How to turn on the LED backlighting on LG TV
Repair of LED backlighting in Samsung and LG TV sets
Warning! This information is for technically qualified specialists! Owners and users of TV sets should remember that unqualified intervention can significantly increase the cost of TV repair or lead to its complete unrepairability in the future!
Many people know for a long time that Samsung and LG LED TVs of the fifth and sixth series, which use matrices (LED panels) with Direct LED backlighting, the LEDs can burn out sometimes in the first or second year of use.
The most popular Samsung models which were the first to come for repair with backlight: UE32F5000, UE32F5020, UE32F5300, UE320F5500 and others where backlight panels are installed, such as HF320BGSV1V, HF320BGA-B1 with direct backlight.
Among LG TVs, it all started with the 2013 32LN540 models. 32LN541. 32LN548 with LC320DUE and LC320DXE panels, in general almost all models of 32″ and larger diagonal LN, LA series with direct illumination and 3 volt LEDs. Later, the 2014 models began to arrive en masse to replace the 6-volt LEDs with large lenses. LG’s situation continued with the 2015, 2016 TVs with LF, LH series. Then they started to use encapsulated LEDs coated with phosphor on the outside, which in a couple of years would crumble and the TV would only show blue. Ultraviolet radiation of the crystal. But more about that later.
It should be noted, the manufacturer Samsung more correctly responded to the situation, in a timely manner sent to the service centers bulletins to repair and limit current in the LED drivers, and the mass extinction of diodes from Samsung significantly decreased after the 2013 and 2014 models of release. While LG and Kalina TV manufacturers have successfully continued what they started. But there is a possibility that Samsung may start again with the 2018 model UE43NU. UE49NU. UE55NU.
The most common symptoms of backlight failure. There is sound, there is no picture. LED-driver is faulty and gives maximum output voltage due to lack of current in the load. Breakage in the diode circuit can be checked by the current source (stabilizer). When you open the panel you find one broken LED and usually a few more broken in the short circuit. The point is that the protective stabilitrons mounted in the case and connected in parallel to the LED junction in reverse polarity are subject to avalanche and then thermal breakdown, if the LED is broken. Usually the stabilizer breaks in a short circuit, and the current in the line is stabilized regardless of the number of remaining LEDs. The TV works, the diffusers are sometimes good at masking the dark spots on the screen from the owner. It can happen with all of the remaining LED’s until one of the avalanche mode stabilizing diodes fails in a partial breakdown, for example in a few ohms or tens of ohms. Then, when heated by the regular driver current, this remnant of the PN junction will simply burn to dust from excessive temperature exposure. As a result we get a complete breakage of the LED and the absence of current in the strip, as well as the result, which will force the user to go to the repair service. Image is gone.Often already after 2 years of operation you have to observe more than a half of punctured LEDs.
Works to replace the LED strips (strings) or individual LEDs in the strings have become commonplace for repairers, but not all of the masters guess to reduce the current LEDs and in these cases, the TV owners are soon forced to seek their help again.Over, the manufacturers (or their dealers) by default set the backlight level to maximum in all modes, most likely for advertising purposes, which greatly accelerates the failure of the LEDs. And the user enjoys the quality of contrasting images and does not notice the catch. For the time being.
Samsung manufacturers sent to their authorized service centers bulletins with recommendations on the improvement of the modules that describe how to limit the current in diodes by about 10%, which allows the TV to work out at least the warranty period. On the modification of the popular Samsung BN44-00605. BN44-00615. BN44-00620. If you want, you can find the bulletin on the internet, or download it here.
It is almost always technically possible to turn down the backlighting current after replacing the LEDs.
Sometimes the driver circuitry uses PWM controllers with an ISET (RISET) pin to connect the Rset resistor and set the maximum current value. Usually there are resistors (two or more) from this output on the case to allow you to change the current within certain limits. By increasing the total resistance Rset, you can proportionally reduce the current in the LEDs.
In any case, the LED current from the LED driver can be somewhat reduced, based on the driver circuitry, in particular the organization of the Negative Current Feedback of the driver PWM controller. Usually in such cases, it is enough to increase the resistor rating. Of the current sensor in the chain of LEDs in series. Resistor rating in ohms should be changed inversely proportional to current in diodes.
