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No image on LG LED TV: LED strip and backlight repair. LG TV LED backlight repair LG TV matrix LED backlight repair

If, after turning on the LCD television 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 fix the problem, you can call a service center representative, but if you know the procedure, have spare parts and the necessary tools, you can repair the LED backlight of the TV yourself. The rules and algorithm of actions for this process are further 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 applied to them, then they “come to life” and form a picture. LED technology in LCD TVs is a new way to backlight the screen using LEDs, replacing CCFL fluorescent lamps. LED-backlit devices are characterized by excellent color rendering, high contrast, incredible image clarity and realism, low power consumption and small thickness.

Backlight types

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

  • edge (edge, side) lighting involves the placement of LEDs along the left and right edges, top and bottom, or along the entire perimeter;
  • Direct (matrix) backlighting indicates the distribution of LEDs over the entire area of ​​the 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 discovers that there is no picture or video, but the sound is still being played, this may indicate a backlight failure.

Important! To verify that the backlight is faulty, just point a burning flashlight at the screen. If a picture appears, this confirms the assumption.

There are several reasons why LED backlighting fails. Firstly, 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 supplied. Secondly, maybe brokenLED-driver. In this case, the lamps do not receive an image, so they do not light up.

Sometimes a TV comes from the factory defective. 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 screen brightness to maximum - the voltage rises, the LEDs cannot cope with it and burn out. The problem may also be caused by a store where salespeople try to attract the attention of customers with a bright image on the television panel screen.

Troubleshooting

To troubleshoot the problem, you need to understand whether the LED strip is actually causing the problem. For this purpose, you need to disassemble the television 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 a specialist in order not to risk the device and prevent the situation from worsening.

To diagnose you need to perform partial disassembly television panel and a series of measurements. So, the TV needs to be placed screen down on a hard surface, for example, a table covered with a blanket or sheet, to prevent damage to the matrix. Next, you should remove the leg, and then unscrew all the fasteners holding the back cover and put the latter aside. If it cannot be 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 operational and supplies 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 repairs, 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 is needed to fix the problem?

To fix the problem, the user will need a tool, as well as new LEDs. You won’t be able to buy an LED strip at a service center - they don’t order or sell them there. It is possible to order such a product from the manufacturer, but delivery will take a very long time, and the price will be too high. The best way out is replace faulty LEDs separately.

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

Different models of the same company may have different numbers of LEDs. For example, if an LG TV with a diagonal of 32 inches 32LN540V-ZA has only 21 LEDs (3 rows of 7 lamps), then on a 32LB522U this figure may be different. In addition, the larger the diagonal, the greater the number of LEDs used to illuminate the matrix. For example, the Samsung UE40ES5507K TV has 112 light bulbs. Therefore, you can determine the number of elements in your television receiver by just disassembled his.

Disassembling the TV receiver

The steps to replace LEDs are performed the same way on all television panels, be it LG, Samsung, Philips, Toshiba or another brand. Before starting work, you should prepare: next to the table on which the TV is lying, place a second one to put the parts (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 detrimental effect on the quality of the picture.

Advice! When disassembling the television panel, you need to handle the decoders very carefully - any careless action can tear off the cable.

Any 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 television 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 in place;

  • Unscrew the bolts holding the front frame, turn the TV set over to the back and remove the frame;

  • carefully turn the TV over while holding the matrix;
  • disconnect the rubber clamps holding the decoders;

  • remove the matrix and put it 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 the light. In TV receivers with LED backlighting, the LEDs are connected in series, which means that if one of them is damaged, the others will not light up. To fix the problem, you need to replace the LED with a new one. If there are no signs of burning, you will need check each one separately.

Testing the bar

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

Replacement

To eliminate a damaged element, you need to remove the reflective lens from it. The bar is secured with double-sided tape, so to dismantle it you need to warm it up with a hairdryer. Next, you should securely fix the part and heat it with a soldering hair dryer from below near the LED until the tin melts and the lamp can be disconnected. The new LED is soldered in the same way or with a very thin soldering iron.

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


If lenses are removed during work, it must be taken into account that they are secured with a compound - a polymer resin that acts as protection and an insulator. They should be disconnected very carefully, and installed in their original place - using superglue and in the same position so as not to disturb the focus.

