Friday, July 15, 2022 at 6:10:11 AM GMT+00:00
LED display not only brightens the landscape of the city, but also brings convenience to people's lives. What should we do when the LED display fails?
In addition to the lamp beads in the LED module, the LED display screen also needs to rely on three other hardware: control card, unit board, and switching power supply.
1. Electric soldering iron, suction gun, soldering tin.
2. 5V regulated power supply, supplying power to receiving card and module or unit board for maintenance.
3. Electric screwdriver for quick disassembly of module or unit board.
4. PC, sending card, sending program to receiving card.
5. Receiving card, HUB board, used to observe module or unit board failure.
6. Multimeter, used to detect specific failure of module or unit board.
7. Tweezers, scissors, scissors.
Turn the multimeter to the short circuit detection gear (generally with alarm function, such as beeping when conducting), detect whether there is a short circuit, and solve it immediately after finding a short circuit, which is also the most common LED display module fault. Some can be found by observing IC pin and pin array. Short circuit detection shall be conducted when the circuit is powered off to avoid damaging the multimeter. This method is the most commonly used, simple and efficient. 90% of faults can be detected and judged by this method.
Adjust the multimeter to the resistance range, check the resistance to ground at a point of a normal circuit board, and then check the same point of another same circuit board to see if it is different from the normal resistance value. If it is different, the problem range is determined.
Adjust the multimeter to the voltage range, detect the ground voltage at a point of the suspected circuit, and compare whether it is similar to the normal value, which can easily determine the problem range.
Adjust the multimeter to the diode voltage drop detection gear. Because all ICs are composed of many basic single components, which are just miniaturized, there will be a voltage drop on a pin when there is current passing through it. Generally, the voltage drop on the same pin of the same type of IC is similar. According to the voltage drop value on the pin, it must be operated when the circuit is powered off.
One unit board in the entire display screen is not lit, which may be caused by power failure of the unit board, data cable problem, chip problem, and failure to connect the upper and lower modules with the corresponding pins of the 595; Corresponding solution: replace the power supply; Replace the data cable; Replace the control chip; If the upper and lower modules are not connected to the corresponding pins of the 595, the corresponding hardware needs to be replaced.
The whole screen does not light up because there is no power input to the main control card. At this time, check whether the LED power supply of the control card is damaged; Then check whether there is a problem with the power supply circuit of the display screen; If the settings of the computer or control card are accidentally tampered with, the entire display screen will not light up. In this case, a new control card needs to be replaced.
The horizontal light failure may be caused by a problem with the data cable between the unit boards or a damaged unit board chip. The control chip can be replaced for troubleshooting and maintenance. The longitudinal direction is not lit because there is a problem with the LED power supply of the unit board, and the power supply needs to be replaced.
This problem is probably caused by the inconsistency between the information size and the screen size. It is not a problem of the display screen. You just need to edit the font size again.
1. Determine the type of HUB board used by the module or unit board, so that the interface definition of the flat cable can be the same.
2. According to different models of modules or unit boards, send corresponding programs to the receiving card to ensure that the modules and unit boards are displayed under the correct program, which is the premise of finding out the cause of the failure. Generally, the model of the module or unit board is printed on the PCB.
3. Observe the phenomenon of module or unit board to determine the initial failure. For example, common blind lights, string points, small squares, etc.
4. Use a multimeter to find out the fault, mainly by using the above short circuit detection method to detect between the chip and the lamp pin.
5. Test again.
LED display solution