Diagnostics of the display Xiaomi: test for broken pixels and touchscreen

Modern Xiaomi, Redmi and Poco smartphones are equipped with high-quality AMOLED and IPS arrays, but even reliable equipment is subject to wear and tear or production defects. Users often face the need to assess the condition of the device after buying, falling or simply scheduled maintenance of the gadget. Competent diagnostics allows you to identify hidden defects that are not visible on a surface inspection of the interface.

There are several effective ways to do a deep screen and touch screen check without going to a service center. Built-in engineering codes, special applications and visual tests help determine if there are broken pixels, touchscreen dead zones or color reproduction problems. It is important to understand the difference between a software failure and physical damage to make the right decision about repair or replacement.

In this article, we will take a look at all the available testing methods, from simple visual checks to the use of professional software. You will learn to interpret the test results and understand when to worry about the condition of your Mi device. Proper and timely diagnosis can save you from buying defective goods or prevent further damage to the device.

Visual inspection and preparation for testing

Before running complex software tests, you need to conduct a thorough visual analysis of the screen surface. In good light, carefully examine the matrix for cracks, chips or deep scratches that can interfere with the sensor. Even microscopic damage to the glass often leads to “dead zones” or chaotic pressing in the future.

Be sure to wipe the display with a soft microfiber to remove greasy spots and dust.Mud on the surface can distort the results of the check for broken pixels or create the illusion of an image defect.Surface cleanliness is a basic requirement for quality diagnosis.

⚠️ Warning: Do not use aggressive chemicals or alcohol-containing liquids to clean the screen, as they can damage the oleophobic coating, which will lead to rapid contamination and deterioration of tactile sensations.

Make sure that the device does not have a protective film or glass of poor quality, which can create a rainbow effect or distort the color reproduction. If you just bought a phone, remove the factory transport film before you start checking, this will allow you to see the real state of the matrix without foreign artifacts.

Checking for broken pixels and color reproduction

One of the most common problems with modern displays is broken or stuck pixels, which require filling the screen with monochrome images of different colors: black, white, red, green and blue, with bright dots (hot pixels) visible on a black background, and dark spots on a white background.

There's an easy way to check the color rendering without installing any additional software: Open any image in the gallery, expand it to the full screen and try changing the color scheme through the theme settings or just search the Internet for pictures for a screen test. Switch colors sequentially, looking carefully at each corner of the monitor.

If you find a point that is lit in a color other than the surroundings, try to massage the area gently with a stylus turned off or a soft cloth. Sometimes this helps to "pasd" the stuck subpixel. However, if the defect manifests itself on all colors in the same way, it is a physical damage to the matrix that cannot be fixed programmatically.

To make your diagnosis more accurate, you can use online services by opening them in Chrome or Mi Browser. Type in a search for a “screen test” and select any site that displays images. This is a quick way to assess the uniformity of the backlight and the absence of lights at the edges of the screen.

Diagnosis of touch screen through the engineering menu

The most reliable method of checking sensor responsiveness is using the built-in CIT (Customer Information Test) menu, which is available on all Xiaomi smartphones and allows you to test every millimeter of the display surface. To enter the menu, open the Phone app and type the combination ##6484##.

When you go to the menu, look for "Touchpanel" or "Display," and you'll be asked to swipe along special lines or paint over certain areas, and the system records every touch, and if the line is interrupted or the sector doesn't paint over, the touchscreen isn't working properly in that area.

It's important to do the test calmly, without putting too much effort. High pressure can distort the results because the sensor responds to the contact area. If you notice that in a certain area the finger slips or the cursor twitches, this is a sign of local damage to the digitizer.

⚠️ Note: If the test is successful in the engineering menu, but problems arise in games or when printing, it is possible that a third-party application or incorrectly configured sensitivity of the gloves causes a conflict.

In some models, especially global versions, access to full CIT functionality may be limited, so you can try the alternative code ##4636##, although it is more focused on network and battery information, sometimes there are hidden diagnostic points.

Multi-touch and sensitivity testing

Multitouch is a critical feature for user experience and games, and you can check the number of simultaneous touches using simple tools from Google Play, such as the MultiTouch Tester. The app displays touch points and their coordinates in real time.

Put all the fingers of one hand on the screen, then add the fingers of the other hand. Xiaomi's high-quality screen should handle 10 simultaneous touches without any problems. If the app shows a smaller number or dots "shimmer" and disappear, this is a signal of problems with the touchscreen controller.

It is also worth checking the sensitivity when working with gloves. This feature is activated in the Settings menu → Additional settings → Gloves mode. Turn on the option and check if the screen responds to touch in dense fabric, which is especially true for users in winter.

Notice the behavior of the cursor or touchpoint when you move your finger diagonally quickly, the line should be flat, without jerking or jumping, and if you see a line shaking, you may need to calibrate or replace components.

Using third-party applications for deep verification

If the built-in tools are not enough, specialized applications from the Play Market store come to the rescue, one of the most popular and functional tools is TestM or Phone Doctor Plus, which performs comprehensive diagnostics of all nodes of the smartphone, including detailed screen analysis.

The apps automatically check the accelerometer, the gyroscope, the proximity sensor, and of course the display, and they give you a final report as a percentage of the serviceability of each component, which is convenient for quickly assessing the condition of the used device before you buy it.

Using third-party software gives you more detailed statistics than standard tests, such as a sensor response graph or a click history, but remember that these applications require access to the system, so download them only from trusted sources.

💡

Before installing diagnostic apps, be sure to check the permissions they request. Screen tests usually don't require access to contacts or a microphone to work.

How to distinguish the original screen from the copy

When replacing broken glass in informal services, there is a high risk of installing a poor copy. Xiaomi’s original displays have bright, saturated colors and the right viewing angle. Copies often have a dim picture, distorted colors (go yellow or blue), and low brightness.

Notice the frames around the matrix. The original components tend to be thinner and more evenly glued. Also important is the presence of the Mi or Redmi logotpa when turned on (on some models) and the absence of artifacts on the menu. The original matrix always clearly displays fonts without "soapiness."

Another test is to test the proximity sensor and autobrightness, which in copies often doesn't work properly or at all, because the sensor calibration is tied to a specific display module, and if the speaker or light sensor stops working after the replacement, the screen is likely to be unoriginal.

A critical sign of counterfeiting is the absence of factory film with QR-code on the back of the new module (if the screen was changed entirely), although in modern conditions this is not always a guaranteed method, since the films have learned to fake the entire screen.

Check the refresh rate in the settings. If the smartphone supports 90 Hz or 120 Hz, and the menu is only 60 Hz or high frequency mode is not turned on – this is a clear sign of incompatibility or defective part.

Frequently Asked Questions (FAQ)