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

Completion of repairs

Having completed the work of replacing the LEDs, before completely assembling the television panel, you need to connect voltage to the strips and check whether the tape is lit. If all the lamps are functioning properly, it is necessary to restore the television receiver in the reverse order, performing all actions as carefully as possible.

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

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 highlights on the matrix, as well as any spots, this indicates that the work was done correctly and the LED backlight repair operation was successfully completed.

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.

The best TVs according to buyers

TV LG 43UK6200 on Yandex Market

TV Sony KD-55XF9005 on Yandex Market

TV LG 49UK6200 on Yandex Market

TV Sony KD-65XF9005 on Yandex Market

TV LG OLED55C8 on Yandex Market

Without such backlighting, no LCD TV can operate normally, regardless of its brand. We will tell you how you can repair your TV's LED backlight at home using an Lg device as an example, and what you will need for this.

How can you tell if the backlight is broken? Let's assume that the problem with the LCD TV is as follows: it turns on from the remote control, but the screen does not light up (if your TV does not turn on even from the remote control, read about). When pointed at the display flashlight light(i.e. forced illumination is applied), then the image appears. Verdict - the ice driver or similar backlight does not work, perhaps due to the fact that the special lines with soldered LEDs have burned out. You need to disassemble the TV and visually inspect the parts to find a fault.

Attention! You can only open the case of an LCD TV if you have the skills to work with complex devices and a little experience, otherwise it’s better not to risk it.

Remove the back cover For any LG TV, this is not a difficult task, you just need to do everything carefully and without haste: disconnect the legs of the stand and unscrew the mount around the entire perimeter of the product. If the cover does not come off, it means there is a blocking bolt, you should not make any effort, you need to find it and unscrew it.

After removing the back cover, check the output voltage.

If it is normal, we check it voltage ice backlight the screen itself. Its value is only 100V, which indicates a malfunction in the backlight of the LCD TV.

These TVs use a special LED set with lenses that are installed across the entire screen area to provide clear illumination. To get to them and repair the LG TV backlight, you must first remove the matrix.

Disassembling the product

The TV has three main boards - main, T-con and power supply, all of which are clearly visible in the photo.

Removing and disassembling the matrix do it yourself - the work is very painstaking, one careless movement, and you can buy a new TV, so without experience it is better not to undertake repairs. Experts highlight the following main points when disassembling the matrix:

  • it is necessary to prepare a work area and two tables on which to lay matrices and scattering films;
  • Before starting this work, you should thoroughly wash your hands so as not to accidentally leave traces of dirty fingers on the filters and the matrix itself - this can harm the quality of the image later;
  • Special attention should be paid to decoders - one inaccurate movement can lead to a break in the cable.

Subsequent dismantling is carried out in several stages.

Troubleshooting

Now the actual repair of the LED backlight of the TV begins: to do this, you need to carefully unclip all the latches along the contour, remove the plastic frame and remove the diffusing films to expose the LEDs.

Different models of LG TVs will have their own set of LED backlights: for LG 32LN541U there are three rows of 7 LEDs, and for LG 32LB582V there are three rows of 6 LEDs.

In all TVs that use such backlighting, the LEDs are connected in series, so if one of them burns out, the entire system stops working. If the LED driver is faulty, then no voltage is supplied to the entire system, and when one of the LEDs burns out, then the voltage flows, but all the efforts of the device to illuminate the system are in vain: even if you supply 200 volts, the circuit is open.

As we can see from the photograph, the backlight consists of 18 LEDs; during measurements, the voltage without load was 140 V, that is, each one accounted for 7.8 V. When we take into account the voltage drop on each strip and the total load, the conclusion will be as follows: this model uses 6V LEDs.

Finding a burnt-out LED is not easy: if there is no burnout at the mounting location, then you need to check each element separately.

Replacing LEDs

Replacing the Lg TV backlight can be a bit of a hassle. Let's say that the test results revealed several faulty LEDs. It is quite difficult to buy a replacement bar - these parts are not supplied to service centers, you can order them on the manufacturer's website, but this is time-consuming and very expensive. So there is only one way - replace individual diodes, although it will not be easy to find them on the radio market. Experts assure that you can buy already soldered ones, but in good working order; after a long search, these are exactly what we purchased.