Let’s consider the work of LED-driver, implemented on the basis of PWM controller, in our case on the picture SEM5027, which controls the width of the opening pulses in the gate of the transistor switch Q1.
The operation of such step-up converter can be briefly described as follows:
During the open state of the switch, the current from the pin Vin through the choke L, the switch Q1 and the resistor Ri goes to ground and grows linearly, and the choke core at this time stores the magnetic energy. When the rising current reaches a critical value for the transistor, the transistor will be closed by the comparator, which will work by the voltage on the measuring resistor Ri, rising in proportion to the current in the choke and open key.After the switch is closed the stored magnetic energy in the core of the choke will produce an induced current in the winding which will continue in the same direction, now through the diode D, charging the capacitor C.The self-induction current that charges the capacitor depends on the amount of stored magnetic energy, therefore, on the open time of the switch, i.E. On the width of the pulses that open the switch. In the starting mode they are maximum and are limited only by the voltage on resistor Ri.After just a few such trigger pulses the capacitor voltage (Vout ) will be higher than the input Vin and then, as soon as the LEDs open, the current in the load and the voltage proportional to it at the resistor Rd. This voltage goes to the control input of the PWM controller, inside it is inverted and fed to the second input of the comparator, which will now close the transistor with the reference voltage on the resistor Rd. This will set the stabilization mode.
“Turning on” the backlight on the TV/monitor. Bojan, but a lot of people haven’t seen it.
Many people have asked: “I only know how to fix mobile electronics?” This post, for those who haven’t/can’t see. Here I have not mentioned the word rubbers. Yeah, it was a good time. There is no need to put it in the top, just browse.
Good day, dear peekaboo players! This post will describe how to fix the backlight, if it oxidized. About a year ago I was approached by an acquaintance who said, “The TV doesn’t work, but it has sound. In the repair shop said 9500, but money is not rich”.
If there is sound but “no picture”, it is not as bad as it seems. Asked her to take a flashlight and shine it point-blank on the screen matrix, says “people” are running. That’s right. I thought. It’s about the backlighting. TV, at the time early 2014, was an average Smart TV.
(don’t scold me for pictures, the leftovers are shown here)
Unfortunately I have not saved a picture of the muzzle/face and there is nothing interesting there, just a black rectangular board with Samsung written on it. Disassembled, looked visually, but did not find anything. You can see that the backlighting of the screen is realized by “cold cathodes”, the lamps that is. You can tell from the gray wires in the upper right corner.
All these operations can be applied to the monitors as well. Naturally for modern flat-screen TVs. The difference over there is in the left green board, in the monitor it simply will not. This board, the “television component of the monitor”. The middle one is a “decryptor” of video signal into a signal which can be understood by the matrix of the monitor / TV set. On the right, the power supply.
Older TV’s and monitors, those with CRT are similar in their own way.
A bigger picture of the TV power supply.
After checking the voltages, which should be on the outputs of inverters, and there should be hundreds of 400 volts (I do not remember exactly, but it seems so), and there are dozens.
NOTES: You can’t plug these power supplies in without a load, it can fail, especially if this power supply inverters (cold cathodes). And most importantly. Obey the rules of electrical safety can NOTHING.HTI. I’M FINE. So, neat, and better not sue, give a few kopecks familiar master, let him take his chances.
So that’s what I mean. Oh, yeah. Thought it was PWM (who cares what PWM is? Wide-Impulse Modulation) died, but no, it was rustling. Thought it was blown by the short circuit, but it was alive. I read on the internet that this series of TVs often blow out these transformers. Lucky for me, it’s intact. I checked the overvoltage boost and it was showing tens of volts instead of hundreds. I unsoldered one leg of the diode (diodes highlighted in red), tested it, and it shows a breakdown. That’s what the problem was. Replaced all 3 at once.
And another thing about these diodes is that they are not ordinary diodes, but HF, and they can not be replaced with other diodes, so I had to go and buy the same ones, but with extra voltage. The characteristics of the diodes, very dependent on the temperature. The higher the temperature, the more current in the reverse bias. In short failed at high temperature. Replaced it, it works. Repair cost 75 C expensive 130 It’s been 2 years, everything is still working.
