Self-repair of LED TV LCD monitors. Malfunctions, cases from repair practice. Fuses can also “burn out” - either due to a short circuit or due to constant overvoltage. To check the fuses you may need
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 is the case on some Samsung models is happening. 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.
A Samsung TV has broken down and its warranty has already expired - a familiar situation. You take the TV to a workshop or call a TV technician to your home and they tell you that repairs will cost several thousand rubles - it’s easier to buy a new one. Quite often you can hear from technicians that your equipment cannot be repaired at all. Is it so? The question is ambiguous. Let's try to consider a specific situation and the main algorithm of actions.
And so, the Samsung TV of a modern LCD or plasma model is broken. Let's assume the most radical option - the black screen does not turn on. What to do? Firstly, do not call a TV technician to your home based on newspaper advertisements - this is a “pig in a poke.” A good master may come across, or a former plumber may come along. In general, there is such a category of “miracle craftsmen” who come with the businesslike appearance of a highly qualified specialist, delve for a long time inside the case and then sadly declare that “repair is not possible...”, take money for the call and diagnostics and leave. Also, an on-call technician can also fix a trivial problem, but pass it off as an expensive repair, charging you a tidy sum - then try to prove it and find this craftsman.
In general, let’s immediately make a reservation that identifying a fault in a broken TV and diagnosing it at home is extremely difficult. Therefore, don’t be lazy, take the TV under your arm and go to a reputable professional television workshop. We take the TV there for diagnostics and troubleshooting. This procedure is usually inexpensive and anyone can afford it. The technician will examine your TV using modern diagnostic equipment and specialized software. In a few tens of minutes you will know exactly what is broken on your TV.
Now we will find out from the master how much the repair will cost. If the repair is inexpensive, then we leave the TV in the workshop, especially since the repair will then remain under warranty. If the repair is expensive and it is comparable to buying a new one Samsung TV, then we take the TV under our arm again, say thank you for the diagnosis and go home. Find out in advance, before going to the workshop, the price of purchasing a new Samsung TV of the same model. This is very easy to do by going to any advertisement on the Internet on specialized sites.
It is noteworthy that, unlike other industrial and food products, Appliances, including televisions, are becoming cheaper every year, and their quality is improving. So the TV you bought two years ago will cost much less today. You can verify this by looking at the links on this site for current prices.
Having bought a new Samsung TV, do not rush to throw away the old broken unit. A second TV in the household is not a superfluous thing - you can place it in the kitchen or bedroom and then not quarrel with your family over the choice of watching TV programs. Almost any Samsung TV can be revived and repaired yourself at home, especially now that you know its malfunction after going to the workshop.
Let's take a closer look at how to repair a Samsung TV yourself at home. First of all, you need to remember that modern Samsung TVs have a rather complex device, so repairing it requires special equipment, devices and conditions. But quite ordinary household items from your workshop will also work.
First of all, inspect the power cord from the network - “ring” it with a tester. It is quite possible that it is simply frayed, bent inside the insulation and current from the network does not flow into the TV. Try installing a cord from another TV, they are all standard now.
If this does not help, then carefully unscrew the bolts on back cover TV and inspect the fuses. A burnt fuse is immediately visible - inside the glass bulb the thread is burned out and missing. Traces of soot may also be visible. Before replacing the fuse in your TV, remember: only in less than 10% of cases (i.e. 10 TVs out of 100 faulty) replacing the fuse will return it to working condition. In other cases, further repair of the TV power supply is required.
Before you begin repairing your TV, prepare necessary tool: tweezers, side cutters, soldering iron with temperature regulator and a set of tips, multimeter, microscope or strong magnifying glass (for working with small parts).
Each Samsung TV has its own characteristics, which are important when repairing it. Therefore, the approach to finding a fault is strictly individual. Determine when exactly the malfunction appeared and what it was expressed in. Sometimes the problem can be rooted in poorly inserted connectors, shorted wiring, cracked, burnt or simply broken parts. How to repair a Samsung TV yourself? You can fix the problem in minutes, or it may take hours. The purpose of our article is to explain methods for self-repair of modern television equipment.
