Without such a backlight, no LCD TV can work normally, regardless of its brand. We will tell you how you can repair LED TV backlighting at home using the example of a device from Lg, and what you need for this.
How can you tell if the backlight is broken? Suppose that the LCD TV's malfunction 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 the display is directed flashlight (i.e. forced illumination is performed), the image is developed. Verdict - the ice driver or similar backlighting does not work, maybe due to the fact that special rulers with soldered LEDs burned out. It is necessary to disassemble the TV and visually inspect the parts in search of a malfunction.
Attention! You can open the case of an LCD TV only if you have the skills to work with complex devices and a little experience, otherwise it is better not to risk it.
Remove the back cover any LG TV is a simple matter, only you 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 cannot be removed, then there is a locking bolt, you should not make any efforts, you need to find it and unscrew it.
After removing the back cover, we check the output voltage.
If it is normal - check backlight ice voltage the screen itself. Its value is only 100V, which indicates the presence of a malfunction of the LCD TV backlight.
In such TVs, a special LED set with lenses is used, which is installed over the entire area of \u200b\u200bthe screen to provide clear illumination. To get to them and repair the LG TV backlight, you must first remove the matrix.
Disassembly of 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 set, 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 place of work 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 image quality later;
- special attention should be paid to decoders - one inaccurate movement can lead to a loop break.
Subsequent dismantling is carried out in several stages.
Troubleshooting
Now the direct repair of the LED TV backlight begins: for this, you need to carefully unscrew all the latches along the contour, remove the plastic frame and remove the diffusing films to open the LEDs.
Have different models LG TVs will have their own set of ice backlighting: for LG 32LN541U - these are three rows of 7 LEDs, and for LG 32LB582V - three rows of 6 pieces.
In all TVs that use such a backlight, LEDs are connected in series, so if one of them burns out, the entire system stops working. If the LED driver is faulty, then the voltage is not supplied to the entire system, and when one of the LEDs burns out, the voltage goes on, but all the efforts of the device to light up the system are in vain: at least supply 200 volts, the circuit is open.
As you can see from the photo, the backlight consists of 18 LEDs, when measuring, the voltage without load was 140 V, that is, for each there was 7.8 V. When we take into account the voltage drop on each bar and the total load, the conclusion will be as follows: this model uses 6V LEDs.
Finding a burned-out LED is not easy: if there is no burning at the attachment point, then each element must be checked separately.
Replacing LEDs
Replacing the Lg TV backlight can be difficult. Let's say that the test 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 long 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, but serviceable ones, after a long search, these are exactly the ones that were purchased.
Users should be aware that all planks are glued with double sided tape, so you need to warm them up with a special soldering hairdryer 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. Solder in exactly the same way so as not to damage the LED.
Important! All lenses are fixed at the factory with a compound, therefore, when removing them, you must act very carefully, while each must then be reinstalled in order not to disturb the initial focusing.
Another nuance: you may come across LEDs with a minus pad that is slightly larger than the plus pad, so you need to cut the contact point to solder the diode. This is what a soldered LED looks like:
The fact that the paint is slightly damaged is not a problem. We solder the rest of the LEDs in the same way, and we glue the lenses on superglue... And this is a repaired view of the assembled and ready-to-use backlight panel:
As we can see in practice, there are many specific nuances in the repair of the LED backlight of the LG TV matrix, and without knowing them, it is impossible to achieve a positive result.
Final work
When the repair of the LED system of LG TVs has been carried out completely, before making the 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 care, as in the case of dismantling.
After the end, it is better not to set the backlight brightness to maximum, but to limit yourself to 75% - in this mode, the LEDs work 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, then the repair was carried out correctly, following all the recommendations. And to get the most out of your TV, you can learn how to
The most reliable LG TVs of 2018
LG 22LH450V TV
LG 49UJ651V TV
LG OLED55C8 TV
LG 55LJ622V TV
LG 55UK6100 TV
Hello everyone!
Sometimes, when repairing LCD backlight , there are difficulties in acquiring the necessary luminescent (CCFL ) lamps ... In such cases, you can convert the lamp backlight to LED. Such alteration is not so difficult, and there are no special problems with spare parts.
In this article I offer you the principle of such a reconstruction in the form of some kind of instruction.