The most important reason why in this series of TVs, fail power supplies, it’s a banal terrible overheating. The cooling in this case is convection cooling, you should have forced cooling, then no one would have any grief.
How Ambilight and its counterparts work
First you need to understand how it all works. The special module captures and analyzes the image on the screen to understand the color of the area around the perimeter of the matrix. After that, a similar signal is applied to the RGB addressable strip on the back.
Capture several times a second, with the same frequency of updating the glow of the diode tape on the back. Of course, that takes serious resources. The higher the resolution of the picture, the more pixels have to be processed during capture.
All solutions that replicate Ambilight technology are divided into two types: based on an external decoder or based on a set-top box.
◉ The first type is a separate box with an HDMI input and a similar output. Inside is a small single-board computer (usually Raspberry Pi-based) which receives the output signal from any source. You can connect your set-top box or console to the input. The capture process takes place internally, and the output is the picture on the TV.
The advantage of this solution is the simplicity of connection. No complicated circuitry, no extra software and no setups. The box is just placed between the signal source and its receiver (TV set).
The disadvantage of such a box is also evident. Most often it will give a worse picture than the input. Module power may not be enough to rebroadcast 4K, sometimes there will be no support for HDR, there are cases when the box does not support the required FPS or is banal does not transmit surround sound. Here everything rests either in the power of equipment or in the standard of HDMI port.
Buy a ready-made solution for backlighting. From 6528
The second option is more affordable, but the capture process takes place on the set-top box with special software. In this case only a small low-power module for controlling the diode tape is needed.
The advantage of such a system is its price. And here are the main disadvantages in the serious requirements to the used TV set-top box. You need a fairly powerful processor that can handle both content playback and picture capturing for decoding.
In addition, some chips do not have the physical ability to capture images due to the peculiarities of its output. For example, quite common Amlogic processors, when decoding a picture, create a special protective layer that does not allow to make the image capture. Most often there is a way out of the situation, but you will have to fiddle with the settings of the capture application, look for suitable players and pick up a successful combination of parameters.
Buy backlighting assembly kit based on TV set-top box. From 831
For today’s review I chose the second option: it’s cheaper and I wanted to tinker with the setup.
How not to do TV backlighting. LED. Repair
Recently they bring a lot of TV sets with repaired LED backlighting. They die after 9 months. 1 year of use, after repair.
I usually have a flow of 1-2 TVs with this kind of problem a week, all parts are available, repairs are done within a day. But this week I got something, 4 TV, two of which are after the other masters. Here are the actual Masterpieces:
P.S: At the bottom of the post I will write what you need to do to make it last longer.
What burned out is the norm for samsung, but the way they did it is of course ptz
Well, that the technician restored the reflector, in the place of burnout, but why was it necessary to paint the diffusers at the LEDs in white, and cover them with a piece of paper?
Since I buy up broken TV’s and have donor organs where to get them ;), I replaced all the suspicious and non-working LED’s and put good diffusers on them. Here is the result:
After that I trimmed the reflector a little more to prevent it from fitting on the diffusers and assembled, and voila.
Another TV, this time it is LG, here in general typo. How not to do it!Just a jumper instead of a LED. The finished result does not see the point in showing, but in fact just say, for the masters, do not so.
Suppose even a stabilization of the current bypasses this jam, and lowers the current, and the other LEDs will not burn out, but hell, a dark spot on the screen no one confuses??
