[Worth to share collection] LED display repair information Daquan

1. Resistance detection method, adjust the multimeter to the resistance file, detect the resistance value of a certain point of a normal circuit board, and then test whether the same point of the same circuit board is tested and the normal resistance value is different. If it is different, the scope of the problem is determined.

2. Voltage detection method, adjust the multimeter to the voltage file, detect the voltage to the ground at a certain point of the circuit suspected of having a problem, and compare whether it is similar to the normal value, otherwise the range of the problem is determined. 3. Short-circuit detection method, adjust the multimeter to the short-circuit detection block (some diode voltage drop or resistance file, generally have alarm function), detect whether there is a short circuit phenomenon, and find that the short circuit should be solved first, so that it does not burn out. Other devices. This method must be operated in the event of a power failure to avoid damage to the meter.

4, the voltage drop detection method, the multimeter is adjusted to the diode drop detection file, because all ICs are composed of a basic number of unit parts, but miniaturized, so when there is current on one of its pins, There will be a voltage drop across the pin. Generally, the voltage drop on the same pin of the IC of the same model is similar. According to the voltage drop value on the pin, the circuit must be powered off. This method has certain limitations. For example, if the device under test is high-resistance, it will not be detected.

Unit board failure:

A. The whole board is not bright

1. Check if the power supply and signal cable are connected.

2. Check whether the test card is identified by the interface. If the test card flashes red, it will not be identified. Check whether the lamp board is connected to the test card or the lamp board interface has a signal and ground short circuit. (smart test card)

3. Detect whether the 74HC245 has a short circuit or not, and the corresponding enable (EN) signal input and output pin on the 245 is soldered or short-circuited to other lines. Note: Mainly check the power and enable (EN) signals.

B. In the oblique scan, the regular interlacing does not light up and the screen overlaps.

1. Check if the A, B, C, D signal input port to 245 is broken or short-circuited or short-circuited.

2. Detect whether there is an open circuit or a virtual solder or a short circuit between the output terminals A, B, C, and D of 245 corresponding to 245.

3. Detect whether there is a short circuit between the signals of A, B, C and D or a short circuit between the signal and the ground. Note: The ABCD line signal is mainly detected.

C. One line or several lines are not lit when fully lit

1. Detect whether the line between 138 and 4953 is open circuit or virtual welding or short circuit.

D. When scanning a line, two lines or a few lines (usually a multiple of 2, regular) are illuminated at the same time.

1. Detect whether there is a short circuit between the signals of A, B, C, and D.

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

E. Single or multiple points (irregular) are not bright when fully illuminated

1. Find whether the control pin corresponding to the module is short-circuited with the line.

2. Replace the module or single lamp.

F. One column or several columns are not lit when fully illuminated

1. Find the pin that controls the column on the module and test whether it is connected to the output of the driver IC (74HC595/TB62726...).

G. Single or single column highlighting, or full line highlighting, and uncontrolled

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

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

3. Replace the driver IC.

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

1. Detect whether the STB latch output corresponding to 245 is connected to the latch terminal of the driver IC or the signal is shorted to other lines.

I. Display confusion, output is not normal

1. Detect whether the clock CLK latches the STB signal for short circuit.

2. Check if the clock CLK of 245 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. Detect whether there is input and output on the data end of the color of 245.

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

3. Check whether the cascaded data port between the driver ICs of this color has an open circuit or short circuit or a virtual solder.

Note: It is easier to find the problem by using the voltage detection method, and check whether the voltage of the data port is different from the normal one, and determine the fault area.

K. Have a problem with the output

1. Check if the line from the output interface to the signal output IC is connected or shorted.

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

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

4. Whether the output signals are shorted to each other or shorted to ground.

5. Check if the output cable is good.

L. The unit board appears eight or 16 points, the column or single point is not bright, long bright, dark.

1. Visually check the module pins and leads corresponding to the fault for short circuit, virtual soldering or open circuit.

