White Spots Appear On The LG TV Screen
Hello. Glad to see you on the pages of the my-chIP.info blog. Today there will be a repair of the Saturn ST-TV21F2 TV, which will be possible for any beginner to do, but let’s talk about everything in order.
A TV set for repair came with a declared malfunction of “spots on the screen”. Since I am NOT in the workshop all the time, I didn’t manage to see the TV with the client. After turning it on, it became clear that the TV has a problem not only with color, but also with frame scanning, since the ramp is narrowed vertically, and there are small stripes on top.
Learn to repair CRT, LED and LCD TVs together. Disassembly, visual inspection, determination of the order of repair.
As often happens, after disassembling the TV, cleaning the board from dust, you can immediately see the culprits of one of the malfunctions. At the output of the power supply, 3 swollen electrolytic capacitors are visible, which must be replaced. I will start the repair just with the elimination of this malfunction, replace the capacitors and I will fight with spots at the end of the repair.
The culprit of the first trouble
So, there were 3 faulty capacitors, one with a nominal value of 470 uF for 50 volts, the other 2 for 1000 uF for 25 volts.
After a successful replacement, I turned on the TV. There is a clear progress in the quality of the picture, namely the image has become normal, stretched to full screen. It remains only to fix the problem with spots on the screen.
Image after replacing capacitors
If there are colored spots on the screen, the first step is to make sure that the TV does not fall on the screen. Very often TV sets are brought for repair after falls, and these TVs have minimal chances of successful repair, since the picture tube mask (fine mesh inside the screen) gets lost, and this can only be cured by replacing the picture tube. In this case, the owner claims that the TV did not fall, which means we will repair it. The work of the CRT demagnetization system was described in detail here.
The main breakdown in which spots are observed on the TV screen is a posistor. We will change it to a new one.
After replacing and energizing, I heard a characteristic click of the demagnetizing loop, which confirmed that it was working. The TV turned on and the image returned to normal.
If there is a heater or other strong heat source next to the TV-equipment, the matrix may stratify in LCD devices, or even stop working if it is a plasma panel. In this case, small flares appear, which gradually fill the entire screen space.
The shape and color of the spots can also tell a lot about the nature of the problem, which allows you to immediately start solving it. For example, on old analog TVs, colored spots indicate excessive screen magnetization. To eliminate this trouble, it is enough just to move the device to another place, away from the electromagnetic equipment affecting it.
Yellow spots indicate the already begun process of matrix stratification, which is typical for budget models, which have been actively used for more than 5 years. expensive TV equipment for the most part only for such problems.
Ingress of moisture and air into the matrix
There may be a violation of the transport rules by the seller or improper operation of the equipment by the user. Even a few drops of water or dust particles trapped in the matrix body can cause unpleasant spots to appear on the LCD TV screen.
How to remove dark spots
“Torn” bright spots on a dark-colored TV, located almost across the entire screen, indicate a malfunction of the polarizer or diffuser, which are located in the matrix body. Only a specialist who has the appropriate tools and equipment at his disposal can independently eliminate such a defect.
Dark spots on a regular LCD TV screen. round or oval, with decreasing intensity closer to the edges of the shape, are most likely caused by dust entering the matrix. Most often this happens due to sharp temperature fluctuations. The layers of the matrix begin to move, and dust particles penetrate into the vacated space.
In a good half of the cases, you can remove such stains on your own.
- We lay the TV on a soft surface with the back side up.
- Unscrew the screws securing the back wall and carefully remove it.
- Using a vacuum cleaner set for blowing, or a compressed air cylinder, blow through all the edges of the matrix, directed the air stream at an angle.
- We wait 5-10 minutes and put the TV cover back in place.
If the black spot from dust that has penetrated inside is very small, then you can try to get rid of it in an easier way. Take a dry soft cloth and, turned it over your finger, tap on the screen. Small particles Must fall.
