After a monitoring system enters the commissioning phase, trial operation phase, and after delivery, there may be failures such as: abnormal operation, the system fails to meet the technical specifications of the design requirements, and the overall performance and quality are not ideal, that is Some "soft faults". These problems are inevitable for a monitoring project, especially for a complex, large-scale monitoring project.

 

1. Equipment failure caused by incorrect power supply. The incorrect power supply has the following possibilities.

• The power supply line or voltage is incorrect.

· Insufficient power (or the diameter of a certain power supply line is insufficient, the voltage is too large, etc.).

· The transmission line of the power supply system has a short circuit, an open circuit, or an instantaneous overvoltage.

· In particular, equipment damage may occur due to power supply errors or transient overvoltage. Therefore, before system commissioning, power supply must be checked and inspected carefully and must not be taken lightly.

2.Three-variable camera and gimbal do not rotate / the lens does not move

· There are many connections between these devices, and problems such as open circuit, short circuit, poor insulation between wires, and incorrect wiring often cause equipment damage and performance degradation.

· It is particularly worth pointing out that due to the all-round movement of the camera with the pan / tilt head, it is common that the connection is disconnected and broken. Therefore, special attention should be paid to the connection between the equipment and various lines in this case to meet the requirements of long-term operation.

3. The quality of the equipment or component itself.

· In theory, quality problems can occur with various equipment and components. However, from the experience point of view, purely the quality problem of the product itself, mostly occurs in the decoder, electric pan and tilt, transmission parts and other equipment. It is worth pointing out that, on the whole, the quality of some equipment may not be unusable, but some technical indicators may not reach the indicators given in the product manual. Therefore, the necessary sampling tests must be performed on the selected products. If it is indeed a product quality problem, the best way is to replace the product, instead of disassembling and repairing it yourself.

4. Problems caused by improper adjustment of equipment.

· For example, the adjustment of the camera's rear intercept is a very detailed and precise work. If it is not adjusted carefully, problems such as poor focus or defocusing during various operations of the three-variable lens will occur.

· Whether the positions of some switches and adjustment knobs on the camera are correct, whether they meet the technical requirements of the system, and whether the decoder code switch or other adjustable parts are set correctly will directly affect the normal use of the device itself or the normal performance of the entire system.

5. The problems caused by the incorrect connection between the device (or component) and the device (or component) will occur in the following areas:

· Impedance mismatch.

· The communication interface or communication method does not correspond.

· The drive capacity is insufficient or exceeds the specified number of device connections.

1. A black or white bar appears on the monitor screen, and scrolls slowly up or down. There may be two different causes for the failure.

· To distinguish between a power supply problem and a ground loop problem, a simple method is to connect the control host with the output signal of a camera with no problem from the nearest power source. If the above-mentioned interference does not appear on the monitor Phenomenon, it means that there is no problem with the control host. Next, a portable monitor can be connected to the video output of the front-end camera, and check each camera one by one.

· If there is any, handle it; if not, the interference is caused by other reasons such as the ground loop.

2. Wood grain interference appears on the monitor.

The appearance of such interference will not overwhelm the normal image when it is slight, and the image will not be viewable when it is severe (or even break the synchronization). There are many and complicated reasons for this failure phenomenon. There are roughly the following reasons:

· The quality of the video transmission line is not good, especially the shielding performance is poor (the shielding network is not a good quality copper wire network, or the shielding network is too thin to serve the shielding function). At the same time, the line resistance of this type of video cable is too large, resulting in large attenuation of the signal is also a cause of aggravating the failure. In addition, the characteristic impedance of this type of video cable is not 75 ohms, and the main parameter exceeds the specification is also one of the intentional reasons. Because the above-mentioned interference phenomenon is not necessarily a failure caused by a bad video, the cause of this failure must be accurate and cautious when judging. Only after excluding other possibilities can we consider it from the perspective of poor video lines. If it is really a problem of cable quality, the best way is of course to replace all such cables with cables that meet the requirements. This is the best way to completely solve the problem.

· Caused by the power supply system not being "clean". The power supply is not "clean", which means that the interference signal is superimposed on the normal power supply (50-cycle sine wave). And most of the interference signals on this power source come from the silicon controlled equipment in this power grid. In particular, high-current, high-voltage thyristor equipment has a very serious pollution to the power grid, which has caused the power supply in the same power grid to be "clean". For example, there are high-power thyristor frequency and speed regulation devices, thyristor rectifiers, thyristor AC-DC converters, and so on in this grid, which will pollute the power supply. The solution to this situation is relatively simple, as long as the entire system is powered by purified power or online UPS. ]

· There are strong sources of interference near the system. This can be judged through investigation and understanding. If this is the reason, the solution is to strengthen the shielding of the camera and ground the pipeline of the video cable.

3. A large-scale and large-area moire interference is generated on the monitor, so that all the images are destroyed, and an image and a synchronization signal cannot be formed.

· Malfunction due to short circuit or open circuit between the core wire of the video cable and the shielded network. This kind of failure often appears on BNC connectors or other types of video connectors. That is to say, when this kind of failure phenomenon occurs, it is often not that all the signals of the entire system are out of order, but only appear on those that have bad connections. Just check these joints one by one and you can solve it.

