It is a common fault of tripod head that it doesn't work well or doesn't turn at all after being used for a long time. Apart from the factors of product quality, this situation is generally caused by the following reasons:

(1) Hoist the Yuntai platform where only cameras are allowed to be installed. In this case, the lifting mode will increase the working load of the pan/tilt, so the transmission mechanism of the pan/tilt will be damaged or even the motor will be burned soon after use.

(2) The total weight of the camera and its protective cover exceeds the bearing capacity of the tripod head. Especially for outdoor use, the weight of the protective cover is often too large, which often leads to the problem that the platform cannot turn (especially in the vertical direction).

(3) The outdoor pan/tilt is out of order or even damaged due to too high or too low ambient temperature and poor waterproof and antifreezing measures.

(4) When the distance is too far, the operating keyboard can't remotely control the camera (including lens) and pan/tilt through the decoder. This is mainly because the control signal is too attenuated when the distance is too far, and the control signal received by the decoder is too weak. At this time, it is necessary to install a relay box at a certain distance to amplify the shaping control signal.

2. The image contrast of the monitor is too small and the image is very weak.

This phenomenon is either the problem of the control host and the display itself, or the transmission distance is too long or the video transmission line is too attenuated. In this case, line amplification and compensation devices should be added.

3. The image definition is not high, and the details are lost. In severe cases, the color signal is lost or the color saturation is too small.

This is because the high-frequency loss of image signals is too large, and the signals with frequencies above 3MHz are basically lost. In this case, the transmission distance is too long, and there is no amplification compensation device in the middle; Or the distributed capacitance of the video transmission cable is too large; Or the concentrated distribution of equivalent capacitance between the core wire and the shielding wire of the transmission line in the transmission link.

4. Tone distortion.

This is a common fault phenomenon in long-distance video baseband transmission mode. The main reason is that the high frequency phase shift of the signal caused by the transmission line is too large. In this case, a phase compensator should be added.

5. There is something wrong with the keyboard.

This phenomenon can basically be determined to be caused by the "crash" of the operating keyboard when there is no problem with the connection. In the operating instructions of the keyboard, there are generally methods to solve the "crash", such as "reset the whole machine", which can be solved by this method. If it cannot be solved, the keyboard itself may be damaged.

6. The switch from host to image is not clean.

The performance of this fault phenomenon is that the interference of other pictures or the interference of line synchronization signals of other images is superimposed on the selected picture. This is caused by the poor quality of the matrix switch of the main mechanism, which meets the requirements of image isolation.

7. If RF transmission system is used, it may also be caused by excessive cross modulation and mutual modulation of the system.

8. In video transmission, the most common fault phenomenon is that a black bar or white bar appears on the monitor screen and slowly scrolls up or down. Therefore, when analyzing this fault phenomenon, we should distinguish two different fault causes.

A simple way to distinguish between power supply problems and ground loop problems is to connect only one camera without power supply problems to the control host. If the above interference phenomenon does not appear on the display, there is no problem with the control host. Next, you can connect a portable monitor to the video output end of the nearby front camera and check each camera one by one. If there is, it will be handled. If not, the interference is caused by other reasons such as grounding circuit.

9. There is wood grain interference on the monitor. The appearance of this kind of interference will not slightly drown the normal image, but in severe cases, it will be impossible to watch the image (or even destroy the synchronization). There are many complicated reasons for this failure. There are roughly the following reasons:

(1) The quality of video transmission line is not good, especially the shielding performance is poor (the shielding net is not a good copper net, or it is too thin to shield). At the same time, the line resistance of this video line is too large, which leads to a large signal attenuation and aggravates the fault. In addition, the characteristic impedance of this video cable is not 75 Ω, and the parameters are not in conformity with the specifications, which is also one of the reasons for the failure. Because the above interference phenomenon is not necessarily a fault caused by poor video lines, it is necessary to accurately and carefully judge the cause of this fault. Only by excluding other possibilities can we consider it from the perspective of bad video lines. If it is really a cable quality problem, of course, the best way is to replace all these cables and replace them with cables that meet the requirements. This is the best way to solve the problem completely.

(2) The power supply of the power supply system is not "clean". The power supply here is not "clean", which means that the interference signal is superimposed on the normal power supply (50-cycle sine wave). The interference signal on the power supply mainly comes from the equipment using SCR in the power grid. Especially the SCR equipment with high current and high voltage, the pollution to the power grid is very serious, resulting in the power supply of the same power grid is not "clean". For example, there are high-power SCR frequency modulation and speed regulation devices, SCR rectifier devices, SCR AC /DC conversion devices and so on. In this power grid, it will pollute the power supply. The solution to this situation is relatively simple, as long as the whole system adopts purified power supply or online UPS power supply, it can basically be solved.

(3) There are strong interference sources near the system. This can be judged by investigation. If this is the case, the solution is to strengthen the shielding of the camera and ground the pipeline of the video line.

10. Fault caused by short circuit or open circuit between video cable core and shielding net. The performance of this fault is that there is deep and chaotic moire interference in a large area on the display, which destroys all the images and does not form images and synchronization signals. This often happens on BNC interfaces or other types of video interfaces. That is to say, when this kind of fault phenomenon occurs, it is often not that all signals of the whole system have problems, but only those signals with bad joints. As long as these connectors are carefully checked one by one, they can be solved.

1 1. Fault phenomenon caused by mismatch of characteristic impedance of transmission line. The performance of this phenomenon is to produce several vertical bars with equal spacing on the monitor screen, and the frequency of the interference signal is basically an integer multiple of the line frequency. This is because the characteristic impedance of the video transmission line is not 75 Ω, resulting in impedance mismatch. It can also be said that this interference phenomenon is caused by the fact that the characteristic impedance and distribution parameters of video cable do not meet the requirements. The solution is generally "series resistance at the beginning" or "parallel resistance at the end". In addition, it is worth noting that when the video transmission distance is very short (generally within150m), the above interference phenomenon may not necessarily occur when using the video cable with unmatched impedance and too large distribution parameters.

12. Space radiation interference caused by transmission lines. This interference phenomenon is mostly caused by the strong high frequency space radiation source near the transmission system, the front end of the system or the central control room. One of the ways to solve this situation is to understand the surrounding environment and try to avoid or stay away from the radiation source when the system is established; Another method is to avoid radiation sources, front-end and central equipment.