On a plasma TV, such problems are solved, alas, in only one way. by calling the master at home or by going to a service center. In this case, it is impossible to remove black spots on your own. This requires expensive equipment and special tools.
Why do spots appear on the screen?
To begin with, let’s consider the common problems inherent to all modern TV equipment, regardless of its type. Fortunately, there are much fewer of them than in old analog TVs, because although a rather complex, but only one element is responsible for correct visualization. the matrix.
Pressing or bumping the TV screen can cause colored spots to appear. over, the broken pixels can spread to the rest of the matrix, which is typical for budget models, where there is no independent protection for each sector. This kind of damage excludes any repair. only replacement of the matrix.
How to remove stains on a TV screen
Modern TV technology pleases with a clear and realistic picture, but, like in the case of old analog TVs, it is burdened with its own specific problems. One of the most common troubles is the appearance of spots: black, light or colored.
All this clearly does not contribute to a comfortable viewing of content, indicating a malfunction of the technology. We will deal with the causes of the appearance of spots, the consequences and consider options for solving such problems. The information will be relevant for plasma, LCD and LED TVs.
This is the fault of Not only budget, but even premium models of famous brands. Samsung, LG, PhilIPs and others.
Removing light spots
If white spots in the “starry sky” format appear on the TV screen, then, most likely, the reflector or diffuser is out of order. The problem appears some time after the purchase of the device. The geometry of the pattern can gradually change and capture the rest of the screen. Replacing broken elements is NOT possible at home, so the best option is to contact specialists who have the equipment necessary for repairs.
Sometimes there are backlight problems. The latter can be unevenly distributed and change shade in places. Most often this is manifested by the appearance of barely noticeable light spots. In some cases, the problem is easily solved. The fact is that the back walls of some TV models are so tightly tightened that it leads to deformation of the matrix, which is why light gaps appear. In this case, you need to put the TV screen down on a soft surface and Unscrew the screws, then tighten them again, but not so much.
Another reason for the appearance of pronounced white spots is the liquid in the matrix. It gets there most often through ventilation holes (accidentally spilled drink, watering flowers in the neighborhood) and less often as a result of condensation. It’s good if this is ordinary water: it will simply dry out after a while, and there will be no problems. But if it is tea, coffee or alcoholic drinks, then the matter becomes noticeably more complicated.
If you have experience with equipment, you can get rid of extraneous liquids on your own.
- Remove the back cover of the TV, after placing it on a soft surface.
- Removing the matrix by disconnecting all the cables.
- We dip it in a pre-prepared container with warm purified water and leave it to soak for a couple of hours.
- Then we wipe all Visible parts with a microfiber cloth.
- Finally dry with a hair dryer with warm air.
- We put the matrix in place in the reverse order of disassembly and fixing the back cover.
You can turn on the TV only after a while after assembly.
White spots appear on LG TV screen
Almost every LCD TV today suffers one way or another from this problem. uneven screen backlighting. Some areas of the screen, upon close examination, may appear brighter than others against a dark background. And, what happens less often, darker spots are on a general light background. When viewing real material, this flaw can become clearly noticeable in dark scenes.
So what is the reason for this phenomenon? And is there anything you can do?
What is the essence of the problem
All LCD TVs consist essentially of two parts: a backlight system and a liquid crystal panel, consisting of a matrix of cells that completely transmit or block light to varying degrees. Light sources are CCFL lamps or light emitting diodes (LEDs). Today’s LED TVs are exactly the same LCD TVs in design with the introduction of LED sources for backlighting instead of lamps.
In the simplest LCD TVs, the backlight creates a constant stream of light, set by the adjustment of the regulator. On more expensive TVs, the backlight system can automatically adjust the flow of light in time and space, depending on the nature of the displayed material. In other words, during dark scenes, backlighting can reduce light levels, making the image appear darker than on a basic LCD TV.