2. The connection line between the upper and lower and left and right modules of each cell (the unit board is divided into two upper and lower cells) is normal (put the multimeter to the ring end, measure the input of the module line and the lead connections of each control input), and if so It is judged that the module is bad. If it is not, it can be eliminated by directly connecting it with a thin wire instead of turning it on.

3. The multimeter can be used to directly measure whether a single module is normal. If yes, it is judged as an internal short circuit between the circuit board and the module. If it is judged that the module is bad, replace it with the same type of module.

M. A few lines in the unit board or the entire cell (the unit board is divided into two upper and lower cells) are not bright, long bright, and dark.

1. Visually test the corresponding tube, core inductor, integrated circuit for solder joint, short circuit, open circuit, if so, disconnect the short circuit and solder joint, re-weld at the open circuit.

2. Use a multimeter to measure whether the voltage at the output of each row tube is normal. (Multimeter measurement method: black meter pen connected to GND, red meter pen to measure the voltage of each pin); if yes, it is judged that the line output end and the corresponding module pin are open; If not, measure whether the input end of the line tube is normal; if yes, the line tube is broken and replaced with the same type of line tube; if not, the output of the HC138 corresponding to the measurement is normal; if yes, the output and line of the HC138 are judged. The input of the tube is broken; if not, it is judged that the HC138 is broken.

3. Replace the test with a good 16P cable, measure the voltage of the IC138 address input terminals 1, 2, 3, strobe 4, 5 (active low), 6 (active high) and integrated circuit power supply. Whether it is normal, if it is, it is judged that HC138 is bad, and then (2) continue to check. (4) Whether the 5V cable between the two cells is disconnected. If yes, it can be directly connected with the same power cable (the general phenomenon is that the whole cell is not bright or dark).

4. Measure the line signal at the input end of the unit board (Golden finger 26P can be regarded as 13 groups, among which 8, 9, 10, and 11 are L0, L1, L2, and L3, respectively). Is there any internal short circuit, open circuit, and input HC244? Whether the rear drive is normal, if yes, measure whether the signal input by the HC244 drive input HC138 is normal, and then continue to check (2). If not, it is judged that the HC244 is bad and replaced with the same type of integrated circuit.

N. The cell in the cell board (the cell board is divided into two upper and lower cells) is not red or green.

1. Visually check whether the integrated circuit and 26P cable corresponding to the fault have any solder joints, open circuit and 5V power supply. (It can be replaced directly with a good 26P cable).

2. 26P connection line between unit boards (1 and 2 feet of 26P cable are red signal, 3 and 4 feet are green signals) and front unit board output (judgment method: take a long 26P line If the cross-interchange connection is normal, it is judged to be a problem later; otherwise, there is a problem in the front) Is it normal? If yes, measure the input to the HC244 red signal, and the 14-pin sent to the HC595 after driving is normal (if yes, and HC595 other If the pins are normal, it is judged that the HC595 is broken and replaced with the same type of integrated circuit. If no, check the 26P cable for problems and the input is not normal.

O. Fault phenomenon: The upper and lower modules in the middle of the cell (cell board is divided into two cells) are red, green, or red and green.

1. Visually check whether the integrated circuit corresponding to the fault on the cell board, such as HC595, is soldered, shorted or broken; if so, solder the pins.

2. Check if the 5V power supply is normal.

3. Use the multimeter to measure the fault of the HC595 input terminal 14 [HC595 measurement should be distinguished from the red 渌 integrated circuit, the order is: red, green (R, G) HC595 9 feet for the signal output, 14 feet for Signal input terminal] Whether the voltage is normal; if yes, it is judged that the HC595 is bad (in the case of other normal power supply), and replaced with the same type of integrated circuit; if not, check the voltage of the 9-pin output terminal corresponding to the HC595 and the circuit connection Whether the line is disconnected, if not, it is judged that the HC595 is broken, and replaced with the same type of HC595 integrated circuit (when replacing the integrated circuit HC595, pay attention to disconnect the circuit lead).

