Technical answers to frequently asked questions about LED displays
* 来源: * 作者: admin * 发表时间: 2021/04/19 11:41:26 * 浏览: 140
(1) Half of the whole row of the unit board is not displayed on the whole screen, or it is all red (green) or all red (green) in every other row?
Fault symptoms can be caused by the following reasons:
A. If the output port of the corresponding adapter board is faulty, please take the signal from the other output port through the data cable to see if it is normal (the upper and lower half of the signal of a unit board should be replaced and debugged), if it is not normal, it means that there is no problem with the output port; If it is normal, there is no problem with the unit board, please replace the riser card. B. For the corresponding wiring problem, please replace and debug; C. There is a problem with the first unit board, because the data behind it is transmitted from him, and a long cable is directly crossed to the second unit board to see if it is normal or not. (There will be a misalignment of Chinese characters after jumping, as long as there is no fault phenomenon at the beginning, you can ignore it)
(2) The half-area of a row of the whole screen is displayed abnormally from behind a certain unit board: all red (green), no display, large interlacing, incomplete display?
The cause of the fault may be caused by the following reasons: A. If the unit board with the fault phenomenon is damaged, you can use a long row to cross the next unit board backward or downward, and if the display is normal, it means that the unit board is damaged. B. If the data cable is broken, replace one for debugging. C. The output of the first unit board is bad, you can use the long cable to bridge the output of the first 2 unit boards, if it is normal, the output of the first unit board is problematic, you can exchange this unit board with the last 1 unit board of this line on this screen.
(3) The upper and lower parts of a certain part of a certain unit board appear red or green solid?
The cause of the fault may be a problem with the clock and blanking signal of the 11th and 12th pins of a 74HC595 that controls red or green, check whether there is a short circuit at both ends of the universal meter, or whether the two pins of the other 595 on this unit board are connected, if not, please jump the wire directly. In addition, the resistance value between these two pins should not be too small, if it is too small, the display will also be abnormal, and it may be that one of the 595s is damaged.
(4) A module on the unit board does not light up?
If a line does not light up, the corresponding line of the display module is soldered or the printed wire is broken, and the soldering iron can be used to tin the pin or fly 1 wire from any point in the same row in the peer module to connect with this.
(5) The 1st column of a module on the unit board does not light up?
The cause of the fault is the same as above, you can use a soldering iron to add tin to the pins or fly a line from the point of the same column of another module in the same display area, and the RG should also correspond well.
(6) The same row of each module on the unit board is not lit?
If the same line is not bright, it may be that the TP127 (or 4953) of the row drive pipe is damaged or the printing line is broken; B. The signal from base B of 138 to 127 (or 4953) does not come. C. Replace 127 (or 4953) or virtual welding repair welding or flying wire!
(7) The whole screen does not light up?
A, whether +5V electric or GND is short-circuited to the main control B, whether +5V and GND are short-circuited C, check whether the STR signal on the 20-pin on the panel is short-circuited with GND D, replace IC1 (245).
(8) The whole screen is fully bright?
A. Check whether the CLK signal and GND on the 20-pin plug-in on the panel are short-circuited B. Replace IC1 (245).
(9) One column on the screen is on, one column is not lit, and there is no regularity?
A. Check whether there is a short circuit between the CLK signal and GND or VCC on the 20-pin pin on the panel; B. Check whether there is a short circuit between the STR signal and GND on the 20-pin pin on the panel; C. Check whether there is a short circuit between the CLK signal and the STR signal on the 20-pin pin on the panel.
(10) Is 1 module on the screen always on?
A. Check whether the 595 corresponding to the module has virtual soldering B. Check whether the CLK signal of 595 on the always-on module is connected to the adjacent 595 C. If the signal connection is good, replace the 595 on the always-on module.
(11) How many columns will light up on a module on the screen?
A. See if the 595 corresponding to the module has virtual soldering B. Check whether there is a STR signal on the 595, and whether the 595STR pin is connected to the adjacent 595 C. Replace the 595
(12) A line on the screen or a row of the corresponding module is not lit up or displayed abnormally?
A. Check whether the pins of the corresponding line signal are soldered or missing B. Check whether the pins corresponding to the line signal and 138 or 4953 are disconnected or short-circuited with other signals; C. Check whether the up and down resistors of the line signal are not soldered or missed D. Check whether the line signal output by 138 is disconnected or short-circuited with other signals between the line signal output by 138 and the 4953 you want to correspond to E. Replace the IC
(13) Is the unit board lacking color?
A. Check whether there is an output input at the color data end of 245. B. Detect whether the data signal of the color is short-circuited to other lines. C. Detect whether there is an open circuit or short circuit or virtual soldering of the cascading data port between the driver ICs of this color.
