Tcon timing controller for matrix 800 480. Diagnostics and repair of t-con board. What can you repair yourself?
CTRL removed all faulty ones from panels with defective scans and dead Y-SUS; if Y-SUS remained operational, 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.
Most often repairs boards T -con only makes sense if it is built into LCD TV matrix or monitor , and not attached to it trains , since a complete replacement in this case would be too expensive. It is better to exchange a separate board for a new one or a donor one.
Signs of board failure t -con
Because the pay t -con connects the main board of the TV or monitor with matrix , you can suspect its failure with almost any image distortion. At the same time, it may be impossible to distinguish between a motherboard failure and a t-con failure, so you have to check all the possibilities.
A broken t-con board can cause the following problems with your TV:
when turned on, sound and lighting appear, but there is no image;
the image is shown in a color negative - there are not enough brightness gradations;
Instead of an image, a gray screen with light stripes is shown;
colored vertical stripes are displayed, as when a diagnostic TV signal is supplied;
the image is only on half the screen;
one of the colors predominates in the image;
white stripes are shown;
the image disappears soon after turning on the TV;
wrong range of colors - they are too light or too dark;
Noise is displayed instead of black;
wrong contrast.
The easiest way to determine if the t-con board is faulty is if image distortion is observed in only one area of the screen - this is unlikely to be caused by a faulty motherboard, since in this case the entire image would be damaged.
To definitely exclude the possibility of a motherboard failure, some models of TVs and monitors provide a diagnostic mode for the t-con board. To do this, you need to disconnect the LVDS cable, apply power to the board and close the service contacts. At the same time, a special image will appear on the screen - if it is distorted, then it is in the t-con that you need to look for the problem.
Types of faults
One of the main parts of the t-con board may break:
DC-DC converter - it can only be repaired in older models of LCD TVs and monitors that use a key field-effect transistor, while modern devices use a PWM controller that cannot be replaced;
gamma corrector, consisting of a complex of transistors;
microprocessor;
LVDS bus input;
paths.
There are two ways to diagnose a faulty DC-DC converter:
Disconnect power, connect trains and ring control points. It is also possible to diagnose a broken fuse on the board t -con .
Disable trains drivers matrices , connect power to the board and check the voltage at the test points. You can find out which indicators will be correct only on forums, from people who have already repaired a similar board - there are no diagrams from manufacturers. Using the same method, you can determine if a fuse has blown, which occurs due to a short circuit on the driver capacitors LCD panels .
If the DC-DC converter breaks down, the image disappears partially or completely. If there is a picture, but the colors are distorted, the gamma corrector is to blame. You can verify this by displaying a grayscale image on the screen. If part of the scale is distorted or replaced by colored noise, a problem has been detected.
Replacing the gamma corrector is very simple. The AS15-F corrector is very often used, which costs about $2 in Chinese stores. If necessary, it can be replaced with models HX8915-A or SL1014I - the TV or monitor will work exactly the same. After replacing the part, the gray scale and the normal picture return to normal, noise and incorrect contrast disappear.
If the problem is in the microprocessor or traces, the board cannot be repaired. Everything is clear with the processor - this is the main part of the board, and it is cheaper to buy a new board than to replace one element. The tracks are simply impossible to restore - they run inside the board, which is multi-layered. They usually break due to corrosion when liquid gets on the microcircuit.
Due to careless handling, the contacts on the LVDS connector may oxidize. This can be determined with the naked eye during disassembly. TV or monitor - copper will be blackened. The problem is fixed very simply - you need to clean the contacts with an eraser until they shine.
During the repair process, you need to act very carefully - the LVDS cable and matrix driver cables are very fragile. The latter usually take the form of a tape connected to the board with a special clamp. You must disconnect it carefully and always with your hands; you cannot use a screwdriver or other devices.
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 distortion appears. 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 Kiev 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.
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 block diagram
Timing controller includes
- Processor for processing LVDS input data pipelines into independent R, G, B pipelines and clock signals for horizontal and vertical matrix drivers. The processor exchanges information with RAM and Eeprom ROM. A fixed supply voltage of 5 or 12 volts supplied from the motherboard is converted into several secondary voltages necessary for the operation of the controller using DC/DC converters.
- Reference voltage generator for DAC drivers that provide the necessary curvature of the image histogram. Otherwise, this process is called gamma correction.
- The voltage generation unit for powering the drivers, usually made on a PWM controller and a key field-effect transistor.
T-con diagnostics and repair
Diagnosing a malfunction in a 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 switching T-con into 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.
To eliminate the influence of the LCD panel on the matrix controller when measuring the supply voltage of the drivers or the reference voltages for the DAC drivers, use a short-term disconnection of the cables, one or two, on the LCD panel. Based on the nature of changes in instrument readings and the visual perception of the image on the screen, one can draw certain conclusions about the causes of the malfunction. To reliably monitor the performance of a unit when taking measurements, it is necessary to control the presence, shape, amplitude, frequency and duty cycle of pulses, which can be done using an oscilloscope. The presence of an oscilloscope makes it easier to find a defect and is always used for diagnostics in a stationary service center.
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 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 any opportunity to repair the 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.
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 switching T-con into 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 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.
