Image defects and t con faults. Diagnostics and repair of T-con board faults in LCD TVs. TV repair. one of the colors predominates in the image
Repair of T-con timing controller
The timing controller, also known as T-con or matrix controller, is a device independent of commands from the central processor for converting video data transmitted from the main board into signals understandable by the LCD television matrix. As a result of its work, we see the image we need on the TV screen. Violation of color rendition, integrity, colorfulness and naturalness of the picture, ripples and blurriness on the screen may be a consequence of a defect in this block.
T-con diagnostics and repair
Replacing the gamma corrector Diagnosing a malfunction in the timing controller can sometimes be extremely difficult. The fact is that the connection of this block with the main board and the LCD matrix is so great that it is sometimes not possible to visually determine what is the source of the defect. Only measurements at T-con control points can indirectly indicate its inoperability. When repairing a matrix controller yourself, you need to have a large amount of information, which the Internet can provide with a careful and painstaking search. The controller itself is considered an integral part of the LCD panel, and manufacturers do not provide electrical diagrams for this unit. This situation forces the teleworker, when repairing this unit, to be guided primarily by his professional instincts and experience in similar repairs.
If your TV begins to show a low-contrast, negative, whitish image with moire of various shades in light or dark areas of the picture, there is a high probability that the matrix controller unit is not working correctly. To exclude the influence of the motherboard and carry out diagnostics, many manufacturers of LCD matrices provide for turning on the T-con in offline mode. In this case, the cable connecting these boards is removed, only the supply voltage is supplied to the controller, and the panel is entered into test mode by closing the service contacts. If the LCD panel and timing controller are working properly, the panel’s self-diagnosis is observed on the screen in the form of alternating colored fields and stripes, as from a television test signal generator. Each type of LCD panel has its own method of entering test mode.
In some cases, doubt about the serviceability of the matrix controller occurs due to the absence of an image when the monitor screen is dark or very light (white). It is necessary to control the passage of the supply voltage from the main board and the formation of secondary voltages by DC/DC converters in the unit itself. Sometimes problems with the timing controller, and even with the matrix itself, can arise due to the owner being too careful, wiping the TV screen with a too damp cloth, or, conversely, being careless, spilling liquid on the LCD panel or inside the device. If moisture gets on the matrix, irreparable consequences can occur in the form of destruction of current-carrying cables, their corrosion, short-circuiting of drivers and failure of the matrix controller due to a critical violation of its operating mode.
Repair of the timing controller is not provided by the manufacturer of the LCD matrices, only its replacement. Therefore, technical information on restoring the block is not provided and there are no diagrams for it. However, in our workshop we use every opportunity to repair a TV at the component level without replacing blocks and boards. During restoration, technical information is used in the form of “datasheets” - descriptions, characteristics, connection diagrams of components included in the controller, which allows the TV technician to successfully carry out repair work on such a complex unit of a modern TV as T-con.
TV 32LG5000 received repair. This popular model is available in diagonals of 32 - 37 - 42 - 47 - 52 inches and is of good quality at an affordable price. Also, these LCD TVs are reliable in operation. Of course, like any other technology, TV has its weak points. Repair of one typical malfunction is discussed in this article.
The TV, which needed repair, had picture defects. In the dark areas of the picture, colored red-green interference appeared, the black color was highlighted, and the image was blurred.
This defect is caused by a faulty display controller ( T-CON), and in particular gamma corrector chips EC5575(designation AS15-G), which gets quite hot during operation and often fails. At the same time, signs of a malfunction are not limited to these symptoms; the picture may have too much brightness, vertical light stripes, or even a negative image. But let's do everything in order.
First of all, you need to check the power supply and the voltage it produces. Inspect the unit carefully for swollen capacitors. Then measure the voltage on the connector with a digital voltmeter; their values are indicated nearby on the board.
If the measured value differs from the indicated value by more than 0.2% or changes with warming up or changing image brightness– the power supply is clearly faulty. Fortunately, in our case there are no issues with nutrition.
Other similar symptoms (white screen, low-contrast image, color distortion) may be caused by a break, poor soldering of the connector or simply oxidized cable contacts, connecting T-CON and main board ( Main). A break may occur during repairs due to frequent disconnections and connections of the board. Therefore, ring the cable and clean the connector contacts if necessary.