If the fault is in the element being tested, the voltage at the incandescent lamp will drop. In the same way, we check the filter capacitor, input circuits, transistor and mains rectifier. If the incandescent light bulb comes on and goes off or remains dim, the power supply is likely good. This means that we next carry out the test without using an incandescent lamp. Then you should measure the voltage across the load when the power supply is turned on. If the voltage is higher than 130-150 V, then the test should be directed to the primary circuit of the unit. Pay attention to the capacitance of the capacitors. If it has decreased, the voltage will be higher than the specified value. On the contrary, if the voltage is below normal, we check the secondary circuits.
Now let's check
monitor power circuits. If the screen does not light up when the scanner and power supply are working, check the integrity of the monitor and the contacts of the cables to it. Perhaps the breaks can be removed by soldering. What else should you look for as the cause of the malfunction? If there is no picture or sound, the problem is most likely in the radio channel. If there is no image, but there is sound, the reason should be sought in the color block or video amplifier. If there is sound, but no picture, the problem is in the low-frequency amplifier or video processor. If there is both sound and image, look for the reason in the tuner or in its harness. Special attention should be given to the control unit. To check it, use the reference data or diagram for the Samsung TV processor. They can be downloaded from the manufacturer’s website, just follow any advertising link on this page and you will find yourself there.. Samsung TVs often suffer from defects such as vertical stripes, quite well known to all repairmen. These are problems with the drivers (also called decoders, controllers, decoders) of the LCD panel matrix. These are chips that convert the color signal to address and turn on each pixel. Manufacturers usually place these drivers on flexible cables as close as possible to the matrix, dividing its entire length into several sections. On TV Samsung Samsung On top of the matrix there are 8 cables with drivers soldered on them.We place our Samsung LCD panel face down on a soft substrate and unscrew the screws and screws on the back panel. The back cover of the TV should be removed without problems. Below it we see a power supply board in the middle, a signal processing unit board on the right, and a backlight board under the black cover. Now our task is to get to the cables on top of the matrix, that is, we need to remove the front frame of the TV. In general, the power supply boards do not need to be removed, but if there are suspicions about its operation, unscrew the screws and release the cables. Not necessary, but if necessary, remove the signal processing board and disconnect the cables again. There is no need to remove the backlight board - you just need to check that the connectors are securely fastened.
The speakers of the Samsung TV are installed at the bottom and are mounted on rubber suspensions to eliminate vibrations on the body. There is a metal plate on top of the power supply unit that needs to be unscrewed. Below it there is an intermediate board with matrix cables. We carefully disconnect the cables and inspect the board for microcracks or cold soldering. Having removed the front frame and installed the boards in place (if everything is in order with them), we turn the TV over and turn it on. Stripes in the image will indicate faulty drivers. Most often, due to overheating, mechanical stress or manufacturing defects, the flexible cable detaches from the matrix contacts. Detachment of the driver from the flexible cable is also common. Less often, detachment occurs from the cable routing board.
When you click on the places of the cable shown in the photo, the stripes disappear - which means soldering is necessary. Please note that if the cable is slightly curved on one side and smooth on the other, this indicates mechanical stress in the cable. This shouldn't happen. Most likely this is a manufacturer defect. You can also simply press the cable in the right places with the appropriate design. To do this, glue double-sided tape along the entire screen to the metal frame that is located on top of the matrix from the inside so that the pressure is uniform everywhere and no new mechanical stress arises. On this strip of tape, glue a strip of sealing material in which motherboards and other computer parts are packaged. It turned out that there will be a sealing pad just opposite the contact of the cable with the matrix. The meaning of the design is to press the cables to the matrix.
In addition, we can talk about successful restoration of contact with an iron or soldering station. The cable turns out to be glued with a special conductive glue, which only under pressing has a low resistance, and without it – high. Using a heated soldering iron with pressure, it is possible to restore contact between the cable and the matrix. At the same time, check that the contact between the matrix decoder and the cable has steadily begun to deteriorate.
:
Samsung TV monitor.
If you are absolutely sure that it is the Samsung TV monitor that is faulty, and not the signal source, then we will consider your further actions. Let us remind you that you can verify that a monitor is faulty by connecting this monitor to another, known-good source (for example, a computer, laptop, multimedia box, external TV tuner).1. First stage: Opening the monitor and initial inspection of internal components. First of all, you need to disconnect all cables from your TV monitor. On some Samsung TV models, the signal cable has a permanent external connection to the monitor.
