Common Fault Judgment of LCD TV Backlight

Common Fault Judgment of LCD TV Backlight

The TV maintenance engineer reminds you that if you are not a professional engineer, please do not repair it yourself, so as not to cause more troubles. The following are some common fault judgments of LCD TV backlights summarized by the maintenance engineer for you. Hope it will be helpful to you.

1. The backlight is turned off when the LCD screen is on when the AC is turned on. At this time, the audio, remote control, and panel button control functions are all normal. This phenomenon is caused by the backlight circuit protection, mostly due to the abnormal power supply of the backlight booster board. For CCFL backlight Source circuit, if a certain backlight tube is open (usually the circuit protection caused by the opening of the tube socket on the backlight booster board or the socket is not plugged tightly) or a certain tube break can cause the above failures

2. There is no change in the backlight switch machine, the sound, remote control, and panel button control are all normal. This fault needs to detect the following working conditions:

1) The power supply of the backlight booster board circuit is usually 24 volts for large screens, a few use 120 volts, and small screens generally use 12 volts.

2) The switching control signal of the backlight boost board oscillator output by the CPU control circuit is usually high-level start, mostly 3V-5V lamp lighting control signal. If the above working conditions are all available, it can be replaced The backlight booster board, if it fails after replacing the backlight booster board, the backlight tube in the LCD panel is mostly damaged.

3 The backlight is on when the backlight is on and not on. It is usually caused by the poor contact between the lamp socket of the backlight booster board and the lamp, and the backlight power supply is high or low. In actual maintenance, the 24V power supply digital meter should not have a 1V error (power supply board). The 24V output voltage should be stable regardless of whether it is no-load or loaded).