and ways to solve them

Usually, expensive equipment is repaired at a service center, but sometimes the problem may turn out to be minor, and you can solve it yourself. Let's look at a few common problems and how to fix them yourself.

TV won't turn on

This problem is the most common, and almost every third LG TV owner encounters it. You shouldn’t immediately assume that TV receivers are of poor quality, everything is much more banal. The batteries on the remote control may be dead or the electrical cable may be damaged. Check that the plug fits tightly into the socket and that the socket itself is in good condition. If basic measures did not help or correct the situation, then you need to look deeper, namely in the hardware.

No image on screen

If the sound works, but the image is not displayed, then most likely the problem is the backlight. How to check the LED backlight on a TV is described above in this article. There may be several reasons:

• no current is supplied to the light bulbs if gas-discharge lamps are used;
• the diodes have burned out if strips with LEDs are used;
• scanning electrodes are faulty.

There is no image, but the bar is lit

The type of stripe can be different: located vertically and horizontally. This indicates that there is a problem with the sweep electrode. To confirm this, you need to connect another TV device with a working matrix. This situation can only be corrected by completely replacing the damaged part. If a spot appears on the display rather than a stripe, then the reason is most likely the same.

If backlight repair is required

Backlight repairs should be carried out in the following order:

1. Turn the TV device over and unscrew the fasteners on the back of the case.
2. Disconnect the cable from the chip boards.
3. Remove the latches on the matrix and unscrew the connecting elements.
4. Remove the top of the screen to access the diodes.
5. Use a tester to check the performance of each strip.
6. Identify the faulty strip.
7. Using hot air from a hair dryer, heat the tape under the strips and remove the faulty diodes.
8. Replace broken diodes.
9. Test the connection to the current and the flow of electricity.
10. If there are no problems, then tighten everything in the reverse order.

Reasons for backlight failure

High-quality television equipment can work for quite a long time, so problems with backlighting appear after an impressive period of time. Unfortunately, the same cannot be said about Chinese manufacturers.

Why is there no backlight? There are several reasons for the malfunction, let's analyze each of them:

1. A certain line of diodes has burned out. LEDs are characterized by a serial connection type, which means that if one element stops working, the entire component fails. However, voltage (approximately 200 volts) continues to flow to the light bulbs.

1. Problems with LED driver. The image disappears on the LG TV due to the fact that voltage, on the contrary, is not supplied to the LEDs, so they do not light up.

1. Manufacturing defects. Sometimes only one LED does not work, but the screen of the TV device does not light up.

1. The user sets the maximum brightness of the image, which leads to an increase in voltage, as a result of which the diodes cannot withstand and burn out.

1. Sometimes incorrect settings of the voltage supplied to the LEDs are the fault of the store where you purchased the TV. They try to attract customers with a bright picture.

Now you know why the LED backlight of your TV fails. This breakdown occurs quite often, but if you follow the manufacturer’s recommendations, you can significantly extend the service life of the device.

Professional repairmen using special equipment will determine which module has failed. How can an ordinary user understand that the backlight of the LG TV screen is not working? Now let's look at the basics of diagnostics.

Why do they trust us?

• Home visit within 24 hours. This is the corporate standard of our service. We arrive on the same day as your request, the next day, or when it’s convenient for you.
• Call and diagnostics of the backlight as a gift. If you agree to repair the backlight, we do not charge money for the visit and diagnostics.
• TV removal costs 0 rubles. We take the TV to the service center and bring back a working one completely free of charge.
• Convenient work schedule. We accept calls and visit clients daily from 8.00 to 22.00.
• Warranty 3 months. After the repair, we issue a receipt indicating the warranty period.

TV diagnostics

How to determine that it is the backlight that has failed? It all depends on the symptoms. For example, an LCD TV starts from the remote control, but there is no image on the screen. Point a flashlight at the screen and you will see a dim picture. Essentially, the flashlight functions as forced illumination.

Based on this, we come to the conclusion that either the LED driver or the backlight is broken. To specify the source of the problem, you should disassemble the TV and carefully inspect the hardware components.

Remember that you should only disassemble the TV case if you have previously had similar experience. If you don’t have the skills, then it’s better to contact a service center. Once again it’s better not to take risks. Since there is always the possibility of making things worse, that is, aggravating the initial breakdown.

To dismantle the back panel of an LG TV device, simply unscrew the special bolts that provide fixation. This is not difficult to do. First, disconnect the supply and remove the fasteners. If the cover still does not come off, then you need to find the blocking bolt.

With the back panel removed, you should check the backlight and output voltage. For example, if the backlight voltage is 100 volts, then the component has failed.

In most cases, LG TVs are equipped with an LED lens array, which is located around the entire perimeter of the screen, providing clear lighting. To get to this part and repair it, you must first dismantle the matrix.

Now you know what to do if the TV turns on, but there is no picture.

Where to get spare parts

Today, finding spare parts for your TV is not difficult. The easiest way is to order them from the model manufacturer. In this case, you can buy ready-made rulers assembled, with conductors, diodes and lenses glued to them. They just need to be installed in their regular places and connected. But there is a problem of long delivery and quite high prices.

