Why the LG TV does not turn on: diagnostics, search and elimination of causes

Content:

• 1 LCD TV matrix backlight - what is it and how to fix it
• 2 Possible causes of failure
• 3 Diagnosis of failure
• 4 Risks of self-repair
• 5 Preparation of the workplace and tools
• 6 Getting to the backlight itself
• 7 Diagnosis of problems
• 8 Order new parts
• 9 Replacement of failed elements
• 10 Putting the TV back together
• 11 Calculating repair costs
• 12 How much does it cost to change LED backlighting at a service center?

Any, even the most reliable and expensive equipment can fail, and LG TVs, despite their high quality, are no exception. One of the most vulnerable places on a TV is the backlight of the matrix, which consists of several strips with LEDs. The number and power of LEDs, as well as their location, depends only on the specific TV model. There are many reasons why this matrix can fail. And instead of a bright and colorful picture, we get a dull and faded image that is almost impossible to see with the naked eye. And then the question arises: to repair the TV backlight yourself or contact a specialist.

Frequent malfunctions of LG plasma TVs

A plasma TV can also experience a number of unpleasant problems.

Lg plasma TVs is fundamentally different from liquid crystal devices. The image in an Lg is formed by applying current to gas-filled cells. Under the influence of current, the gas turns into plasma, and the cells covered with a multi-colored phosphor begin to glow. The shades of the glow are determined by the color of the coating.

The plasma may fail due to burnout of the phosphor coating. To avoid burnout, do not place your LG in direct sunlight and do not force the device to broadcast the same static picture for a long time.

If a problem occurs in the plasma TV program, it must be resolved by flashing the device. To fix this problem and successfully repair the Lg , no experience in soldering is required, and the likelihood of permanently breaking something is low.

This technology has long been present in people’s daily lives, so plasma TV repairs are carried out by many companies and private specialists.

If the plasma does not turn on, locate the faulty scan strip. A bar is a number of scan controllers responsible for a row or column of the screen. However, it is better to entrust repairs in cases where the plasma does not turn on to specialists from the service center.

Source

LCD TV matrix backlight - what is it and how to fix it

LED backlighting arrived not so long ago and replaced the once popular gas-discharge lamps. The backlight is made in the form of three or four strips with evenly distributed LEDs. These strips act as a bright background for the matrix, which consists of pixels with adjustable transparency and color intensity. The transition to LED lighting has become more profitable for everyone: for consumers, for manufacturing companies, and for service centers. There are several main advantages of LED backlighting:

• Aesthetics. Not a single gas-discharge lamp would fit into a modern, sophisticated TV, the thickness of which is several millimeters, and LED backlighting is easy. It is thanks to her that we can see modern thin TVs that no longer resemble a “black box” and fit perfectly into any interior.
• Resistance to external factors. The LEDs are permanently attached to the bar, so they are immune to vibration.
• Durability. High-quality LED backlight will last much longer than any gas-discharge lamp.
• Safety. Gas discharge lights operate using mercury vapor, a dangerous metal whose vapor is toxic to humans. If a child accidentally breaks a modern TV, the worst problem will be - the child broke the TV, the issue of toxic fumes throughout the house has lost its relevance.
• Ease of repair. And the point is not only that the entire LED backlight repair process takes no more than two hours, but also that burnt-out diodes can simply be thrown away. While recycling gas-discharge lamps is a whole science.
• Energy saving. Diodes consume significantly less electricity, while producing a negligible amount of heat compared to mercury lamps.

And the most important thing is the quality of the resulting image. LED-backlit LCD screens will always be brighter than older counterparts. Therefore, it is impossible to overestimate the importance of the modern type of lighting. Rare breakdowns can be fixed in just a few hours with proper experience working with equipment. Let's look at how to repair the matrix backlight on an LG TV, what it will take and what costs it will all cost.

No image

But there are situations when a perfectly working LG TV has no image. Or the image fades and turns off immediately, the device decides to go dark and the screen goes blank for no apparent reason. It may not be immediately clear to the consumer why there is no image and what is the reason for such a breakdown.

There are several reasons why the screen might darken. The main ones:

• lack of power supply to the lamps;
• their breakdown;
• malfunction of the scanning electrodes.

