There are several possibilities for incorrect power supply: incorrect power supply line or power supply voltage, insufficient power (or insufficient wire diameter of a certain power supply line, excessive step-down, etc.), short circuit, open circuit, instantaneous overvoltage, etc. in the transmission line of the power supply system. In particular, equipment damage occurs from time to time due to power supply error or instantaneous overvoltage. Therefore, in the system commissioning, before power supply, we must carefully and strictly check and check, and we should never take it lightly.

In particular, if the lines connected to the equipment are not handled well, there will be problems such as open circuit, short circuit, poor insulation between lines, wrong wiring and so on, resulting in equipment damage and performance degradation. In this case, the fault phenomenon shall be analyzed calmly to determine which lines have problems in connection on several lines. This will narrow the scope of the problem. In particular, it is worth pointing out that it is common for the camera with PTZ to fall off and break the connection due to omni-directional movement for a long time. Therefore, special attention should be paid to the connection between the equipment in this situation and various lines should meet the requirements of long-term operation.

3. Quality problems of equipment or parts
Theoretically, all kinds of equipment and components may have quality problems. However, from the perspective of experience, it is purely a quality problem of the product itself, which mostly occurs in equipment such as decoder, electric PTZ and transmission components. It is worth pointing out that some equipment may not be unusable in terms of quality as a whole, but some technical indexes can not reach the indexes given in the product manual. Therefore, necessary sampling inspection must be carried out for the selected products. If it is a product quality problem, the best way is to replace the product instead of dismantling and repairing it by yourself.

In addition, the most common problem in monitoring engineering is the problem caused by improper adjustment of equipment. For example, the focal length adjustment of the camera after installation is very detailed and accurate. If it is not carefully adjusted, there will be problems such as poor focusing or defocus during various operations of the three variable lens. In addition, 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 coding switch or other adjustable parts are set correctly will directly affect the normal use of the equipment itself or the normal performance of the whole system.

4. The problems caused by incorrect connection between equipment (or parts) and equipment (or parts) generally occur in the following aspects
(1) impedance mismatch.

(2) the communication interface or communication mode does not correspond. This situation mostly occurs between the control host and the equipment with communication control relationship such as decoder or control keyboard, that is, the selected control host and decoder or control keyboard are not caused by the products of the same manufacturer. Therefore, the products of the same manufacturer shall be selected for the host, decoder and control keyboard.

(3) the driving capacity is insufficient or exceeds the specified number of equipment connections. For example, some picture dividers have alarm input interfaces, and the product manual shows that the system host connected with the alarm probe and long-time delay video recorder is connected into a system. If the alarm probe is connected to the alarm input end of the picture divider, the alarm signal of the probe will drive both the alarm host and the picture divider. In this case, the problem of insufficient driving capacity often occurs. The phenomenon shown is that although the picture splitter can alarm, it works unstable due to the weak input alarm signal, resulting in the image picture of the camera corresponding to the alarm signal is instantaneously converted into a full screen picture on the monitor, but it is lost (unable to hold), so that the image on the monitoring project monitor is still a multi picture before the alarm.