A backlight system is never perfect, either due to manufacturing defects or design inefficiencies or other disadvantages. Because of them, individual areas of the screen begin to spontaneously transmit more light than adjacent ones.
Click on the picture to enlarge it
Disassembled layer-by-layer LCD TV. The layer on the far left is the clear screen covering. The next layer (where you see the image) is the liquid crystal matrix (LCD panel). The next layer (bright white plane) is the diffuser. In fact, it is translucent “matt” plastic. Far right. backlight system in the frame of the TV frame.
Ideally, the scattering layer should distribute light evenly across the entire surface of the screen. But this is very difficult to achieve. To get a result close to optimal, you need to increase the number of lamps, use high-quality diffusing materials, improve the entire structure.
Therefore, cases with lighter stripes across the screen opposite the backlight lamps and darker ones in the gaps are likely. For displays with small screens in the backlight system, only lamps located at the edges may be enough, which makes them structurally similar to models with a side LED backlight system.
All LED TVs are the same LCD TVs
On LED-backlit TVs, unfortunate enough to be named in commercial reviews “LED TVs”, instead of CCFL lamps, miniature and at the same time bright LEDs are used. Their poor placement can seriously affect the effectiveness of the screen backlight. In most LCD LED displays produced today, the LEDs are located at the edge (edge) of the LCD panel, which has a very negative effect on the efficiency of light distribution across the entire plane of the screen. Some models have two LED emitters, structurally installed on the side of the LCD panel (top / bottom or sides), and in SEPARATE models they stand on all four sides.
If you put a flashlight on the table, you will get an idea of the problem that exists when the LEDs are located at the edge of the TV screen. The space immediately in front of the LEDs will be brighter, the farther ones will be dimmer. In such HDTV designs, rather complex optical fibers are used, along which light propagates along the screen and is partially reflected in the direction of the LCD panel and through it to the viewer.
Each of THESE edge lighting methods has its own characteristics in terms of uneven illumination of the pixels of the LCD panel. For example, on TVs with sources located on the side faces, a completely black screen may look like this:
When the backlights are placed above and below the panel, a completely dark screen with blown out light areas will look like this:
If the LED backlight is placed around the entire perimeter of the screen and the backlight can be observed around the entire perimeter with a completely dark screen:
Potentially, there may be problems similar to those noted below, but less Visible and in smaller numbers:
The opposite pattern for screen non-uniformity will be for LCD LED TVs with a side lighting system in the case of a completely light screen. If the LEDs are placed around the entire perimeter of the screen, there will be a darker area in the center than around the edges. Here is a clear illustration of a similar case.
With top / bottom backlights, the darker bar may run horizontally across the center of the screen. And in the case of backlight sources along the sides of the screen. a dimmer streak may run vertically.
Some high-end LCD LED models have the backlight located directly behind the LCD panel. This so-called Full LED system, it can provide more uniform illumination of the entire surface of the screen, due to the more even distribution of INDIVIDUAL sources. In addition, in this case, the so-called local dimming system can work quite efficiently, which makes it possible to independently adjust the brightness of SEPARATE, divided into zones, groups of backlight sources. As a result, it is possible to reduce the blackness of the dark parts of the image, but also the light.
In plasma panels of the previous generation, sometimes similar problems with uneven illumination of the screen could be observed. But these problems were reversed. The turbidity was observed not in a dark screen, but in a white field. Modern plasma models no longer have such disadvantages.
What can be done?
There is practically nothing that users themselves can do to eliminate uneven backlight problems. Except for the advice on loosening the fastening of SEPARATE points of the rear panel, where the laminated structure of the panel can be unnecessarily squeezed in SEPARATE places. But everyone follows such advice at their own peril and risk.!
Manufacturers, of course, spend a lot of money on improving existing systems and developing new systems with more advanced LCD panel backlights. However, there are several problems that make it difficult to create a perfect backlight system. The thinner the TV (and therefore the shorter the distance between the backlight and the LCD panel), the more difficult it is to achieve uniform light diffusion by taking the limited space between the source and the LCD panel. Another problem is that better diffusion means more light loss, which is always undesirable.