For most Samsung LCD TVs, the body consists of a front frame and a back cover, which often serves as the basis of the entire structure. It should be noted that there is no one recommendation for all designs and each manufacturer has its own characteristics that are unique to certain models.
Before starting the opening, you need to take care of a flat surface (for example, a table) and a soft material covering the flat surface and preventing the LCD matrix from scratching. It is also necessary to organize sufficient lighting of the workplace.
In order to disassemble the TV monitor, you will need to separate the stand bracket from the body by unscrewing the mounting screws or screws. You will need Phillips screwdrivers, types PH1, PH2, and for some models of devices, you may need types in the form of a six-pointed star. It is convenient to use a universal bit holder with a set of interchangeable bits of different sizes and types.
The elements are not able to perfectly block the flow of light - the black color on an LCD TV screen is not actually completely black.
Disadvantages also include color distortion and loss of contrast, since the viewing angle of the LCD is not that wide. Because of this feature, LCD TVs could not gain popularity for a long time, but now, thanks to the efforts of the developers, distortion has become almost invisible.
The advantages of LCD TVs include a wide selection of models with different brightness (from 250 to 1500 cd/m2) and contrast (from 500:1 to 5,000,000:1). Thanks to this, the buyer can purchase a device that optimally combines the required image quality and an affordable price. In addition, LCD TVs are lightweight and thin, so they can be placed on the wall.
But the greatest merit of liquid crystal technology is its mass availability. Due to large-scale production, prices for LCD TVs are now lower than for other similar devices.
After unscrewing and removing the fastening threaded elements, it is advisable to remember which fastening element was screwed into which hole. The next step is to separate the front frame from the back cover. Particular attention should be paid to the fact that in many designs, the front frame is attached to the back cover using plastic latches. We do not recommend using a slotted screwdriver, kitchen knife or other unsuitable objects at this stage to avoid deformation of the case, the appearance of burrs and chips. We do not recommend using excessive force if the front frame cannot be separated. Careless movement and excessive, misdirected forces can lead to irreparable damage to the latches, which in turn will lead to the appearance of unnatural gaps and changes appearance Your device.After separating the front frame, you need to disconnect the connectors high voltage wires on the inverter board going to the LCD panel. We do not recommend pulling the wires to avoid breaking the conductors, but removing the connectors of high-voltage wires with special tweezers.
Four main nodes can be distinguished LCD monitor Samsung TV:
· Power supply providing power to the signal processing unit, LCD module and high-voltage converters (inverters)
· Unit of high-voltage voltage converters (inverters) powering CCFL backlight lamps.
· Signal processing unit. In multimedia monitors, the signal processing unit is much more complex and contains large quantity elements.
· LCD module.
Before starting to search for the cause of the malfunction, you should carry out an initial inspection of the components to identify elements with a changed shape, as well as darkening on the boards, indicating heating of the components. Heating of a component until the board material underneath darkens may indicate a faulty component or a fault in the circuit to which the component belongs. 2. Second stage
To determine the cause of the malfunction, you will need a device diagram (or service manual).As we already mentioned, you can find it by going to any advertisement
located on this page. Also take a multimeter with the functions of continuity testing, measuring DC voltage and alternating current, measuring capacitance of capacitors.
3. Third stage : Replacement of faulty components.
Replacement of faulty components may require Soldering Station with temperature control of the tip, and to replace elements of the signal processing unit - a special hot-air soldering station. Note that some microcircuits are sensitive to excessive heat and may fail if overheated. Also, pads and traces should not be allowed to overheat, since excessive heating may cause peeling and breakage of the conductor on the printed circuit board.
4. Fourth stage:Monitor assembly.
Assembling the Samsung TV monitor should occur in the reverse order of opening. Particular attention should be paid to the screwing force and the length of the screws and screws being screwed in. If the screw or self-tapping screw is longer, there is a risk of damage to the housing elements and the LCD panel.
If there is NO SOUND on your Samsung TV, then first check the UMZCH U103 and the dynamic heads (you can send an audio signal of 0.25 V/1000 Hz to one of the inputs - pin 1 or 9). If the test signal does not work, check the power supply of the microcircuit (15 V on pin 7), the absence of a sound blocking signal (there should be a low potential on pin 8 U103). If the UMZCH is working, check the audio signal path (see description), identify and replace the faulty element of the path.