(14) Is there a single point or a single column highlight, or a whole line highlight, and it is not controlled?
A. Check whether the column is short-circuited to the power supply. B. Detect whether the line is short-circuited to the positive pole of the power supply. C. Replace the driver IC.
(15) The display is chaotic but the signal output to the next 1 board is normal?
A. Check whether the STR latch output corresponding to 245 is connected to the latch terminal of the driver IC or the signal is short-circuited to other lines.
(16) The display is chaotic and the output is not normal?
A. Detect whether the STB signal latched by the CLK clock is short-circuited. B. Check whether the clock CLK of 245 has input and output. C. Detect whether the clock signal is short-circuited to other lines.
(17) Is there a problem with the output?
A. Detect whether the line from the output interface to the signal output IC is connected or short-circuited. B. Check whether the clock latch signal (STR) of the output port is normal. C. Check whether the cascaded output data port between the last driver IC and the data port connection of the output interface are short-circuited. D. Whether the output signal is short-circuited with each other or short-circuited to the ground. E. Check whether the output cable is good. (18) When the font moves, two or more lines (generally a multiple of 2. Regular) at the same time?
A. Detect whether there is a short circuit between the signals A, B, C, and D. B. Detect whether the output of 4953 is short-circuited with other outputs.
(19) Is there a single point or multiple points (irregular) that are not bright?
A. Find the control pin corresponding to the module to measure whether it is short-circuited with the bank B. Replace the module or the light-emitting tube that does not light up. (20) Can't communicate?
(20) The on-screen electric display is sloppy, and the buzzer is often called?
A. - First see whether the motherboard has electricity and whether the power supply is short-circuited; B. Replace the firmware; C. If the customer has a single-chip microcomputer, replace one single-chip microcomputer, download the firmware and font; D. Replace the main controller.
(21) Is the display time wrong?
A. If the second hand does not go, it is a problem with the clock crystal oscillator, and the battery is dead; If the time is displayed as 01:3:3, it means that there is a problem with the 1302 chip; If there is a big difference in time, it is a problem with the clock crystal.
(22) The content cannot be saved when the power is off?
A. The storage mode is wrong, and the flash mode should be selected; B. There is an error in the firmware download; C. The flash memory of the motherboard is broken, and the main control is replaced (23) How many points does a full-bright picture not light up on the screen?
A. If the dots that are not lit up when the picture is fully lit when it moves, it may be that there is a problem with the picture itself; B. Replace the light-emitting tube or module that is not bright.
Fault symptoms can be caused by the following reasons:
A. If the output port of the corresponding adapter board is faulty, please take the signal from the other output port through the data cable to see if it is normal (the upper and lower half of the signal of a unit board should be replaced and debugged), if it is not normal, it means that there is no problem with the output port; If it is normal, there is no problem with the unit board, please replace the riser card. B. For the corresponding wiring problem, please replace and debug; C. There is a problem with the first unit board, because the data behind it is transmitted from him, and a long cable is directly crossed to the second unit board to see if it is normal or not. (There will be a misalignment of Chinese characters after jumping, as long as there is no fault phenomenon at the beginning, you can ignore it)
(2) The half-area of a row of the whole screen is displayed abnormally from behind a certain unit board: all red (green), no display, large interlacing, incomplete display?
The cause of the fault may be caused by the following reasons: A. If the unit board with the fault phenomenon is damaged, you can use a long row to cross the next unit board backward or downward, and if the display is normal, it means that the unit board is damaged. B. If the data cable is broken, replace one for debugging. C. The output of the first unit board is bad, you can use the long cable to bridge the output of the first 2 unit boards, if it is normal, the output of the first unit board is problematic, you can exchange this unit board with the last 1 unit board of this line on this screen.
(3) The upper and lower parts of a certain part of a certain unit board appear red or green solid?
The cause of the fault may be a problem with the clock and blanking signal of the 11th and 12th pins of a 74HC595 that controls red or green, check whether there is a short circuit at both ends of the universal meter, or whether the two pins of the other 595 on this unit board are connected, if not, please jump the wire directly. In addition, the resistance value between these two pins should not be too small, if it is too small, the display will also be abnormal, and it may be that one of the 595s is damaged.
(4) A module on the unit board does not light up?
If a line does not light up, the corresponding line of the display module is soldered or the printed wire is broken, and the soldering iron can be used to tin the pin or fly 1 wire from any point in the same row in the peer module to connect with this.
(5) The 1st column of a module on the unit board does not light up?
The cause of the fault is the same as above, you can use a soldering iron to add tin to the pins or fly a line from the point of the same column of another module in the same display area, and the RG should also correspond well.
(6) The same row of each module on the unit board is not lit?