Replacement steps LCD backlight on LED:
Disassemble a monitor or TV. After removing the plastic case, carefully disconnect the wires from the board, remove the metal frame from the LCD module and take out the matrix. With the matrix, you need to be especially careful not to damage the fragile connecting cables. If everything is done correctly, then full access to the electronic board, power inverter and backlight elements will be open.
2. Disconnect the canisters from lamps from the matrix or the lamps themselves, if they are installed without cases.
3. Disconnect old lamps and dispose of them. With elements CCFL you also need to be extremely careful, because they contain mercury.
4. We pass to the stage of replacement. First you need to purchase an LED strip, preferably with a margin so that it is enough to replace all the lamps (measure the length of the lamp and multiply by their number). It should be as narrow as possible and with at least 120 LEDs per meter. To make the backlight more pleasing to the eye, it is better to take LEDs with white glow.
5. The tape with LEDs must be glued to the double-sided tape where the lamps were. Further, wires from old lamps are soldered to the contact terminals of the tapes and insulated with hot glue. You can immediately check the performance of this design by connecting the wires to an external power source.
6. Now you need to connect the backlight on the monitor or TV power board. To do this, you need to find the jumpers marked with the inscription "12 V" and solder the backlight wires there, observing the polarity accordingly. Reassemble the monitor in reverse order and enjoy your invention.
Backlight in this case will work when the device is connected to the network.
To control the backlight and bring it back to normal, you still have to work hard. The wires leading to the LEDs must be powered in such a way that it is possible to turn on the backlight when you press the on / off buttons and adjust its brightness. There are 2 options for this:
1.Create a power supply circuit and adjust the brightness of the backlight by ourselves:
On the power microcircuit of the monitor or TV, we are looking for a plastic box (connector) with wires removed from it, where each socket is signed on the board.
Here we are interested in the "DIM" output. He will be responsible for supplying a signal to on / off and adjusting the brightness by changing the duty cycle in the PWM controller. The duty cycle of the pulses changes until the desired brightness level is set, and the limit values \u200b\u200bwill just correspond to the on and off.
Now we need an N-channel field-effect transistor (field worker) anyone. To its drain (Drain) wires are soldered from led strip with a minus, a common wire from the backlight is also connected to the source (source), and the gate (gate) through a 100-200Ω resistor and any wire is connected to the "DIM" pin.
We still have wires from the backlight with a plus, we bring them to the + 12V power source on a microcircuit and solder them.
Now we set the backlight to its rightful place and assemble the monitor in reverse order. Do not forget about caution and accuracy in handling the matrix and filters, so that dust does not get in and the loops are not damaged. Everything, you can use it.
The second way, more costly but convenient, is to buy a ready-made lED backlight with its own inverter :
Again, pay attention to the plastic connector and the DIM (brightness) pin and the on / of pin (it's better to use the pinout).
Using a multimeter, the places on the control unit of old lamps are determined, from which the signal to brightness and on / of goes.
Now the wires are soldered to the found places inverter new lED backlight .
Still, it is better to unsolder the jumpers from the inverter power supply of the old lamps so that the backlight is regulated by the new inverter.
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LED LED backlighting is another characteristic of TVs and monitors, which recently complicates the choice of the buyer, requiring him to think too much and make a responsible decision ... The fact is that LCD (LCD) TVs are becoming more and more, and its types are all time is multiplying.
Indeed, when purchasing a TV, one wants not to make a mistake, not to buy something representing yesterday or the day before yesterday, which will soon be impossible to use ...
Fortunately, there are no big difficulties in this matter, its importance is greatly exaggerated - more on this below on the page ...
There is a good rule of thumb: when buying a TV, it is recommended to pay less attention to the names of the technologies used, and more guided by your impressions of its look and picture quality.
At the same time, of course, more modern (and expensive) TV in most cases will be of better quality.
The best results in terms of image quality today, perhaps, are given by the type of backlight - Direct (Full) LED. Moreover, it is being improved all the time - now a very large number of LEDs can be used in this technology, which, naturally, has a very positive effect.
Edge LED or its derivatives also show more and more best performance, allowing, moreover, to make the TV very thin.
In both cases, in best models TVs also use the "Local Dimming" method - Local dimming... In LG TV, the backlight using it is called LED plus.
