There are many reasons why dark black spots appear on the TV. But in most cases, their presence indicates damage to the matrix. And it doesn’t have to be mechanical. It is possible that the diffuser peeled off due to a manufacturing defect. And sometimes a dark spot on the TV can be eliminated by yourself! But in most cases, you have to seek help from an authorized service center of the manufacturer.
- 1 Causes of black spots and gray shading on the TV matrix
- 2 Additional Causes of Dark Spots on Different TV Brands
- 3 What you can do at home to fix smudges and blackouts on your smart TV
Causes of black spots and gray shading on the TV matrix
The basis of any modern TV (and monitor too) is a matrix. And it consists of several layers, in particular:
- Polarizing filter . Adjusts the transmission of light emitted by the backlight.
- Liquid crystals . They create the final “picture” on the screen. The color of each pixel is regulated by a generating electromagnetic field.
- External polarizing filter . If it is missing, then instead of the image on the screen there will be only a dark gray background. Even if the layer of liquid crystals, as well as the backlight, function properly.
Also behind the matrix is an LED backlight. It is placed evenly over the entire diagonal plane of the TV. As a rule, this is an LED strip, where each element is connected in parallel (in some TVs it also happens in series, but this design is usually not used now).
And LEDs also have their own operational resource (on average – from 30 to 50 thousand hours).
Accordingly, the following main reasons why dark spots appeared on the LCD TV can be distinguished:
- “broken” pixels ;
- mechanical damage to the matrix;
- failure of the backlight mechanism (consists directly of LED lamps, as well as an inverter that converts current or regulates its voltage);
- scattering layer defect;
- stratification of one of the layers of the matrix (polarization);
- failure of the video chip (graphic processor, which is responsible for processing the digital signal, converting it and outputting it to the liquid crystal matrix).
The image in liquid crystal matrices consists of miniature pixels. And in about 95% of cases, a dark spot on the screen is just a consequence of their damage. It looks like multi-colored small dots without any halo around. Their color can be almost any: blue, green, black, white, red. Unfortunately, such a breakdown cannot be repaired, especially on its own. But at the same time, many manufacturers in the instructions for use directly indicate that the presence of several “broken” pixels is the norm. For example, for Samsung, if there are only 3 of them on the screen, then this is not considered a warranty case. If more, then the matrix will be replaced free of charge. For more detailed information, please contact the manufacturer directly.
What causes “broken” pixels to appear on LCD screens?
Experts say that they can be provoked either by mechanical damage to the TV (impact on the matrix), or sudden voltage drops (in particular, exceeding its permissible value, over 230 – 250 Volts). Therefore, if the current in the home electrical network is not stable, then it is recommended to connect the TV through an external voltage regulator – this really helps to extend the operational life of the equipment.
Matrix mechanical damage
Most often it looks like a round black spot on a TV screen with unequal edges.
Occurs even after mild blows to the matrix or TV case!
Indicates an open circuit supplying one of the liquid crystal zones. It is impossible to repair such a breakdown. There is also always a risk that such spots will increase in size over time. That is, with a probability of 95%, the matrix will soon become unusable. It should also be noted that operating a TV with a damaged mechanically damaged matrix is not a good idea. There is a possibility that there is a short circuit between the supply circuits of the matrix, which will also lead to the failure of the inverter, or even the GPU. Repairing such breakdowns is impractical. That is, in the future you will have to purchase a new TV to replace the old one.
Failure of the backlight mechanism
There are 2 variations of such a breakdown:
- Failure of the LED itself . That is, the semiconductor of which it consists, corny burned out. It is impossible to replace, in service centers they offer only a complete replacement of all LED-backlight strips. But this is a relatively inexpensive procedure.
- Failure of the inverter, which is responsible for supplying current to the backlight . In this case, the LED may initially not work only in a certain zone (for example, in the upper left corner). But in the future, other lighting zones will definitely be de-energized.
It looks more like a blackout zone with a corresponding halo rather than a separate dark spot. But at the same time, if you shine a powerful flashlight on the darkened part, you will notice that the image is displayed normally on the liquid crystal matrix. It just doesn’t light up. You should not do something on your own, it is better to contact an authorized service center for help as soon as possible. It should also be noted that if the backlight is damaged, it can periodically recover on its own. But this is a short-term effect. It is only additional confirmation that there is a violation in the supply circuits of LED strips.
