Reasons for LCD Screen Backlight Not Lighting Up

As an important component of LCD screen, backlight mainly provides lighting for the screen to make images and texts clearly visible. It is very important for POS machines and customer displays that need to display prompts. If the backlight is not lighting up, the LCD screen will become very dark and may not be able to be used normally.

There are several potential reasons for LCD backlight failure, and troubleshooting should be done step by step. Here are some common causes and possible solutions:

1. If the LCD is squeezed or dropped during use, the backlight element may be damaged or the circuit may be disconnected, and the ambient temperature may be too high or too low, which may cause the backlight to shut down protectively, which will cause the LCD backlight to not light up.

2. The LCD screen backlight will not light up if there is no power connection or a power failure or an internal power circuit failure during use. Check whether the power adapter and battery are powered normally (such as the indicator light status), and try to replace the power cord or adapter.

3. LCD has many LED lamp beads built in, and the structure of the lamp beads is a string of strings. They are connected in parallel or in series in the LCD display. If a single LED lamp bead is not lit or damaged, then the entire light strip will not light up. When the backlight of the LCD display is not lit, we need to rule out whether the lamp bead is damaged.

4. In addition, we also need to rule out the driver problem. If the constant current driver and rectifier, buck and other devices in the driver are damaged, once the voltage is too high, too low or the backlight is abnormal, it may cause screen burn-in.

5. Wrong brightness setting, abnormal driver or firmware or BIOS/UEFI setting error can also cause the backlight to not light up. Enter BIOS to check whether the backlight-related options (such as “backlight control”) are disabled.

For the problem, Sunany has also thoughtfully prepared some simple troubleshooting steps. Even ordinary users can use these methods for preliminary troubleshooting and simple processing, effectively saving maintenance time and cost.

1. Disconnect the power supply and press and hold the power button to release the residual power, and then restart the machine for testing.

2. Use a flashlight to illuminate the screen at a certain angle. If you can see an image, the backlight is faulty. If there is no display at all, it may be a problem with the screen panel or motherboard.

3. Connect an external monitor. If the display is normal, the motherbroad card problem can be ruled out and the backlight failure can be confirmed.