NO TV RECEPTION. Check for the presence of a PTsTS with a swing of at least 1 V on pin 8 of connector P1018 (radio channel module). If there is no signal, the module is repaired. If there is a signal, check the signal flow through the video card, determine and fix the problem.
Teletext mode does not work. If, when you turn on the teletext mode from the remote control, the form (fields, buttons, etc.) is not displayed, check the microcontroller IC101 and the “firmware” of the EEPROMIC102. if the teletext mode is turned on but does not work, check the arrival of the PTsTS from the output of the video processor (pin 70 of IC501 through the VT302 buffer) to the input of the decoder (pin 12 of IC101).
NO COLOR WHEN RECEIVING TV PROGRAMS
The level of the television signal received by the antenna may be insufficient. If this is not the case (the other TV is working fine), check the color system setting (in our case, SECAM) and the color saturation level in the user menu. If everything is in order, check the presence of a signal with a frequency of 4.43 MHz at the output. 34 U7, at If not available, replace resonator Z1. If the generator is working, check external elements U7 microcircuits connected to the color path (connected to pins 37, 45, 46). If they are working, replace the U7 chip.
Samsung TV processor.
If the processor is made in the form of a chip (microcircuit), radiators are used to remove heat. The heatsink looks like a battery of aluminum or copper plates mounted on the surface of the CPU. Place the vacuum cleaner on blower and use a stream of air to clean all the devices on the TV unit, including the radiator fins, from dust.
To improve heat transfer between the chip and the heatsink, special thermal paste is used. If thermal paste dries out, its thermal conductivity decreases and the processor begins to overheat. Carefully remove the radiator and wipe its contact pad with cotton wool soaked in alcohol. Clean the surface of the chip in the same way. Apply a drop of paste with a diameter of 2-3 mm to the radiator and apply a thin layer to the surface. Place the radiator in place and secure it.
The connector on the board into which the CPU chip is inserted is called a socket. When trying to install the processor into the socket, the pins of the microcircuit may bend or break. To level the outlet, use a narrow, hard object with a flat surface, such as a metal ruler or a medical needle.
If the leg (contact pin) breaks off, you can try to glue it. Insert a piece of copper wire into the desired socket connector of such length that it rises slightly above the surface. Apply a drop of conductive glue to the contact pad of the chip from which the lead broke off using a needle or toothpick and carefully insert the processor into the socket so that the pad with the glue is pressed tightly against the “prosthetic” leg.
Be careful not to let the glue get on other terminals of the microcircuit, otherwise a short circuit will occur between them. You should not remove the repaired processor from the socket again - the leg may break off again.
If you have a broken processor, you can use its parts to repair it. Separate one of the pins from it and glue it to the processor you are trying to restore. A thin needle of a suitable diameter can also become a “prosthesis”. Cut the required length with wire cutters, file the wider end part and stick it onto the contact pad of the processor.
Samsung TV DOES NOT RESPOND TO REMOTE CONTROL COMMANDS
Check the remote control batteries and circuit elements: IC1, Z1 (455 kHz), Q2, D1 (Fig. 6.5). If a signal with a swing of 2...2.5 V is present at the collector of transistor Q1 and LED D1 is working, then check the photodetector U3. On the pin. 1 (OUT) there should be a signal with a swing of about 5 V. If there is a signal and it arrives at the input of the microcontroller (pin 24 U2), replace this microcircuit. It is very easy to check the functionality of the Samsung TV remote control. Point the turned on video camera or digital camera at him and look at their monitor. The diode on the working remote control will blink, which is not visible to the naked eye.
Well, if the repair fails, then just go andbuy a new Samsung TV
.
Today, the selection of literature on the topic “Do-it-yourself TV repair” is huge. Among other things, you can find training videos or manuals on this topic on the Internet.
Of course, to repair LCD TVs with your own hands, you need at least some knowledge in electronics. Anything that could threaten your safety and the safety of your loved ones should be eliminated.
Each TV has its own characteristics, which are important when repairing it. Therefore, the approach to finding a fault is strictly individual.
Determine when exactly the malfunction appeared and what it was expressed in. Sometimes the problem can be rooted in poorly inserted connectors, shorted wiring, cracked, burnt or simply broken parts.
How to repair a TV yourself?
Troubleshooting techniques
Faults can be fixed in minutes, but detecting them is much more difficult. The purpose of our article is to explain the diagnostic methods of modern television equipment.
Let's start... Where?
