Prompt "No send card detected" at start-up


    01. The serial cable or USB cable is not connected to the sending card.

    02. Computer COM or USB port is bad

    03. Serial cable or USB cable is bad

    04. Sending card is bad

    05. No USB driver installed


    System troubleshooting LED display system failure


    The first step:

    Check that the graphics card settings are set up properly.

    The second step:

    Check the basic connection of the system, such as DVI line, correct network line socket, connection between main control card and PC PCI cable, serial line connection, etc.

    The third step:

    Check that the computer and LED power system meet the usage requirements. When the power of the LED screen is insufficient, when it is close to white (more power consumption), it will cause the screen to flicker, and prepare a suitable power supply according to the power requirements of the cabinet.

    The fourth step:

    Check if the green light of the sending card flashes regularly. Blink to step 6. If it does not flash, restart it. Check if the green light flashes regularly before entering the windows system. If the flashing goes to the second step, please check if the DVI cable is connected well, if the problem is not solved, one of the sender card, graphics card (or graphics card settings) and DV cable I is faulty, please repeat step 3 after replacing.

    The fifth step:

    Please follow the software instructions to set or re-install and then set it until the green light of the sending card flashes, otherwise repeat step 3.

    The sixth step:

    Check if the green light (data light) of the receiving card flashes synchronously with the green light of the sending card. If it flashes to step 8, check if the red light (power) is on. If it turns on the seventh step, it does not light up to check whether the yellow light (power protection) is on. If it is not lit, check whether the power supply is connected or the power supply has no output. If it is bright, check if the power supply voltage is 5V. If the power is turned off, remove the adapter card and cable and try again. If the problem is not solved, the receiving card is faulty. Replace the receiving card. , repeat step 6. 

    The seventh step:

    Check whether the network cable is connected well or too long (must use the standard Super Category 5 network cable, the longest distance of the cable without repeater is 100 meters), check whether the network cable is made according to the standard (please refer to the installation and setting), If the receiving card is not resolved, replace the receiving card and repeat step 6.

    The eighth step;

    Check whether the large-screen power light is on. If it does not turn on, go to step 7 and check if the adapter card interface definition line matches the  cell board.


    After most screens are connected, there may be no screen or flower screen in a certain box. Because the RJ45 interface of the network cable is not securely connected, or the receiving card power is not connected, the signal is not passed, so please re-plug it. The network cable (or swap), or plug in the receiving card power (pay attention to the direction) can solve the problem.


    LED display electrostatic protection principle and protective measures


    The main component of the LED display is the LED semiconductor product, and its rated maximum voltage value between the pins, once exceeded, the LED display will be malfunctioning or even damaged. Static electricity is often the main reason, so protecting static electricity is critical to LED displays.

    So how do we protect the LED display from static electricity? First of all, we should follow the three basic principles of electrostatic protection:
    1.Regularly check whether all the electrostatic protection systems of the LED display are normal. Usually we use a surface impedance tester or an electrostatic tester to detect the presence of static electricity. If found, the electrostatic protection system should be repaired in time.
    2.Adhere to the electrostatic sensitive components of the LED display in the electrostatic protection work area. Generally, we use table mats, conductive floors, bracelets, foot rings or ion fans to isolate static electricity.
    3.Electrostatic sensitive components of LED displays must be shielded or stored in static electricity during transportation and storage, usually using electrostatic shielding bags, conductive boxes, conductive boxes, conductive plates, etc.

    Then there are the main measures for electrostatic protection of LED display:
    (1)Neutralization method
    Using an ion wind or ion gun to blow a large amount of positive and negative ions to neutralize the static charge on the surface of the non-conductor (insulator)
    (2)Divergence mode 
    Eliminate static electricity on the conductor by grounding treatment; or limit the current rate by path resistance, and control the length of static dissipation time;
    (3)Shelter mode Use a shielding bag or a conductive box to shield the electromagnetically sensitive components of the LED display from being shielded during transfer.
    Static electricity is extremely harmful to the LED display. Therefore, whether it is in production or in use, we should do static electricity protection to ensure the normal operation and service life of the LED display.


    LED display safe power distribution


    After the LED display is installed, it needs to be tested. Power distribution is one of the most important tasks. The safe power distribution operation can not only extend the life of the LED display, but also avoid unnecessary losses and dangers.

    Safety distribution knowledge usually includes the following six elements:
    1. The phase arrangement of the power distribution device should meet the following requirements:  
    ① The circuits and phase sequence in the same power distribution device should be arranged consistently;
    ② hard busbars  should be painted, the color is: A phase yellow, B phase green, C phase red, zero line black;
    ③  soft busbars  should be marked as distinct.

    2. The arrangement of the wires in the interval of the power distribution device shall be left at the position where the temporary grounding wire is suspended, and no phase lacquer shall be applied at this place  

    3.The layout of distribution devices and the selection of conductors, electrical appliances and frames should meet the requirements of normal operation, overhaul and short circuit.

    Voltage requirements do not endanger personal safety and peripheral equipment.

    4.High voltage isolation switch operation sequence
    (1) Power-off operation sequence: (a) disconnect the low-voltage branch air switch, (b) the isolating switch. (c) Disconnect the low voltage main switch. (d) Disconnect the high pressure oil switch. (e) Disconnect the high voltage disconnector.
    (2) The power transmission operation sequence is opposite to the power failure sequence.

