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LED Display Maintenance

Walking in the streets, LED display screen can be seen everywhere, full color, single color LED display abound, While we enjoy the visual feast and economic benefits brought by LED display, We should also learn more about the LED display Maintenance in order to make the LED display safe and normal operation.

Walking in the streets, led display screen can be seen everywhere, full color, single color LED display abound. LED display not only enhances the image of the city but also enriches people’s cultural life. In this respect, it can reflect the rapid development of the LED industry. While we enjoy the visual feast and economic benefits brought by LED display, We should also learn more about the LED display Maintenance in order to make the LED display safe and normal operation.

Like traditional electronic products, to make the LED display life longer, not only need to pay attention to methods in the use process, but also need to maintain the display screen. With the wide use of LED display screens, accompanied by increasing use issues, various problems, resulting in LED display screen life is reduced, can not display normally, black screen and other issues. The following describes some of the LED display precautions and maintenance methods. LED display precautions and repair methods.

First, the daily maintenance and maintenance of the main control computer

The computer is usually placed in the control room. To ensure the stability of the display program and good display effect, we should always maintain the main control computer as follows:

1.1 Keep the control room clean. Clean the computer and peripheral equipment regularly. Dust can contaminate key components such as computer keyboards, disks, monitors, and the host circuit board, which may cause serious problems.

1.2 When the computer is working, it will emit a lot of heat. If the heat is not good and the room temperature is too high, it can easily cause the computer to crash, and long-term use will reduce the service life of the host computer. Therefore, attention should be paid to indoor ventilation.

1.3 If the ambient temperature is high (such as hot summer), the fan should be installed in the control room. Conditional air conditioning equipment can be installed. The temperature should be maintained at 10°C to 35°C, and the relative humidity should be 30% to 80%. Avoid the computer working in high temperature and high humidity environment.

1.4 Regularly check the computer’s hardware and peripheral devices, such as the graphics card, whether the sending card is loose, whether the DVI cable, RS232 serial cable is loose or damaged, etc.

1.5 Regular anti-virus treatment of computers, especially those with Internet access, should also install anti-virus software, and regularly update the playback software to ensure that the version of the playback software is up-to-date.

Second, the control part changes notes

2.1 The power line of computer and control part is zero, and the fire cannot be reversed. It should be plugged in according to the original position. If there are peripherals, after the connection is complete, test whether the chassis is powered.

2.2 When controlling equipment such as mobile computers, check the connection lines and the control board for looseness before powering on.

2.3 The position and length of communication lines and flat connection lines cannot be arbitrarily changed.

2.4 If abnormalities such as short-circuit, tripping, burning, or smoking are found after moving, the power-on test should not be repeated and the problem should be promptly searched.

Third, the use of software operation precautions

3.1 Software Backup: WIN2003, WINXP, Applications, Software Installer, Database, etc. It is recommended to use “One-click Restore” software for easy operation.

3.2 Proficient in installation methods, original data recovery, backup.

3.3 master control parameter settings, basic data preset modifications.

3.4 Skilled use of procedures, operations and editing.

3.5 Regularly check for viruses and delete unrelated data.

Fourth, LED display maintenance methods

Judgment of the problem must be dealt with by the primary and secondary modes first, with obvious and serious first steps and minor problems afterwards. Short circuit should be the highest priority.

Resistance detection method

Adjust the multimeter to the resistance file, detect the resistance value of a certain point of a normal circuit board to the ground, and then test whether the same point of another same circuit board is tested and the resistance value of the circuit is different. If it is different, then it is determined. The scope of the problem.

2. Voltage detection method

The multimeter is adjusted to the voltage level, and the voltage to the ground at a certain point in the circuit in question is detected. The comparison is similar to the normal value, otherwise the range of the problem is determined.

3. Short-circuit detection method

Turn the multimeter to the short-circuit detection block (some diode deceleration or resistance, generally have an alarm function), detect if there is a short circuit phenomenon, and find that the short-circuit should be given priority, so that it does not burn other devices. This method must be operated with the circuit powered down to avoid damage to the watch.

4. Pressure drop detection method

The multimeter is adjusted to the diode drop detection level, because all the ICs are made up of many basic units and are only miniaturized, so when there is a current passing through one of its pins, it will exist on the pins. Voltage drop. Generally, the voltage drop on the same pin of the same type of IC is similar, and the voltage drop on the pin is better or worse, and the circuit must be operated with the power off. This method has certain limitations. For example, if the device under test is high-impedance, it cannot be detected.

A. The entire board is not bright

1. Check whether the power supply and signal line are connected.

2. Check whether the test card recognizes the interface. If the red flashing of the test card is not identified, check whether the light board is in the same power source as the test card, or whether there is a short circuit between the light board and the ground, and the interface cannot be identified. (Smart Test Card)

3. Check whether the 74HC245 is short-circuited by imaginary welding and whether the corresponding input/output pin of the 245 signal is imaginary or short circuited to other lines. Note: Mainly check the power and enable (EN) signals.

B. Regular interlaced display overlaps during point-sweep scanning

1. Check whether there is any broken wire, or cold welding or short circuit between A, B, C, D signal input ports to 245.

2. Check whether the 245 corresponding A, B, C, D output terminals and 138 are disconnected or inadvertently welded or short-circuited.

3, detect A, B, C, D each signal is short-circuited or a signal and ground short circuit. Note: The main test ABCD line signal.