Where to start repairing TVs yourself?
In situations where the TV has “died” completely, that is, it cannot be turned on, it is very difficult to locate the fault. But we need to find the defect that has arisen as soon as possible, and then eliminate it as quickly as possible.
We start by cleaning the TV. First we clean the housing, then the surface of the kinescope and the receiver board. We do this with a vacuum cleaner and a brush. The malfunction can be detected immediately if you find burnt resistors, swollen capacitors, burnt-out microcircuits and transistors. If, while cleaning the kinescope, you see a white bulb instead of a transparent one, this means a loss of vacuum.
Checking the power supply
The first thing you need to check is the functionality of the power supply. How to do it? First you need to turn off the load and connect the incandescent lamp. If the voltage in it is less than 110 V, then we conclude that the power supply is inoperable. Then we check the unit’s transformer, then the filter capacitor, the voltage of which should be approximately 160 V. The voltage goes through the inductor to the output stage. You need to unsolder the inductor or fuse, thus disconnecting the power supply from the horizontal scan. As a load simulator we use an incandescent lamp, which we connect in parallel with the capacitor.
If the fault is in the element being tested, the voltage at the incandescent lamp will drop. In the same way, we check the filter capacitor, input circuits, transistor and mains rectifier. If it turns on and off or remains dim, the power supply is most likely good. This means that we next carry out the test without using an incandescent lamp.
Then you should measure the voltage across the load when the power supply is turned on. If 130-150 V, then the test should be directed to the primary circuit of the unit. Pay attention to the capacitance of the capacitors. If it has decreased, the voltage will be higher than the specified value. On the contrary, if the voltage is below normal, we check. Thus, you are already on the way to repairing TVs yourself.
The next step is to check the horizontal scan
If the power supply is working, check the horizontal output stage using an incandescent lamp. If the output stage is working properly, the same lamp effect will be observed - it will glow faintly or light up and go out.
The transistor should only be checked if the lamp lights up and does not go out. If it is OK and the voltage is low, make sure that the control pulses are in place. If the lamp lights up and does not go out, and the unit does not turn on, then the problem is most likely with the horizontal coils. Try disconnecting the coils and turning on the TV. If it turns on, then the fault must be sought in the deflection system. You can verify that the deflection system is faulty by replacing it with a working one. In this case, turn on the TV for a short time so as not to burn through the kinescope.
It's a matter of staffing
If appeared on the screen horizontal stripe, then line scan is ok. You should look for a problem in personnel. First, let's check the output stage and generator. If their voltage is less than 24 V, then the cause of the malfunction should be sought in them. If the problem is a break or breakdown rectifier diode, should be replaced faulty coil to work.
Checking the power supply circuit of the kinescope
If the screen does not light up when the scanner and power supply are working, check the integrity of the kinescope filament. Perhaps the breaks can be removed by soldering.
What else should you look for as the cause of the malfunction?
If there is no picture or sound, the problem is most likely in the radio channel. If there is no image, but there is sound, the reason should be sought in the color block or video amplifier. If there is sound, but no picture, the problem is in the low-frequency amplifier or video processor. If there is both sound and image, look for the reason in the tuner or in its harness.
Particular attention should be paid to the control unit. To check it, use reference data or a circuit diagram for the processor. They can be downloaded from the manufacturer's website.
The article indicates only a small part of the faults that you can fix yourself.
Repairing TVs with your own hands is not a reckless task, but a responsible one. And if you doubt even for a split second that you can do it yourself, you should seek help from a specialist.
It is certainly possible to repair the TV yourself, without resorting to the services of a television technician. What does this require? Basic technical literacy, ability to hold a soldering iron and the ability to carry out basic measurements with a simple tester. A large amount of information about typical defects that the Internet is replete with can encourage even a doubter to start restoring a broken device. Self-confidence is a wonderful quality, but the likelihood of ending up with a completely “killed” device is quite high. Maybe after all?
So, let's start disassembling. Remove the cover from the TV if it is secured with screws or self-tapping screws. Modern TV models, in addition to fasteners, also have a cunning system of latches, which can be quite difficult to open without breaking them or scratching the case. The craftsmen have experience in opening devices and necessary equipment for this purpose, remembering that the connection of the cover with the body resembles the structure of a modern remote control remote control TV, made entirely with latches.