Outdoor (module) failure:

1. The group is not lit continuously or has an abnormality:

Check the signal direction. The cable and power cable of the first abnormal module are in good contact. If the module has no LED, it indicates that there is no power input. Please check the power supply part (check with a multimeter). If there is color, there is color confusion. The highlights indicate that the module has no signal input. Please check whether the input end of the first abnormal module cable is tightly touched. It can be inserted and tested multiple times. If the problem is still possible, the new cable can be exchanged.

2. The single module does not light up:

Check if the power supply of the module is good, mainly to check whether the power socket on the module is loose. If the whole module has color confusion or color inconsistency (but there is signal input, there is a correct picture), the signal transmission is poorly connected to the county, the cable is re-plugged, or the tested cable is replaced. If the replacement of the cable is still the same problem, please check the interface of the PCB board for any problems.

3, single lamp does not shine problem detection method:

Use a multimeter to check if the LED is damaged. If the lamp is broken, change the lamp according to item 5 below. The specific method of measuring the light: the multimeter is hit to the resistance X1 file, the pointer type multimeter black table pen is connected to the positive pole of the LED, the red meter pen is connected to the negative pole (the digital table black pen is connected negatively, the red pen is connected positively), if the LED is bright, the measured lamp is Ok, if the light is off, the measured light is bad.

4, LED dead point maintenance (out of control points):

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

4-1 Frontal maintenance: Remove the fixed mask screws from the front with the corresponding type of screwdriver (retain the screws), take the cover and replace the lamp (please change the lamp according to the following lamp replacement method), change the lamp and seal the gel. After the end, restore the original mask, tighten the screws (be careful not to hold the lamp when screwing up), and finally remove the gel if the glue remains on the surface of the LED.

4-2 Rear Maintenance: Remove the screws from the back with the corresponding type of screwdriver (note the screws), unplug the signal cable. For safety, please do not unplug the power cable to prevent accidents. Be careful to remove the module. Remove the sheet metal hole, move it to the back of the box, and then perform maintenance and replacement of the individual modules according to the front maintenance method (please change the lamp according to the following lamp replacement method) or repair other.

5, change the light:

Remove the gel around the damaged LED with a sharp tool (such as tweezers), and make the LED pin clearly visible in the line of sight. Hold the LED with the tweezers in the right hand and the soldering iron in the left hand. The temperature is about 40 degrees. The temperature will be too high. The LED causes damage. Contact the solder and make a slight dwell (no more than 3 seconds, if it exceeds the time but does not meet the disassembly requirements, please try again after cooling). The solder is melted and the LED is removed with tweezers. Insert the LED lamp that meets the requirements into the hole of the PCB circuit board correctly. (The long leg of the LED lamp is positive, the short leg is negative, the square hole on the PCB is the LED positive pin jack, and the "round hole" is LED. Negative pin socket), melt a little solder wire, glue it on the soldering iron tip, adjust the LED direction with tweezers to make it smooth, solder the solder to the LED and PCB connection, use the same type of colloid (pH = 7) Seal the LEDs.

Full screen failure:

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

1. Check if the power supply is powered.

2. Check if the communication line is connected, and if there is any error. (synchronous screen)

3. Synchronous screen detects whether the green light of the sending card and the receiving card communicate with or without flashing.

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

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

1. The horizontal direction of several consecutive boards is not bright, 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. The longitudinal direction of several consecutive boards is not bright. Check whether the power supply of this column is normal.

