What are the reasons for the black spots or stains on the display screen? How to repair it?

Reason analysis: Because the image and accompanying sound are normal, black spots or stains are fixed, and have nothing to do with the image. So judging the fault phenomenon is not caused by the image processing circuit, but by the impurities in the screen. That is to say, the faults are caused by in-screen optical components.

For the faults of optical components in the display screen, new screen maintenance is required. As a matter of fact, the price of replacing a new screen is too expensive for a foreign-keeping machine, which is much more expensive than buying a new machine now produced. In fact, the failure of the optical components in the screen is very simple and easy to remove, so it is necessary to try to repair the display module.

Maintenance process: First of all, the LCD display screen is removed from the whole machine, and the optical components of the LCD module are decomposed. The outermost layer is the liquid crystal plate, under which there are two thin polarizers, and under which there is a thick layer of white translucent plate which can uniform light. Under this thick board is the lamp box.

For a machine with stain failure, after decomposing the display module, it is found that there is black dust powder on the opposite side of the white light transmitter board and the lamp box. After cleaning, the display module is assembled, boot up and troubleshooting. For another machine with black spots, it was found that there was a black dirt between the two polarizers.

Solution: Use clean soft cloth to dip in pure water and clean the dirt. However, it should be noted that there are several layers of optical slices in the LCD display module. When splitting the screen module, we must remember the steps of splitting, so as not to forget the position of each lens when assembling.