What causes the white screen of LCD
Author:Wang Feng Time:2021-10-14 08:04 Browse(653)
We know that in computer failure, there are black screens and blue screens on the display screen. However, is there another situation that you have encountered? That is the phenomenon of white screen on the display screen. If you don't understand this fault, you can follow us to install the system. Maybe it will be useful for you in the future. First of all, this paper introduces the causes of the white screen failure of the power on display
We know that in computer failure, there are black screens and blue screens on the display screen. However, is there another situation that you have encountered? That is the phenomenon of white screen on the display screen. If you don't understand this fault, you can look down with the installation of the system, which may be useful for you in the future.
first, introduce the causes of the white screen fault of the power on display screen:

What causes the white screen of LCD

the white screen fault of the LCD may be caused by the driving circuit of the LCD panel, the power supply circuit of the LCD panel, the poor contact of the screen wire, the power supply circuit of the LCD panel
the LCD screen is white when it is turned on.
it indicates that the backlight and high voltage generation circuit work normally, but the LCD panel does not get the driving signal.
if the laptop computer is turned off, the screen disappears.
and then the screen is white again, It may be caused by the problem of the power board.

from the analysis of the fault phenomenon.
no matter the LCD is turned on or off, as long as the power is plugged in, the high voltage generation circuit is always in the working state, and the backlight is always on.
that is to say,
the high voltage generation circuit is not controlled by the switch, That is to say, the switch signal sent by the main board to the high voltage generation circuit is out of control.
because the switch signal sent by the main board microprocessor is generally controlled by several transistors.
therefore, the failure may be caused by the damage of the transistor controlling the switch signal.

Maintenance ideas for the white screen of the power on display screen First, remove the shell of the LCD screen.
and then check whether the screen cable interface is loose or not connected properly.
after checking, the screen cable connection is normal.

Second, turn on the power switch of the notebook computer.
then use a multimeter to measure whether the power supply voltage of the screen cable interface is normal.
if the power supply voltage is normal.
if the power supply voltage is normalGo to step 5; If it is abnormal, then check whether the safety resistor or inductance near the output end of the screen line is open or damaged.
if it is damaged.
replace the damaged components.

III If the fuse resistance or fuse inductance near the output end of the screen line is normal,
then check whether the output voltage of the DC-DC voltage conversion circuit supplying power to the LCD is normal.
if the output voltage is abnormal,
check the fuse resistance, PWM controller, switch tube, inductance coil, filter capacitor and other components in the power supply circuit, Then replace the damaged components.

IV. if the output voltage of DC-DC
voltage conversion circuit is normal,
then there are damaged capacitors and other components between the output end of DC-DC
voltage conversion circuit and the screen line interface. Check and replace the damaged components.

v If the power supply voltage of the screen line interface is normal,
then check whether the timing signal and driving signal in the LCD panel driving circuit are normal.
if not,
check the output signal, input signal and power supply voltage of the chip generating the signal respectively, So as to judge whether the driver chip is damaged.
if it is damaged.
then replace it.
through the above understanding.
have a preliminary understanding of the phenomenon of LCD white screen, because the maintenance of LCD white screen is difficult, so it is very difficult for individuals to repair, the safest way is to ask more professional personnel to help you, Find out the reason and solve it.
the reason of LCD TV white screen

1. The screen cable falling off will lead to LCD TV white screen.
usually this is just a small fault,During maintenance, you only need to check which line is loose and plug it in again.


2. If the fuse of TV screen circuit board is blown, it will also lead to the appearance of LCD TV white screen.
at this time, you need to replace its screen circuit fuse.


3. There is a problem with the picture tube on the TV monitor.


4 If the voltage regulator is damaged, sometimes there is a short display or no display, and then the screen is white.


5. The main board control chip of TV display has poor characteristics or is damaged.


6 The components of TV have been aging.
usually, this phenomenon is caused by capacitance.


7. The problem of insufficient positive and negative power supply voltage of LCD will also lead to the appearance of white screen.
at this time, the main fault of maintaining voltage stability can be solved.


8 Abnormal signal leads to white screen.


if the white screen of LCD TV is caused by a small fault, we can repair it by ourselves.
but usually we can't solve the problem by ourselves. In this case, we suggest that you turn off the TV first, It's better to avoid the mainboard burning when the TV is running, and contact the special maintenance personnel to repair the mainboard.


Samsung LCD TV white screen

LCD TV white screen indicates that its backlight panel can work normally.

the LCD TV white screen of Samsung LCD TV shows that the backlight panel can work normallyAt this time, the first thing we need to judge is whether the TV motherboard can work normally. If the TV indicator light can change color, it means that the motherboard can work normally.
when checking, we should focus on the following aspects:

1 Whether the signal output of the main board and the connection line of the screen are in poor contact.


2. Whether the voltage at each working point of the main board is normal.
especially whether the power supply voltage of the display screen is normal.


3 Use an oscilloscope to check whether the line field signal and clock signal of the TV are normal.


if the indicator light of the TV doesn't respond,
then it means that the main board can't work normally. At this time, we should check these places:

1. Whether the voltage of each working point of the main board is normal, especially the voltage of EEPROM, Its voltage is usually about 4.8V, as well as reset voltage and MCU voltage. In case of power short circuit, it is necessary to find out the location of the short circuit carefully, and whether there is a possibility of short circuit in PCB copper foil.


2. Check whether the connecting lines between MCU pins and main board are normal.


3 Whether the main board chip and MCU can work normally.
at the same time, use the oscilloscope to detect whether the crystal oscillator can start up
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