With the continuous improvement of people's living standards, the application of LED large screen has also become very extensive. For example, in our daily life, there are LED large screen LCD TVs, LED large screen computers, etc. it can be seen that led large screen plays an important role in our life today, but for friends who often use LED large screen, they will have a common feeling, that is, how to repair when the LED screen breaks down, What kind of faults will occur? Next, I will introduce the LED large screen maintenance in detail.
Fault analysis of LED display screen
Fault analysis is for beginners Direct The effective method is the elimination method, in which we need to know a foundation first. In addition to the light beads in the LED module, the LED display also needs to rely on three other hardware, which are: control card, unit board and switching power supply.
First: judge whether the control card is good. First, turn the power on and check whether the indicator light of the control card is on. If not, check whether there is 5V power supply and whether the display screen can show the content. If it can show the content, it indicates that the function of the control card to show the content is good; Then you use the control card software to find the control card. If you can find it, it means that the function of sending content of the control card is normal. If you can\'t find it, first check whether the communication line is connected properly. If it is connected properly, there may be a problem with the card.
Conclusion: if the indicator light of the control card is on normally, the software of the control card can find the control card, and there is no problem with the line connection, it indicates that the control card is good, otherwise, the control card needs to be replaced.
secondly; Check whether the power supply is normal. If the power supply breaks down, it will directly cause several boards in the link to not light up or abnormal or flicker. Generally, one power supply can control 4-8 boards. If the adjacent 4-8 boards are abnormal, it should be considered that the power supply may be abnormal. If the power supply is abnormal, you can measure whether the output voltage is between 4.9~5.5v through the DC voltage gear of the multimeter. If so, replace the power supply.
Summary: when there is a problem with several adjacent boards, first look for whether the power supply is abnormal.
We need to judge whether the unit board is good or not. The display screen signal is the input signal transmitted from the output row pin of one unit board to another board. Therefore, if there is a problem with one board, the whole row behind it will not be bright or abnormal. Therefore, when there is a problem with the display screen row, we should replace the board with the abnormal one at the beginning of this row, or jump this board with a long line, and then see whether the board behind appears normal.
Summary: when checking the picture of horizontal or vertical rows, if the whole row is abnormal or the signal input is abnormal at a certain position, there may be a problem with the unit board.
Failure analysis of LED unit board for LED display screen repair
A. There is a problem with the output
1. Check whether the line from the output interface to the signal output IC is connected or short circuited.
2. Testing Whether the cascade output data port between the last drive IC is connected with the data port of the output interface or whether it is short circuited.
3. Check whether the clock latch signal of the output port is normal.
4. Whether the output signals are short circuited to each other or to the ground.
5. Check whether the output cable is in good condition.
B. The whole board is not bright
1. Check whether the power supply is connected with the signal line.
2. Detect whether 74hc245 has faulty soldering or short circuit, and whether the corresponding enable (EN) signal input and output pin on 245 has faulty soldering or short circuit to other lines.
3. Check whether the test card can identify the interface. If the red light of the test card flashes, it will not be identified. Check whether the light board is connected to the power ground of the test card, or there is a short circuit between the signal and the ground of the light board interface, so that the interface cannot be identified. (smart test card)
Note: mainly check the power supply and enable (EN) signal.
C. One or more lines do not light up when it is fully lit
Detect whether the circuit between 138 and 4953 is open circuit, faulty soldering or short circuit.
D. During oblique scanning, the regular interlaced light is not on, and the display screen overlaps
1. Check whether there is broken wire, faulty soldering or short circuit between a, B, C, D signal input port and 245.
2. Check whether there is open circuit, faulty soldering or short circuit between output terminals a, B, C and d corresponding to 245 and 138.
3. Detect whether there is a short circuit between signals a, B, C and D or whether a signal is shorted to ground.
Note: it mainly detects the ABCD line signal.
E. The display is chaotic, but the signal output to the next board is normal
Detect whether the STB latch output corresponding to 245 is connected with the latch end of the drive IC or whether the signal is short circuited to other lines.
Led synchronous video screen system fault maintenance
Turn on the computer and there is no response on the display screen. Cause: the communication line is faulty (such as poor connection).
When the computer is turned on, the display screen flashes, but there is no signal cause: drive software L Edsetup did not start.
The display screen displays normally, but the whole screen has flashing reasons: the communication line, sending card, receiving card or receiving card are faulty.
Reason for abnormal display color: there is a problem with the display mode setting.
Cause of abnormal display on the display: check the corresponding scanning board, and there may be no power supply, or HC541, 74f245, 1016 are faulty, or there may be poor contact.
Asynchronous text screen system
Reason for no display when starting up: the main control board may have no power supply, or the voltage is too low.
The old content is displayed when starting up, but the communication is not good. Reason: the communication line is abnormal and the wiring is wrong.
The communication interface chip 232 is broken or the computer communication interface is broken.
Cause of content loss: the 3.6V battery is dead.
Thank you for watching. Sostron is a provider of commercial display solutions.We provide all kinds of display screens, display leasing and display solutions all over the world.If you have any questions, you can consult us!