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LED display unit board failure and methods of trea

LED display unit board failure, and treatment methods :
A. The entire board is not lit
1, check the power supply and signal cable is connected .
2, check whether the test card to identify interfaces, test card is not recognized red light flashing , check the light board whether the test card with the power ground , or light board interfaces between signal and ground short circuit causes not recognize interface. ( Intelligent Test Card )
3, the detection circuit 74HC245 whether the Weld , 245 corresponding enable (EN) signal input and output pins are soldered or shorted to other lines .
NOTE : The main power supply and check Enable (EN) signal.

B. In the point-slope scan, regularity interlaced display does not light overlap
1, check the A, B, C, D between the signal input port to 245 are plugged or soldered , short-circuit .
2, detection 245 corresponds to A, B, C, D between the output terminal 138 is open or Weld, shorted.
3 , test A, B, C, D each signal or a short circuit between the signal and ground circuit .
Note: The main testing line ABCD signaling .

C. Full bright line or lines when not lit
1, the detection 138-4953 between Weld line is open or short circuit .

D. Scanning line , two lines or lines ( usually a multiple of 2 , with regularity ) simultaneously lit
1 , test A, B, C, D short circuit between the respective signals .
2 , detect whether the 4953 output with other output short circuit.

E. Full light when a single or multi-point ( irregular ) does not shine
1 , find the module corresponding control foot measurement is shorted with the Bank .
2 , the replacement module or a single lamp .

F. When there is a full bright or not bright columns
1, in the control module to find the column pin , measuring whether the driver IC (74HC595/TB62726,,,) output connections.

G. There are single-point or single highlight , or highlight the entire line , and is not controlled
1, check whether the column with the power to short circuit.
2 , detect whether the row with the positive power supply circuit .
3 , the replacement of the driving IC.

H. Show confusion, but the output signal to the next one plate normal
1, the detection output of the latch 245 corresponding to the terminal STB of the latch end of the driver IC is connected or the signal line is shorted to the other .

I. Show confusion , the output is not normal
1 , testing whether the clock CLK STB signal latch circuit .
2, detection 245 has the input clock CLK output.
3, the detection clock signal is shorted to other lines .
Note: The main test clock and latch signal .

J. Lack of color display
1, the detection of the color data 245 whether there are input and output .
2, detection data of the color signal is shorted to another line .
3, the detection of the color of the driver IC data port between level even if there is open or shorted , Weld.
Note: You can use the voltage detection method is easier to find the problem , test data port voltage is different than the normal , the fault zone.

K. Output problem
1, the detection signal is output to the output interface is connected to the IC circuit or short circuit.
2 , the detection output of the latch clock signal is normal .
3 , the last driver IC detection level between the output data port is connected with the output interface data port connection or short circuit.
4, the output signal if there are short-circuited or short circuit to ground .
5 , check the output of the cable is good.