LCD TV backlight common fault
Time:2019-12-16 Click:2
1. When the backlight is turned on, the LCD screen will be turned off.
At this time, the sound, remote control, and panel button control
functions are normal. This phenomenon is caused by the backlight circuit
protection. The reason is mostly that the backlight booster board is
abnormally powered. CCFL backlight circuit, if one of the backlight
tubes is open (commonly the circuit protection caused by the lamp socket
on the backlight booster board is open or the socket is not inserted)
or a certain lamp is broken, the above fault can be caused.
2. There is no change in the backlight switch, sound, remote control,
panel button control are normal. This fault needs to detect the
following working conditions: 1), the power supply of the backlight
booster circuit, the common large screen is 24 volts, very few 120
volts, the small screen is generally 12 volts, 2), the CPU control
circuit output backlight backlight booster oscillator working switch
control signal, usually high level start, mostly 3V-5V lamp lighting
control signal if If the above working conditions are met, the backlight
booster board can be replaced. If the backlight booster board is
replaced, the backlight is damaged. The backlight tube in the LCD panel
is damaged.
3. When the backlight is on, it is not bright. It is common for the
backlight of the backlight booster board to have poor contact with the
lamp. The backlight supply is high or low. In actual maintenance, the
24V power supply digital meter should not have 1V error. The 24V output
on the board should be stable whether it is empty or loaded.)