The LCD elements that make up LCD TV panels will not produce images on their own unless they are backlit. Therefore, this or that type of backlighting is always present in modern TVs. It should be borne in mind that technologies are constantly being improved, and the type of highlighting with the same or a similar name next year may be very different in performance from last year. For example, Full LED screens are now almost as thin as Edge LEDs.
Among the types of TV backlight used or used by SONY are the following:
CCFL (Cold Cathode Fluorescent Lamp Illumination).
WCG-CCFL (CCFL Wide Color Gamut Illumination).
RGB LED or dynamic rgb led life. See page below for details).
Full LED. Another name for Direct LED (the backlighting diodes are evenly located behind the screen over its entire area. This simplifies control and improves quality. But it negatively affects the thickness of the screen.) . Allows to manufacture very thin Slim-TVs).
Dynamic Edge LED (In addition, Local Dimming technology is used, which controls the amount of luminescence of individual groups of LEDs depending on the displayed image).
Intelligent Dynamic LED. Another name is Full LED or Direct LED (Compared to previous technologies, there are many more white backlighting LEDs located right behind the TV screen evenly throughout its entire area and illuminating the image. By controlling the glow of individual LED blocks, the system can illuminate specific areas of the image, leaving others dark. This technology simplifies operation and improves quality, but negatively affects screen thickness.)
Other TV makers such as Samsung, Sharp, LG or Toshiba use different technologies to varying degrees. Accordingly, the TV backlight options may also have a different name (you can find a lot of information on the Internet for more information on technologies, but from the point of view of choosing an option for a purchase, this information will not give much. It is more important, as we have already said, to evaluate the TV picture visually).
By the way, Full LED (Intelligent Dynamic LED) from Sony is not the same as full LED backlighting as originally understood in the early days of technology, when the fluorescent lamp backlight of LCD TVs was simply replaced by thousands of individual light-emitting diodes (LEDs).
Compared to previous technologies, LED LED backlight LCD TVs have enough advantages, but there are also disadvantages (inherent in the technology itself):
Disadvantages of LED technology
Initially, this type of backlight does not improve the viewing angles of the LCD display.
- Thinner models with side LED backlighting may suffer from uneven backlighting
- LED backlighting can cause local unwanted dimming.Of course, these disadvantages in most cases are successfully overcome in specific models TVs and monitors, since the technology itself is constantly being improved. Besides, not only the backlight affects the quality of the picture on the screen.
Benefits of LED TVs
All types of LED backlighting are more economical
- Technologies such as Edge LED allow you to create TVs with an extremely thin screen
- LEDs do not contain mercury (although their manufacturing technology uses gallium and arsenic)Of course, miracles do not happen. As a rule, the more expensive model will have both a better image and the type of screen backlight that is considered the most promising at the moment. But the image will be good not only and not necessarily because of the backlight. All other TV devices, including the video processor, can be very good quality... The TV can be very well tuned (what used to be called "calibrated"). In the end, the adjustments can be correctly and appropriately for the given lighting ...
From all this, in our opinion, we can conclude:
When choosing a TV, you should not pay much attention to the type of backlight. It will be better if you personally compare the image quality of several models, and choose the one with the most pleasant picture.
And it is up to the manufacturers to choose which type of backlighting is better. So far, they themselves cannot come to an established opinion (which is natural, because technologies are moving forward very quickly).
Take for example RGB LED backlight. It is believed to provide much richer color range, an extremely clear and contrasting image on the screen, but its ubiquity has not been observed over time. On the contrary, it seems that manufacturers are abandoning it. First, it is significantly more expensive than other types. And it also has technical limitations: the number of backlighting elements is limited, since it is too difficult and costly to control every part of the monitor. As a result, some of the scene illumination that should have been bright may decrease.
Addition:
Recent times there are reports of successful improvements to this technology by Mitsubishi. Moreover, they are developing a completely new type of RGB Backlit using a tri-color laser. Perhaps, soon about RGB backlighting will again start talking in full voice.
Sergey Filinov
LED TVs dominate the market for a reason. In this article, we will look at the types of LED backlights. modern TVs and evaluate their effectiveness.
