The cheapest P3.91 LED display as a carrier of various information display, has played a great role in information transmission, but in daily use, if you are not careful, you will encounter failures. Let’s share the common problems of the cheapest P3.91 LED display Faults and solutions for reference.
1. Bright lines or screen changes
After the screen controller is properly connected to the computer, HUB distribution board and screen, it is necessary to provide +5V power supply to the controller to make it work normally. It is a normal test phenomenon that the screen appears bright lines or blurred screen for a few seconds at the moment of power on. The user screen will start working normally. Within 2 seconds, this phenomenon will be eliminated automatically, and the screen will enter the normal working state.

2. Part of the screen is off or dimly lit
Check whether the power connection cable, the 26P cable between the unit boards, and the indicator light of the power module are normal. Use a multimeter to measure whether there is normal voltage on the unit board, and then measure whether the voltage output of the power module is normal. If not, it is judged that the power module is broken.
Measure the voltage of the power module is low, and adjust the fine-tuning to make the voltage reach the standard.
3. What does automatic or manual brightness adjustment mean?
Brightness adjustment refers to the adjustment made between the darkest and brightest that the the cheapest P3.91 LED display can display, rather than light sensitivity adjustment. Automatic brightness adjustment is automatically adjusted to a predetermined brightness by the P3.91 LED display control system according to the different brightness that should appear in different time periods. Manual brightness adjustment means that the end user can make the LED screen reach the desired specified brightness through the operation of the the cheapest P3.91 LED display control system.