The common bad phenomena and reasons of LCD screen are as follows: appearance item 

1. LCD-black spots, white spots, debris spots, fibers (box dirt, polarizer impurities, PI coating impurities can be caused)

2. LCD-scratches, scratches (friction with hard or sharp objects, impact, extrusion)

3. LCD-frame color (box thickness, UV glue shrinkage, soldering iron, assembly extrusion, etc. are likely to cause)

4. LED backlight-uneven brightness (uneven light guide plate mesh point, backlight into the liquid, etc. are likely to cause)

5. LED backlight-bright spot, Black Spot (light guide plate surface has glue, impurities, dot shortage, alcohol, etc. are likely to cause)

6. Cob-copper (green undercoat, scratches, soldering iron burns, etc.)7. Cob-welding spot dirty, tin bead tin slag (after welding not washing plate)

Function 

1. LED backlight is invisible (LED lamp is damaged by high voltage and current)

2. LCD screen without display (COB's IC was damaged by a sudden high current voltage shock)

3. LCD display lack of strokes (box etching short circuit, welding caused metal PIN PIN PIN PIN PIN loose, etc.)

4. LCD display gibberish (COB IC damage, program burning error, etc.)

5. LCD leakage damage (drop, collision, extrusion, violent assembly, etc.)

The above is the LCD screen of bad knowledge points, if the product has bad phenomenon, the first time to understand how to produce bad, if not, you can consult the supplier. Shenzhen Jingyao Photoelectric Co. , Ltd. focus on LCD LCD screen for 20 years, with professional r & D, design, production and sales experience.