How To QC | Dead Pixel Check Sony Bravia X8000G 55″ 4K UHD LED TV 2020 [BANGLA]
There are a number of free and paid apps available to fix the flaw. Among the popular ones:
- Bad Pixel. According to the developer, the program helps in 90% of cases. Offered for a fee.
- PixelFixel. Activates a video sequence that changes colors on the panel for 12 hours. Active influence helps to activate the transistor.
- DeadPix. A program for a computer, smartphone that can bring a broken point back to life.
- JScreenFix. A specialized site where the screen is configured online, while the user can indicate the damaged zone, start the recovery process.
Does the warranty cover
Matrix is a panel that requires complex, time-consuming production. The defect can only be identified after the TV is fully assembled.
If the manufacturer eliminated all defective panels, even with one defective pixel, the cost of the panels would increase significantly. Therefore, a compromise solution was spelled out in the standard:
How dead pixels affect the image
Pixel. the point from which the image is formed on the screen. A separately taken unit consists of three subpixels: green, red, blue. A transistor is responsible for each, turning on or off one of the colors on command.
In the simple model, the matrix consists of more than 6 million subpixels, and in the new panels that support the 4K format, their number can go up to 37 million. With this indicator, the likelihood that several transistors will fail is high.
When the presence of dead pixels is recognized as a defect
The permissible number of dead pixels on a new LCD panel is determined by the international standard ISO 13406-2.
This document describes the normal operating parameters of the display. So, the standard defines 3 types of dead pixels:
- open. highlighted in white, cannot be restored;
- closed. black dots to be repaired in a service center;
- colored. the broken pixel glows with a red, blue, green tint, which indicates a breakdown of the transistor.
Most manufacturers divide matrices into four segments:
- there should be no dead pixels in class A. This technique belongs to the premium class;
- category B allows from 2 to 4 black dots, up to 5 colored dots per million;
- in class C, a TV is not considered defective if there are up to 5 black, 15 white and 50 color pix. Such matrices are typical for state employees;
- category D. devices with up to 700 defective points. Such TVs are practically not found on sale.
How to check your TV for dead pixels yourself
The buyer in the salon can test the matrix for defects himself. This procedure is provided for at the legislative level. If the seller-consultant denies the possibility of inspection, insists on paying for the inspection service, it is better to refuse to purchase at this outlet.
To carry out the test, you need to prepare a USB flash drive in advance by throwing on it monochrome pictures of black, white, green, blue, red, or 4K videos for checking TV, capable of showing the operation of the LED panel:
Before testing, the TV must work for a few minutes, since defects appear only on a warmed-up screen. If there is a defect on the screen, it will be noticeable when checking.
- connect a TV to it via an HDMI cable;
- open a website or an application (for example, Dead Pixel Tester, available for free for Windows 7,8,10);
- view pictures, videos to determine the presence of burnt zones.
How to recover
It happens that the TV is bought, and a dead pixel is revealed at home. Also, the presence of a marriage can manifest itself during operation.
In such a situation, you can try to fix the problem (you can restore performance only when the dot glows in color), but the presented methods are considered insufficiently effective. The defect often returns after a few days of viewing.
Checking the TV for dead pixels
By applying physical effort to the damaged area, you can restore the contact between the diode and the transistor. To do this, gently massage the area around the broken pixel with a leaf. In this case, manipulations should be carried out with the TV turned off, the desired place is determined in advance.
After making circular motions, there is a chance that the point will work. The main thing is not to overdo it, as you can damage other pixels, exacerbating the situation.
Why are some dead pixels allowed? The fact is that the technology for the production of LCD matrixes is very complex, and not even every device manufacturer can afford their own production. And such a defect can only be detected on the assembled device. If the manufacturer scraps screens even with minor defects, then the price of TVs and monitors will increase several times. Therefore, such a compromise was found:
- Manufacturers keep production at the same level and do not raise prices.
- Buyers allow the presence of a certain number of dead pixels, which is not a warranty case. In this case, the buyer has the right to check the display before purchasing.
Test the screen for dead pixels yourself
When buying a TV or monitor, sellers offer to use an additional service. check for dead pixels. over, the service is paid and higher. If you find a defect at home, you will no longer be able to return the TV back, they explain. After all, this is not a guarantee case, and they are right. In fact, you can perform such a matrix test yourself and for free, there is nothing complicated about it. You just need to bring a special video or pictures with you on a flash drive for verification, after reading our article before.
How to check
To check the screen for defects, you need to consistently submit pictures of the primary colors to it, and at the same time carefully look at it, trying to find points of a different color. This is what broken pixels look like. For example, when there is a white picture on the screen, it is easy to detect black and colored dots. If the color is black, then it is easy to find white dots, etc. Before the test, with the TV turned off, make sure there are no dust particles or other debris on the screen.
How many dead pixels are acceptable? The answer to this question is contained in the international quality standard for LCD TVs ISO 13406-2. It identifies 3 types of defective points:
Dead pixels on LG OLED,will they cover it under warranty? today we find out !
- Open or white. such pixels freeze in the open state and constantly glow white.
- Closed or black. such pixels freeze when closed and constantly glow black.
- Colored. the control transistor of such pixels fails, and they are constantly lit in one of 3 colors: red, green or blue.