And now it’s time ohuivschih stories tell you how to do it right: after repairing, replacing all non-working and suspicious (those that flash before turning on) LEDs, you need to lower the software or hardware maximum brightness by 20 percent, the eye does not have any difference, but the service life will be extended at times. From the factory is overcurrent at the LEDs, because of this actually they burn out. LG on the LG enter the service menu and adjust the percentage of maximum brightness (a little painful to do it without the service panel, but after all you and the master, either you have it or find a workaround in the form of two LEDs and sound file ;))) Samsungah looking for resistor next to the plane backlight, the nominal value is usually 3.17 3.Repair of the backlight of LG 32LN541U TV, and add in series with this resistor 1 Ohm, thus increasing the total resistance in the chain, and the voltage drop across these resistors, which actually controls the brightness of the backlight: the higher the resistance / current the greater the voltage drop, the less brightness of the backlight (stabilization occurs in relation to these parameters)
That’s all, good masters, and masters have a good repair
Repair of LG 32LN541U Led TV backlight
Well, the first dead Led TV came into my naughty arms from my relatives. LG 32LN541U. No backlight, there is image and sound. The TV was once already repaired in the studio (repairs cost 3).LG 32LN541U. No backlight, no picture, no sound) for the same reason and died again, bought another one, this one accidentally suggested to me to watch. Youtube clips to repair this or similar TVs a few pieces, and like everything is told, but, but some points are not quite detailed. In some videos, unobtrusively, it is recommended not to repair it yourself so as not to spoil the matrix, it’s better to give it to a master. Uh-huh, let’s see the repair “mastersff” from the TV shop.Disassembling.
I did not even poke the power supply with a voltmeter, went straight to the backlight diodes. Three lines of 7 diodes, all connected in series, each diode is a stabilitron, if the crystal burns out, the stabilitron works, if the stabilitron blows out, the circuit is interrupted in the whole chain, the light goes out at the speed of light. On the top ruler I found two buttons sewn incorrectly and covered abundantly with superglue. Diodes in TVs come in 3 and 6 volts. Started to check the whole ferrules. Got 21 volts from the power supply and turned the current regulator to minimum. The lower lens bar is lit up completely, the middle one at 5 diodes, the upper one does not do anything. Started to check the 3 volt one by one, found in the top bar completely burned out mounting, and a diode and a regulator, it incidentally even managed to look through the compound then. A black spot burned out next to the crystal.Unscrewed the lens from the top ruler, not to spoil the legs of the lens should be heated with a hair dryer, then gently pry something thin. The reflectors are okay to remove if there is no hurry. Under two lenses opened the results of the previous repair. A beauty:
Diodes can be called with a tester. On the arrow instrument to one side is 40Ω, to the other. Infinity. So on the top ruler diodes were ringing and 100Ω, and 200Ω, and about a kilo ohm, despite the fact that they were glowing, and on the bodies were dark spots, I poked one. There was a blown resistor.
All native diodes showed hardening and cracking of yellow compound over the crystal, the new ones are soft.
I decided to change everything (the similar case was shown in one of the repair videos), maybe I made such a fuss for nothing, the hell with it, with this compound. Now I think that already disassemble and solder if something not long at all, would be diodes in the presence of.I need a 35×28 3v 1w diode with a big positive contact (35×28 is its size 3).5mm at 2.8mm). In the repair video links on youtube, some nonsense, or not at all, or very expensive. I searched aliexpress found the required LEDs, at a normal price (110pcs for 230r), with good reviews, however, took a long time to arrive (4 weeks).Here’s the link ru.Aliexpress.Com/item/50=a2g0s.9042311.0.0.There are several varieties, not more than 5pcs each by number, I do not need, and the price tag 35r/pc.Diodes came almost matching the original, only a little smaller minus contact and another inscription on the back side. On the photo new (it is a little scratched by experiments) and original.
Removed all the rulers, lenses, soldered off all the diodes with a hair dryer (heated the top of the crystal at 460°C). I used a Lukey 701. Tin-plated pads and soldered diodes (400 ° C under the ruler). I glued the rulers to the frame with double-sided adhesive tape, and even attached them to the top with another adhesive tape, which I trust more =). By the way, from the factory the rulers were glued very unreliably, they were mostly hanging in the air, maybe because of this poor heat transfer to the body, and the “craftsmen” glued the top ruler on the superglue in three places, it would be better to leave the old adhesive tape.
I glued the lenses with some clear “Moment”, put spacers in the places where the “craftsman” had torn the legs off. For this case, I think, you can use the laminate lining of the right thickness. With lenses you have to be very careful not to get in their alignment, I placed them on the removed sockets, then glued them in the same places, and still had to straighten some, they shone a little crooked. Alignment, if anything, is done by the matte screen on the legs.Well, on the recommendation of a video from YouTube reduced the current on the diodes, soldered off one of the circuits in the ballast kit.