To determine the problem, remove the metal cover covering the T-CON boards and reconnect all cables. Turn on the TV and after 10 minutes feel the AS15-G. The faulty microcircuit gets hot so strong that it is difficult to hold your finger for more than a second. This is the first, preliminary sign of a breakdown.
For complete confidence you need to measure the voltages at the inputs and outputs of the corrector. The chip itself consists of 15 buffers, the inputs are designated “Xi” (input), the outputs are “Xo” (output). Voltage values for working AS15-G indicated in the picture.
These values may differ depending on your TV model. What matters is that in a working microcircuit, the voltages at the input and output of the channel do not differ by more than 0.3 volts. If such a difference occurs, then either the gamma corrector is faulty, or the problem is in the load - the matrix.
To exclude the matrix, you can turn off two of its loops and take measurements on the “suspicious” channels again. In the case of the TV being repaired, the voltage at the output of the “AO” channel was zero; this value did not change even after the matrix was turned off.
The picture below shows a gamma corrector circuit based on an analogue of the AS15-G, the HX8915 chip. You can also use AS15-F when replacing.
To replace the microcircuit you need to use a soldering station. Before dismantling the element, in case you accidentally blow off nearby parts, it is better to take a high-resolution photo of the board. If such a problem occurs, use the photo below.
After replacing the chip, the image was restored; no additional settings were required. To avoid recurrence of such a malfunction, before assembly, place thermally conductive rubber on the chip to dissipate heat on the metal module cover.
Additional information useful when repairing the 32LG5000 TV (T-CON V315B1-C07, V315B1-L07 matrix) has been collected in an archive that can be downloaded from the link below.
The archive contains:
- Firmware version 03.55.01
- Instructions for TV firmware
- Datasheet EC5575 (AS15-X)
- Service Manual 42LG5000
- Specification for matrix V315B1-L07
- Russian user manual for TV
TV repair 32LG3000:
LG Led TV repair, no picture:
LCD TVs have now practically replaced ray tube TVs. LCD panels are distinguished by high picture quality, smaller dimensions (thin body), which allows them to be hung on the wall, and lower energy consumption. But, despite all these advantages over older TV models, breakdowns of LCD TVs have not decreased. Therefore, if your LCD TV fails, you have 3 options:
- carry out repairs at a service center;
- call a specialist to your home;
- repair the equipment yourself.
But first you need to decide what kind of malfunction appeared in your TV. Should I contact a specialist or can I repair my LCD TV myself?
To find the cause of a breakdown, a technician often has to use special equipment. But sometimes a fault on an electronic board can be determined visually, for example, if the capacitors are swollen. In any case, the one who undertakes the repair must have the necessary skills and knowledge, without which it is possible to “kill” the TV completely. Below we list the main blocks included in the design of LCD/LCD TVs, which are most often subject to breakdowns.
Main board
All the main components of the device are under the control of the motherboard: inverter, timing controller, power supply. The motherboard contains a processor, memory, tuner, converters, etc. If any malfunction occurs with the main board, the following symptoms may appear:
- it is impossible to configure the device,
- inputs don't work
- the picture on the screen is displayed with noise,
- difficulties arise with management.
Power supply (PSU)
This node supplies power to all modules of the television receiver, including the motherboard. Although the power supply has different types of protection, in some cases they turn out to be ineffective.
If the power supply burns out, or some of its components fail, the following symptoms appear:
- TV does not turn on;
- the indicator blinks or does not light up at all;
- the device turns off spontaneously;
- When turned on, the indicator starts to glow and immediately goes out;
- When the TV is on, the screen turns black, but the sound does not disappear.
Matrix (screen)
Most often, the screen is either broken or filled with liquid (tea, juice, coffee, etc.).
In case of mechanical damage (and in some cases chemical damage), the matrix cannot be repaired and must be replaced with a new one.
But if in it one or more lamps have burned out, then screen restoration is possible. The following matrix problems can be repaired:
- gray screen;
- hazy image (as if filled with milk);
- the appearance of vertical stripes;
- image slowdown;
- moving objects split into two.
