LG TV UQ9000 BLACK SCREEN SOUND WORKING General Troubleshooting

LED Backlight Strip Kit

The UQ9000 uses direct-lit LED strips that are prone to burnout. When an LED fails, the image remains visible only under a flashlight, while the audio remains functional because the main board is still processing signals. Replacing the full set of strips ensures uniform brightness and prevents future failures caused by old LEDs in the same circuit.

Power Supply Board (EAY Series)

The LED driver circuit on the power supply board manages the voltage to the backlight array. If the driver FET or capacitor fails, it cannot provide the necessary strike voltage to ignite the LEDs. This is less common than LED failure but is the secondary cause for a total backlight outage.

Main Logic Board

The main board sends the 'Backlight On' (BL_ON) signal to the power supply. If this logic gate is damaged, the TV will process sound and picture but fail to tell the backlight to illuminate. This is typically ruled out if the BL_ON voltage pin measures high (3.3V) during startup.