Well, the TV works, now let’s see how long it will last.
After start-up on the matrix found a dull spot, and the pixel under it is lit, or it is stripped polarizer, or a pixel from the impact came to an end, painted it black, it is better to be, it will need to find out where this dull spot, whether the “master” to blame =).
Happy Repairs to all.P.S. Try to make the brightness level down, in stores is set to maximum, people bring home so and races, on this TV was at 100% backlighting.
Power Supply Repair
The power supply unit of the TV set is one of those parts that fail most often and power supply repair belongs to the vital needs of most consumers. The sign of its failure is that the device simply refuses to turn on. Over, the TV set not only doesn’t show an image, it doesn’t show any signs of life. In that case, the only effective way to fix the breakage is to replace the unit with a new one. The Smart-TV repaired in this way often lives even longer than the one with the original PSU.
In order to show Smart TV constantly, it must be repaired from time to time. Even if it comes from such a respected manufacturer as Elgidi. But it is not as expensive as it may seem, since many breakdowns can be fixed with your own hands.
Комментарии и мнения владельцев 94
Lots of online articles: Myself! And the result is something like this, not for long. And 30% of them can’t do anything at all. The matrix is ruined! (Of course they are silent about it. Shameful to say: the TV is only 32 inches, and the “ear” was torn off, or the corner was broken off)!). I repair TVs myself, and for a long time before LCD did Soviet VELS, Rubin, Beryozka, Horizon, and others. There are two options: to make a long, high quality, with a guarantee. Go to the master; or, if you do not feel sorry (well, for fun, where will pop out, add posts). To open yourself. It’s up to you. You can find me in contact.
Could you advise an illiterate person: In this TV set, is the backlight connected in parallel or in series??I was given a TV with a faulty backlight. Disassembled. Someone has already tinkered with it before me. I soldered the LEDs, checked, the line is all lit up. When I reassembled it, two of the connectors that connect to the LEDs were missing.How to connect it, can anyone advise?? TV konka kl32as528
This is bullshit. I lowered the current, but after six months the TV came back with seven burned out LEDs! Had to change everything under warranty.
Yeah. I also burned. Both with a new ribbon and with less current. Nothing lasts forever
How to fix LED TV LG32LF510B image blue Screen Backlight Problem Easy fixing method TV Picture
Tell me if you can.The problem is this. I turn on the TV (LG42LF620V), c remote control, it turns on, but no image and no sound. And I can’t turn it off with the remote.Let’s say it stays on for a day or two, nothing happens, then it can appear suddenly.Today, for example, turned on in the morning at 11 am, working at 6 pm.
All this time while the device is turned on without displaying any picture, the diode is blinking with a certain interval and LG logo is showing on the screen at the same time
Hi. The problem is probably the power supply. One of the voltages can not start. Check PSU and mainboard. It looks like one of the inverters isn’t starting
Guessing by coffee grounds. Too bad I don’t do fortune telling, I’d probably be broke by now. Without measuring, t.Е. Without diagnostics, it’s likely the motherboard is faulty. But there are a lot of buts! And t.Д., and t.П.
I hate to disappoint you but you still haven’t fixed the TV. Soon the rest of the diodes will die too.
Yesterday I turned on my lg42la615v blinks once and then dimly and still blinks with the frequency of a second) TV in 2014, we look at it God only an hour 3 times a week) I think to take the whole strip on or replace all. It’s easier than buying a b.У., I don’t know what the other strips are either.Is it necessary to modify the power supply, remove the resistor? Or maybe just watch TV in a dimmer mode, in movie mode instead of dynamic mode?)
It is definitely better to replace all the strips with new ones. And remove the shunt resistor.
Yesterday I turned on my lg42la615v Blink once and then dimly and still blinks with the frequency of a second) TV in 2014, we look at it God only an hour 3 times a week) I think to take the whole strip on or replace all. It is easier than buying LEDs.У., I don’t know what the other strips are either.Should I rework the power supply, remove the resistor? Or maybe just watch TV in dimmer mode, in movie mode instead of dynamic mode?)
