The fault of LED electronic display panel and its treatment method

Time:2018-11-29 Views:128

The fault of LED electronic display panel and its treatment method are as follows:

A.The board is not bright

1. Check whether the power supply is connected to the signal line.

2. Check whether the test card has identified the interface, while the test card does not recognize when the red light flashes. Check whether the lamp board is at the same power source as the test card, or whether the lamp board has signals at the interface with the ground, so that the interface cannot be identified due to short circuit with the ground.(smart test card)

3. Check whether 74HC245 has virtual welding short circuit, and whether the enabling (EN) signal input and output pin on 245 has virtual welding or short circuit to other lines.

Note: check the power supply and enable (EN) signal.

B.In point-to-point scanning, regular interlaced lines do not highlight the overlap of the display screen

1. Check whether there is any wire break or virtual welding or short circuit between signal input ports A, B, C and D and 245.

2. Check whether the output terminals of 245 corresponding to A, B, C and D and 138 are disconnected or have virtual welding or short circuit.

3. Check whether there is short circuit between signals A, B, C and D or between A signal and the ground.

Note: mainly detect ABCD line signal.

C.There is a line or a few lines of light when it is all on

1. Check whether the line between 138 and 4953 is open circuit or virtual welding or short circuit.

D.In line scanning, two or more lines (usually multiples of 2, with regularity) are lit simultaneously

1. Check whether there is A short circuit between signals A, B, C and D.

2. Check whether the 4953 output end is short-circuited with other output ends.

E.There is a single or multiple (irregular) dimming at full brightness

1. Find out whether the corresponding control pin of this module is short-circuited with the bank.

2. Replace modules or single lights.

F.There is one or several columns of full light

1. Find the pin controlling this column on the module and test whether it is connected to the output end of driver IC (74HC595/TB62726,,,,).

G.There is single point or single column highlighting, or entire row highlighting, and it is not controlled

1. Check whether the column is short-circuited with the power supply.

2. Check whether the line is short-circuited with the positive pole of the power supply.

3. Replace its drive IC.

H.The LED display is confused, but the signal output to the next board is normal

1. Check whether the 245 STB latch output end is connected to the latch end of the driver IC or whether the signal is short-circuited to other lines.

I.The display is confused and the output is abnormal

1. Detect whether the clock CLK latch STB signal is short-circuited.

2. Check whether 245 clock CLK has input and output.

3. Check whether the clock signal is short-circuited to other lines.

Note: it mainly detects clock and latch signal.

J.Show lack of color

1. Check whether the data terminal of 245 of this color has input and output.

2. Check whether the data signal of this color shorted to other lines.

3. Check whether there is a break or short circuit or virtual welding in the cascade connection data port between the driving IC of this color.

Note: it is easier to find the problem by using the voltage detection method, detect whether the voltage of the data port is different from the normal one, and determine the fault area.

K.Output problem

1. Check whether the circuit from the output interface to the signal output IC is connected or short-circuited.

2. Check whether the clock latch signal at the output port is normal.

3. Check whether the output data port of the cascade connection between the last driver IC is connected with the data port of the output interface or whether it is short-circuited.

4. Whether the output signals are short-circuited to each other or to the ground.

5. Check whether the output alignment is good.