C. One or several lines are not lit when all lights are on

1. Check if the line between 138 and 4953 is open or short circuited.

D. Two or more lines (usually a multiple of 2, regular) light up at the same time

1. Check if the A, B, C, D signals are short-circuited.

2. Check if the output of 4953 is shorted to other output terminals.

E. Single or multiple points (irregular) are not bright at full bright

1. Find out whether the corresponding control pin of this module measures a short circuit with this one.

2, replace the module or single lamp.

F. One or more columns are not bright

1. Find the pins that control the column on the module and check if the output of the driver IC (74HC595/TB62726) is connected.

G. Single or single column highlighting, or full row highlighting, and no control

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

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

3, replace its driver IC.

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

1. The detection 245 corresponds to whether the output of the STB latch and the latch of the driver IC are connected or the signal is shorted to other lines.

I. Display confusion, abnormal output

1, detection clock CLK latch STB signal is short circuit.

2. Detect whether the 245 clock CLK 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. Check whether the data of the color of 245 has input and output.

2. Detect if the data signal of this color is shorted to other lines.

3. Check whether the cascaded data port between the driver ICs of this color is open circuited or short circuited and soldered. Note: The available voltage detection method is easier to find the problem, whether the voltage of the data port is different from the normal one, and the fault area is determined.

K. There is a problem with the output

1. Check whether the output interface to the signal output IC is connected or short-circuited.

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

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

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

5, check the output cable is good.

Full screen failure:

A. The whole screen is not bright (black screen)

1. Check if the power supply is powered on.

2. Check whether the communication line is connected or not. (Sync screen)

3. The sync screen detects whether the sending card and receiving card communicate green light flicker.

4. Whether the computer monitor is protected or the display area is black or pure blue. (Sync screen)

B. The whole unit board is not bright (black screen)

1. If several consecutive boards are not in the horizontal direction, check whether the cable connection between the normal unit board and the abnormal unit board is connected; or whether the chip 245 is normal.

2. When several boards are not in the vertical direction, check whether the power supply of this column is normal.

C. Lines on the cell board are not lit

1. Check if there is any communication between the line foot and the 4953 output pin.

2, check 138 is normal.

3, check 4953 is hot or burned.

4, check 4953 whether there is a high level.

5. Check whether the 138 and 4953 control pins are connected.

D. Unit board is not bright

1, check 595 is normal.

2. Check whether the corresponding module is connected to the upper and lower modules.

3, check 595 output pin to the module pin is connected.

E. Cell board lack of color

1, check 245R.G data output.

2. Check whether the normal 595 output pin and the abnormal 595 input pin are connected.

The above is the way that we wants to share with you information about LED display maintenance. It is common that there is problem when we use LED display, but it doesn’t matter, we just grasp the LED display maintenance methods described above. Some common faults are easily tolerated.

Common Erros

Multi-block LED display modules are bad:

Check whether the signal of the LED display module is in good connection with the power cable. If there is no LED on the module, there is no power input. Please check the power supply (check with a multimeter). The bright spot) indicates that the module has no signal input. Please check whether the input terminal of the cable of the first non-normal module is in close connection. You can remove and insert to test it with several times. If the problem is still exist you can replace the new cable.

Single LED display module is bad:

Check whether the power supply of the module is good, mainly to check whether the power socket on the module is loose. If the entire module has color confusion or color inconsistencies (but there is a signal input, there is a correct picture) for the signal transmission row County bad contact, re-inserted cable, or replace the tested cable. If you have a good replacement cable, it still has the same problem, please check the PCB board interface.

Single LED lamp is not light:

Use a multimeter to check if the LED is damaged. If the lamp is broken, change the lamp. Specific measurement methods: put the multimeter into the resistance X1 file, the black port of the pointer multimeter is connected to the positive pole of the LED, the red port is connected to the negative pole. If the LED is light, the measured lamp is OK, if the lights are not on, the measured light is bad.

LED bad point maintenance:

After a single lamp test confirms that the LED is damaged, the following maintenance methods are selectively used according to actual needs.

Frontal maintenance: Remove the fixed mask screw from the front with a corresponding type of screwdriver (be careful to keep the screw), take the lower cover, and change the lamp (please change the lamp according to the following lamp replacement method). After the lamp and colloidal seal are finished, the The original mask is restored and the screws are tightened (be careful not to press the lamp when tightening the screws). If there is any glue remaining on the surface of the LED, please carefully remove the colloid.

Rear maintenance: remove the screws from the back with the corresponding model screwdriver (remember to keep the screws) and unplug the signal cable. For safety, please do not unplug the power cable to prevent accidents. Carefully insert the module from the hole in the plate. Take it out, move it to the back of the cabinet, and then perform maintenance on the individual modules according to the front maintenance method to change the lamp (please replace the lamp by changing the lamp method below) or overhaul others.

Change LED lamp:

Remove the glue around the damaged LED with a sharp tool (such as tweezers), and make the LED pin clearly visible in the line of sight. The right hand clamps the LED with a tweezers, and the left hand uses a soldering iron (a temperature of about 40 degrees Celsius, the high temperature will be LED damage), Connect with solder, and stay for a little while (no more than 3 seconds, if it does not reach the dismantling requirement after exceeding the time, please cool down and try again) Melt the solder and remove the LED with tweezers.

Take the LED lamp that meets the requirements into the hole of the PCB circuit board. (The LED lamp’s long leg is positive and the short leg is negative. The PCB’s “square hole” is the LED positive pin socket. The “round hole” is LED’s. Negative electrode pin jack) Melts a little solder wire and sticks it on the soldering iron head. Use tweezers to adjust the LED direction to make it smooth. Solder the LED and the PCB. Use the same type of colloid (pH = 7) to seal the LED.

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