Users should be aware that all planks are glued using double sided tape, so you need to warm them up with a special soldering hair dryer so that the adhesive tape comes off. To do this, the bar is fixed in the holder and heated from below with a hairdryer, the tin is melted, and the faulty part is removed. Soldering should be done using exactly the same method to avoid damaging the LED.

Important! All lenses are secured with a compound at the factory, so when removing them you must act very carefully, and each one must then be installed in its original place so as not to disturb the original focusing.

One more nuance: you may come across LEDs whose negative pad is slightly larger than the positive one, so you need to trim the contact point in order to solder the diode. This is what a soldered LED looks like:

The fact that the paint is a little damaged is not a problem. We solder the rest of the LEDs in the same way, and Glue the lenses with superglue. And this is a repaired view of the backlight panel assembled and ready for further use:

As we see in practice, there are many specific nuances in repairing the LED backlight of an LG TV matrix, and without knowing them, it is impossible to achieve a positive result.

Final works

When the LG TV system has been completely repaired, before final assembly, we connect the voltage to the strips and check the glow of all LEDs. If everything is fine, then we assemble the TV, performing all operations sequentially and with caution, as during dismantling.

After finishing, it is better not to turn the backlight brightness to maximum, but to limit it to 75% - in this mode, the LEDs operate in normal mode and, according to experts, will last much longer.

We install the TV in its original place, turn it on and enjoy the quality: if there are no extraneous spots of light or dark color anywhere on the screen, it means that the repair was carried out correctly, in compliance with all recommendations. And you can get the most out of your TV by learning how to properly

The most reliable LG TVs of 2018

TV LG 22LH450V


TV LG 49UJ651V

TV LG OLED55C8

TV LG 55LJ622V

TV LG 55UK6100

LED backlight repair involves disassembling, diagnosing and replacing burnt-out LEDs in an LCD TV. This requires knowledge, skills in soldering and repairing household equipment.

You can start work only when you have:

  • soldering gun or station;
  • professional measuring instruments for electrical circuits;
  • a set of screwdrivers, tweezers and other tools;
  • workplace;
  • spare parts.

The latter may be the main difficulty. The LED model can be found out in advance on specialized thematic forums, but if this was not possible, then it will only be possible to find out after completely disassembling the panel. Some manufacturers offer the supply of not just one individual luminous element, but the entire bar. It must be ordered in advance.

When you turn on the TV using the remote control, there is sound, but no picture. If you look closely, you can see it on the matrix, or even better, direct a beam of light from a flashlight onto the display, you will see that the image has appeared. This means that the backlight of the LCD TV does not work on the TV. It follows from this that there can be only two reasons:

  • The backlight control driver is faulty;
  • The LED backlight itself is faulty, that is, one or more lines with soldered LEDs have burned out.

How LG repairs are done. Let's look at this using model 32LB582V as an example. LED TV LEDs are connected in series. When at least one of them burns out, the circuit breaks, so the entire backlight stops working.

If the reason lies in a faulty driver, then the LEDs will not connect because there will be no voltage supplied to them. You will have to disassemble the TV to visually inspect all its parts and find the fault. To do this, first remove the back cover, disconnect the legs of the stand, and then unscrew all the fastening bolts around the perimeter. If after this it still does not come off, then you need to find the blocking bolt and unscrew it.

After removing the cover, check the voltage. The output voltage from the driver is 220 volts. This means that it is working properly and is trying to illuminate the LED backlight.

Now we check the voltage of the LED backlight itself. If it is very small, for example, only up to 100 V, this indicates that the backlight of the LCD TV is faulty. There was a need to get to the LED strips, which, to ensure good lighting, are installed in the TV across the entire screen. To get to it, you will have to remove the matrix.

Disassembly

Disconnect the device from the network. The TV has the following main boards: main, T-con and power supply. The most difficult work, which requires maximum care, is associated with removing the matrix. You have to be very careful here, make the wrong move and you can be left without TV. Necessary:

  • prepare free tables to have enough space to stack the removed parts;
  • hands must be clean and not leave marks on the matrix and other parts;
  • you have to be extremely careful with decryptors so as not to make a break.

