1. Line failure caused by abnormal signal transmission

​​Why does abnormal signal transmission cause lines to be displayed? ​ ​
When horizontal or vertical penetrating lines appear on the display,​ ​Focus on checking signal transmission links​ ​. Frequently asked questions include:

• Poor network cable contact between the sending card and the receiving card (38% of the incidence)
• Signal processor FPGA chip pin oxidation (highly occurring in humid environments)
• The impedance of the differential signal line does not match (the error exceeds 5Ω may be triggered)

​​Solution:​​
Use a multimeter to measure the signal line resistance value.​ ​The standard impedance should be controlled in the range of 100±5Ω​ ​. It is recommended to use a Class 6 network cable with a shielding layer and check the plug-in status of the gold finger regularly.

2. Display abnormalities caused by fluctuations in the power module

​​How does instability in voltage affect the display effect? ​ ​
​​An abnormal power module can cause three typical line phenomena:​​

1. Vertical light and dark stripes (appear when the switching power supply corrugation coefficient is > 3%)
2. Horizontal jitter ripple (characteristics of capacitance attenuation of more than 20%)
3. Local mosaic-like patches (early warning signal of DC-DC converter temperature exceeding 85℃)

​​Key points for testing:​​

• Measure the fluctuation value of the power supply output voltage (permitted range ±0.25V)
• Use a thermal imager to scan the temperature distribution of the module (warning if the temperature difference is > 8℃)

3. Measures for physical damage to the display screen

​​How to distinguish between software failure and hardware damage? ​ ​
When a fixed position line appears,​ ​The accuracy of the compression test method can reach 92%​​：

1. Slightly press the faulty area LED module
2. Observe whether the lines move with pressure
3. Use 3.3V to test pen touch lamp bead pin

​​Physical damage determination characteristics:​​

• Broken copper foil on the lamp plate (the cracks can be seen under the microscope)
• COB packaging colloid cracking (caused by the difference in thermal expansion coefficient)
• Driver IC Binding Line Shedding (Requires 200x magnifying glass to detect)

Professional maintenance personnel recommend that the "soft first, hard" inspection principle should be followed, and the three core parameters of signal link impedance value, power supply corrugation coefficient, and box temperature gradient should be monitored. For equipment that adopts high refresh rate technology of 1920Hz, it is recommended to conduct grayscale gradient tests every quarter, and more than 95% of potential line failures can be found in advance.

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