Inverter (backlight unit)
The task of the inverter is to convert low voltage (12-24V), which comes from the power supply, into the high voltage necessary for the operation of the backlight lamps. If the inverter is faulty, the following can be observed:
- after turning on the device, only sound works, but no image;
- When you turn on the TV, the picture appears for a moment and then disappears completely.
It is worth noting that the picture has not disappeared anywhere. If you turn on an ordinary flashlight and point it at the screen, you can see moving shadows on it. This fact confirms the lack of backlight due to inverter failure.
May also power supply protection triggered if the backlight unit fails. In this case, all attempts to turn on the device become unsuccessful, since it turns off immediately (sometimes a click is heard).
T-Con (timing controller)
This node converts signals coming from the motherboard into signals that the matrix can recognize, and thereby form an image. A broken T-Con causes the following symptoms:
- the color scheme is disrupted;
- “goosebumps” and various stripes appear;
- the screen turns white or gray.
What can you repair yourself?
Since an LCD TV is a rather complex electronic device, you can fix only some problems yourself, and only on condition that you have minimal knowledge and radio electronics skills. So, you can do it yourself:
- troubleshoot problems with the remote control or lack of TV signal;
- repair the power supply;
- replace the backlight bulbs.
Replacing the matrix itself, if it is damaged, is not always justified from a financial point of view, since its price is approximately 80% of the cost of the device.
Problems with the remote control
If you try to turn on the device from the remote control, but it does not respond to your actions, then first of all, you should check the validity of the batteries. Dead batteries should be replaced. If dirt has accumulated under the remote control buttons, you will also not be able to use it. Disassemble it and clean all dirt from the contacts. Another reason that the remote control stopped working is that it fell, resulting in the quartz emitter is damaged which will need to be replaced. If the remote control was filled with liquid and drying it did not help bring it back to “life”, you will have to throw it away and buy a new one.
No TV signal
A situation often arises when a working TV refuses to turn on. But not everyone immediately realizes that this behavior of the device can be caused by a banal lack of a TV signal. This fact is explained by the fact that modern TVs use a noise reduction function. If there is no TV signal, protection is triggered and the TV switches to standby mode. Therefore, if your TV receiver stops turning on, first check the presence of a TV signal, and only after that look for other reasons for the equipment failure.
Power supply repair
To generally understand how to troubleshoot a power supply, the whole process can be followed using the example of repairing a DAEWOO TV.
Before proceeding with repairs, make sure that the device is unplugged from the outlet.
Replacing capacitors is the simplest operation that a home mechanic can perform. In other cases, you cannot do without special knowledge, and it is better to entrust the troubleshooting to a specialist, since your incorrect actions can cause the motherboard to burn out.
Replacing backlight bulbs
You can also replace burnt-out backlight lamps installed in the matrix yourself. The process of replacing lamps will be demonstrated using the example of a Sharp device. Using this description, you can change lamps in LCD matrices of TVs of other brands.
When to contact a service center
In most cases, when malfunctions appear on the TV, you will need to contact a service center. Below is a list of problems that require mandatory intervention from specialists.
- All breakdowns listed at the beginning of this article(repairing the power supply and replacing lamps, if you can handle it, can be excluded from the list).
- HDMI input does not work. A breakdown occurs when devices are connected to this input while the TV is running. Users often forget that this needs to be done when the device is turned off.
- The image is missing. Before calling a technician, check the equipment settings and the presence of a TV signal. If the problem persists, turn off the device and call a specialist.
- Screen noise. First check the TV signal, antenna cable and all connections. If that doesn't work, check with your service provider to see if any maintenance work is being done. Check which electrical appliances in your home are currently turned on and which ones may be causing interference. In other cases, this problem may be caused by internal failures in the TV receiver units, and to get rid of them, you will need to call a technician.
- Can't set up and save channels. This indicates a failure of the memory chips.
- Stripes on the screen. The reason for this could be anything: poor contact of the cables at the connection points, problems with the matrix and motherboard, etc.
- No sound. The system board may be faulty, the contact of the cable may be broken, or the speakers themselves may be damaged. But first, check to see if you accidentally pressed the mute button on the remote control (meaning the one-touch mute button with the speaker icon crossed out).