To determine the cause of the breakdown and how to fix it, the first step is to understand the general principles of operation of LCD devices and what is the main difference between their related CRT and picture tube.
The product diagram, in particular, does not imply the presence of all kinds of posistors. In most cases, the problem lies in one place - the backlight. And the master is faced with the task of determining what disabled it. To do this, it is necessary to take into account that LCD screens come in two main types:

• diode;
• based on gas-discharge lamps.

It is important not to confuse gas lamps on televisions and those used for indoor lighting. Their structure is very different. The first step is to check whether the lamp is receiving power. To do this, open the back wall of the LG TV and conduct a visual inspection, determining the functionality of the cables connected to the matrix. After a visual inspection, you can disconnect them and check their performance using the standard method - by connecting a light bulb.

In some models, illumination is provided not by one, but by several discharge light sources. In this case, they pull out the matrix and connect it to see which specific lamps work and which do not. If necessary, replace the burnt-out LED.

When making repairs, do not forget that there are several types of LCD screens

Other models provide the ability to detach the lamp from the end of the product, without any intervention in the matrix itself. The required element is covered with a special protective gasket, which is pushed aside and the broken part is soldered off. In its place, a new one is installed in this way.

Attention! When replacing lamps, their position must be taken into account. It can be either top or side. In addition, there are cases when several devices are located in one cell.

Sometimes consumers are faced not just with the absence of a picture, but with the presence of a line on the LG TV screen. Such a strip can be either vertical or horizontal. It is a symptom of problems with the sweep electrode. In order to verify the correctness of the diagnosis, it is enough to connect to it another product with a working matrix. The only way to repair is to replace the part. The same reason is most likely for the appearance of a spot on the LG TV screen.

Possible causes of failure

One of the most common causes of malfunction, especially in new models, is a manufacturing defect. During production, the diode track could have been soldered poorly, which is why a completely functional diode could easily fall off. Since a serial connection is used when soldering the matrix backlight, even one failed element leads to a complete loss of functionality of the entire circuit. But there are other factors that can cause a breakdown:

• Long-term use of diodes at the upper power limits. Typically, marketers and salespeople in hardware stores use such tricks, because in an already bright room they need to attract the attention of a potential buyer to an incredibly bright screen. That's why they set the brightness to maximum, and the TV works at least 14 hours a day. This mode of operation depletes the diodes and one of them may fail.
• Physical impact. A ball hitting the TV or strong shaking during transportation can also lead to the destruction of the solder joint or to the detachment of the bar.
• Poor quality repairs. This problem is more typical for used TVs. If the previous owner repaired the backlight and did not properly solder the elements or used a used LED or a diode of obviously inappropriate rating, this could also be the cause of a repeated breakdown. It is worth considering that replacement with unsuitable LEDs or used elements is also the fault of quite reputable service centers.

In any case, a backlight failure is far from the worst problem. Compared with more serious damage, repairing the TV backlight can not be called either labor-intensive or expensive.

How LCD TVs work

The average user is sure that the main part of LCD TVs is the screen. Yes, this functional unit is indeed complex. But the image on it is formed thanks to signals supplied by the central processing platform, roughly speaking, the device’s motherboard.

The main role in the design of LED TVs, despite its relative simplicity, is played by the power supply . It is this that allows a particular model to work with a wide range of voltages, while simultaneously supplying all functional units with a controlled level of energy supply necessary for their stable and correct operation.

If any structural unit fails, the TV stops showing. In particular, it is impossible to understand from the image on the screen how its backlight works. But when it fails, you can see the picture only by shining a flashlight on the matrix. So, the main failures of LCD TVs can occur:

• in the matrix, the area where controlled translucent cells are located;
• in the power supply;
• in the backlight inverter assembly;
• due to failure of electronic components of the motherboard and timing control unit.

Diagnosis of failure

Before you start repairing the TV backlight, you need to make sure that the cause of the device malfunction lies precisely in the backlight. Diagnostics is very simple:

1. The TV connects to the network.
2. It turns on, but the image is either not visible at all, or it is barely noticeable.
3. You need to take a flashlight and shine it on the device screen in low light.

