The main function of the LCD TV is to display colorful dynamic or static images through the LCD screen, and to emit sound through the left and right speakers. Therefore, the failure of the LCD TV mainly occurs in three aspects: image display, sound and control status. Therefore, common failures of LCD TVs are mainly manifested in poor image display, poor display screen, poor sound accompaniment, and abnormal operation.
1. Poor image display
Display images is one of the main functions of LCD TVs, so many failures of LCD TVs are related to image display. Failures of poor image display are manifested as abnormal image color (color cast, colorless), no image, dark screen, image interference, flower screen, white screen, t color screen, etc.
1. Dark screen: The sound is good, there are images, but the image is dark and the brightness cannot be adjusted.
Reasons: backlight aging, inverter circuit, digital signal processing circuit, and system control circuit are caused by some defects.
2. No image: the sound is good, the backlight is on, but no image.
method: check the image signal input, processing and output channels.
3. Color cast: The sound is normal, there is an image display, but the image color is abnormal.
method: Check the digital circuit board and clock crystal.
4. Reticular interference: the sound is normal, the picture is distorted or there is reticular pattern.
method: check image memory and bus communication lines.
5, Colorful Screen: The sound is good, the backlight is lit, and the picture is in the shape of colorful strips.
Reason: Most of them are caused by abnormal video decoder on digital circuit boards.
6, Flower screen or rain-like interference: good sound, unclear picture.
Reason: Most of them are caused by abnormal display driving voltage or poor image memory.
7. White screen: The sound is good and the picture is white.
Reason: This kind of fault is mostly due to abnormal driving voltage of the display screen. Focus on the connection line between the driver circuit board and the digital circuit board.
2. Poor display screen
There are circuits in LCD TVs that specifically drive LCD screens. The production process of this part of the circuit and LCD screen is very special and prone to damage. The faults caused are manifested through the displayed image, but there is a clear difference from the faults of poor image display. Failures of poor display screens are usually not repairable, and the entire LCD screen component can only be replaced.
(light band or dark line)
cracks, light leakage
3. Poor sound accompaniment
This part focuses on various chips and electronic components in the audio signal processing channel.
4. Operation failure
When there is an abnormality in manual control (remote control) or automatic control (searching, power-on protection), the LCD TV may experience remote control failure, no program search, no program left, backlight light first, power-on protection, etc. Focus on checking the system control circuit part (microprocessor, memory, crystal )