C. The unit board does not light up.

1. Check if the foot is connected to the output of the 4953.

2. Check if 138 is normal.

3. Check if the 4953 is hot or burnt.

4. Check if the 4953 has a high level.

5. Check if the control feet of 138 and 4953 are connected.

D. The unit board is not bright

1. Check if 595 is normal.

2. Check whether the corresponding pin of the upper and lower modules is connected.

3. Check if the 595 output pin is connected to the module pin.

E. Cell board lack of color

1. Check if the 245 RG data has output.

2. Check if the normal 595 output pin is connected to the abnormal 595 input pin.

3. Detect whether there is a short circuit between the signals of A, B, C, and D.

4. Detect if the output of the 4953 is shorted to other outputs.

F. Single or multiple points (irregular) are not bright when fully illuminated

1. Find whether the control pin corresponding to the module is short-circuited with the line.

2. Replace the module or single lamp.

G. One column or several columns are not lit when fully illuminated

1. Find the pin that controls the column on the module and measure whether it is connected to the output of the driver IC (74HC595/TB62726).

2. Visually check whether the module pins and integrated circuits corresponding to the faults on the unit board are soldered, shorted or broken; if so, solder the pins.

3. Use a multimeter to measure the output of the HC595. The output pins of the HC595 are 1, 2, 3, and 4.

Control system failure:

1, the whole screen is not bright or a square appears

·Control whether the host is turned on

·Is the communication line plugged in?

· Is the sending card inserted?

·Multimedia card and capture card, whether the data cable between the sending card is connected

·The receiving card JP1 or JP2 switch is not in the correct position

·Open the host

·Insert the communication line

·Reinsert the sending card

· Connect the multimedia card and the capture card, and send the data line between the cards.

·Adjust the JP1, JP2 switch position

• Whether the computer monitor is protected, or the display area is black or pure blue. (synchronous screen)

2. Every time you start the LED studio, you can't find the signal acquisition line between the COM port of the control system and the data sending card is not connected or the COM port of the computer itself is broken.

·Connect the cable or replace the computer

3, the whole screen is shaking or ghosting

·Check the communication line between the computer and the big screen

• Check the DVI cable of the multimedia card and the sending card.

· The sending card is broken. "Reinsert or replace the communication cable and replace the DVI cable to replace the sending card.

Drive section

1, a unit board is not bright

·+5V power or GND supply

· Is there a short circuit between +5V and GND?

·138 Is there any OE signal on the fifth leg?

·245 Is the connected OE signal normal (open or shorted);

· Give +5V power or GND

· Disconnect the short circuit

· Supply the OE signal

· Disconnect the open circuit and disconnect the short circuit

2. The half or lower part of the unit is not lit or the display is abnormal.

· Is there a leg OE signal of 138?

· Is the signal of the 11th and 12th legs of the 74HC595 normal (SCLK, RCK)

· Is the connected OE signal normal; (open or shorted)

· Is the SCLK and RCK signals connected to the 245 in the double-row pin normal; (open or short)

·Connect the OE signal

· Connect the SCLK and RCK signals

· Disconnect the circuit that is shorted

· Disconnect the circuit that is shorted

3. A row of a unit board or a corresponding module is not lit or not displayed properly.

· Check whether the pin of the row signal of the corresponding module is soldered or missed;

· Check if the line signal is disconnected from the corresponding pin of the 4953 or shorted to other signals.

·Check whether the upper and lower pull-down resistors of its row signal are not soldered or missed.

·Whether the line signal output by the 74HC138 is disconnected from the corresponding 4953 or shorted to other signals

·Weld welding of virtual welding and leak welding

· Disconnect the circuit that is shorted

·Weld the welding without soldering

· Disconnect the circuit that is shorted

4, one unit board has two lines at the same time (one line is normal when the text is displayed, one line is always bright)

· Check if the two lines corresponding to the module are shorted

· View the output leg of 138, the pull-up resistor and module pin, and the 4953 short circuit

· Disconnect the short circuit

5, the upper part or the lower part of the red or green is not bright or not displayed properly

· Check if the input pin is normal or shorted to GND, +5V

· Check if the signal between the input pin and 245 is normal (short circuit or open circuit)

·IC245 is bad"

· Disconnect the short circuit

·Replace the IC

System troubleshooting

Step 1: Check if the graphics card settings section is set. If necessary, set the method in the CD electronic file, please refer to it.