If the image begins to more or less appear, it means that the whole point is really in the backlight. This could be either a violation of the internal wiring, or a failed LED, or a control driver. A more accurate diagnosis can only be made by disassembling the TV and removing the matrix from it.

If the TV is under warranty, then the damage can be repaired within the framework of the warranty card at the expense of the manufacturer in a specialized service center.

Why doesn't the TV start?

An LG TV receiver may not show “signs of life” for many reasons, so there is no point in starting a chaotic check. It is necessary to sort out the possible breakdowns and then carry out an inspection. There can be three types of faults:

1. Incorrect settings. The LG device does not turn on because... is blocked by settings that are activated by the user and are not related to the problem.
2. System failure. Problem with software or third party applications.
3. Peripheral problems. They arise as a result of incorrect operation of one of the devices connected to the TV.
4. Hardware failures. Failure of the TV receiver itself.

A black screen after a network startup does not mean that the LG TV does not turn on.
This is the order in which you should inspect the TV, because... simpler problems occur more often and are easier to fix.

Risks of DIY repairs

Despite the fact that replacing the TV backlight is not the most difficult task, it is quite a task and has certain risks. Firstly, to get to the backlight, you will need to completely disassemble the TV, which means removing the matrix, cables and other “delicate” parts. Careless dismantling of the cover can lead to a break in the cable or damage to the matrix, which can increase the cost of repairs by at least ten times. To perform diode replacement or other backlight repair work, you need to be confident in your abilities and have soldering experience, an understanding of the TV structure and a special tool.

If you have any doubts, it is better to contact the service center. Repairing the backlight will cost less than repairing the consequences of unqualified intervention.

How is LG TV repair performed?

TV has long been one of the most necessary technical devices in any family, because it is the main source of information for many families for several decades.

One of the most popular brands that produce televisions is the South Korean company LG. The devices of this company are reliable, affordable and have excellent technical characteristics. But, like any other technology, even such high-quality devices can break down. Let's try to figure out how you can repair such a TV with your own hands and what kind of breakdowns they have.

Preparing the workplace and tools

If you decide to repair the TV backlight yourself, you should prepare your workplace and the necessary tools in advance. You will need enough space; moreover, it is recommended to immediately prepare a separate table with a soft surface (for example, cover it with a blanket) so that you can put the matrix on it without scratching it. Tools you will need:

1. Screwdrivers, usually Phillips (00, 0, 1).
2. Blowtorch.
3. Soldering Station.
4. Tin, solder.
5. Multimeter with probes.

It is worth considering that an ordinary soldering iron with a thick tip is completely unsuitable for such delicate manipulations. Otherwise, there is a risk of complete damage to the track and plank, which will lead to more expensive repairs.

Before starting repairs, it is recommended to wash your hands thoroughly to prevent dust from getting on the inside of the matrix.

We get to the backlight

So, when everything is ready, you can start repairing. The first step is to unplug the TV and carefully place it on a soft surface with the matrix facing down. This will allow you to reach the back panel and unscrew the fixing bolts. Once all the bolts are unscrewed, the back panel can be removed without much effort and, regardless of the LG TV model, we will be faced with three boards. The first board is located at the very bottom; two cables will come out of it. The cables are detached very easily and under one of them there will be a bolt for fixing the bottom (T-con) board. After unscrewing the bolt, the board can be removed and set aside. Next, remove all the cables. Most often they are fastened with rubber fasteners, but some models may have additional fixing bolts. It is enough to simply unscrew them, and the trains will easily come away from the fasteners. We put everything aside and move on to disassembling the front part of the TV - remove the matrix.

Important! If you have not performed similar repairs before, be sure to take a photo of the TV after removing the back panel. This may be useful at the assembly stage after repair work is completed.

You will need to unscrew all the fixing bolts of the upper frame, which supports the matrix. This should be done extremely carefully, not forgetting that the frame is not attached to the matrix in any way. As soon as the frame is removed, it and the matrix can be transferred to a previously prepared table. An LED panel will be located immediately below the matrix.

When removing the front frame, do not forget to carefully support the matrix!