If the same line is not bright, it may be that the TP127 (or 4953) of the row drive pipe is damaged or the printing line is broken; B. The signal from base B of 138 to 127 (or 4953) does not come. C. Replace 127 (or 4953) or virtual welding repair welding or flying wire!
(7) The whole screen does not light up?
A, whether +5V electric or GND is short-circuited to the main control B, whether +5V and GND are short-circuited C, check whether the STR signal on the 20-pin on the panel is short-circuited with GND D, replace IC1 (245).
(8) The whole screen is fully bright?
A. Check whether the CLK signal and GND on the 20-pin plug-in on the panel are short-circuited B. Replace IC1 (245).
(9) One column on the screen is on, one column is not lit, and there is no regularity?
A. Check whether there is a short circuit between the CLK signal and GND or VCC on the 20-pin pin on the panel; B. Check whether there is a short circuit between the STR signal and GND on the 20-pin pin on the panel; C. Check whether there is a short circuit between the CLK signal and the STR signal on the 20-pin pin on the panel.
(10) Is 1 module on the screen always on?
A. Check whether the 595 corresponding to the module has virtual soldering B. Check whether the CLK signal of 595 on the always-on module is connected to the adjacent 595 C. If the signal connection is good, replace the 595 on the always-on module.
(11) How many columns will light up on a module on the screen?
A. See if the 595 corresponding to the module has virtual soldering B. Check whether there is a STR signal on the 595, and whether the 595STR pin is connected to the adjacent 595 C. Replace the 595
(12) A line on the screen or a row of the corresponding module is not lit up or displayed abnormally?
A. Check whether the pins of the corresponding line signal are soldered or missing B. Check whether the pins corresponding to the line signal and 138 or 4953 are disconnected or short-circuited with other signals; C. Check whether the up and down resistors of the line signal are not soldered or missed D. Check whether the line signal output by 138 is disconnected or short-circuited with other signals between the line signal output by 138 and the 4953 you want to correspond to E. Replace the IC
(13) Is the unit board lacking color?
A. Check whether there is an output input at the color data end of 245. B. Detect whether the data signal of the color is short-circuited to other lines. C. Detect whether there is an open circuit or short circuit or virtual soldering of the cascading data port between the driver ICs of this color.
(14) Is there a single point or a single column highlight, or a whole line highlight, and it is not controlled?
A. Check whether the column is short-circuited to the power supply. B. Detect whether the line is short-circuited to the positive pole of the power supply. C. Replace the driver IC.
(15) The display is chaotic but the signal output to the next 1 board is normal?
A. Check whether the STR latch output corresponding to 245 is connected to the latch terminal of the driver IC or the signal is short-circuited to other lines.
(16) The display is chaotic and the output is not normal?
A. Detect whether the STB signal latched by the CLK clock is short-circuited. B. Check whether the clock CLK of 245 has input and output. C. Detect whether the clock signal is short-circuited to other lines.
(17) Is there a problem with the output?
A. Detect whether the line from the output interface to the signal output IC is connected or short-circuited. B. Check whether the clock latch signal (STR) of the output port is normal. C. Check whether the cascaded output data port between the last driver IC and the data port connection of the output interface are short-circuited. D. Whether the output signal is short-circuited with each other or short-circuited to the ground. E. Check whether the output cable is good. (18) When the font moves, two or more lines (generally a multiple of 2. Regular) at the same time?
A. Detect whether there is a short circuit between the signals A, B, C, and D. B. Detect whether the output of 4953 is short-circuited with other outputs.
(19) Is there a single point or multiple points (irregular) that are not bright?
A. Find the control pin corresponding to the module to measure whether it is short-circuited with the bank B. Replace the module or the light-emitting tube that does not light up. (20) Can't communicate?
(20) The on-screen electric display is sloppy, and the buzzer is often called?
A. - First see whether the motherboard has electricity and whether the power supply is short-circuited; B. Replace the firmware; C. If the customer has a single-chip microcomputer, replace one single-chip microcomputer, download the firmware and font; D. Replace the main controller.
(21) Is the display time wrong?
A. If the second hand does not go, it is a problem with the clock crystal oscillator, and the battery is dead; If the time is displayed as 01:3:3, it means that there is a problem with the 1302 chip; If there is a big difference in time, it is a problem with the clock crystal.
(22) The content cannot be saved when the power is off?
A. The storage mode is wrong, and the flash mode should be selected; B. There is an error in the firmware download; C. The flash memory of the motherboard is broken, and the main control is replaced (23) How many points does a full-bright picture not light up on the screen?
A. If the dots that are not lit up when the picture is fully lit when it moves, it may be that there is a problem with the picture itself; B. Replace the light-emitting tube or module that is not bright.
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