Step 2: Check the basic connection of the system, such as DVI cable, whether the network cable socket is correct, the connection between the main control card and the computer PCI plug, the serial cable connection, etc. The connection method has a legend, please refer to the reference carefully.

Step 3: Check if the computer and LED power system meet the usage requirements. When the power of the LED screen is insufficient, when it is close to white (more power consumption), it will cause the screen to flicker, and prepare a suitable power supply according to the power requirements of the cabinet.

Step 4: Check if the green light of the sending card flashes regularly: flashing to step 6, if it is not flashing, restart, check if the green light flashes regularly before entering win98/2k/xp, such as blinking to the second step, Please check if the DVI cable connection is connected. If the problem is not solved, one of the sending card, the graphics card and the DV cable I is faulty. Please repeat step 3 after replacing.

Step 5: Please follow the software instructions to set or re-install and then set, until the green light of the sending card flashes, otherwise repeat step 3.

Step 6: Check if the green light (data light) of the receiving card flashes synchronously with the green light of the sending card. If it flashes to step 8, check if the red light (power) is on. If it turns on the seventh step, it does not light up to check the yellow light (power supply). Protection) Is it bright, if it is not lit, check if the power supply is reversed or the power supply has no output. If it is bright, check if the power supply voltage is 5V. If the power is turned off, remove the adapter card and cable and try again. If the problem is not solved, the receiving card is faulty. , replace the receiving card, repeat step 6.

Step 7: Check if the network cable is connected well or too long (must use the standard Super Category 5 network cable, the longest distance of the network cable without repeater is 100 meters), check whether the network cable is made according to the standard (please refer to the installation and setting) If the problem is not resolved, the receiving card is faulty, replace the receiving card, and repeat step 6.

Step 8: Check if the large screen power light is on. If it is not on, go to step 7 and check if the adapter card interface definition line matches the unit board.

Note: After most screens are connected, there may be no screen or flower screen in a certain box. Because the RJ45 interface of the network cable is not securely connected, or the receiving card power is not connected, the signal is not transmitted, so please re-plug it. The network cable (or swap), or plug in the receiving card power (pay attention to the direction) can solve the problem.

Display Error

I. The whole screen is not lit (black screen)

1. Check if the power supply is powered.

2. Check if the communication line is connected, and if there is any error. (synchronous screen)

3. Synchronous screen detects whether the green light of the sending card and the receiving card communicate with or without flashing.

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

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

1. The horizontal direction of several consecutive boards is not bright, 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. The longitudinal direction of several consecutive boards is not bright. Check whether the power supply of this column is normal.

III. The unit board does not light up.

1. Check if the foot is connected to the output of the 4953.

2. Check if 138 is normal.

3. Check if the 4953 is hot or burnt.

4. Check if the 4953 has a high level.

5. Check if the control feet of 138 and 4953 are connected.

IV. The unit board is not bright

1. Check if 595 is normal.

2. Check whether the corresponding pin of the upper and lower modules is connected.

3. Check if the 595 output pin is connected to the module pin.

V. Cell board lack of color

1. Check if the 245 RG data has output.

2. Check if the normal 595 output pin is connected to the abnormal 595 input pin.

Graphics card settings

This description only uses ATI's RADEON series 9550 computer graphics card as an example. If you use other graphics cards, please use this as a reference for debugging. Note: There are 3 settings in the graphics card settings section and must be met. : 2, 3 options are in the graphics driver software, so you must install the graphics driver software for the graphics card type.

1 The screen refresh rate must be 60HZ, otherwise there is no screen display.

2 Display options need to be in “Copy” mode (different graphics cards mean different meanings, please note).

3 There should be an “all the same” in the display options of the graphics card (“Video—Cinema Mode—all the same (in the drop-down menu)” in the graphics card condition software of ATI 9550.