4. A number of vertical bars with equal spacing are generated on the screen of the monitor, and the frequency of the interference signal is an integer multiple.

· Symptoms due to transmission line characteristic impedance mismatch: This is caused by impedance mismatch caused by the characteristic impedance of the video transmission line is not 75 ohms. It can also be said that the occurrence of this interference phenomenon is caused by the combination of the characteristic impedance and distribution parameters of the video cable.

· The solution usually depends on the method of “resistance in series” or “resistance in series”. In addition, it is worth noting that when the video transmission distance is short (usually within 150 meters), using the video cable with the above impedance mismatch and excessive distribution parameters does not necessarily cause the above-mentioned interference phenomenon. The fundamental way to solve the above problems is to ensure quality when purchasing video cables. If necessary, the cables should be sampled.

5. There are several fine streaks on the screen.

· Most of this interference is caused by strong, high-frequency spatial radiation sources near the transmission system, the front end of the system, or near the central control room.

· One solution to this situation is to understand the surrounding environment when the system is established, and try to avoid or stay away from the radiation source:

· Another method is to strengthen the shielding of the front-end and center equipment when the radiation source cannot be avoided, use steel pipes for transmission lines and pipelines and ground them well.

 

1.PTZ failure

A gimbal does not work well or cannot turn at all shortly after use, which is a common malfunction of the gimbal. In addition to the factors of product quality, this situation generally occurs due to the following reasons:

(1) Only the gimbal with the camera installed is allowed to be hoisted. In this case, the lifting method results in an increase in the operation load of the gimbal. Therefore, the rotation mechanism of the gimbal will be damaged or the motor will be burned soon after use.

(2) The total weight of the camera and its protective cover exceeds the weight of the gimbal. Especially for outdoor gimbals, the weight of the protective cover is often too large, and the gimbal can't turn (especially vertical).

(3) The outdoor PTZ malfunctions or is damaged due to excessively high or low ambient temperature, poor waterproofing, and antifreeze measures.

2. When the distance is too far, the operation keyboard cannot remotely control the camera (including the lens) and the PTZ through the decoder.

· This is mainly because the control signal attenuation is too large and the control signal received by the decoder is too weak when the distance is too far. At this time, a relay box should be installed at a certain distance to amplify the shaping control signal.

3. The image contrast of the monitor is too small and the image is faint.

· This phenomenon is either a problem of controlling the main unit and the monitor itself, or the transmission distance is too long or the video transmission line attenuation is too large.

· In this case, devices for line amplification and compensation should be added.

4. The image clarity is not high, the details are lost, the color signal is lost in severe cases, or the degree of saturation is too small.

· This is because the high-frequency loss of the image signal is too large, and the signal above 3MHz is basically lost.

· In this case, either 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 equivalent of the concentrated distribution between the core and shielded wires of the transmission line during the transmission Caused by capacitance.

5. Tone distortion.

· This is a malfunction that easily occurs in the 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.

6. The operation keyboard fails.

· This phenomenon can basically be determined to be caused by the "crash" of the operating keyboard when the connection is checked without any problems. On the keyboard and operation instructions, there are generally methods to solve the "crash." For example, “Reset the whole machine” and other methods can be solved by this method. If it cannot be resolved, the keyboard itself may be damaged.

7, the host switch to the image is not clean.

· This kind of failure phenomenon manifests in the picture after selecting and cutting, superimposed by the interference of other pictures, or the interference of the line synchronization signal of other pictures. This is caused by the poor quality of the host or matrix switch, which cannot meet the requirements of the isolation of the image.

· If a radio frequency transmission system is used, it may also be caused by the system's crosstalk modulation being too large.

9. The digital hard disk video recorder cannot start, there may be the following reasons.

· The main unit power switch fails.

· Main unit power is damaged.

The host motherboard or CPU card is broken

· The main system hard disk boot sector is damaged, or the hard disk itself is faulty.

· The operating system is corrupted.

· Carefully analyze the above reasons and eliminate them one by one.

10. The digital hard disk recorder freezes (the image monitored on site is still or the time information superimposed on the image does not go)

· Software problems. For PC-based hard disk hosts, there are two aspects of operating system or monitoring software failures; for embedded hard disk video recording hosts, it is a monitoring software problem. The main causes are as follows:

· A certain file of the system software is damaged, reinstall the system or monitoring software for the PC-type hard disk host; the embedded host needs to upgrade the software.

· The hard disk in the host has bad sectors. You need to repair or replace the hard disk.

· The power supply in the main unit is insufficient. Replace the high-power supply.

· There are too many hard disks in the main unit, and the heat generation is too large, causing the machine to die.

· The video card of the host computer is overheated, causing a crash. Replace the video card or the host computer.

A large-scale television monitoring system operating in conjunction with burglar alarms is a high-tech and complex system. Although various failure phenomena may occur, as long as the quality of the equipment and equipment selected is strictly controlled, and construction is strictly in accordance with standards and specifications, generally no major problems will occur. If you do not blindly dismantle and unload, it will solve the problem better.