11 common faults and solutions for cell boards

11 common faults and solutions for cell boards
After-sales engineers based on maintenance technology and experience, for everyone to sum up the LED display unit board common 11 kinds of failures and solutions.
A. The entire board is not bright
1. Check if the power supply and signal line are connected.
2. Check whether the test card recognizes the interface. The red flashing of the test card is not recognized. Check whether the light board is in the same power ground as the test card, or if the light board interface has a signal and ground short circuit, the interface cannot be identified. (Smart Test Card)
3. Check whether the 74HC245 is short-circuited by a short circuit or not, and whether the corresponding input/output pin of the 245 signal is pinned or short-circuited to other lines. Note: Mainly check the power and enable (EN) signals.
B. Regular interlaced display overlaps during point-sweep scanning
1. Check whether there is any broken wire, or short circuit or welding between A, B, C, and D signal input ports.
2. Check whether the 245 corresponding A, B, C, D output terminals and 138 are open circuited or soldered or short circuited.
3. Detect whether the A, B, C, D signals are short-circuited or a signal is shorted to ground. Note: The main test ABCD line signal.
C. One or several lines are not lit when all lights are on
1. Check if the line between 138 and 4953 is open or short circuited.
D. Two or more lines (generally a multiple of 2, regular) light up at the same time
1. Check if the A, B, C, D signals are short-circuited.
2. Check if the output of 4953 is shorted to other output terminals.
E. Single or multiple points (irregular) are not bright at full bright
1. Find out whether the corresponding control pin of this module measures a short circuit with this one.
2. Replace module or single lamp.
F. One or more columns are not bright when all lights are on
1. Find the pins that control the column on the module and test if it is connected to the output of the driver IC (74HC595/TB62726).
G. There is single or single column highlighting, or the entire row is highlighted, and is not controlled
1. Check if the column is shorted to the power ground.
2. Check if the line is shorted to the positive side of the power supply.
3, replace its driver IC.
H. The display is confusing, but the signal output to the next board is normal
1. Test 245 corresponds to whether the output of the STB latch and the latch of the driver IC are connected or the signal is shorted to other lines.
I. Display confusion, abnormal output
1, detect the clock CLK latch STB signal is short circuit.
2. Check whether the 245 clock CLK has input and output.
3. Check if the clock signal is shorted to other lines.
Note: The main detection clock and latch signal.
J. display lack of color
1. Check whether the data of the color of 245 has input and output.
2. Check if the color data signal is shorted to other lines.
3. Check whether the cascaded data port between the driver ICs of this color is open circuited or short circuited and soldered. Note: The available voltage detection method is easier to find the problem, whether the voltage of the data port is different from the normal one, and the fault area is determined.
K. There is a problem with the output
1. Check if the output interface to the signal output IC is connected or short-circuited.
2. Check if the clock latch signal of the output port is normal.
3. Check whether the cascade output data port between the last driver IC is connected to the data interface of the output interface or whether it is short-circuited.
4. Whether the output signals are short-circuited or shorted to ground.
5, check the output cable is good.

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