[ Huaqiang Security Network News ] It is understood that the current community has installed the building intercom system, at the same time, the building intercom system has entered thousands of households, there are networked systems, visual systems, intercom systems, etc., a wide variety of systems The problems encountered by the engineering company during the installation process are also varied. Based on many years of field experience, the author summarizes the most common types of problems, and each type of problem has been analyzed in detail, hoping to help the project. 
I. Sanmenxia Site <br> Fault phenomenon: Directly press the color visual system, there are 12 households on the sixth floor, and there is no color on the sixth floor.
Exclusion process: First call the Sanmenxia customer to check the line, the other manager also let the construction workers check, the construction workers have always said that there is no problem. Our engineers once again telephoned: Change the six-story non-color extension to the fifth floor. The result is colored, indicating that there is no problem with the extension host. The problem is on the online road, so the emphasis is on the fifth floor. However, the construction workers are not willing to take responsibility, let the other manager call us, and strongly demand that the factory send engineers to the site for inspection. After the engineer went there, he found that there were two 18-volt power cables at the extension on the fifth floor. One of the multi-core wires was stripped of more than ten copper wires by the constructor. The wires with a cross-sectional area of ​​0.5 had 28 copper wires. Now There are more than a dozen of them left, causing a severe drop in voltage, which always affects no color.
Solution: Reconnect the partially broken 18V power cord.
Lessons learned: The responsibility of the construction and wiring staff and the rigor of the work attitude are very important. For individual construction workers who are not responsible, a small mistake can lead to serious consequences.
Second, Xinyang Yihe Garden Community Site <br> Fault phenomenon: Code color visual system, the extension image is distorted and the color reproduction is excessive.
Solution: Add a 75 ohm matching resistor to the ground on the video main line.
Principle analysis: The video signals of each extension of the building system are superimposed in parallel on a video main line, making the video signal stronger, so the image of the extension has a phenomenon of image distortion and strong color. Add a 75 ohm resistor to the ground on the video main line to weaken part of the video signal and restore the normal image.
3. Site of Longyuan Jiayuan Community, Xinyang City <br> Fault phenomenon: Coded black and white visual system, in which one of the extensions monitors the image of the host computer and has serious moire interference.
Solution: Replace an extension video cable.
Principle analysis: The user-purchased video cable production process is too poor, for the non-standard video cable, the video cable copper core is not wrapped in the middle position, which belongs to the eccentric core, causing problems in the extension video.
Lessons learned: Users can't just pursue the low price when purchasing the wire. When the price is low to a certain extent, the quality of the wire should be strictly checked. There are copper clad aluminum, copper clad steel, non-standard, doping and so on. It is recommended to use the wires of regular manufacturers. Hong Kong TPV has a wire and cable factory in Beijing, and the quality is relatively reliable.
Fourth, the Weihe Jindi Ziwei Garden scene <br> Fault phenomenon: Directly press the visual system, the door host has noise during standby.
Solution: Use a wire to connect the 20V power supply to the ground. It is connected to a 20 volt negative electrode on the main casing or the door. If the door is not well grounded, you can also pull the 20 volt negative wire directly to the ground, and use the steel bar to nail it into the ground for about 1 meter, and splash the salt water around it.
Principle analysis: The power supply grounding condition of the residential area is not good, and the interference signal cannot be directly introduced into the earth, but is amplified by the host power amplifier to form noise.
V. Xinyuan Boyuan Longjun Garden Scene <br> Fault phenomenon: coded visual card swipe system, electric control lock can not be opened Solution: Reconnect 12V power cord principle analysis: workers cut off 12V power cord copper wire when wiring A lot caused. Because the unlocking current is very large, if the copper wire of the 12V power supply line is broken, it is equivalent to the 12V power supply line is very thin, and the current and voltage are insufficient to appear unlocking.
Sixth, Jiaozuo City Liberated Area Education Bureau on-site <br> Fault phenomenon: coded black and white visual system, 16 floors and two households, the image appears ghost and the lower the floor, the more serious solution: (1) use building type isolator.
(2) Disconnect the video cable at the seven-story building, and then pull a video cable from the host to have more than eight layers of extensions. The video output of the host should add a video isolator, so that the video signal is divided into two channels, one video. The cable has 1-7 layers and the other video cable has 8-16 layers.
