LED Sign Repair Guide: Everything You Need To Know

LED screens have high upfront and operating costs, making them a valuable investment you do NOT want to damage. They are relatively simpler to repair than other display types, thanks to the “individuality” of each LED and module. However, some issues can’t be addressed by simply tinkering with the display and require professional help.

For those who are tech-savvy and comfortable working with electrical parts, you can try your hands at simple troubleshooting as long as you have the correct tools. However, do practice caution in handling LED sign components as they can be sensitive. If you’re ready, let’s explore some of the most frequent problems that may require LED sign repair along with the related troubleshooting instructions.

Common Issues That Need LED Sign Module Repair

No Display

One of the most common issues with LED screens is not having a display. This may be caused by several factors:

  • Signal Line Problem: The signal line transfers data from the controller to the LED modules. If it encounters any issue, the screen won’t display anything. Check the module’s signal status and replace the signal line if needed.
  • Power Cord Issues: The power cord supplies electricity to the LED display. Check if the cord in the first affected module is connected properly. If the connection is secure and the problem persists, replace the power cord.
  • Faulty Amplification IC: The Amplification IC amplifies the signal for the LED modules. If the screen doesn’t display anything, the amplification IC might be compromised. Replace it if needed.

TIP: Sometimes, simply unplugging and replugging the cords might address the issue.

Dead Pixels

Dead pixels result in black spots on the LED display screen. While one dead pixel is hardly noticeable and doesn’t affect the entire display much, multiple dead pixels can create a large black spot that’s hard to miss. Because LEDs work independently from one another, you can get away with just replacing a single dead pixel.

A dead pixel is often caused by weak soldering or an open circuit. Check the soldering quality of the affected pixel. If you can, re-solder the connection. If this doesn’t resolve the issue, replace the pixel with a new one.

Issues with LED Lamp Beads

A lamp bead consists of red, green, and blue LEDs along with a “+”. When a lamp bead is defective, it will appear darkened or dimmed. If you find a single defective lamp bead, it might be due to weak soldering. To fix, use a tweezer to scrape out the glue that is present on LEDs. Make sure that the pins are exposed, then solder them carefully.


Multiple Defective Lamp Beads

If your display has multiple defective lamp beads, it might be due to an issue with the driver IC of the circuit. Check the soldering on the driver IC. Ensure that the IC pins are securely soldered. If the issue persists, consider replacing the IC.

Color Blocks Missing

Another issue connected with a faulty driver IC is missing color blocks. The IC is responsible for controlling the red, green, and blue lamp beads. Every integrated circuit (IC) includes sixteen pins, each of which regulates sixteen lamp beads. If one pin is defective, 16 beads won’t light up, and if an entire IC is faulty, 256 beads won’t work.

If you encounter this issue, check the power and signal lines of the module. A loose or faulty connection can cause missing color blocks. Secure the connection or consider replacing the IC and/or the whole module

Multiple Columns Not Lighting Up

Multiple columns not lighting up can also be linked to IC driver issues. Examine the LED display module and locate the pin connected to the affected columns. Verify that the IC driver’s output terminal is connected correctly.

One Column Lighting Up

If only one column is lighting up, it might be due to an issue with the column’s control circuit, including the positive charge of the power supply. Consider replacing the IC driver.

Receiving card indicator light judgment problem and repair suggestions

The working status of the indicator light of the receiving card can directly and quickly reflect where the problem of the LED display is, which can help you quickly find and solve the problem. The basis for checking the problem is shown in the following table:

Indicator model Color Indicator status Feedback problem Repair suggestions
Working indicator Green  Flashes once per second Normal operation None
Flashes once per 3 seconds Network cable connection problem Check the network cable connection before the problem place, which can be solved by unplugging and replacing
Flashes 3 times per 0.5 seconds The network cable connection is good, the video source input problem Unplug or replace cables related to video source transmission, such as HDMI, DVI, VGA, etc., and select the correct video source input
Flashes once per 0.2 seconds Application area program loading error, backup program working status Re-make or import and send the program
Flashes 8 times per 0.5 seconds Network port redundancy replaced, backup effective None
Power supply Red  Always on  Normal work None

Troubleshooting & LED Sign Board Repair Tips

Now that you have an idea of the most common LED sign issues, it’s time to teach you some basic troubleshooting tips to try. Remember to do these with caution.