Finally, there is the issue of cost. The uniformity of the backlight is only one of the characteristics of the TV, and far from the first in the list, where the first positions are located cost, luminous flux, contrast, color, processing. In any case, the TV is designed taking into account the final cost, which will limit certain quality characteristics.
Unevenness in brightness is difficult to notice on TV screens in sales areas and at home in a lighted room. Given this circumstance, the task for developers is simplified, allowing them to make compromises on the uniformity of the backlight in order to achieve increased brightness or other parameters, as well as reduce the cost of materials and the product as a whole.
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In some situations, stripes appear on the screen due to damage to the matrix loop. Broken conductors are far from always amenable to restoration. Sometimes you have to replace them with new components. You can order a new cable at the service center, inform the managers of your TV model in advance.
It is better to entrust the elimination of hardware breakdowns to the masters, but if you want to do everything yourself, then you need to prepare the following tools: screwdrivers or bits PH, PZ, TORX, HEX, SL. The matrix connecting cable is located inside the TV, so work begins with removing the back cover. Unscrew all screws and gradually open access to the broken components.
All connections are fastened using special connectors. You won’t have to solder it. Apply enough pressure to the latch. The connection principle can be compared to an Ethernet cable.
The arrangement system of the base modules is different for all manufacturers. Therefore, you need to carefully study the detail of the assembly. You can find it on the Internet on the official website of the manufacturer.
causes of malfunction
Vertical and horizontal stripes on a TV screen are not always an indicator of serious technical malfunctions. Such defects can appear for easily explainable reasons:
- incorrect adjustment of the image so that the stripes disappear, it is enough to start the automatic selection of the optimal parameters;
- incorrect cable connection. Also, the cables can be clogged, clogged with dust, they simply need to be cleaned.
Stripes on the Samsung TV screen may also appear intermittently. This defect is mainly accompanied by flickering of the picture, “sticking” of the frame or other distortions. All these nuances are of tremendous importance. Since they allow you to determine the nature of the breakdown.
Thin vertical line
Mechanical damage to the matrix
Vertical multicolored stripes
Malfunctions of matrix components
Colored horizontal lines, spots
Bad contact of the matrix loop
Horizontal stripe white
Frame scan defect
Conventionally, all reasons Incorrect TV operation can be divided into several groups: mechanical damage, short circuits, incorrect settings. The last category does NOT need extensive research. Consider the subtleties of determining the failure of hardware components, as well as the features of their recovery.
Other mechanical damage
Black horizontal stripes on the TV screen may occur due to cable connection problems. To fix the problem, it is enough to disassemble the TV, and then connect the cables correctly. It is possible that some conductors are damaged as a result of mechanical damage. In this case, they need to be replaced.
A white narrow horizontal stripe on the TV screen may also appear due to broken matrix wires. It is extremely easy to determine this breakdown, just push the loop a little or move it to the side: if all defects disappear, then the malfunction is diagnosed correctly. Eliminating such a malfunction is an extremely complex process. Take a magnifying glass or other magnifying tool to locate where the wires are broken. Restoration is carried out using conductive varnish or by heating the contacts to the appropriate temperature. If you overheat the contacts, the malfunction will be aggravated.
Due to the ingress of moisture inside the LCD TV, oxidation of the contacts occurs. You can determine this breakdown by the characteristic green plaque on the trains and contacts. If the scale of the malfunction is insignificant, then you can remove plaque from the surface of the conductor yourself. Cleaning with a knife or blade.
When, due to moisture, large stripes or spots appear at the bottom or in the middle of the screen, then the problem has reached a serious scale. Simply removing plaque does NOT solve the situation. First, you need to check the voltage of the contact circuit with a multimeter. In this case, contact the service center.