The indicator lights up steadily

Most problems with an LG TV that prevent it from turning on are not related to the power supply. If the power light comes on, the screen itself is immediately checked - perhaps it’s just not showing.

You can verify this by calling any menu:

1. If calling the menu from the remote control and buttons on the case did not bring any results, then you can skip this section and move on to the next one;
2. When the screen responds and the settings are displayed, the problem arises with the display itself.

In the second case, three options are possible:

1. The antenna or its amplifier is faulty.
2. The antenna jack or AV input is damaged.
3. The TV channel settings are lost.

Advice! Finding a fault faster is as easy as shelling pears - use signal reception from another source. For example, display an image from a computer and see the results.

If it shows, there is a problem with the antenna, otherwise the problem may be with the firmware.

After successfully calling the menu, you can say that the LG Smart TV is working, but does not show

You need to perform a repeat auto-search for TV channels.

If this does not help, then the antenna with the socket is inspected. It is possible that it was blown around by a strong wind or that the amplifier failed. You can read more about this in the topic “TV does not show”.

If the TV just recently worked, but stopped turning on.

You need to pay attention to proactive screen blocking by settings or a third-party utility:

1. Custom modes. These are “Energy Saving”, “Sleep” and other modes that can block operation or completely turn off the TV receiver immediately after startup. To do this, you need to check the settings on the TV and exit this mode. Afterwards you will need to deactivate the timer, otherwise it will start working again.
2. Child protection. The mode differs from those described above in that it blocks the buttons on the TV body. And if the remote control is faulty, you won’t be able to get out of it right away. This will require a network restart. Afterwards it is deactivated in the same user settings.
3. Third party utilities. Not all LG TV receivers support multifunctional operating modes and additional widgets are installed to obtain them. They will also need to be checked.

Advice! If this does not help, do not rush to update the software. Perhaps the failure is caused by a third-party utility, or a specific timer was not found simply due to lack of familiarity with the equipment. In this situation, resetting the current settings helps a lot.

All timers must be deactivated and disabled in the settings

After making changes to the settings, it is recommended to perform a network restart of the equipment, and then enter the settings again and check that the changes are saved.

Video instruction: resetting LG TV to factory settings

Firmware

An LG TV often does not turn on because the executive files (drivers) responsible for image output are damaged or the software is outdated. Searching for specific libraries and utilities is too routine; it is much better to completely reflash the TV.

But first you need to clarify what exactly happened to the software:

1. If there is no information in the system settings, you can use an existing drive with a bootable firmware file;
2. When there is a notification that the current version of the software is out of date, then an update over the network will be required.

Video instructions: how to restore the current software version or update the firmware of an LG TV.
In the second case, you will no longer be able to use the installation file, because it contains an outdated firmware version. You can learn more about this in the topic “How to flash a TV.” After installing the new software, the equipment will restart itself and turn on.

Troubleshooting

The primary diagnosis is carried out visually - it is enough to simply pay attention to the object of objectively melted diodes or blackening at the solder points. As a rule, these places indicate the location of the faulty element. If everything is clear, you should proceed with further diagnostics:

• Checking the LED driver. This diagnostic stage is carried out under voltage, so the disassembled TV will need to be connected to the network. Using a multimeter, you need to check whether voltage is coming out from the driver. If it is not there, a fault has been detected - you just need to replace the driver. If there is voltage, we proceed to ringing the diodes.
• Checking each diode. The serial connection type forces each LED to ring individually. To do this, you need to set the multimeter to the “diode” mode and ring each diode with probes, taking into account their polarities. Diodes that have not passed the test (as a rule, there will be only one) are the cause of the entire malfunction.
• If all the diodes are intact, you need to look for a broken track and ring the chain according to the sequential principle.

If the reason is a violation of the integrity of the track, it can be easily restored. This does not require any additional diodes. If the problem turns out to be in the driver or LEDs, they will need to be replaced - purchase new ones.

We order new parts

If the cause of the malfunction is the driver, then you can always buy it at any electrical and radio equipment store or online. The cost of such a device is from 400 to 1000 rubles, depending on the manufacturer. Considering that it is unsafe to disassemble and reassemble the TV every time, it is better not to save money. The option of purchasing an original driver in this case is not advisable, since, firstly, you will have to overpay, and secondly, you will have to wait at least a week, or even several weeks, for the driver to arrive.

