(1) No image.
The appearance of no image failure usually has the following reasons:
1) There is no video signal output from the camera gun itself.
2) The camera power supply is damaged or the power cord is off.
3) The camera gun video line has a broken circuit.
4) The video lightning arrester BNC head is released.
For the occurrence of no image failure, we first use the elimination method to eliminate the fault, because the camera gun image is normal before installing the arrester, due to the camera gun and the array host installed two video SPD, in order to quickly To detect the fault, we can use:
1) Voltage method to measure.
That is, remove the BNC head from the array host and measure the AC voltage with a multimeter. Under normal circumstances, the video signal output by the camera is between AC 0.1V and 0.3V. In order to facilitate the measurement, we made a special tool, as shown in Figure 4.
The experiment proves that it is helpful for us to make a test line with BNC head to quickly find the fault location. There is no voltage in Figure 4, and we gradually insert the test line with BNC head into the previous interface to measure until there is voltage. This method is very convenient and can be used to measure BNC head joint open circuit, core wire off welding and camera gun etc. It is highly recommended.
For video line disconnection faults, we can also use the voltage method to measure. The specific method is as follows: Connect one end of the broken core video cable to the live line of the 220V AC power supply, and the other end is left unconnected. Put the digital multimeter to AC 2V, insert the red pen, and leave the black pen port blank. From the end of the line of fire, move the red leads along the insulation of the wire and the voltage displayed should be at a few tenths of a volt. If the red meter drops to a certain point, the voltage drops abruptly to a few tenths of a volt (approximately one-tenth of the original), indicating that the core has broken. When using this method, be sure to pay attention to safety.
2) Resistance measurement.
With the resistance method can also be found fault location, first to disconnect the power, then the video camera at the video core and shielded wire together, and then measured at the matrix host resistance, this method is too much trouble, it is recommended not to use. Of course, according to the actual situation, different methods can be used flexibly to judge the fault to help us improve work efficiency.
(2) Larger and more chaotic large-area moires are generated on individual monitors, and even images are completely destroyed and images and synchronization signals cannot be formed.
This phenomenon is usually caused by the short circuit or open circuit of the core wire of the video cable and the shield network. Where these problems occur are on BNC heads or other types of video connectors. We must seriously check these connectors. Special attention should be paid to the fact that sometimes it is a short circuit between the shielded cable and the core. It is not easy to find; there are some broken circuit faults. The BNC head connection is wrapped with tape. It is not easy to find or convenient to check. We can use the voltage method to detect and quickly determine the fault location.
The above failures occurred when we installed the monitoring system for lightning protection. Since the monitoring system of this community was put into use before it was used as a lightning protection project, as long as we do the necessary preparation work before the project, the installation will be relatively smooth. At the same time, it can quickly resolve the problems that have occurred.
The appearance of no image failure usually has the following reasons:
1) There is no video signal output from the camera gun itself.
2) The camera power supply is damaged or the power cord is off.
3) The camera gun video line has a broken circuit.
4) The video lightning arrester BNC head is released.
For the occurrence of no image failure, we first use the elimination method to eliminate the fault, because the camera gun image is normal before installing the arrester, due to the camera gun and the array host installed two video SPD, in order to quickly To detect the fault, we can use:
1) Voltage method to measure.
That is, remove the BNC head from the array host and measure the AC voltage with a multimeter. Under normal circumstances, the video signal output by the camera is between AC 0.1V and 0.3V. In order to facilitate the measurement, we made a special tool, as shown in Figure 4.
The experiment proves that it is helpful for us to make a test line with BNC head to quickly find the fault location. There is no voltage in Figure 4, and we gradually insert the test line with BNC head into the previous interface to measure until there is voltage. This method is very convenient and can be used to measure BNC head joint open circuit, core wire off welding and camera gun etc. It is highly recommended.
For video line disconnection faults, we can also use the voltage method to measure. The specific method is as follows: Connect one end of the broken core video cable to the live line of the 220V AC power supply, and the other end is left unconnected. Put the digital multimeter to AC 2V, insert the red pen, and leave the black pen port blank. From the end of the line of fire, move the red leads along the insulation of the wire and the voltage displayed should be at a few tenths of a volt. If the red meter drops to a certain point, the voltage drops abruptly to a few tenths of a volt (approximately one-tenth of the original), indicating that the core has broken. When using this method, be sure to pay attention to safety.
2) Resistance measurement.
With the resistance method can also be found fault location, first to disconnect the power, then the video camera at the video core and shielded wire together, and then measured at the matrix host resistance, this method is too much trouble, it is recommended not to use. Of course, according to the actual situation, different methods can be used flexibly to judge the fault to help us improve work efficiency.
(2) Larger and more chaotic large-area moires are generated on individual monitors, and even images are completely destroyed and images and synchronization signals cannot be formed.
This phenomenon is usually caused by the short circuit or open circuit of the core wire of the video cable and the shield network. Where these problems occur are on BNC heads or other types of video connectors. We must seriously check these connectors. Special attention should be paid to the fact that sometimes it is a short circuit between the shielded cable and the core. It is not easy to find; there are some broken circuit faults. The BNC head connection is wrapped with tape. It is not easy to find or convenient to check. We can use the voltage method to detect and quickly determine the fault location.
The above failures occurred when we installed the monitoring system for lightning protection. Since the monitoring system of this community was put into use before it was used as a lightning protection project, as long as we do the necessary preparation work before the project, the installation will be relatively smooth. At the same time, it can quickly resolve the problems that have occurred.
Hundreds Flooring Co., Ltd , http://www.chglassmosaic.com