The second option is to order LEDs in online stores or on the Aliexpress site. In this case, the price of the kit will be acceptable, but you will have to wait quite a long time. Finally, there is the option of going to service workshops in order to select and purchase light elements that have already been used.

Disassembling the product

Regardless of the model, television equipment is equipped with three key boards: main, T-con and power adapter. You will see them immediately after removing the cover.

Disassembling an LG LCD TV is an extremely complex and time-consuming process; use extreme caution as there is a risk of damaging other hardware elements. To carefully disassemble the TV, follow these recommendations:

• prepare in advance the work area and two tables close to each other, on which the components will be placed: matrix, LED strip, bar;
• Before starting disassembly, wash your hands to avoid contaminating the filters or matrix. In the future, this will negatively affect the image quality;
• special attention should be paid to decryptors; if you are not careful, you will simply break the cable.

Step-by-step instructions for disassembling television equipment:

1. Disconnect the cables and unscrew the bolts located between them to disconnect and remove the T-con board.

1. Remove the metal protective elements from the decoders. To do this, unscrew the fastenings located on the sides and the bolts. As a result, decoders will be supported exclusively by rubber mounts.

1. It's time to remove the front frame of the device. Unscrew the screws around the entire perimeter and place the product on the back panel. Remove the frame.

1. Turn the screen over while holding the matrix. The decoders should be on top, you can disconnect the rubber fasteners holding them, the main thing is to do everything very carefully.

1. We disconnect the matrix and place it on a previously prepared table so that it does not interfere with the backlight repair.

In principle, anyone can disassemble a TV device, the main thing is to be as careful as possible.

How to call a specialist

You can call a service engineer to diagnose and repair the matrix backlight by phone or electronically.

When contacting, be prepared to provide:

• Your name, phone number and address.
• TV brand.
• If possible, the diagonal of the screen (found in the operating instructions or you can measure it yourself; to do this, stretch a measuring tape diagonally between the corners of the screen).
• The day and time when it will be convenient for you to see the master.

On the day of the repair, the technician will call you in advance to confirm that everything is in order.

Determination of non-working LEDs

Previously, we looked at the process of disassembling the TV, now let's proceed directly to the repair. To replace the LEDs in the backlight, carefully unclip all fasteners and then remove the plastic frame. We remove the scattering films to open access to faulty elements.

The structure of the LED backlight directly depends on which particular model of television equipment we are talking about. For example, for LG 32LB582V there are three rows of LEDs for 6 pieces. Model 32LN541U has one more diode in each row.

Television equipment that uses this lighting technology is characterized by a series connection of diodes, so if only one element burns out, then absolutely the entire system will fail.

If the driver breaks down, the entire system will lose power. If only one diode burns out, then there will be voltage, but there is no proper lighting. The circuit is open. Therefore, you need to change the faulty LEDs of your LG TV for correct viewing.

Approximately, the backlight system has about 18 diodes; voltage measurements showed that 140 V is supplied without loading, which means that each element separately accounts for approximately 7.8 V.

Why are all these calculations needed? The voltage level of each strip and the total load allow you to calculate the power of the LEDs used. Finding a faulty system element is extremely difficult. If the fasteners are not burnt, then you will have to recheck absolutely all the diodes one by one.

Parts used in the repair

See other LEDs for LED backlight repair here.

4

Author of the publication

offline 4 months

Replacing LEDs

Replacing the backlight of an LG TV yourself is extremely difficult, and it is possible that you will encounter certain difficulties. Let's assume that during the diagnostic process you were able to identify a couple of damaged diodes. Purchasing a strip of new light bulbs is very problematic. Service centers do not supply these parts, so the only option is to purchase from the manufacturer. It is clear that you will have to wait a very long time for delivery, not to mention the cost.

To avoid buying a strip, you should replace the LEDs in LG LED TVs one by one. You can buy it on the market. Mostly they sell already soldered parts, but that’s okay, the main thing is that they work.

Remember that absolutely all planks are fixed with double-sided tape. Therefore, they need to be heated with a soldering hair dryer to loosen the fixation of the adhesive tape. Fix the LED strip in a special holder. Warm it up with a hairdryer from below, eventually the tin will melt. This is how the broken part is removed. Soldering is carried out in a similar way; this is the only way to change a part without damaging it.

Remember that in the factory, absolutely all lenses are attached with a compound, therefore, be extremely careful when dismantling them. Each of them will have to be installed in its place. So as not to disturb focus.

There is one more subtlety: it is possible that you will come across LEDs with a large negative platform, therefore, the positive one will be smaller. Trim the contact point to solder the diode.

If the paint is slightly damaged, that's okay. The remaining structural elements are soldered using a similar principle. As for the lenses, they need to be glued using superglue.

Prevention

To prevent the problem from reoccurring, you need to open the TV menu, find the backlight brightness in it (not to be confused with the screen brightness) and set this indicator to 75%. In this case, the lamps will function in normal mode, and they will be supplied with normal (and not 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 if you know the correct procedure and buy new parts, you can fix the TV yourself at home. However, if you do not have confidence in your abilities and experience in delicate electronic work, then it is better to use the services of a professional technician so as not to aggravate the situation.