Replace the faulty one and be sure to reduce the backlighting current.
You need to change all! Leds. The mastic on them cracks, the wires going to the crystal contact with air oxygen, oxidize, thin, burn out.
Hello ! Help to understand the cause of the TV MYSTERY MTV-4031LTA2 breakage. The top of the screen is a bit dim, like the brightness is half off. Backlighting that is strip LED working (not sure of 100 percent). I opened the lid of the TV, wiggled all the connectors, assembled everything as it was, the screen worked. The next day the problem appeared again, then 2 days later everything was fine again the next day it appeared again and is no longer missing. I took it to a mechanic, they said the backlight is not working, the repair is 8000t.Р. I blame the power supply (I may be wrong) wanted to order in China board power supply for 700 p. But I’m not sure (maybe the problem is not in it). Please help me !
It is very likely that the ribbon or ribbons on top do not light up from time to time. Need to figure out how they are connected. And draw a conclusion.
Hello ! Here are all the TV parameters on this site.Tel-spb.I opened the lid of the TV, wiggled all the plugs, reassembled everything as it was
It seems that the ribbon or ribbons on top do not light up from time to time. We need to figure out how they’re wired. And draw a conclusion.
There’s four 12-LED strips, 3 volts each. The diodes are connected in series of 2 strips of 24. By 2.The problem is probably the problem with the light strips. If the problem is with the upper strips, the upper part of the screen should go out completely and it only shows a weak brightness. Or am I wrong ?
Will show. Approximately the same as yours. That’s because the light at the bottom is shining on the top. The problem is most likely in the strips. Some kind of diode is broken.
Thanks ! Yeah,that’s right,the problem is the strips. Disassembled the TV again, swapped the places of the plugs on the board, the top did not light up and does not shine. After assembly, turned on, 2 days of normal display. It’s kind of a mystery, isn’t it? I just swapped the plugs and put them back on, and took off the board inspected the solder on the pins. Thanks a lot for the tip. I will try to remove the matrix to get to the ribbons.
How to adjust
There are several ways to add brightness on your LG TV if it’s gone. This can be done by setting the necessary parameters. You need to do the following:
How to Replace the LED Strips on LG TV No Backlights / No Picture. EASY AND CHEAP!
- Enter the “Home” section.
- Click on the “Settings” item (the gear wheel).
- Click on the three dots in the corner.
- In the list that appears, click “Screen.”.
- Find “Smart Picture Mode” and click on it.
If this option is not available, you can manually increase/decrease the brightness on your LG TV if it is missing. Do the following:
- Click on the “Home” button.
- Click on the gear.
- Enter the three dots, and after “Screen.”.
- Go to “Picture Mode Settings.”.
- Click on “Screen Mode
- Set “Bright” to add brightness to your LG TV if it’s gone. At this stage, you can do other settings. Standard, Eco, Cinema, Sports, Games, Photos, and others.
If there is a question of how to increase the brightness on the LG TV for the screen, you can use the standard setting. So, when you go to “Adjust Picture Mode,” you can set other options:
- Set the backlighting. This method often helps if the previous picture quality is lost.
- Set the contrast. The essence of the setting is to adjust the light / dark parts.
- Change the OLED light. This should be done when you want to improve the performance of OLED panel on your LG TV.
- Brightness. Allows you to change this indicator of the picture on the screen. Helps to solve the problem if you have lost your previous settings.
At this stage you can make other changes, such as setting the horizontal/vertical sharpness, changing color, tints, white balance, and other settings.
Knowing how to reduce / increase the brightness on a LG TV, you can make a quality picture.
You need to do the following steps to get a clearer picture:
- Start a widescreen movie.
- Pause the picture when there are light and dark tones on the screen.
- Adjust the brightness and other parameters with the above settings. Also pay attention to contrast.
- Start the video and freeze the picture on the face.
- Adjust the saturation.
After setting the above parameters you can count on a quality picture. If the setting is lost and cannot be restored, try resetting or contact the service center. The backlight may have been damaged and need repair.
In your Комментарии и мнения владельцев, can you tell us if you were in a situation where you lost brightness on your LG, what you had to do, and which of the following methods helped you to solve the problem.