Fault Analysis & Solutions for TV Screen Abnormal Display

Fri Jan 18 16:08:31 CST 2019

The LCD TV mainly consists of five functional modules, including:Power board, TV motherboard, logic board, backlight module and screen.If any one of the modules is disabled, the screen may display abnormality. In addition, Poor contact of lvds wire is also an important cause of the screen display error.

LCD Screen Error

General causes include knocking, crushing or circuit damage. The LCD screen is relatively fragile, very easy to get damaged. Especially when the TV case is not equipped with a tempered glass and played by naughty child.

If the screen display fails, usually the phenomenon is stable. Positions of the blurred screen, bright line, black belt, white strip and anymore are fixed,  Every time when switching on or off, the phenomenon is always same.

As the figure below shows, the stable vertical line and the black belt of the picture can conclude that the liquid crystal glass is damaged.

Poor Contact of LVDS Wire

(1) The image displays normally, but the blurred screen comes up randomly. Or there are many small “snowflake” color spots in part area. This phenomenon is likely to be poor contact of LVDS wire. Checking whether the LVDS wire is loosing or aging.

(2) While discovering the TV Screen has the phenomenon of getting blurred screen, beating or black. Firstly, to check whether the LVDS wire is in good contact, because the contact point of the LVDS wire will oxidize and cause poor contact. Unplug the LVDS wire and carefully wipe the contact points with a soft cloth. After cleaning, use a cotton swab to apply some lubricating oil on the contact points. Then test the machine to see if it can work normally.

 

Signal Source Error

The TV menu is displayed normally, but the image is abnormal. This type of problem may be caused of the source. It can be verified by switching to other channels, such as AV video, TV or network channel.

The logic Board Error

After repeated power-on, the streaks or colors of the TV screen is getting different from time to time, and the position of the interference is unstable. This type of phenomenon is most likely because of the logic board. In addition, the phenomenon of the logic board and the motherboard fault may be similar. It is also necessary to check whether it is a problem of the motherboard.

The Motherboard Error

If there is no signal, the blue screen is normal. But the screen is getting blurred when the signal is input. Or the position of the blurred screen and interference is changing with the image. It is likely to be a malfunction of the motherboard.

Backlight Failure

It is very easy to judge the error of backlight. Either the lamp is not lit, or the backlight is bright but extinguished after a while. The backlight and LCD screen are two relatively independent modules. The backlight problems that do not affect the screen display. At this time, we only need to take flash light to illuminate the screen and look carefully. If there is shadow of the image and the backlight is not bright, it is probably the problem of the backlight module or the power module error.

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