- The device stopped turning on. If the socket, plug and power cord are working properly, the power supply is not turned off, then it is better not to tempt fate, but to disconnect the device from the network and call a technician. If you do not do this and continue to “conjure” the electrical appliance, then the main components of the TV may fail, after which more serious repairs will be required.
As practice shows, restoring the T-con board is advisable when it is integrated into the matrix of the LCD TV, and not connected to it with cables. This is due to the fact that its complete replacement will be quite expensive. It is better to replace the separate board with a new one. When this happens, complex TV repairs should be performed by experienced TV technicians at a service center. What are the signs of a t-con board failure? Since this component connects the main board with the matrix, you can find out about its malfunction if any image distortions appear. However, it is worth remembering that it is not so easy to distinguish between a motherboard failure and a t-con failure, so experienced specialists check all situations, since further TV repairs will depend on this. When the t-con board fails, a variety of problems can arise in the operation of the TV. This is when, when turned on, there is backlight and sound, but there is no image, the picture on the screen is in color negative, when instead of an image the screen is gray with stripes. This also manifests itself if there are vertical color stripes on the screen, the image is present on half of the matrix, the predominance of one color in the image, white stripes. When, after turning on the TV, the image immediately disappears, there is an incorrect spectrum of colors on the screen, the black color is replaced by incorrect contrast or noise, all these symptoms indicate that repair of all TV models in Kyiv will be required, because the T-con board has failed. It is easier to determine the failure of a given board if the image is distorted in only one part of the matrix. This is unlikely to be caused by a motherboard failure, since the entire image would be damaged. To accurately exclude the possibility of failure of the motherboard, some TV models are equipped with a diagnostic mode for the t-con board. Before performing any TV repairs, you are guaranteed to need diagnostics that will help you correctly determine the malfunction. In the T-con board, such main parts as the DC-DC converter, the gamma corrector, which consists of a set of transistors, the microprocessor, tracks, and the LVDS bus input are subject to breakdowns. Whatever the cause of the malfunction, repairing TVs will be quite complex, so it must be carried out with great care and precision. In addition, to perform such a procedure as repairing a TV, namely restoring the functionality of the t-con board, you are guaranteed to need the most modern special equipment.
There is no image in the outdated Sanyo 3022D CRT TV.
They brought to our service center a rather outdated TV with a 37 cm picture tube - Sanyo 3022D. This TV has been in use for many years; it has already been opened and repaired before. Its body is very dusty, in some places even damaged. Despite this, we always meet our customers halfway, repairing TVs of any type. There is no picture on this TV, there is a horizontal line on the screen. According to the user, we learned that when a stripe appeared, he independently removed the cover, bent the board a little, and the image became normal.
This TV is from the back. Despite the fact that the device is many years old, the label with all the data about the TV is well preserved. It clearly shows the model, serial number and other information, which is extremely important for the technician who will be repairing TVs. The body of the device is in satisfactory condition, it is dusty, especially a lot of dust has collected in the ventilation grilles. You can also see the damage above the label.
After the back cover was removed from the TV, it immediately became clear that no maintenance work had been carried out throughout its operation. The entire kinescope, the inner walls of the case and the board itself are covered in a uniform layer of dust. The kinescope board is in place, visually it is not damaged. This model was put into operation so that TV repairs could be carried out at a high professional level.
During the diagnostics performed, the TV technician accurately determined that the cause of the failure of the TV was simultaneously two modules - power supply and frame scanning. That is why TV repair consisted primarily of restoring their functionality. The installation was also restored and general preventative maintenance was carried out.
At this stage, the TV repair was not completed, since many different parts had to be changed and soldered. So, for example, 2 pieces of C 100.0 * 35 V were replaced. After all the work done, this CRT TV works well, the image appeared, it is of fairly good quality, in addition, the horizontal strip has completely disappeared. The user is recommended to carry out preventive maintenance from time to time and clean the TV from dust.
40-inch LED TV Toshiba 40PU201V1 does not turn on.