First, you need to disconnect the cables that go from the LCD panel to the T-con board and unscrew the bolt between them. Carefully remove this board, as well as the metal protection from the decoders, by unscrewing the side bolts. Now only rubber fasteners will hold them.

To remove the front frame of the TV, unscrew its mounting bolts along the contour. After this, place the TV on the back wall and remove its frame. Now you have to turn the screen over again. We must remember that the matrix is ​​not fixed, so they do this very carefully, holding it. Now the decoders will be on top, carefully remove them from the rubber mounts. We take the matrix and place it on a table prepared in advance.

Troubleshooting

Now we need to get to the LED lines and find the fault locations. Carefully release all the latches that are located along the contour. Remove the frame and remove the scattering films (reflectors) under which the LEDs are located. All LEDs in the line are connected in series, which means if even one LED burns out, the system will fail. After all, a burnt-out LED breaks the power supply circuit for the entire LED backlight.

Each TV model has a different number of diodes in LED strips. For example, the backlight system of the LG 32LB582V TV consists of three rows of 6 LEDs. Some TVs may have 3 lines of 7, or five lines of 9 LEDs. Inspect each line of LEDs visually; if you can find a burnt area, this will make it easier to repair the LED backlight of the TV. If not, you will have to check each of its elements separately.

We know that a voltage of 140 V is supplied to the line of LEDs. We divide it by the number of LEDs (140:18 = 7.8), which means that for each of the 18 pieces, 7.8 V falls. Considering that the voltage on the strips always decreases, we have to install 6 V LEDs.

Replacing LEDs

Replacing your LG TV backlight is easy. The only difficulty is finding a replacement bar. It can be ordered on the manufacturer's website, but it is expensive and takes a long time to wait. There is only one way out - to replace individual LEDs. To do this, you will have to look for them in workshops and markets. You can even use soldered ones from once broken TVs, as long as they are in working order.

Another tip, if you need 3V LEDs, they can be removed from LED strips, which are freely sold in stores. This means that it was determined how many LEDs burned out, and something was found to replace them. Armed with a soldering hair dryer, remove the strips that were attached by the manufacturer using double-sided tape, to do this, warm up these places, then the strips easily come off. To make it easier to unsolder the diode, the board is also heated from below. They pick out (unsolder) the burnt diodes from the lens, soldering new ones, making sure that they are correctly placed according to the poles.

Lenses in factories are fixed with a compound. This is a special thermoplastic polymer resin used as an insulator and protection. If there is a need to remove them, you must be extremely careful and attentive when performing such work. Be sure to install them in the same place so as to maintain the same focus.

If you come across an LED that is not the right size, that is, its negative pad is larger than its positive one, then the contact point is slightly trimmed, this will make it possible to solder it into the lens. The remaining diodes, if necessary, are adjusted in the same way. They don't pay attention to the fact that the paint is damaged. New lenses are glued with superglue.

LED repair of LCD TV backlight is completed. Reinstall all previously removed parts in their original place. The repaired TV is ready for use. Connect it to the mains. If the TV starts working, it means the repair was successful. Also read,.

Savings and design in lighting have brought advanced technology into almost every home. Many people are replacing conventional plinth chandeliers with economical LED products. Not everyone knows how to repair an LED lamp on their own, especially what parts it consists of inside. How to use a tool when it breaks, where to start the whole process. Let's try to understand in detail what breakdowns occur in devices and how to repair some LED chandeliers with your own hands.

Types of breakdowns and their causes

Typical breakdowns: partial or complete absence of lighting, short-term blinking or spontaneous shutdown, failure.

Causes: The temperature has reached above 50 degrees, the contact between the filament itself and the holder has broken, if the paid version is not a lamp version, the contacts on the board have peeled off.

The LED has burned out, partially or completely. Cause: Overvoltage in the network, capacitor burnt out (breakdown). Typically, failure occurs in cheap board options.

There are additional reasons leading to device failure, namely: a short circuit in the circuit, incorrect connection to the network, non-compliance with the device connection diagram during installation.

Poor soldering of circuit contacts, LEDs to the board, weak fastening of wires in the base of the lamps. Poor soldering of conductive elements (wires, busbars). Cause: Factory defect. Many LED chandeliers with remote control are repaired precisely for this reason.