No Display + Green Flashes

If your LED board doesn’t have a display and the sending card flashes green:

  • Check the panel power. Make sure that the display is receiving enough power supply to function properly.
  • Inspect the signal wiring. Check if the signal wiring is properly connected to make sure data is transmitted.
  • Check the receiving card’s power. It should be between 5 – 5.2V for proper functionality. Consider replacing it if it can’t reach 5 – 5.2V.

No Display, No Green Flashes

If your LED screen doesn’t have a display and no green flashes:

  • Check the HDMI/DVI Wiring. The graphic control panel should be in extend or copy mode to ensure the signal is properly routed to the display.
  • Reinsert the sending card. Ensure that it is properly connected. If the issue persists, replace the sending card.

No Large Screen System Found

If the display flashes “No Large Screen System”:

  • Check that the serial wiring is properly connected. A loose connection will fail to recognize the screen
  • Connect the screen to a different computer to check whether the issue is with the original computer or not.
  • Install a new software. An updated software has all the bugs and issues fixed.
  • If the issue persists, consider replacing the serial line or the sending card.

No Display on Some Parts of the LED Screen

If the LED screen has displays on some parts and none on the other, it might be due to two issues: a faulty AC cable, ethernet cable, or power supply, or a loose power cord connection.

No Display on the Entire LED Screen

If the entire LED screen doesn’t have a display, check the main power and the network wiring. If the connections are secure, the issue might be a faulty receiving card. For a synchronized system, ensure you enable the copy mode and select the correct source signal on the video processor.

No Light on Multiple LED Display Cabinets

If multiple LED display cabinets don’t light up, check if their network cable and power supply are working properly. Unplug and re-plug the cables and check if it resolves the issue. If it doesn’t, replace the power supply.

No Display on One Cabinet

If only one display cabinet is not working, it might be due to several reasons:

  • Faulty receiving card. Replace if needed.
  • Lost program file. Reload the program file to restore the display’s functionality.
  • The receiving card is not receiving enough power. Replace the power supply.

No Display on Multiple Modules

If multiple modules don’t have a display, a loose or faulty input flat cable might be the cause. Unplug and replug or replace the cable if needed.

Blinking Display

A blinking display can be caused by several factors:

  • Faulty sending and receiving cards. Check if the green light is on to ensure the display is receiving a signal.
  • Loose DVI cable.
  • Loose connection between the display cabinet and the signal cable. Unplug and replug or replace the cable if needed.

Same Content on All Displays

If all the displays are showing the same content, reset the connection file and inspect the network cable. Make sure the cable is properly connected. The computer can successfully send data to the display if you see the indicator light turned on.

Display Not In Sync

If the display is not in sync, check the DVI card settings. Go to multiple display mode and make sure it’s in duplicate mode.

Blurry/Dark Images

If your LED screen is showing blurry and dark images, it might not be properly configured. Identify your display’s minimum brightness level and adjust it to 80 units higher. You can also try restoring the sending card settings to default.

Image Ghosting

Image ghosting refers to a trail of pixels following a moving image on the screen. It’s typically noticeable when you play high-action content. To address this issue, ensure the communication line is properly inserted. Check the DVI cable connection and the sending card cable as well.

Final Thoughts

LED repairs don’t have to cost you an arm and a leg. If you know the basic issues LED screens encounter and their corresponding troubleshooting steps, you won’t have to hire a professional to do a task you can perform. This doesn’t only help you save money, it also gives you an idea of how to take care of your precious investment.

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