The Toshiba 40PU201V1 40-inch LED TV stopped turning on. According to the user who delivered it to our workshop, at first the duty light was still on, but after the technician arrived from another service, it stopped. This model has one TV tuner (analog), a panel refresh rate of 50 Hz and a screen resolution of 1920x1080 pixels. The device does not support features such as Smart TV and Wi-Fi. We always repair TVs, so we took him to work. To determine the malfunction as accurately as possible, diagnostics is required. We do it for free. As practice shows, such faults as in this case are quite complex, so restoration work will not be easy either.
This TV, shot from behind. The TV body is in fairly good condition, without any mechanical damage (no scratches or chips). All screws are also in place. It is not dusty, which means it was operated correctly and in good conditions. Our service center repairs TVs with any malfunction, including this one.
CTRL removed all faulty ones from panels with defective scans and dead Y-SUS; if Y-SUS remained working, Logik-Board did not suffer. But even in cases with a dead Y-SUS, you shouldn’t immediately rush into panic and buy a new CTRL 6871QCH034A or reprogram it in vain. With 30 dead Y-SUS, approximately 2-3 CTRLs suffer. If Z-SUS or the panel itself is dead, the firmware does not crash, at least I haven’t had this happen yet... LG recommends replacing Logik with dead scans in any case, but I will say from experience that CTRL is not a weak weak link in this system. Sometimes replacing electrolytes and soldering helps. It takes a lot, but it's worth it.....
ADDED 07/07/2009 12:06
A little about cooling and repairing Scan and other boards. There is a lot of debate here about whether certain microcircuits need to be cooled. If you listen to the advice of those who believe that all electronic elements can withstand fairly high temperatures under heavy loads and are tested many times at manufacturing plants, etc. Everything can be right. But practice shows something completely different. I have been using the principle of cooling parts for many years and I can tell you that this activity is quite successful. If it were up to me, I would open new devices and remake them right away. The most vulnerable point of the PDP2V6 and similar models is the scan drivers; after 2-3 years of operation, the SN755866 and similar chips simply burn out and drag a rather expensive Y-SUS board with them into oblivion (though not always, if the client understands that You can’t turn on the TV - then Y can be saved). The driver boards themselves are not exactly cheap and are not sold in every store, so you have to patch them.... The ideal option is to purchase new boards. If there is no opportunity and money, you can repair the old ones, especially since all the microcircuits do not burn out at the same time, as happens on some Samsung models. It is better to use new SN755866, because the donor ones were most likely already overheated, overloaded, and desoldering them is an additional burden (in addition, you need to be 100% sure that the microcircuit is in order; if it is shorted, the Y-SUS will immediately fail). Dead microcircuits are soldered off quite easily; you can even carefully cut off all the legs and heat the soldering iron from below (SN755866 are also soldered from below to remove heat) to remove the faulty microcircuit. I personally use hot air for desoldering. (less fear of ruining the tracks). First, of course, you need to remove the silicone, first roughly (you can directly with your fingernail), then soak it all in a Nitro-Acetone-based solvent, etc. (Careful with solvent; many boards have connectors (plastic), for which nitro is death). Silicone becomes like gelatin when soaked in water and can be easily removed with an old toothbrush. It’s another matter if the mikruha is filled with eboxy, but this is in Samsung and more on that another time... Of course, the landing site needs to be cleaned, remove excess tin Entlötlitze, copper braid is now sold everywhere (otherwise it will be difficult to put the mikruha in place), wipe the place again a fat remover, nitro will also work. After an accurate fit, solder 3-4 legs on all sides with a mini-soldering iron; it is best to check the symmetry under a magnifying glass. Then use a large soldering iron to solder the microcircuit at the bottom, there is no need to spare tin here, it is important that the microcircuit is soldered at the bottom, otherwise there will be no heat transfer to the board below, and you won’t be able to dissipate much heat through the legs. Afterwards, you can completely solder the SN-ku with a mini-soldering iron on all 4 sides, preferably having contact with each leg. for washing after soldering I use the same nitro. Below I added a file about the FD3284F (unfortunately, there is no complete Datasheet yet, but from the block diagram you can understand the device and operating principle). This is an analogue for SN755866, it has been noted that they are more reliable and durable in operation, but are currently available for sale only to manufacturers of strips.