The ingress of moisture becomes a prerequisite for the breakdown of LED backlighting. Therefore, blackouts may appear in certain areas of the screen. It is not excluded that the problem has arisen due to improper care. Under no circumstances should you spray copious amounts of cleaning products onto the screen surface. Special liquids need to be sprayed onto a microfiber or dry cloth, and only then wipe the display.
Why did I see vertical stripes on my Samsung TV
During operation, the TV is exposed to mechanical damage. Because of this, there are malfunctions in the operation of hardware modules, which manifest themselves in the form of various defects. Vertical stripes on the Samsung TV screen may indicate the failure of several modules at once.
Now let’s take a closer look at how to quickly diagnose a TV breakdown. We will analyze the troubleshooting methods, as well as We will compose a list of useful recommendations to prevent the appearance of all kinds of defects on the TV screen.
It is easy to guess that the prerequisite for this malfunction is the users, namely, their violation of the operating conditions of the equipment. A single-color vertical stripe on the TV screen is a sign of matrix mechanical damage. This is a very narrow line, its width does not exceed two pixels.
In some situations, this defect appears, but later disappears. If more than 7 days have passed since the band appeared, then this is a sign of serious hardware damage to the TV.
Replacing the die is an extremely time consuming and costly process. Therefore, if the fears were confirmed, and the strip appeared on the Samsung TV due to damage to the matrix, it makes sense to think about purchasing new technology. If the warranty period is NOT expired, then Contact the service center representatives.
You absolutely cannot replace the damaged matrix on your own. Since this requires special equipment. The use of improvised means will provoke an aggravation of the malfunction. It is more rational to contact the service center.
In addition to the breakdown of the matrix itself, there are also violations in the operation of its components. For example, the appearance of black lines on the screen is a sign of failure of the column decoder, which is located directly on the matrix. Over time, the line thickness will increase. Therefore, it is not worth delaying the repair.
If you want to repair the TV yourself, then you need to take into account a few fundamental points:
- Mostly all cables, loops and conductors are very thin. They can be easily damaged. Therefore, you need to be as careful as possible.
- To re-solder the contacts, you need to have the appropriate equipment (infrared and hot air PS, magnifying devices) and professional skills.
- You need to know the location system of the base TV modules so as not to accidentally damage the operable components.
The equipment is not insured against damage and premature failure. TVs are also no exception to this rule. Mostly all disturbances in plasma operation can be eliminated. The main disadvantage is that the cost of some components is comparable to the price of a new TV. Therefore, it does not always make sense to change the matrix. It is not excluded that after a while other nodes will stop working.
What should I do if streaks appear on the display at the end of the warranty period? Much depends on the cause of the defect. For example, if mechanical damage to the screen became the catalyst of the problem due to the fact that the TV fell corny and hit a hard surface, then you should not count on free service. However, if defects have arisen due to incorrect factory assembly, then the manufacturer compensates for the elimination of the malfunctions. It is more expedient to refuse repairs. Insist on getting a new TV.
Don’t forget about prevention to prevent black and white and color stripes from appearing on your TV screen. Here are some helpful tips from experts:
If you plan to hang the equipment on the wall, then you need to use a special bracket for this. Do NOT use homemade fixing systems. Follow the suggested tips, and then stripes or any other defects will definitely not appear on the TV screen.
manifestation of malfunction
Often, a dark spot appears on LCD TV screens, even the proven and popular Samsung, Sony, LG maars. They can be localized in one corner, located in the center or in several places at once.
Spots DO NOT disappear when switching channels. Even when the TV is off, glare is visible in their place. over, blackouts can be Not only black or dark gray, but also white or colored. This indicates color errors or other problems.
Dark spots on the TV screen
How to get rid of dust spots
Rarely wiping the surface from dirt and dust leads to the ingress of microparticles on the matrix. Over time, a large dark spot is born from a small black dot. The following actions will help to save from the first manifestations:
- Tap your finger very gently on the screen surface where the small black dot appears.