Preparation for repair of LED devices

Before repairing an LED lamp, the device must be removed. You will need some tools; a thin screwdriver with a flat end, cross-shaped. If the connection was made using twists, you will need pliers with insulated handles, insulating tape and a multimeter to check the contacts. Tweezers are useful when working with small parts.

You will need a soldering iron with a thin tip and solder (it is advisable to use a special nozzle). A drill with a 2.5 mm drill can also be useful to disconnect the base part of the lamp by drilling out the fasteners. Several thin wires, 10 cm long.
Attention! It is prohibited to carry out electrical work without special protected tools!

Design of LED chandeliers and visual inspection

Chandeliers with remote control appeared not so long ago. Few people are familiar with their structure. When repairing LED ceiling chandeliers, you need to know the design, just in general terms. Let's take a closer look at what it may consist of.

A simple LED chandelier consists of a housing, a controller unit or a driver. It is used as a voltage rectifier. It contains terminals, or terminal clamps, to which the mains power is connected. Then wires run from the block to the lamps. There can be from one wire, for a regular lamp, to 12 for a designer version of the device.

A more complex version of the product consists of an antenna, a control unit for the lighting itself, a voltage regulator or several
small blocks that perform automatic tuning. Raster lamps can have several drivers and different types of LED elements and lamps. From a specific type of lighting The device depends on checking and repairing components.

Why is it necessary to know or find out the design before
start repairing the LED chandelier. The reason is simple, you need to determine where the control units are located, inside the chandelier or in
the lighting element itself, the lamp. Here we need the same LED chandelier circuit.

Repairing an LED chandelier operating without a remote control is easier. There is nothing complicated in it, they are assembled according to one type: one or more diodes (a compact bridge is possible), electrolytes (capacitors), a pair of resistances (resistors), and a coil with a winding. This is the simplest scheme without protection, there are many options, but now we will analyze the simplest scheme.

The easiest way to check a lamp's LED circuit

First we try to disassemble the lamp itself. There are collapsible models, but sometimes you will need to heat them with a hairdryer or trim the body. First, of course, a visual inspection. As a rule, a burnt-out LED is different in color or has a burnt leg and the LED solder pads are burnt or peeled off.

Method 1.

It is better to supply power with a separate power supply to the lamp. Usually 3.7 volts is supplied to each LED, but there are other ratings. Please note that the voltage changes depending on the number of LEDs. To quickly check the LED elements of an ice lamp using improvised methods, you can use any 3-volt battery and paper clips by connecting the contacts. Just observe the polarity of the connection.

Having connected the contacts to the paper clip and observing the polarity, we check the LEDs one by one

We also use a similar testing device when checking the built-in lighting of a lamp.

Checking all backlight LEDs for functionality

The failure of one LED will result in all of them being turned off!

Method 2.

The device needs to ring all undamaged LEDs in the circuit. But there is an easier way: connect the lamp to the power supply and carry out simple manipulations

  • Close (throw a jumper) the contacts of each LED one by one with tweezers or a wire with stripped and tinned contacts.
  • The lamp will light up when you find (close the contacts) on the burnt out LED. If this does not happen, look further down the chain.
  • Check the board for the cause of burnouts, swelling of capacitors, carefully check the tracks on the regulator board itself. Solder the broken contacts.

You cannot replace an LED with a jumper when there are less than 10 of them in the overall circuit; the capacitors will be overloaded; block LEDs will burn out when there are 3 of them in one case. They can be identified by three dark dots inside a yellow or white crystal.

LED lamp repair

It is important to know that the LED has polarity and when replacing it, you need to install it correctly on the board. All LEDs are printed soldered, that is, immersed in tin.

Typically, a soldering gun is used to seal the LED. At home, although it is difficult, it is possible to apply more tin with a soldering iron.

To install it, just install it on the printed circuit board and heat its ends with the contact pads with a soldering iron. With powerful soldering, you will have to additionally heat the board from the bottom with a soldering iron. It is important not to overheat the LED element when soldering!

A possible way to repair LED lamps using conductive paste.

The usual circuit of an inexpensive Chinese lamp for 220 volts. Instead of a reliable driver, they contain a simple transformerless power supply circuit with capacitors and a rectifier.