LED TVs
To begin with, LED TV is not a new type of HDTV . Unlike plasma and OLED TVs, which are made on the basis of emitting technologies, where each pixel is a separate light source, in liquid crystal models, each pixel of the LCD matrix requires illumination (from behind, or from the side through a lens system). So LED HDTV models are the same liquid crystal (LCD or LCD) TVs, but they have built-in light-emitting diode (LED) backlighting, which replaces the standard fluorescent lamps cold cathode (abbreviated as CCFL).
2 types of LED backlighting by design: matrix and side
LED backlight with local dimming.First, televisions with LED backlight, used to illuminate the cells of the LCD matrix " full array»(Full array) of LEDs, similar to standard TVs based on backlighting using CCFL lamps. But to change the thickness of the TVs down, the developers refused to use the full array LED leds on the back of the screen by installing light bars to the side of the LCD panel Thus, the distribution of light from LED sources over the entire area of \u200b\u200bthe screen is carried out using LEDs of a special shape. Model data LCD TVs called TV with side or regional LED backlight, which are just the same dominate today.LED backlight with local dimming system allows you to automatically dim or completely turn off individual groups of backlight sources. Most modern LCD TVs with rear LED backlighting, in the form of an array of LED sources (full array) placed behind the LCD panel, are equipped with dynamic backlight technology also called local or local dimming. By using local dimming, certain areas of the overall array of backlight LEDs become darker or lighter depending on the brightness and color of the corresponding part of the image on the screen.
The ability to dim a specific area of \u200b\u200bthe screen can reduce the amount of light that passes through the closed pixels of the LCD panel, which positively affects the reproduction of blacks, which become darker and more realistic. Because black levels are critical to contrast, the perception of the depth of black surfaces, a full color image becomes more expressive and crisp. Local dimming technology has only one drawback - the effect of local haze, which is formed when part of the light from brighter zones seeps into neighboring darker ones, which subsequently lightens the dark color at the border. It is rather difficult to notice the effect of blurring on most models, since the disadvantage is directly related to the number of local dimming zones behind the screen, and manufacturers do not always provide such information.
With standard backlighting using CCFL lamps and most LCD TVs with side LED backlights, all backlight sources brighten or dim at the same time (the so-called “ global dimming "), but among the models samsung TVs and LG, it is rare to find side-lit LED displays that can also work with local dimming ("precision dimming" for Samsung and "LED Plus" for LG). Simply put, this is a local dimming props.
Slim models with side LED backlight Of course, they suffer from uneven screen illumination, but not all. Main feature of TVs with side LED backlight - thin body, in this regard, it is difficult to ensure uniform distribution luminous flux across the entire plane of the screen. When purchasing a TV, reproduce a white surface on the side LED display to ensure that there are no brighter areas around the edges of the screen. Likewise, when the screen is filled with a black border, the edges should not appear lighter (gray).
It should also be noted that LED backlighting, regardless of the type, does not improve the viewing angles of the LCD panel. The black level when using LED backlighting and a possible shift of the angle of view by 1-2 meters to the left or right drops.
Don't forget about the energy efficiency of LED backlighting. Of course, the consumption of any model is significantly influenced by the size of the screen and the brightness of the backlight sources. LCD TVs of both types of LED backlighting are significantly more energy efficient than plasma TVs.
LED backlights for LCDs are divided into categories based on the following:
- glow color: white or RGB;
- uniformity of illumination: static or dynamic;
- constructive: matrix or lateral (described in more detail above)
RGB-backlighting is used to realize the possibility of fine-tuning the glow spectrum. In addition, additional compensation for changes in the emission spectrum of LEDs over time is often used. In RGB LED TVs, different areas of the screen are illuminated depending on the color of the picture. Colored backlighting provides enhanced contrast and deep blacks, as many Sony LED TVs show.
Edge LED: Better color rendering
Sony in new flagship models TVs - for example, the W905 line - uses triluminos technology... The LED backlight (Edge LED) built into the TV frame on all sides of the screen is complemented by the so-called quantum dots - fragments of a semiconductor several hundred atoms in size, emitting light in a strictly specified range. Triluminos technology is designed to minimize color distortion and enhance reds and greens. This will achieve extremely uniform and natural images with a much wider color gamut. The tests of the first Triluminos-enabled devices did not disappoint us: the Sony KDL-46W905A has a color gamut comparable to that of OLED solutions and unattainable for LED-backlit LCD TVs. The devices in the W805 and W605 series, which also went on sale this year, do not use Triluminos, which makes their cost significantly lower. In the future, manufacturers will be able to completely ditch LED lighting in favor of quantum dots.
