Frequently Asked Questions about LED Displays
1. Black Screen (No Image)
Issue: The entire screen or a large section shows no content.
Check Power: Ensure the main power distributor is active and the power cables are securely connected to the controller and cabinets.
Signal Input: Verify that the video source (PC, Media Player) is outputting a signal. Check if the HDMI/DVI/DP cable is loose or faulty.
Controller Status: Inspect the indicator lights on the Sending Card. A flashing green light indicates a normal signal; a red or dark light suggests a hardware or configuration error.
2.Partial Module/Cabinet Failure
Issue: A specific square area or a single module is dark or showing garbled colors.
Ribbon Cable Connection: This is often caused by a loose Flat Ribbon Cable inside the cabinet. Power off and re-seat the cables connecting the module to the hub board.
Power Supply Unit (PSU): If an entire cabinet is off, the internal PSU may have failed. Check the DC output voltage with a multimeter.
Data Loop: If a string of cabinets is off, check the Network Cable (RJ45) connecting the last working cabinet to the first dark one.
3. Flickering or Shaking Image
Issue: The image appears to “strobe” or jitter, especially visible through phone cameras.
Refresh Rate: Ensure the Refresh Rate in the control software (e.g., NovaLCT) is set to the recommended value for your LEDs (e.g., 1920Hz or 3840Hz).
Grounding: Improper grounding of the screen’s steel structure can cause electromagnetic interference. Ensure the system is properly Grounded.
Cable Quality: Low-quality or excessively long network cables can cause signal attenuation. Use Cat5e or Cat6 shielded cables.
4. Dead Pixels or "Always-On" Dots
Issue: Individual tiny dots that stay black (dead) or stay a constant color (bright/stuck).
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Physical Damage: These are usually caused by physical impact or static discharge damaging the LED beads.
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Solution: For SMD displays, these can be repaired via precision soldering. For COB displays, since the chips are encapsulated, the module usually needs to be sent back to the factory for specialized repair.
5. Image Tearing or Non-Synchronization
Issue: The image appears split, or there is a delay between different sections of the screen.
Sync Settings: Check the “Graphics Card Expansion” settings in Windows to ensure the resolution and frequency match the LED controller.
Sending Card Configuration: Ensure the “Cascading” order of the receiving cards is correctly configured in the software mapping.
6. Color Inconsistency (Patchy Colors)
Issue: Different modules show slightly different shades of white or red.
Calibration Data: The Calibration Coefficients may have been lost. Re-upload the calibration file (.cpix or .rcfgx) provided by the manufacturer.
Batch Difference: If modules from different production batches are mixed, color differences are inevitable. Use the “Chroma Calibration” tool to manually balance the colors.
Frequently Asked Questions about COB Displays
1. Surface Temperature & Thermal Management
Issue: The front surface of the COB screen feels much hotter to the touch than an SMD screen.
The Difference: In COB, the LED chips are in direct contact with the PCB, and the resin coating conducts heat efficiently to the front.
The Solution: This is usually a sign of normal heat dissipation. However, ensure your installation has a minimum of 10cm clearance for rear ventilation. If the temperature exceeds 65°C, check the “Smart Brightness” settings in the controller to ensure the screen isn’t overdriven.
2. "Moat" or Visible Seams Between Modules
Issue: Even with high-resolution COB, you see thin dark lines or “seams” between modules when displaying bright colors.
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The Difference: Because COB is a continuous flat surface, even a 0.05mm misalignment is highly visible compared to the “bumpy” surface of SMD.
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The Solution: Use a high-precision adjustment tool to calibrate the Z-axis (depth) of the cabinets. COB requires a perfectly flush surface to maintain optical continuity. If the seam persists, use “Seam Brightness Compensation” in the software to digitally hide the gap.
3. Surface Reflectivity & Glossy Glare
Issue: The screen reflects room lights or windows, making the content hard to see.
The Difference: COB displays use a resin or epoxy coating which can be highly reflective (glossy) compared to the matte finish of SMD lamps.
The Solution: If the screen has a glossy finish, adjust the tilt angle of the display slightly or use polarized light filters on room windows. For future purchases, specify Matte Encapsulation or “AG (Anti-Glare) Coating” during the order process.
4. Resin Clouding or Whitening
Issue: The black background of the COB display appears “milky” or cloudy in certain areas.
The Difference: This is often caused by chemical reactions between the resin and improper cleaning agents.
The Solution: Never use glass cleaners or ammonia-based products. Clean the surface only with Anhydrous Ethanol (99% Alcohol) and a lint-free microfiber cloth. If clouding is permanent, the module may need to be re-baked or replaced by the manufacturer.
5. Non-Repairable "Dead Pixels" On-Site
Issue: A single pixel is dead, and the standard soldering method isn’t working.
The Difference: You cannot “solder” a COB pixel. The chip is under a hard protective layer. Attempting to scrape the resin will damage the surrounding pixels.
The Solution: This requires Module Swapping. The faulty module must be sent back to a factory with a COB Rework Station (which uses laser or precision heat to remove the resin and wire-bond a new chip).
6. Color Shift at Extreme Viewing Angles
Issue: The color looks perfect from the center but shifts to a yellow or blue tint when viewed from the side.
The Difference: This is caused by the Refractive Index of the encapsulation layer.
The Solution: Ensure the Calibration Files (.rcfgx) specifically include “Multi-angle Calibration” data. If the shift is severe, check if the modules are from different “Bin” batches; COB is extremely sensitive to batch consistency.