If it was all about the LED, then there are two ways to solve this problem. You can order an LED strip from the manufacturer, which will allow you to simply replace the strip and not fool your head with desoldering the diode. The cost of the original bar can be up to 5,000 rubles. You can also buy a replica online, which will cost at least half as much. Another much more budget-friendly way is to buy a separate SMD LED. This can be done either via the Internet or on any radio market. The cost of one diode can reach 200 rubles.

Important! You only need to replace the LED for your LG TV with a similar one!

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.

Replacement of failed elements

It is much easier to replace the driver - soldering is only required to secure the power and output wires. You will have to tinker with the LED. It will be necessary to first heat the strip using a blowtorch so that it can be separated from the backlight unit itself. Then, using a soldering station with a small tip, carefully remove the old diode, then replace it with a new one and also carefully perform soldering. It is recommended to use pure tin without any flux-type additives to reduce the melting point. Once the diode has been replaced, you need to put the bar back in place and make sure it is securely fastened.

All that remains is to connect the TV to the network and check the functionality of the backlight upon completion of the repair.

Putting the TV back together

We assemble the TV in the reverse order - first we put back the frame with the matrix. Here it is important to be careful not to tighten the bolts too much so as not to create unnecessary pressure on the matrix, but at the same time it must be firmly fixed. Next, we install the cables in place, fix them with bolts if necessary, and then install the T-con board and tighten the fastening bolts. If you took a photo before starting the renovation, you can be sure that it will be useful to you. The final step will be installing the back panel and re-testing the TV for functionality.

If everything works, your LG TV backlight repair has been completed successfully!

LED current limit

To avoid repeated repairs, it is necessary to check the current that comes to the strips. It should be no more than 250mA. Looking at the board, I saw that two resistors responsible for the current to the LEDs had already been removed from the board. This is very good, since the craftsmen who repaired the TV earlier did everything right.

there were resistors in this place

Having measured the current, it was only 150 mA. This is very good, the TV can be assembled.

In the end, everything worked out.

TV in operation

Here's the repair. Attached below is the entire list of parts that were used in the repair. Thank you all for watching and good luck with your repairs!

to contents ↑

Calculating repair costs

The cost of repairs largely depends on the nature of the breakdown. After all, if the malfunction was caused by a violation of the integrity of the track, then such repairs can generally be performed without any costs, not counting the time spent. The cost depends only on which elements were replaced:

• Assembly strip with LEDs (original) – up to 5,000 rubles.
• Assembly strip with LEDs (replica) – up to 3,000 rubles.
• LED backlight driver – up to 1000 rubles.
• A single LED costs up to 200 rubles.

As you can see, in the worst case, the costs would be about 5,000 rubles, and this is provided that the strip is completely replaced. In the best case, the price tag for repairs is 200 rubles.

How much does it cost to change LED backlighting at a service center?

The cost of repairs in a specialized service depends not only on the cause of the breakdown, but also on other factors: region, integrity and qualifications of the technician, repair time and availability of spare parts from service technicians. The spare parts themselves can be even cheaper, since service centers purchase them at wholesale prices. The final price for repairing the LG TV backlight is never indicated in the price lists. Let's consider the price list of one of the large metropolitan companies specializing in the repair of household appliances in Moscow and the region:

Let's say it was all about the LED. Then the repair would have to cost 250 rubles + the cost of the diode itself. But it's not that simple. This amount will be added to the cost of solving the backlight problem:

In addition, the technicians will not forget to charge you for diagnostics and identification of the faulty diode. Particularly “talented” service technicians can also impose additional services, for example, rebuilding the matrix, which is completely unnecessary.

The average price for repairing the backlight of an LG or Samsung TV (in case of a diode burnout) in Moscow is 3,000 rubles, in the regions the average bill is 2,000 rubles. In total, we managed to save at least 1,500 rubles in just a couple of hours of work!

Found a mistake? Select it and press ctrl+enter

• 60