The back cover is removed and we can see the device of the television receiver:
- power supply, which can be made separately or together with an inverter or LED backlight unit
- motherboard
- inverter or LED backlight unit
- matrix with controller (T-con)
- local keyboard, photodetector
The power supply is designed to generate stable voltages of a given power, necessary for the correct operation of the remaining components of the television chassis. It can be in standby or operating mode, depending on the command from the motherboard. It is the most vulnerable link to external adverse influences such as power surges, lightning strikes, etc. The TV's power supply must use high-quality components that can ensure its uninterrupted operation. wide range input voltages in severe temperature conditions.
The motherboard is the “command center” of the entire device. Provides control, switching, adjustments and settings for the TV as a whole. Executes user commands sent from the remote control and local keyboard. It has a developed architecture of data storage devices in the form of Eeproom, Flash, Nand Flash, SpiFlash, RAM chips associated with a central or GPU and signal processing devices on the I2C bus - a serial data bus using two bidirectional communication lines SDA and SCL.
An inverter or LED backlight unit ensures trouble-free operation of light sources in the form of lamps or LEDs to illuminate the liquid crystal matrix. It is controlled by commands from the motherboard to turn on and change the brightness of the backlight. They have a serious protection structure that blocks the system not only in the event of a malfunction of the lamp or LED line, but also in the event of a certain imbalance in their operation. Inverter transformers most often fail when diagnosing malfunctions of this unit.
Currently, among budget TVs, models have begun to appear in which all the blocks presented above are made on one board. The power supply, backlight driver, and motherboard are assembled in one unit. The ability to diagnose such a device is hampered by the lack of free access to fundamental electrical diagrams and firmware for it. In this case, we recommend turning to professionals. A TV technician will repair your TV at home or in a workshop at a very inexpensive price by today’s standards, will give a guarantee on the work performed and spare parts, and will save you time and nerves.
When deciding to repair your TV yourself, you should soberly assess your technical and professional skills and ask yourself the question: “Will I be able to fix my TV without harming either it or myself.” After all, no one has yet canceled 220 volts, as well as the electrical safety rules when working with electrical installations. It’s one thing if you permanently destroy the “box” - this is only material loss, loss of health is a more significant thing. Think and decide: “Is the game worth the candle?”
Hi all!
This article will talk about the simplest, but at the same time the most common, malfunctions. CRT TVs LG, 29 inches (72 cm) diagonal.
Such malfunctions can be dealt with by having the skills to work with a soldering iron, as well as having normal vision. In this case, no more skills other than holding a screwdriver are required.
We will develop this topic using a specific example, i.e. we will produce TV repair LG with your own hands .
So, I entered TV repair LG, model 29FS4RN, chassis MC-05HA.
According to the client, the TV periodically went into standby mode while watching (it turned off, but the indicator on the front panel glowed red). Then, one fine evening, the TV was turned off by the remote control, and the next day it did not turn on. Only after this did the client realize that there was something wrong with the device, and thus this television receiver ended up in my possession.
I’ll say right away that the malfunctions that will be discussed below are very typical for CRT TVs with a large screen diagonal, so the tips for eliminating them will be relevant for any brand of TV.
I tested this device and, indeed, the standby mode indicator glowed red, but the TV did not turn on in operating mode.
Next, I proceeded to disassemble the faulty device, namely, I unscrewed the back cover.
Then I removed the chassis (board) from the case.
Attention! Be careful when disconnecting the chassis from the picture tube! In any picture tube there is always a large current charge remaining. Therefore, disconnecting the high-voltage wire coming fromTDKSto the anode terminal of the kinescope (suction cup), use a well-insulated screwdriver (or something similar that does not conduct electricity). Slide a screwdriver under the suction cup, press the contacts under it and carefully, without touching the metal part of the screwdriver and the contacts with your hands, pull the rubber part of the suction cup to disconnect it from the kinescope. Remember, the current going to the anode of the kinescope has a voltage of 25 kV (25,000 volts).
Also, do not touch the contacts of the power capacitor with your hands (located in the primary power circuit, it is also called a “jar” because it is the largest) while it retains a charge. Under no circumstances discharge it in the board itself by shorting the contacts - this can lead to failure of the power chip. It needs to be carefully removed from the board, and then, at arm's length, bridge the contacts with an insulated screwdriver, thereby discharging it. And after that, solder it into place, observing the polarity.