(3) Or do not pull the video line, then the video signal of more than seven layers will be output from the seven-layer video isolator.
Principle analysis: Because the video signal needs point-to-point transmission, the higher the floor, the more serious the downward reflection of the video signal, so the upper layer must use the above method to solve the video problem.
Seven, Changchun European Garden Scene <br> Fault phenomenon: Directly press the black and white visual system, there is no image solution for the whole unit: the camera is bad, replace the camera.
Principle analysis: The video cable is short-circuited with the 4th line to burn the camera. Because there is 12V voltage on the 4th line, if the video line is short-circuited, the camera video circuit will burn out. In order to prevent this from happening again, our current camera video output has an isolator to prevent such events from happening. (Shenzhen Control Industry Security Network: )
Eight, Zhengzhou West Development Zone, the wisdom garden scene <br> Fault phenomenon: Directly press the code black and white visual system, the visual extension image has moire interference.
Solution: Add a 4700uf/25V capacitor filter to the input of the video isolator 18V on each layer.
Principle analysis: Because the on-site supply voltage is cluttered, 18V output to each floor isolator requires line filtering to filter the clutter.
Nine, Zhengzhou Putian scene <br> Fault phenomenon: coded mixed system, there is a howling phenomenon after the call, there is a sound solution of the radio station: the most distal to the "T" line plus 1UF capacitor filter, the microphone is re Welding, the broadcast sound can be removed, the howling balance, the potentiometer should miss the critical value, that is, adjust to a little when not whistling.
Principle analysis: This area is too close to the radio and television tower. If the wiring is unreasonable, it will be easy to receive the broadcast sound. Therefore, it is necessary to consider the input impedance of a power amplifier at the farthest end of the “T†line. If you don't miss the threshold, it may happen that the extension does not scream, and the other extension screams because the length of the line varies.
X. Zhengzhou Shangdu International Apartment Site <br> Fault phenomenon: The coded intercom network system has 28 floors on each floor of 28 floors. If the first house number is called, then immediately hang up and then call the second house number, but it is still the first one. The room number is ringing.
Solution: Connect a 1K resistor to the ground on the “V†line. The 1K resistor is added to discharge the "V" line, so the line of the system "V", "T" and "G" is too long. When the call is made, the "V" line will have 5V, and the second party will be called immediately. The power of the "V" line has not been exhausted, so the first household is ringing.
Principle analysis: Because the situation of the community is special, each unit has 16 layers, each floor has dozens of households, and one unit has 700 households! So many extension line wires cause the V line voltage not to be completely discharged immediately, thus making the host software Misjudged.
XI. The scene of the family building of the Henan Provincial Inspection Institute <br> Fault phenomenon: The coded intercom system, the whole unit host gives the extension a small voice.
Solution: The microphone hole of the host is blocked by the bug, and it is cleared and returned to normal.
Principle analysis: The microphone hole on the main unit casing is only 1 mm in diameter, and any foreign matter blocking the small hole will weaken the sound transmitted to the microphone.
Twelve, the traffic police brigade family hospital <br> Fault phenomenon: coding intercom system, the host whistling, adjust the volume potentiometer can not be resolved.
Solution: After opening the host, I found a dead moth inside the board, causing a short circuit.
Principle analysis: The moth is drilled into the host, causing the pins of the electronic components on the circuit board to be short-circuited.
Exclusion process: First call the Sanmenxia customer to check the line, the other manager also let the construction workers check, the construction workers have always said that there is no problem. Our engineers once again telephoned: Change the six-story non-color extension to the fifth floor. The result is colored, indicating that there is no problem with the extension host. The problem is on the online road, so the emphasis is on the fifth floor. However, the construction workers are not willing to take responsibility, let the other manager call us, and strongly demand that the factory send engineers to the site for inspection. After the engineer went there, he found that there were two 18-volt power cables at the extension on the fifth floor. One of the multi-core wires was stripped of more than ten copper wires by the constructor. The wires with a cross-sectional area of ​​0.5 had 28 copper wires. Now There are more than a dozen of them left, causing a severe drop in voltage, which always affects no color.
Solution: Reconnect the partially broken 18V power cord.
