How to Fix LED Display Control Card Failure Issue?

LED display control card plays a key role and is one of the core components to run LED video display correctly. The main function of an LED control card is to receive the image display data from the serial interface of the computer, store it into the frame memory, and generate the serial display data and scanning control timing suitable for the LED display according to the driving method. 

However, you may encounter various LED display problems when running an LED display. Next, top used LED screen supplier, IAMLEDWALL will introduce some common LED display control card fault problems and solutions.

How to judge the LED control card in normal working condition?

After you conect the control card to the power supply, please check the power indicator first, the red light indicates that the 5V voltage has been connected, if not, please turn off the 5V power supply immediately. 

Check whether the 5V working voltage is connected properly, whether it is over-voltage, reverse connection, failure, output short circuit, etc. Please use a separate 5V power supply to power the control card. If the red light is not lit, you need to repair.

LED control card failure solution steps

  • Confirm the control card is compatible with the software.
  • Check whether the connection line is off, or loose, check and confirm that the serial line used to connect the control card with the control card mates, some control cards with straight-through (2-2, 3-3, 5-5) some control cards with (2-3, 3-2, 5-5).
  •  To ensure that the LED control system hardware has been properly powered up.
  • Against the control card software and their choice of control card to select the correct model, the correct transmission mode, the correct serial port number, and the correct baud rate and against the software to provide the dial-switch map to correctly set the control system hardware on the address bit and baud rate.
  •  If after the above checks and corrections are still not loaded, please use a multimeter to measure whether the serial port of the connected computer or control system hardware is damaged
  • If the above step is not convenient to carry out, please contact the LED display manufacturer to provide technical support.

Common LED control card failure issues

Issue 1: 

After connecting and powering on, only part of the program is played and then stops playing and starts playing again.

The main reason is that the power supply to provide power is not enough, the control card automatically restarts. 

  •  Reduce the brightness; 
  • With the control card power supply with less than two unit boards; 
  •  Increase the power supply

Issue 2:

The control card is normal, the LED display does not show or abnormal brightness

LED Control card and display driver connected to power on, the default is 16 scanning.

  • If there is no display, please check the control software in the data polarity and OE polarity settings are correct;
  • If the brightness is abnormal, there is a line of particularly bright, and the OE settings are reversed, please set the OE correctly.

Issue 3:

When transmitting information to the control card, the system prompts “Error occurred, transmission failed”.

Please check whether the communication interface is connected correctly

  • whether the jumper on the control card jumps on the corresponding level position
  • whether the parameters in the “control card settings” are correct.
  • whether the working voltage is too low, please use a multimeter to ensure that the voltage is above 4.5V.

Issue 4: 

After loading information, the LED display can not be displayed normally

Check whether the scanning output selection in the “control card settings” is correct.

Issue 5: 

Communication is not smooth in the 485 network.

Please check whether the connection of the communication line is correct. If do not connect the communication line of each screen to the computer interface together, it will produce strong reflected waves and cause serious interference to the transmission signal.

How to solve poor communication when using GSM digital transmission and remote dialing?

First, check whether there is a problem with MODEM, disconnect the MODEM connected to the control card, and connect this MODEM to another computer, so that the MODEM at the LED sending and receiving ends are connected to the computer and detached from the control system.

Download a software called “Serial Debugging Assistant” from the Internet, after installation, use it to set up and debug the MODEM. 


First of all, the MODEM on the receiving end will be set up as an automatic answer, the setup method: 

  • Open the serial port debugging assistant on both ends, on the receiving end of the serial port debugging assistant, 
  • Type in the “ATS0 = 1 Enter”, the command can set the MODEM of the receiving end as the auto answer.
  • If the setting is successful, the AA indicator on the MODEM will be bright.
  • If it does not light up, the setting is not successful, please check whether the connection between MODEM and the computer is correct and whether MODEM is powered on.

Pass some information from the receiving end to the sending end

After auto answer is set successfully, input “phone number of receiving end, enter” in the serial port debugging assistant at the sending end, dial the number to the receiving end.

