LCD splicing screen involves many fields, which can be said to be a major symbol of the city, even a landmark. I believe that everyone can't find the experience of looking at the LCD screen as a sign of finding a way. It is a combination of gorgeous and high technology. But in case the display fails, how to detect and deal with it? This is how to solve the common problems to share with you today:
First, the black screen
A. First of all, it is necessary to determine whether the splicing screen motherboard is a problem or a backlight problem, and check whether the indicator light responds. If the indicator light is not on, please check the power supply part of the motherboard.
1. Use multimeter to measure whether the main power supply working point and fuse of splicing screen are blown. If the fuse is blown, please disconnect the power supply. Measure the short circuit of each main power supply working point with a resistor. If there is a short circuit, carefully check the wiring (whether the copper foil of the circuit board is short-circuited) and various related components (whether it is damaged or even tinned).
2. If there is no short circuit in the splicing screen, it can be repaired with reference to the phenomenon of white screen to ensure that the voltage and signal input and output of each working point are in normal working condition.
B. If the splicing screen motherboard is in normal working condition, please check the backlight board.
1. Check whether the connection between the motherboard and the backlight board is in poor contact.
2. Measure the backlight voltage of splicing screen with multimeter. There should be 12V power supply voltage, 3.3V-5V switching voltage and 0-5V backlight adjustment voltage. The switching voltage of backlight is the most important. If there is no voltage or the voltage is too low, check whether the output level of the single chip microcomputer and the working state of the triode are normal, pay attention to no short circuit phenomenon, and replace all components if necessary.
1) C.heck whether there is any short-circuit virtual welding between the main chip of splicing screen and the connecting seat (pay attention to the chip pin, chip resistance and connecting seat, especially the flat socket).
2). Check whether there is poor contact between connecting wires such as flat cable from splicing screen to motherboard.
3). If necessary, replace the splicing screen motherboard, connecting cable and even screen to find out the problem.
Measure the ground voltage of each key of splicing screen. If the voltage is too low or 0, check whether there is any short circuit, open circuit and pull-up resistance in some lines from the keyboard to the single chip microcomputer, whether there is any wrong value and virtual welding, whether there is poor contact between the seat and the connecting wire, and pay attention to whether the key itself is damaged.
Second, the splicing screen is white.
A. The phenomenon that the splicing screen is white indicates that the backlight panel can work normally. First, judge whether the motherboard can work normally. Press the power switch to check whether the indicator light responds. If the indicator light can change color, it means that the motherboard is working normally.
1. Check whether the connecting cable of splicing screen motherboard signal output to the screen is in poor contact (the connecting cable or screen can be replaced).
2. Check whether the voltage of each working point of the motherboard is normal, especially the power supply voltage of the panel.
3. Check the line field signal and clock signal (from input to output) with an oscilloscope.
B. If the splicing screen indicator does not respond or is not lit, it indicates that the motherboard is not working normally. 1. Check the voltage of each operating point of the motherboard, and pay attention to EEPROM voltage (about 4.8V), reset voltage (high or low level, depending on the model) and MCU voltage. If the power supply is short-circuited, please look for the short-circuit position carefully, which may lead to the short-circuit of the copper foil of the printed circuit board.
2. Find out whether the MCU pin is in good contact with the motherboard.
3. Check whether the splicing screen motherboard chip and single chip microcomputer work, and measure whether the crystal oscillator starts to vibrate with an oscilloscope.
4. If necessary, replace the single chip microcomputer or re-burn the single chip microcomputer.
Third, splicing screens.
1. Measure whether the clock output of the splicing screen motherboard is normal.
2. Check the circuit of splicing screen motherboard signal RGB from the input to the main chip (whether there is a virtual welding short circuit, whether there is a capacitor resistance error).
3. Check whether there is a virtual welding short circuit (IC pin arrangement and double pin arrangement, especially the flat socket) in the connector circuit from the signal output of the splicing screen motherboard to the output to it.
4. Replace the screen if necessaryFourth, the two-color indicator light of splicing screen is not lit or has only one color.
1. Check whether the triode level output to the indicator light controlled by the single-chip microcomputer of splicing screen is normal, which is usually 3.3V at high level and 0V at low level. When the machine is turned on and off, these two levels will become opposite. If it is abnormal, check whether there is short circuit and virtual welding between the circuit and the single chip microcomputer.
2. Check whether the power supply voltage (5V) of the splicing screen triode is normal and whether the output of the triode is normal. The voltage across the indicator lamp can be measured.
3. Check whether the motherboard socket of splicing screen is in poor contact with the keyboard, and whether the circuit board is short-circuited to ground.
4. It is necessary to replace the indicator light.
Fifth, the splicing screen is color cast.
1. Check the circuit of splicing screen motherboard signal from input to main chip (whether there is virtual welding short circuit and whether the values of capacitor and resistor are wrong).
2. Enter the factory mode, adjust the white balance, and adjust the normal color.
3. If necessary, replace the splicing screen microcontroller or re-burn the microcontroller.
Sixth, there is no signal on the splicing screen.
A. there is no input signal after power-on.
1. Check the VGA cable connection.
2. Check the circuit from the input of the line field of the splicing screen motherboard (note whether there is a short circuit between the line field of the VGA mother seat and the ground) to the output of the inverter and then to the main chip (whether there is a virtual welding short circuit and whether the capacitance and resistance value are wrong).
3. Check the voltage of each working point of the splicing screen motherboard (the main chip may be damaged).
B, beyond the display after boot
1. Check whether the computer input signal is out of range.
2. Check the voltage of each working point of the splicing screen motherboard (the main chip may be damaged).
3. Whether the "phase" can be adjusted by automatic adjustment or manual adjustment.
4. Check the voltage of each working point of the motherboard (the main chip may be damaged).
5. Check whether the capacitance resistance of the phase-locked loop has an error value.
6. Check the circuit from the input of the line field to the output of the inverter and then to the main chip (whether there is a virtual welding short-circuit capacitor resistance or not, and whether there is an error value). VII. Double images
1. Check whether the input signal is caused by connection and distribution, or whether the VGA cable does not meet the specifications.
2. Check whether the VGA seat of the splicing screen motherboard has virtual welding or even welding.
3. Check the circuit from splicing screen signal input to the chip for virtual welding, short circuit and capacitor resistance error.
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