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How to Maintain the LED Module?

2019-01-09 www.myddisplay.com

A. The whole led module is not bright


1. Check if the power supply and signal cable are connected.


2. Check whether the test card is identified by the interface. If the test card flashes red, it will not be identified. Check whether the lamp board is connected to the test card or the lamp board interface has a short circuit between the signal and the ground. (smart test card)


3. Detect whether the 74HC245 has a short circuit or not, and the corresponding enable (EN) signal input and output pin on the 245 is soldered or short-circuited to other lines.


Note: Mainly check the power and enable (EN) signals.


B. When oblique scan, the regular interlacing does not light up and the screen overlaps.


1. Check if the A, B, C, D signal input port to 245 is broken or short welded or shorted.

2. Detect whether there is an open circuit or a virtual soldering or short circuit between the output terminals A, B, C and D corresponding to 245.

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

Note: The ABCD line signals are mainly detected.


C. One line or several lines are not lit when fully lit

Check if the line between 138 and 4953 is open circuit or soldered or shorted.


D. When scanning a line, two lines or a few lines (usually a multiple of 2, regular) are illuminated at the same time.


1. Detect whether there is a short circuit between the signals of A, B, C and D.

2. Detect if the output of the 4953 is shorted to other outputs.


E. Single or multiple points (irregular) are not bright when fully illuminated


1. Find whether the control pin corresponding to the module is short-circuited with the line.

2. Replace the led module or led lamp.


Meiyad Flexible LED Display


F. One column or several columns are not lit when fully illuminated

Find the pin that controls the column on the led module and check if it is connected to the output of the driver IC (74HC595/TB62726).


G. Single or single column highlighting, or full line highlighting, and uncontrolled


1. Check if the column is shorted to the power ground.

2. Check if the line is shorted to the positive terminal of the power supply.

3. Replace the driver IC.


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

It is detected whether the corresponding STB latch output terminal of the 245 is connected to the latch terminal of the driver IC or the signal is short-circuited to other lines.


I. Display confusion, output is not normal


1. Detect whether the clock CLK latches the STB signal for short circuit.

2. Check if the clock CLK of 245 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. Detect whether there is input and output on the data end of the color of 245.

2. Check if the data signal of the color is short-circuited to other lines.

3. Check whether the cascaded data port between the driver ICs of this color has an open circuit or short circuit or a virtual solder.


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


K. Have a problem with the output


1. Check whether the line from the output interface to the signal output IC is connected or shorted.

2. Check if the clock latch signal of the output port is normal.

3. Check if the cascaded output data port between the last driver IC is connected to the data port of the output interface or is short-circuited.

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

5. Check if the output cable is good.


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