At this time, you can pass some information from the sending end to the receiving end, you can also pass some information from the receiving end to the sending end.

  • If the information received at both ends is normal, then the communication connection has been established, at this time, the CD indicator on the MODEM will be on. 
  • If the information received from both ends is normal, the communication connection has been established, and the CD indicator on the MODEM is on. 
  • If the above process is normal, it proves that MODEM communication is normal and there is no problem.

Checking control card settings

After checking the MODEM no problem, if the communication is still not smooth, the problem may be in the control card settings. 

  • Connect the MODEM with the control card,
  • Open the control card setting software on the transmitter side, 
  • Click on the readback setting, 
  • Check whether the serial port baud rate, serial port, protocol and other settings are correct
  • Click on the write setting after changing. 
  • Open Offline King software, set the corresponding communication interface mode and parameters in the communication mode, and finally transmit the script.

When the LED card is normal, but the display can’t play correctly?

After checking if when the LED control card is normal, but LED display can not be played correctly, common problems: 

  • Display problems, 
  • Communication problems, 
  • Functional requirements,

The solution to the trilogy: 

  • Press the test button (measure the power supply and wiring connection), serial communication, 
  • Click the software switch (measure the port and communication lines), disconnect the power supply and so on all the lamps and beads go out and then power on (initialization).

When The LED control card is normal, why the LED display does not run or abnormal brightness?

After the control card is connected to the display driver and powered on, the default is 16 scanning.

  • if there is no display, please check whether the data polarity and OE polarity settings in the control software are correct; 
  • if the brightness is abnormal and one line is particularly bright, it means that the OE settings are reversed, please set the OE correctly.

Why can’t the LED display show normally after loading information?

Check “LED display control card settings” in the scanning output selection are correct.

When The LED sending card is normal, the display shows a splash screen, garbled code, and regular movement

Typical scanning mode selection error, semi-outdoor, outdoor general 4 sweeps, indoor 16 sweeps, car screen 8 sweeps, set the screen reference to change and save and send success can be.

When The LED sending card is normal, the display appears horizontal bright line & few rows.

The direction of the line is reversed, pressing the test key (control card comes with), this situation is generally switching not moving, connect the LED display and control card on the reverse end of the connection can be.

LED display receiving card and sending card repair method

check the hardware problem

  •  Check the display line whether the receiver card access is normal: check the interface line, there is no broken line, there is no welding, and the line is not broken, if the line is broken, you can carry out welding repair.
  •  Check the display sender card: The sending card is also a kind of hardware, to check the interface line and power supply, there is no damage.
  •  Check the power supply: check the input voltage of the power supply, the general voltage is maintained at +5V or so there is no problem, large and 5V, too high may damage the card.

Replace the chip

  •  Replace the chip on the receiver card: If the chip on the receiver card is damaged, it has to be replaced, to remove the damaged chip, remove the new chip to be welded on, the welding position should be correct, to ensure good contact, otherwise there will be a receiver card can not be used.
  •  Replace the chip on the transmitter card: If the chip on the transmitter card is damaged, you have to remove the old one, and then weld the new chip on it, the position should also be correct, and keep the contact good, to ensure that the transmitter card can be used normally.

Upgrade software

 Receiver card upgrade: 

  • To determine whether the receiver card is using the latest software version,
  • If not the latest, please upgrade to the latest version, 
  • To use the newer functions and features, and to ensure the stability and reliability of the receiver card.

Transmitter Card Upgrade: 

  • The transmitter card should also check whether its software is the latest version,
  •  If not, you should upgrade the latest version to realize the updated functions and features.
  •  To ensure the stability and reliability of the transmitter card.


The above are the common problems and solutions of LED control cards, We hope it can solve the problems you encountered. When the LED screen does not play properly, it may also be a problem with the quality of the LED screen, and it is also important to get a high-quality LED screen. If you are looking for more high-quality LED screens, you can contact us. As a top used LED display supplier, we offer a large selection of branded LED screens.