How to choose a second-hand LED display screen?

When choosing second-hand LED displays, it is necessary to consider and inspect from multiple aspects to ensure that their performance and quality meet the usage requirements. The following are some key points for selection:

Service life and appearance inspection: Ask the seller about the service life of the display screen. Generally speaking, the shorter the service life, the lower the degree of aging of the display screen and the better its performance. Try to choose products that have been in use for less than three years, as their various performances can usually still remain at a relatively good level.

Appearance condition: Carefully inspect the surface of the display screen for any obvious scratches, wear, cracks or deformations, etc. Special attention should be paid to the edges and corners of the screen, as these areas are prone to damage from impacts during transportation and installation. At the same time, check whether there are any signs of looseness, detachment or damage on the casing of the display screen to ensure its structural integrity and normal protection of the internal components.

Pixels and resolution Pixel pitch: Select the appropriate pixel pitch based on the actual usage scenario and viewing distance. The smaller the pixel pitch is, the clearer the image will be, but the price will also be higher. For example, for display screens used for indoor close-range viewing, such as in meeting rooms and exhibition halls, products with a pixel pitch of less than 2.5mm can be selected. For outdoor display screens used for long-distance viewing, such as those in squares and billboards, the pixel pitch can be 3.0mm or higher.

Resolution: High resolution can provide clearer and more detailed image display effects. When making a selection, the required resolution should be determined based on the purpose of using the display screen and its installation location. For occasions where high-definition videos or images need to be displayed, such as cinemas and TV stations, high-resolution display screens should be chosen. For some occasions where only simple text and graphics need to be displayed, such as the advertising screens at bus stops, lower-resolution display screens may be sufficient to meet the requirements.

Brightness and contrast: Brightness: Select a display screen with an appropriate brightness based on the lighting conditions of the usage environment. In outdoor strong light environments, such as squares directly exposed to sunlight, it is necessary to choose display screens with higher brightness, generally requiring a brightness of over 5000cd/m². In indoor environments such as meeting rooms and shopping malls, a brightness of around 1500-3000cd/m² is sufficient to meet the requirements. The brightness can be evaluated by checking the product specification parameters or observing the display effect of the screen under different lighting conditions on site.

Contrast: High contrast can make the bright parts of an image brighter and the dark parts darker, thereby presenting richer details and more vivid colors. The contrast ratio of high-quality LED display screens is usually above 3000:1. When making a selection, you can observe the display screen playing some videos or pictures with strong light and dark contrasts to see if the black part is dark enough, if the white part is bright enough, and if the gray transition in the middle is natural, so as to judge the quality of the contrast.

Color representation: Color uniformity: Observe whether the colors in each area of the display screen are consistent when showing solid-color images, and whether there are obvious color differences. High-quality display screens have good color uniformity and will not have phenomena such as local colors being too red, too green or too blue. You can check the color uniformity by playing solid-color pictures or videos. Especially in the case of large screen splicing, pay attention to whether the colors at the splicing points are consistent.

Color accuracy: Check whether the colors displayed on the screen are consistent with those in the original image or video, and whether there is any color distortion. Some standard color test images or videos can be played to compare the differences between the colors displayed on the screen and the standard colors. For occasions with high requirements for color, such as advertising displays and film and television production, display screens with high color accuracy should be selected, and their color reproduction rate should reach over 90%.

Drive mode and control system drive mode: Common drive modes include constant current drive and constant voltage drive. Constant current drive can ensure the stability of the current for each LED bead, thereby making the brightness and color of the display screen more uniform and extending its lifespan. When making a selection, give priority to choosing display screens that adopt constant current drive.

Control system: Understand the brand and model of the control system adopted by the display screen, as well as its functions and stability. A high-quality control system is easy to operate, powerful in function, capable of supporting multiple signal inputs and format conversions, and has good compatibility and stability. You can ask the seller for relevant information about the control system and conduct some basic operation tests on site, such as switching screens, adjusting brightness, playing videos, etc., to check if the control system is working properly.

After-sales service and warranty \ nAfter-sales service: Inquire with the seller whether they offer after-sales service, including installation and commissioning, maintenance and repair, technical support, and other aspects. Good after-sales service can promptly solve problems encountered during use, reducing losses. Understand the strength and response time of the seller's after-sales service team, and choose a seller that can provide timely and professional after-sales service.

Warranty period: Understand the warranty period and scope provided by the seller. Generally speaking, a legitimate second-hand LED display seller will offer a warranty period of 3 to 6 months. During the warranty period, if there are any quality issues not caused by human factors, the seller should be responsible for free repair or replacement. Read the warranty terms carefully, clarify the rights and obligations of both parties, and ensure that your own rights and interests are protected.