OLED TVs: brightness and color at the height
OLED TVs have already made their way to stores, and developers rushed to release new models with concave displays for you. LG had planned to launch a 55-inch OLED TV last year, but it did not appear on sale until this summer. In Russia, the 55EM9600 model and its improved analogue 55EM9700 will cost the buyer 500,000 rubles. In addition, the device is sold in Europe, the United States and some other countries.
Benefits of OLED TVs: This is not a type of backlight, but a different technology
- accurate color reproduction
- greater margin of brightness relative to other technologies
- high contrast compared to LCD models (different imaging technology).
- the absence of an LCD matrix and LED backlighting - they were replaced by a matrix made of light-emitting organic diodes.
Samsung and LG have independently developed curved OLED TVs. This design is designed to minimize distortion at the edges of the image and increase detail. New items are still available in limited quantities in South Korea, USA and some European countries. 55-inch model Samsung KN55S9C is estimated by the manufacturer at $ 9,000 (300,000 rubles).
Of particular interest is also the Multi-View technology implemented in many OLED TVs with both flat and concave screens. Due to their extremely fast response time, these devices allow simultaneous display of two or four programs in high definition (Full HD) or two different films in 3D. Shutter glasses are used to separate the image. Each viewer can use the controls on the glasses to choose individual program to view. At the same time, thanks to the built-in headphones, the soundtrack corresponding to the movie is reproduced.
In this article we will look at what is LED technology and where it is applied. I must say right away that not only the matrices of monitors and televisions () are illuminated, but in general everything from the bottom of the car to water from the tap. Now let's talk about this in more detail.
Generally speaking, a liquid crystal monitor is a device that consists of just a few major components. These are the pixel matrix, backlight and the top protective layer. In this case, the image itself is generated by a matrix of pixels, but since it does not emit light at all, you have to illuminate it from behind. You can shine a flashlight in front, but hardly anyone will sit and shine into the monitor during operation;) For this, a backlight is used.
Previously, in older models of LCD monitors, it was electroluminescent, that is, a tube with gas, as in lamps for lighting schools, offices, and so on. It is clear that in monitors and TVs such lamps are much smaller, and the gas there is different, but the main principle of operation is the same. Now, in most of the new models, LED backlights are used, that is, LEDs (light emitting diodes).
When using lamps, they are installed along the perimeter of the screen, and in order to spread the light evenly from the perimeter to the center, reflectors and light-scattering filters are used.
When using LED backlighting, two options are possible. The first is traditional, cheap and practical - the same perimeter installation. In this case, everything is done in the same way as with lamps - diodes are installed around the perimeter and their light is carried to the center by reflectors and various filters. But, of course, there will be no improvement in the quality (uniformity) of the backlight compared to electroluminescent lamps. But, nevertheless, there are pluses! Reducing power consumption when using LED backlighting is reduced by several times. As, in fact, and the release of heat.
All of the above applies to the budget - white backlighting (although it is actually blue, additional yellow filters are simply used). It is installed on the sides for the same purpose - to save money. Such monitors are sold out faster, as they do not frighten off consumers with their price. But there is another option for installing the backlight - over the entire surface of the matrix. It is already much more uniform and of better quality, and in addition, it is also colored. Yes, this is the so-called RGB LED backlight. It consists of RGB LEDs in three colors: red, green and blue. Located over the entire area of \u200b\u200bthe matrix, such a backlight can be turned off to obtain absolutely black color on the screen, but it can be highlighted in a certain color, giving the picture brightness and saturation to the color.
However, since the cells can be quite large, when part of the illumination is completely turned off to obtain black, the part of the image that should be bright may be affected. But, most likely, all this will be solved simply by increasing the number of LED cells or even controlling individual diodes on their own, it will simply require more computing power of the central processor at the monitor.
LED lighting everywhere
In fact, backlighting can be applied anywhere. For example, I have selected for you some successful, in my opinion, pictures with diodes.
LED bike lights
Backlit sofa
As you can see, it all depends on fantasy. LED lighting is great for cars, bicycles, furniture and even showers or faucets. Get enough interesting effects and hands start to itch to do something like that, well, go ahead! Don't hold back :)
