LCD screen common faults and how to repair

3/22/2019 3:29 PM

There are several types of faults of the LCD screen: white screen, flash screen, black screen, screen dark, screen yellow, white spots, bright lines, bright bands, dark lines, dark bands, and outer film scratches. Relatively easy to repair these faults are screen yellow, white spots, and outer membrane scratches.

 

The screen dark is actually the aging of the tube (LED strip), and it can be replaced directly. Both yellow and white spots are backlight problems, which can be solved by replacing the corresponding backlight or light guide plate. The outer film scratch is the damage of the polarizer covered by the surface of the liquid crystal glass, and it can be replaced by hand. Of course, there are many precautions when implementing these faults that can be solved by replacement. The lamp should be installed in place to avoid light leakage. To handle the backlight, pay attention to dustproof. Otherwise, the dust will be spotted after the screen is lit. The replacement of the polarizing film should avoid crushing the screen when the film is torn, and the dust is even more taboo. Once the dust enters during the filming, bubbles will be generated, and it is basically necessary to scrap the film again.

led light

lcd screen

White screens, flash screens, and black screens are basically caused by circuit failures. First, the break of the screen line should be excluded, and then 3.3V (or 5V or 12V, 18V in the early stage) should be added to the screen, and then check whether the rear stage has high voltage and negative voltage output, and whether the main control chip has output. A considerable part of the screen is because the line driver does not work, and it is simple to fly a few lines to solve the problem. A small part of the flash screen is damaged due to the damage of the first driving module of the row or column. Of course, some of the flower screens are screen parameter changes, and the bus adjustment can be entered. The most difficult and highest maintenance cost is the maintenance of the screen line. Most of the causes of these faults are caused by the solder joints or damage of the corresponding drive modules. Everyone knows that some drive modules are connected between the glass and the PCB of the screen. The module is connected to the PCB board and the glass with a very fine solder joint. This kind of soldering foot can not be distinguished by the naked eye, nor is it soldered by a soldering iron or a wind gun. Under the high magnification magnifying glass, the soldering foot should be correspondingly pressed and then hot-pressed by special equipment. Some of the auxiliary materials used during this period, such as ACF glue and ACF cleaning solution, are very expensive, and the cleanliness of the operating environment directly affects the success rate of repair. This operating machine factor and human experience factors account for almost 50% each.

 

So it is not easy to repair or refurbish an original LCD, but can be easy to buy a new copy screen instead.