The network voltage is first reduced by a non-polar metal film capacitor, rectified, and then smoothed and increased to the desired level. The load current is limited by a conventional SMD resistor, which is located on the printed circuit board with LEDs. When diagnosing and repairing LED lamps of this type, it is important to follow safety precautions, because all elements of the electrical circuit are potentially under high voltage. By carelessly touching the live part of the circuit with your finger, you can get an electric shock, and a slipped multimeter probe can short-circuit the wires with unpleasant consequences.

Troubleshooting a remote controlled chandelier

Often, repairs to LED chandeliers need to be done due to overheating of the matrix itself. First, unscrew the fasteners and visually inspect the inside of the chandelier. Then they carefully try to move the board in place. Determine whether there is a break in the wires from the control unit, or whether the wire has burnt out due to overvoltage. If it's burnt out, solder it back in place. We check all the details one by one.

Then you will need an original chandelier diagram. Without it, you can only repair chandeliers without remote control. If there is a remote control unit, change the batteries in it with new elements. LED chandeliers with a control panel are common; here you will need an exact diagram of the chandelier controller to identify a breakdown.

The chandelier control unit is usually tightly sealed into a shell, and manufacturers draw circuits on it. These are just diagrams for connecting wires and lighting elements.

There are also blocks with a collapsible body, then the option is simplified. If the unit is not collapsible, use a tester to check the output signal to the lighting elements (LEDs). If there is no voltage supply, the reason may be a breakdown of the signal receiver. We disassemble it, visually check the contacts and tracks on the board, the integrity of the parts. If voltage is supplied to one lighting branch, then there is a breakdown in the control unit, and not in the signal receiver itself.

The burnt part can be unsoldered and ringed, first, all the resistances (see diagram) by placing an OM symbol on the device. Then the capacitance of the capacitors, fortunately there are symbols on them, polarity and type are also important when checking.

Designation on the diagram

If a discrepancy in the nominal value is detected, we resolder it.

The chandelier control unit is responsible for the intensity and burning modes of the LED elements. Violation of one of the circuits (in the lampshade version of the lamp) does not disable the unit; the fuse may have blown.

But still, check the blocks to see if there are melted places on them, yes, replace it with a new one. If the wires are connected incorrectly, only the parts in the power supply will burn. The regulator block is protected from excessive loads. It can be called according to the diagram.

https://www.youtube.com/watch?time_continue=136&v=kfcfXjM5RH8

I had a chance to change the backlight of the LG32LN570V TV; I ordered LEDs from Ali. The article describes the repair a little and will be updated if repairs using this method or LEDs from China later cause problems.

I won’t describe diagnostics and repairs, TVs have a common problem, there’s a ton of information on the Internet, let’s focus on the little things that weren’t immediately looked for or a few opinions on implementation.

I liked this video on disassembly and assembly

It is clear what to disassemble and assemble in what order.

Now what options were possible and how I did it

Should I change one LED or all of them?

Two of them didn't work for me at all. On one bar, one burned dimmer at low current and another bar was dimmer than the neighboring one. There is no point in looking for and changing one at a time, then the rest will fail.
If one LED failed, I would first try to replace it and lower the brightness.

Should I change entire strips or individual LEDs?

Naturally, it’s easier to change with a strip; you don’t need the ability to solder SMD components. No need to remove and install lenses. Straight hands are enough to carefully disassemble the TV, disconnect the connectors from the strips, tear off the strips from the double-sided tape and glue new ones. The disadvantage of the strips is that you may not select them (inappropriate distance between the LEDs) or you may stumble upon low-quality diodes, off-center lenses and, as a result, glare. I just couldn’t find suitable strips right away and took diodes that had positive links in RuNet and an excellent rating with reviews on Ali. Naturally, LEDs are much cheaper.

How to remove lenses?

It is better to heat it from below with a soldering hair dryer and, for example, pry it up with a thin screwdriver and press upward, the lens will gently come off, the legs will remain intact, and then it will sit well in the old places. There will be a gap left for cooling the diode and you may not have to center it. If there is no hairdryer, people carefully cut it off. If the adhesive layer remains on the tape before heating, it must be removed; the temperature will cause it to warp.

Does each lens need to be put in its place?