Scattering layer defect
From the inside, the plastic case of the TV in the back is pasted over with a special scattering layer, visually similar to ordinary metal foil. It is responsible for reflecting the light that falls on it from the LED backlight, as well as from the polarization layer (it reflects the light falling on it). And if any sweet, damaged, peeling areas form on the scattering layer, then this just looks like a dark spot on the screen. By the way, quite often such a defect appears after the matrix is repaired in unauthorized service centers. Because there the scattering layer is pasted manually, that is, it is almost impossible to achieve absolute smoothness and the absence of bends and folds. In authorized service centers, as a rule, the entire back cover is replaced, on which a scattering layer is applied even in the factory. Accordingly, the likelihood of poor-quality repairs is completely leveled.
Delamination of the polarizing film
These dark spots on a TV screen can take almost any form. Most often – they are rounded, with equal edges, as well as stripes. But with slight pressure, the image may briefly become normal, as with a fully working matrix. Indicates that the polarizing film has peeled off. And this happens either due to mechanical damage, or due to the use of aggressive cleaning products to wipe the TV screen. Less often – because of a factory marriage. In older TVs, there was still a problem when the polarizing film delamination occurred due to overheating of the matrix. Due to the high temperature, the glue simply melted! This is often due to the fact that the TV is placed close to the wall or heaters (and does not cool properly). Fixing it yourself is impossible.
Video chip failure
One of the rarest and at the same time complex breakdowns. The video chip mostly fails due to overheating or factory defects. In this case, various artifacts, spots of almost any color may appear on the screen. But neither a normal image nor a graphical menu can be obtained in any way. The TV only responds to turning it on and off “from the outlet”, because in modern TVs even the signals from the infrared transmitter are also processed by the GPU. This breakdown is also eliminated only in the conditions of the service center. And there is a risk that it will not be possible to fix the TV, since GPU chips are not available for all models (depending on the manufacturer’s internal policy, as well as the supply of spare parts).
Additional Causes of Dark Spots on Different TV Brands
In principle, the causes of spots for almost all TVs are the same, since the structure of the matrix and the principle of displaying the image are similar. But there are a few exceptions:
- On Samsung TVs with AMOLED matrices, dark spots may indicate matrix “burn-in”. There is no backlighting, as each pixel is technically an organic LED. At the same time, the spots look like an afterimage (they are often called “ghosts”).
- Dark spots on the LG TV screen are sometimes the result of a software glitch! More precisely, because of the violation of the AVI and MPEG4 codec coding technology. In such cases, a banal firmware update using the built-in tools of the TV itself helps. With this problem, dark spots appear in different places every time you turn it on, without any cyclical order.
What you can do at home to fix smudges and blackouts on your smart TV
In very rare cases, dark spots disappear on their own over time. This happens if they appear due to delamination of the polarization layer with a slight overheating of the matrix. But this is about 0.5% of all cases. In other situations, a visit to the service center is required. And the faster, the better. How can the risk of stains be minimized? The following recommendations must be followed:
- by any available means to level possible mechanical damage to the TV (for example, if there are small children in the house, then it is better to place the TV on the wall at a height of at least 1.5 – 1.7 meters);
- do not place the TV close to the wall (the minimum required indent, which manufacturers indicate in their instructions, is 15 centimeters);
- do not set the maximum brightness of the backlight (in most cases this is not required, and 50 – 70% of the brightest level is comfortable for most viewers);
- connect the TV through an external voltage regulator (will reduce the likelihood of failure of the inverter and graphics processor).
So, if there is a dark spot on the LCD TV screen, then the best solution is to send the equipment to a service center. At the same time, the master needs to describe under what conditions the defect appeared, what events preceded this. If a complete replacement of the matrix is \u200b\u200bnecessary, then this will cost about 30 – 70% of the cost of a new such TV (depending on the specific model). If the problem is in the graphics processor, then its replacement costs about 30 – 50% of the cost of the TV, but the master does not always manage to get a spare part.