What is a white screen? After the LCD display screen is turned on, the display screen is full white (white screen) fault, this is the fault phenomenon of boot display screen white screen. 

a. Principle error, LAYOUT error. IM0, IM3 connection error, left and right connection is reversed, one of the lead error, power cord connection error, ground wire did not connect and so on. 100% bad. 

b. The test rack connection is wrong. IM0, IM3 connection error, data cable connection error, power cord connection error, ground wire not connected and so on. 100% bad. 

c. Program error. 8 to 16 selection error, high, low 8 bit selection error (P0, P2 port), initialization code error, program reset time is not enough, a function was not called. 100% bad. 

d. Poor contact with the golden finger. Welded, there are tin clip, virtual welding. 

e. Poor connector contact. 

f. Welded FPC, gold finger broken. 

G. Virtual welding of components on FPC (virtual welding of voltage doubling capacitance, virtual welding of crystal resistance), damage of components (diode breaking). 
The crystal resistance is too small. 

h. Plug-and-pull connector, metal wire breaking at the reinforcement (partial wire breaking can be observed under the microscope). 

I. FPC compression joint is poor. There is a foreign body somewhere in the small golden finger, ACF conductive particles, crimping temperature, pressure during crimping, and so on. Cause one or more golden fingers to break or have too much contact resistance. 

J. IC has poor crimping. Abnormal pollution on IC PAD, conductive particles on ACF, crimping temperature, pressure, etc. Cause poor contact (open circuit) or excessive contact resistance of one or more key PAD. 

Summary: the cause of the white screen is divided into two aspects of software and hardware, the software needs to find the analysis program, the hardware part is a certain place to break the line or short connection. Generally, the, VGH, VGL does not boost when the screen is white.