My TV does not, the lenses are the same, but just in case, I laid out and glued the lenses in the order they were removed and how they were turned (on one side of all the lenses there was a small roughness, they were attached to it during manufacturing). This roughness was everywhere, looking up the bar. The top is marked according to the letters. Remnants of factory glue sometimes remain on the site, sometimes on the leg. In theory, if you mix it up or turn it, glue may get on top of the glue and the lens will tilt slightly. There is very little factory glue, perhaps this is an extra precaution.

How to desolder LEDs?

I heated it with a soldering gun from above and moved it with tweezers. If you don’t have a hair dryer, you can use two soldering irons. Or one way - scrape the LED to the base with small nippers and a knife (cutter), then solder off the remaining parts. Then you need to collect the remaining tin using copper braid. The solder on my tape was refractory; if the temperature of the soldering iron is not regulated, for desoldering you need to take a more powerful soldering iron. The tapes have a thick copper base and can be heated quite hot. I soldered the new ones with regular solder.

How to solder LEDs?

Tin the pad and LED with a minimum amount of solder. Use a soldering hair dryer to heat the track from below, the solder will melt and the LED will shrink. Press and straighten with an eraser on the back of the pencil. Clean the solder bar with alcohol. If you don’t have a hair dryer, use two soldering irons or one powerful “hatchet” with a tip to heat it from below. There is no need to do one, if you heat the sides alternately, the diode, if it sits down at all before it overheats, can sit crookedly and cause light to shine on the screen. If you heat it from one side - the metal of the anode and cathode are not connected from below, the second contact will take a long time to warm up through the LED itself, and if it starts working after that, it is not a fact that it will work for a long time.

How to glue LED backlight lenses?

Under no circumstances should you glue it with super glue; the fumes may make the lens cloudy, depending on your luck. I glued it on B7000. It seems to be sticking successfully, but there are concerns that the temperature may soften it and move away. The advantage of this glue is that in case of repeated repairs, the lens can be easily removed; the glue is cheap. If it falls off, I will re-glue it with construction adhesive or sealant. If you are 100% confident in the quality of the diodes and repairs, you can glue them with epoxy and other two-component adhesives.

How to glue LED strips (strips)?

For one tape, the original double-sided tape came off well and remained on the body. Covered it for the duration of the renovation to keep it from gathering dust. The remaining tapes were glued with construction adhesive-sealant. I bought one for outdoor use (UV resistant, high adhesion, wide temperature range, etc.)

Reducing LED strip current

You need to find a method suitable for your TV. My LG 32LN570V LED Driver MAP3202 removes resistors R826 and R827. Even if you set the brightness lower in the settings, when you turn on the TV, it shines at full brightness for a few seconds. You can search on your TV.

When transferring the matrix, you need to hold it in the middle from the top and bottom edges. Ideally, wear gloves to avoid leaving greasy fingerprints and dust on the matrix and light-scattering films. Light-scattering films must be placed in the same order as they were. I actually took everything off together, put it aside and covered it from dust. The matrix should also be covered from dust.

I ordered LATWT470RELZK diodes for TV backlighting. The price is high, but delivery is lightning fast, you can read the reviews. Plus, these diodes are the same size as the original or truly original in the shape of the substrate.

If problems arise with the replaced diodes, I will add.

Some photos of the renovation

Here's what's inside the TV. Case, LEDs, power supply and motherboard, speakers - that's all the features of modern TVs

Removed TV matrix. White - light-scattering films

LED TV strips

TV after LED backlight repair

As I already said, if during operation there are problems with the diodes in the link above or something else, I will write an addition.

Addition

After 11 months the backlight stopped working. The screen flashed on and off for a moment so quickly that it was difficult to see by eye.

The reason was poor-quality repair of the backlight in the service. The first time the TV was repaired there, and instead of replacing all the LEDs, reducing the backlight current, a piece of the LED strip with a non-working LED was cut out and replaced with a piece from another one, with a working one.

It is doubtful that the LED gets so hot and the heat was not sufficiently transferred from the tape to the box. I think the soldering was simply not done well. The solder splashes are large, but the actual contact area is small.

After repair (stripping, tinning, soldering), the backlight of the LG 32LN570V works again. It adds to the knowledge that these places immediately needed to be checked and remade. All LED strips and lenses hold up well.