Xiaomi screen check: how to find broken and stuck pixels

Owners of Xiaomi, Redmi and Poco smartphones often face the need to thoroughly diagnose the display immediately after purchase or when visual artifacts appear. The screen is the most expensive and fragile component of a modern device, so the presence of matrix defects can significantly reduce the comfort of using the gadget. Pixel check allows you to identify hidden factory defects that are not noticeable when you normally view photos or videos in the store.

Matrix defects can vary from barely visible points of a different color to entire areas with impaired color reproduction. If you are planning to purchase a used device or just want to make sure that your new flagship is working, you need to conduct a comprehensive test. In this article, we will analyze all available diagnostic methods, from simple built-in functions to specialized online services.

Timely detection of a problem gives you the right to warranty repairs or return the goods to the store. Ignoring small defects at an early stage can lead to their proliferation, because damage to one part of the matrix sometimes provokes the emergence of new "dead" zones. Let's figure out how to conduct professional diagnosis yourself.

Types of Matrix Defects: What to Look for on Screen

Before we start testing, it's important to understand what kind of anomalies we're looking for. Dead pixels are dots that stay black all the time and don't change color regardless of the content being displayed. They look like tiny dips in the image and are most noticeable against a light background. Often these defects are the result of physical damage or manufacturing defects.

Unlike them, stick pixels burn in the same color (red, green or blue) and don’t switch; they can sometimes be reanimated by software, while broken dots are almost impossible to fix, and there are hot pixels that glow white even when the screen is off, indicating more serious problems with the controller.

⚠️ Warning: Don't confuse software artifacts with physical defects. If the dot disappears after rebooting or changing the picture, it may be a problem to optimize the system MIUI.

And you should pay special attention to areas with uneven lighting, and you can see yellow or bluish spots on a white background, called the cloud effect, which is not always a marriage, but in expensive Xiaomi models with a very different light. AMOLED-The quality matrix must have uniform brightness over the entire area.

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Use maximum screen brightness during the check – with minimal brightness, some backlight defects may not be visible.

Built-in CIT engineering test in MIUI

The most reliable way to test a smartphone’s hardware is to use the built-in engineering menu, which is hidden from the user in the MIUI and HyperOS shell, but is accessible through special code, which requires no third-party apps to be installed and gives access to deep diagnostic settings.

To run the test, you need to open the Phone app and dial the combination ##6484##. If the code didn't work, try the alternative ##4636##, although it is more commonly used for network information. Once you enter the code, the CIT (Customer Information Test) menu will open, where you need to select the item associated with the display.

In the test mode, the screen will consistently change colors: red, green, blue, white and black. Your job is to keep a close eye on the surface. If you see a black dot on a white background or a bright color dot on a black background, that's a defect. The engineering menu also allows you to check the touchscreen, which is important for a comprehensive assessment of screen quality.

⚠️ Note: Some global versions of firmware have access to CIT In this case, use the alternative methods described below.

Online services for screening

If you don't have access to the engineering menu, specialized websites come to the rescue, and they generate a solid color field that fills the entire screen, making it easy to identify any anomalies. A popular resource is JScreenFix or similar services running directly in the browser.

The advantage of the online method is that it's cross-platform: you can run the test on any device, including a PC, and stream the image, or use the browser on the smartphone itself. Just open the site, select Solid Color mode, and open the full screen window, which is especially useful for finding stuck subpixels.

Many services offer a "noise" or dynamic color change mode that helps to "warm up" the matrix. Prolonged exposure to rapidly changing colors sometimes helps restore the work of flooded pixels, although the effectiveness of this method varies.

Use of specialized applications from Google Play

Google Play offers a variety of tools for diagnosing Android devices, apps like TestM, Phone Check, or Screen Test offer more functionality than simple online services, and allow you to test not only colors, but also gradients, which is important for detecting gamma correction problems.

Once you install an app like this, you get access to automated tests, run all the colors on your own, and even ask you to touch certain areas of the screen to check your response, and it's a convenient way to get a status report of the device that you can save or show to a service center.

However, be careful with free versions of such programs, as they are often crowded with advertising. For a one-time screen check, basic functionality is enough, not requiring a subscription, the main thing is to make sure that the application has high ratings and fresh reviews.

Visual analysis and correspondence table

The human eye can detect defects that are missed by automatic systems. For a good check, use a magnifier or macro shot on another phone. Below is a table that helps classify the defects seen and determine their criticality.

When analyzing the table, note that single bit pixels can be considered acceptable by some manufacturers' standards, if their number does not exceed a certain limit (usually, the number of broken pixels is not higher than the standard). 3-5 However, for the AMOLED-Xiaomi’s matrices are stricter, and even one defect could be a reason to replace them.

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The presence of more than 3 bit pixels in the central zone of the screen is a guaranteed basis for contacting the service center.

Programmatic restoration and massage matrix

If the test found stuck pixels, you can try to restore them to work. There is a method based on a rapid change of colors in the area of the defect, which sometimes "prop" the stuck crystal, for this there are special videos on YouTube or applications for noise generators.

The method is to turn on video with fast flashing colors to maximum brightness for 10-20 minutes, it is important not to overheat the device, and there is a mechanical method of "massage" where the screen is neatly pressed on the soft cloth in the defect area, but it requires extreme caution.

If the pixel is broken (physically destroyed), no software can help, and in such cases, only replacing the display module helps. Software methods are effective only when the pixel transistor is stuck in one position.

Frequently Asked Questions (FAQ)