Also LCD devices are divided into 4 classes. The first class is the highest, the presence of defective points is generally not allowed in the matrix of devices of this class. The bulk of the devices on the market are of the second class. The standard defines the allowable number of different types of defective dots depending on the maximum resolution it supports. Information for popular 2nd class devices is shown in the table below.
|pixel type \ max resolution||1280 × 720 (720p, HD Ready)||1920 × 1080 (1080p, Full HD)|
There are several methods for recovering dead pixels found during the test. They give a result extremely rarely and only in the correction of colored dots (3rd type). Also, tests show that it usually helps for a short time, the next day the pixel fails again. Plus, you can easily mess up neighboring points. Therefore, we highly do not recommend doing recovery, but we will still consider the methods:
- Programmatic approach. A matrix picture is sent to the screen, in which dots of different colors are randomly displayed. Within 20 minutes, the problem pixel should be restored;
- Mechanical approach. Turn off the TV, press the broken pixel with a napkin with your finger, turn on the device and stop pressing. This method can harm the matrix.
External inspection upon purchase
First, check the packaging for various damages (dents, breaks), if during transportation there were any blows to the packaging, then the TV got it. Then you check the availability of all correctly completed documents, such as a passport for the device, a warranty card. The coupon must be filled out correctly by the seller (warranty period, date of sale, stamp), the serial number on the coupon must match the number on the TV.
Check the external condition of the TV and the remote control. Look for scuffs, chips, cracks, etc. The screws on the back of the TV must not be tampered with, otherwise your TV was already on sale and being repaired.
By the model name, serial number and product code, you can find out where and when this TV was made and for which country.
After that, you can turn on the TV and check its operation. correct operation of the remote control, work with external sources (USB flash drives, players, etc.). You can take your own flash drive by pre-recording high-resolution videos on it, and pictures to check for dead pixels.
What to check first on TV
Check for dead pixels
When forming a picture on the TV screen, all display pixels must be involved. With a Full HD screen resolution, the entire display field consists of 1920 × 1080 pixels, which is just over 2 million points.
According to the rules, a certain number of non-working pixels is allowed, different norms allow a different number of defective pixels. So, having identified this defect at home in the form of one or two non-working pixels, you will not be able to return the TV back, so it is better to do this check before buying.
To search for defective pixels on the screen, you need to submit an image with a specific picture and examine the screen from a close distance. You can also use a magnifying glass. You need to look for a pixel that glows in a different color than everyone else. The image must match the screen resolution exactly.
Completely inoperative pixels, those that do not respond to the signal and are in a constant position, can be found in a uniform picture (filled with one color). White, black and primary colors (red, blue, green) pictures are alternately fed to the screen and pixels of a different color are looked for on them.
Inoperative pixel on black background Inoperative sub-pixel on screen
There are such defective pixels that start to work poorly when the matrix heats up. You can identify them after the TV has been running for a while.
There are pixels that do not work correctly depending on the work of neighboring sub-pixels. You can find such defects if you present a picture on the screen in the form of a checkerboard fill, color stripes, gradations, a grid. Incorrectly working pixels will stand out from the general structure of the picture.
The necessary pictures for checking the picture on the TV can be downloaded here. Resolution of verification images 1920 x 1080 pixels.
To test Ultra HD 4K TVs test pictures here.
How to use these images can be read here.
Non-uniform screen illumination
When a video signal with a uniform color fill (painted in one color) is input to the TV input, the screen must have this color without any color shades. But, due to the technological peculiarities of manufacturing LED-backlit displays, it is difficult to achieve such a uniform illumination. Therefore, it is advisable to check the uniformity of the color field before purchasing. Usually such a defect is not considered a breakdown and the TV cannot be returned or repaired.
Such screen defects are called banding, flashing and tint.
Tint can be translated as “color tone” and it shows how correctly white is displayed on the screen. When watching a regular video, you may not see this defect, because the picture is constantly changing there. But if the picture is static, then the interference can be very noticeable and interfere with normal viewing.
To identify the tint, you need to submit a white or gray field to the screen. Interference in the form of stripes, spots and other shapes, painted in a different tone, against a uniform background may indicate the presence of a defect in the tint. Such noise is usually pink or greenish in color and is located closer to the edges of the screen.
If the defect is very noticeable, then it is better to choose another TV.
The tint is large and clearly visible. Allowable interference level.
Invalid banding level
Only LED TVs can have glare. To assess the quality of the display by the level of illumination, you need to do this in a completely dark room (turn off the light and shade the windows). In this case, you need to select the maximum backlight level on the TV, for this you can select the appropriate mode (it can be called “bright”, “dynamic” or in another way). You need to disable image enhancement modes such as Dynamic Backlight, Black Level Correction, Eco Sensor, and others. This is done so that the TV does not adjust the backlight when checking.
But even so, errors may occur due to the automation of the TV receiver, when a completely black frame is fed. Indeed, with a black picture, the TV turns off the backlight. Therefore, to detect highlights, it is better to submit a black picture with some bright elements, for example, white titles on a black background at the end of the film.
Then, from a distance, look for screen glare, especially in the corners. Some minimal highlights are fine for normal viewing.
Invalid backlight level
Finding an LED TV completely free of these defects (tint, banding, lightning) is unlikely to work, but you need to choose a model with a minimum level of these interference.