- Try vacuuming the screen. This can be done at a distance of 2-5 cm from the screen and at a low speed of the vacuum cleaner.
- Let’s disassemble the device and wipe the inside of the screen. You can also wipe the matrix from dust, but you need to do everything very carefully.
If the dark spots have not disappeared after all the manipulations, the TV from Sony, Samsung or any other manufacturer must be taken to the workshop for a full diagnosis and repair.
How to get rid of dark stains due to moisture penetration
If a defect appears due to water ingress, the matrix must be rinsed. This requires a special detergent. Running water is not suitable. It contains a large amount of invisible impurities, abrasive particles, which will settle on the matrix and make the situation even worse.
Performs cleaning to remove dark spots from the TV matrix in a well-ventilated area with good ventilation. It is advisable to turn on a humidifier, if available. It is necessary to carry out cleaning with soft cotton gloves.
If you wish, you can carry out the replacement yourself if you have the skills to work with household television appliances. The repair instructions are as follows:
- Prepare the workplace and all the necessary screwdrivers, other tools.
- Disconnect the TV. Using a screwdriver Remove all bolts to remove the housing.
- Disconnect the wires and cables. This should be done as carefully as possible. If the connecting elements are damaged, they will also have to be replaced.
- Remove the bolts holding the die. Carefully remove it and put a new one.
- Assemble the TV in reverse order. Switch on and check the correct operation.
Cleaning the screen protector glass surface
One of the reasons for the appearance of spots in the external adhesion of dirt, dust. In such a situation, it is not necessary to disassemble the equipment or reboot it. It is enough to wash the screen surface. For this:
- Disconnect equipment. It is advisable to disconnect it from the network.
- By purchasing a special cleaner for LCD monitors.
- Take a soft microfiber cloth.
- Apply a small amount of the product to it.
- Wash the screen without pressing hard.
It is advisable to do such care 2 times a week. This will save dust from penetrating under the case and sticking to the matrix.
Causes of dark spots
Repair of equipment depends on the source of the stain and on the type of equipment.
Digital TV allows you to watch your favorite movies, cartoons and series in excellent quality with high definition and good sound. But owners of LCD monitors may encounter the problem of dark spots appearing on the screen. Let’s take a closer look at the reasons for their appearance and equipment repair options.
When it is necessary to carry the device to the masters
If a dark spot appears due to moisture or dust, you can try to fix it yourself. If streaks appeared due to mechanical stress or strong exposure to high temperatures, which led to matrix delamination or failure of loops, it is necessary to carry the equipment to the workshop.
The service center specialist will carry out repairs in the following sequence:
- Accept the equipment and write out a ticket that you handed it over.
- Performs diagnostics, often a PC is used for this to identify the exact causes of a breakdown.
- Will repair parts to be repaired or install new ones.
- Check the performance of the equipment and issue a new warranty card for their services.
On average, it takes from 1 to 5 working days to remove dark spots on a TV screen, depending on the workload of the wizard and the availability of parts in the service. The cost of repairs depends on the degree of damage and the price of spare parts.
How to eliminate inaccuracies in TV settings
To attempts to disassemble an LCD TV or hand it over to a service center, it is worth excluding software failures, which are possible with digital broadcasting. The verification scheme is common for Samsung, Sony and LG. There may be some nuances depending on the TV model.
To avoid software problems when using a digital broadcast set-top box, do the following:
- Save all the necessary information from the tuner to a USB stick.
- Go to the menu using the console from the console.
- Find the section “Settings” or “Reset parameters”.
- Reset parameters to factory settings. If necessary, enter the pin code 0000, 1111, 1234.
- restart the box.
- Go to the settings and restart the automatic channel search.
If the spots on the LCD TV screen disappeared, the cause was a software failure. In such a situation, it is not necessary to disassemble or repair the device in the service. If the malfunction remains, it is better to turn to professionals to repair an expensive modern TV.
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