Common faults and maintenance of LED display_led display failure|LED display repair
In the process of repairing the LED display, the engineers of our company summarized many solutions to the problem of LED display failures. Today, they shared with you, hoping to help everyone's work and the repair and maintenance of the LED display. The entire board of the LED display does not light up 1. Check whether the power supply is connected to the signal line. 2. Check whether the test card recognizes the interface. If the red light of the test card flashes, it is not recognized. Check whether the light board and the test card have the same power ground, or the light board interface has a signal and ground short circuit, which makes the interface unrecognizable. (Intelligent test card) 3. Check whether 74HC245 is short-circuited or not, and whether the corresponding enable (EN) signal input and output pins on the 245 are soldered or short-circuited to other lines. Note: Mainly check the power supply and enable (EN) signal. When the LED display screen is scanning the dots, the regular interlaced lines are not bright and the display screen overlaps. 1. Check whether there is any disconnection, virtual welding, or short circuit between the A, B, C, and D signal input ports to 245. 2. Detect whether the A, B, C, D output terminals corresponding to 245 are open, soldered, or short-circuited between the output terminals 138. 3. Check whether the signals A, B, C, and D are short-circuited or a signal is short-circuited to the ground. Note: Mainly detect ABCD line signals. When the LED display is all on, one or several lines do not light up. 1. Detect whether the circuit between 138 and 4953 is open, soldered, or short-circuited. During line scanning, two or several lines (generally a multiple of 2, regular) will light up at the same time. 1. Detect whether there is a short circuit between the signals of A, B, C, and D. 2. Check whether the 4953 output terminal is short-circuited with other output terminals. When the LED display is all on, there is a single point or multiple points (irregularly) that do not light up. 1. Find the corresponding control pin of the module and measure whether it is short-circuited with the line. 2. Replace the module or single lamp. When the LED display is all on, one or several columns do not light up. 1. Find the pin that controls the column on the module, and check whether it is connected to the output terminal of the driver IC (74HC595/TB62726,,,). A single point or a single column is highlighted, or the entire row is highlighted, and it is not controlled. 1. Check whether the column is short-circuited with the power ground. 2. Check whether the line is short-circuited with the positive pole of the power supply. 3. Replace its driver IC. The LED display shows confusion, but the signal output to the next board is normal. 1. Check whether the STB latch output terminal corresponding to 245 is connected to the latch terminal of the driver IC or the signal is short-circuited to other lines. The LED display shows confusion and the output is abnormal. 1. Check whether the STB signal latched by the clock CLK is short-circuited. 2. Check whether the clock CLK of 245 has input and output. 3. Check whether the clock signal is short-circuited to other lines. Note: Mainly detect clock and latch signals. LED display shows lack of color 1. Check whether there is input and output on the data terminal of the color of 245. 2. Check whether the data signal of this color is short-circuited to other circuits. 3. Check whether the cascaded data ports between the driver ICs of the color are open, short-circuited, or soldered. Note: The voltage detection method can be used to find the problem more easily, check whether the voltage of the data port is different from the normal one, and determine the fault area. There is a problem with the output of the LED display 1. Check whether the line from the output interface to the signal output IC is connected or short-circuited. 2. Check whether the clock latch signal of the output port is normal. 3. Check whether the cascade output data port between the last drive IC is connected to 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 short-circuited to the ground. 5. Check whether the output cable is in good condition.