    5. Low-voltage switch operation sequence:
    (1) Power-off operation sequence: (a) Disconnect the low-pressure branch air switch and disconnector. (b) Disconnect the low voltage main switch.
    (2) The power transmission sequence is opposite to the power failure.

    6. The power distribution requirements of the power distribution cabinet must be greater than the actual power demand. The actual power can only be regarded as 80% of the power of the entire power distribution cabinet.


    Explanation of Nouns for LED Display


    1. Data signal: Provide data needed for displaying images.

    The data must be coordinated with the clock signal in order to be transmitted to any display point.Generally, the red, green and blue data signals are separated in the display screen. If a data signal is short-circuited to the positive or negative poles, the corresponding color will appear bright or not. When the data signal is suspended, the corresponding color display situation is uncertain.

    2. CLK clock signal:

    The shift pulses provided to the shift register, each of which will cause the data to move in or out of one bit.The data on the data port must coordinate with the clock signal in order to transmit data normally. The frequency of the data signal must be 1/2 of that the clock signal.In any case, when the clock signal is abnormal, it will make the whole board display disorderly.

    3. ABCD line signal:

    ABCD exists only when dynamic scanning is displayed. ABCD is actually a binary number. A is the lowest bit. If ABCD signal is represented by binary, the maximum control range is 16 lines (1111). In 1/4 scan, only AB signal can be used, because AB signal is represented by 4 lines (11).When the line control signal is abnormal, display dislocation, highlight or image overlap will occur.

    4. EN Enabling Signal:

    Integral screen brightness control signal, also used for screen blanking.The brightness can be controlled by adjusting its duty cycle.When the enabling signal is abnormal, the whole screen will appear some phenomena such as not bright, dark or trailing.

    5. STB latch signal:

    The data in the shift register is sent to the latch, and the data content is displayed through the driving circuit to light up the LED.However, because the driving circuit is controlled by EN enabling signal, the premise of its lighting must be enabling signal to be in the open state.The latch signal also needs to be coordinated with the clock signal in order to display a complete image.In any case, when the latch signal is abnormal, it will make the whole board display disorderly.

    6. What is a pixel?
    The minimum light-emitting pixel of the LED display screen has the same meaning as the "pixel" in the ordinary computer display.Each LED light-emitting unit (point) in an LED display screen that can be controlled separately is called a pixel (or pixel size).

    7. What is the resolution of the LED display?
    The number of rows and columns of pixels in the LED display screen is called the resolution of the LED display screen. Resolution is the total number of pixels in a display screen, which determines the information capacity of a display screen.

    8. How to calculate the optimum viewing distance of large LED screen?
    L (Optimum viewing distance) = M (Point spacing) * 0.86 For example: P20DF Optimum viewing distance = 20 * 0.86 = 17.2m For various display devices, the optimum viewing distance should be the minimum distance that the human eye can not distinguish pixels.

    9. What is the angle of view? What is the viewing angle?
    Angle of view is the angle between two observation directions and normal direction in the same plane when the brightness of observation direction decreases to 1/2 of the brightness of normal direction of LED display screen. It can be divided into horizontal and vertical perspectives.The viewing angle is the angle between the direction of the image content on the display screen and the normal line of the display screen.

    10. What does contrast mean? What role does it play in the big screen?
    Under certain ambient illumination, the ratio of maximum brightness to background brightness of LED display screen; the higher the contrast, the better the visual effect.

    11. What does gray scale mean?
    Under the same brightness level, the technical processing series between the darkest and brightest of the display screen; also known as color depth, refers to the number of different brightness, red, green and blue have their own gray levels. In full-color system, it is generally 256 gray levels, which can produce 256X256 = 16, 777, 216 colors. It is called 24-bit color in PC and 8-bit system in LED display system.

    12.What is the color temperture?What is the color coordinate?
    When the color of light emitted by a light source is the same as that emitted by a black object at a certain temperature, the temperature of the black object is called the color temperature of the light source. The color coordinate is a coordinate value, reflecting the RGB brightness value.

    The color temperature is expressed by absolute temperature K (kevin). When the temperature rises to a certain degree, the color begins to change gradually from red - > light red - > Orange - > White - > blue and white - > blue. Using the characteristics of the color change, when the light color of a light source is the same as that of a black body at a certain temperature, we call the absolute warmth of the black body at that time. The color temperature of the light source. The color temperature is below 3000K, and the light color begins to be reddish, giving people a warm feeling. The color temperature is over 5000K, and the color is blue, giving a sense of refreshment.

    13. Hot Line Backup Function
    Receiving cards A and B can be used as input or output ports. They can be used for two computers to control one screen at the same time. When one computer is in trouble, another computer can automatically replace it. When one network line is in trouble, another network line can automatically replace it, so that the normal work of the display screen can be guaranteed to the greatest extent. 

    14. Pixel pitch and density
    Central or Point pitch(Dot pitch) of Two Pixel Points in LED Display Screen;The number of pixels per unit area is called pixel density. The smaller the point pitch is, the higher the pixel density is, the closer the distance suitable for viewing is, the larger the point pitch is, the lower the pixel density is, and the farther the distance suitable for viewing is.

    15. Interpretation of IP Protection Level for LED Display Screen
    IP protection level is composed of two digits. The first digit represents the level of lamp dust separation and prevention of foreign invasion. The second digit represents the degree of sealing of lamp moisture and waterproof invasion. The larger the number, the higher the protection level.