1. No image display, no video signal 　　

Description of the fault phenomenon: After the line is normally connected and powered on, there is no image display on the display terminal of the central control room, the hard disk recorder "no video signal", matrix, graphics splitter, etc. "Nosignal" prompts exist

2. No image display, video signal

Description of fault phenomenon: After the line is normally connected and powered on, there is no image display on the display terminal of the central control room, black screen, hard disk recorder "no video signal", matrix, graphics splitter and other "Nosignal" prompts do not exist.

3. The image quality is not good and there is interference 　　

This problem is a high-frequency failure phenomenon, with various manifestations and complex reasons. It is a failure phenomenon that is not easy to handle. It requires specific analysis of specific problems and targeted solutions. The following is classified and described according to different failure phenomena.