Lessons learned: The responsibility of the construction and wiring staff and the rigor of the work attitude are very important. For individual construction workers who are not responsible, a small mistake can lead to serious consequences.
Second, Xinyang Yihe Garden Community Site <br> Fault phenomenon: Code color visual system, the extension image is distorted and the color reproduction is excessive.
Solution: Add a 75 ohm matching resistor to the ground on the video main line.
Principle analysis: The video signals of each extension of the building system are superimposed in parallel on a video main line, making the video signal stronger, so the image of the extension has a phenomenon of image distortion and strong color. Add a 75 ohm resistor to the ground on the video main line to weaken part of the video signal and restore the normal image.
3. Site of Longyuan Jiayuan Community, Xinyang City <br> Fault phenomenon: Coded black and white visual system, in which one of the extensions monitors the image of the host computer and has serious moire interference.
Solution: Replace an extension video cable.
Principle analysis: The user-purchased video cable production process is too poor, for the non-standard video cable, the video cable copper core is not wrapped in the middle position, which belongs to the eccentric core, causing problems in the extension video.
Lessons learned: Users can't just pursue the low price when purchasing the wire. When the price is low to a certain extent, the quality of the wire should be strictly checked. There are copper clad aluminum, copper clad steel, non-standard, doping and so on. It is recommended to use the wires of regular manufacturers. Hong Kong TPV has a wire and cable factory in Beijing, and the quality is relatively reliable.
Fourth, the Weihe Jindi Ziwei Garden scene <br> Fault phenomenon: Directly press the visual system, the door host has noise during standby.
Solution: Use a wire to connect the 20V power supply to the ground. It is connected to a 20 volt negative electrode on the main casing or the door. If the door is not well grounded, you can also pull the 20 volt negative wire directly to the ground, and use the steel bar to nail it into the ground for about 1 meter, and splash the salt water around it.
Principle analysis: The power supply grounding condition of the residential area is not good, and the interference signal cannot be directly introduced into the earth, but is amplified by the host power amplifier to form noise.
V. Xinyuan Boyuan Longjun Garden Scene <br> Fault phenomenon: coded visual card swipe system, electric control lock can not be opened Solution: Reconnect 12V power cord principle analysis: workers cut off 12V power cord copper wire when wiring A lot caused. Because the unlocking current is very large, if the copper wire of the 12V power supply line is broken, it is equivalent to the 12V power supply line is very thin, and the current and voltage are insufficient to appear unlocking.
Sixth, Jiaozuo City Liberated Area Education Bureau on-site <br> Fault phenomenon: coded black and white visual system, 16 floors and two households, the image appears ghost and the lower the floor, the more serious solution: (1) use building type isolator.
(2) Disconnect the video cable at the seven-story building, and then pull a video cable from the host to have more than eight layers of extensions. The video output of the host should add a video isolator, so that the video signal is divided into two channels, one video. The cable has 1-7 layers and the other video cable has 8-16 layers.
(3) Or do not pull the video line, then the video signal of more than seven layers will be output from the seven-layer video isolator.
Principle analysis: Because the video signal needs point-to-point transmission, the higher the floor, the more serious the downward reflection of the video signal, so the upper layer must use the above method to solve the video problem.
Seven, Changchun European Garden Scene <br> Fault phenomenon: Directly press the black and white visual system, there is no image solution for the whole unit: the camera is bad, replace the camera.
Principle analysis: The video cable is short-circuited with the 4th line to burn the camera. Because there is 12V voltage on the 4th line, if the video line is short-circuited, the camera video circuit will burn out. In order to prevent this from happening again, our current camera video output has an isolator to prevent such events from happening. (Shenzhen Control Industry Security Network: )
Eight, Zhengzhou West Development Zone, the wisdom garden scene <br> Fault phenomenon: Directly press the code black and white visual system, the visual extension image has moire interference.
Solution: Add a 4700uf/25V capacitor filter to the input of the video isolator 18V on each layer.
Principle analysis: Because the on-site supply voltage is cluttered, 18V output to each floor isolator requires line filtering to filter the clutter.
Nine, Zhengzhou Putian scene <br> Fault phenomenon: coded mixed system, there is a howling phenomenon after the call, there is a sound solution of the radio station: the most distal to the "T" line plus 1UF capacitor filter, the microphone is re Welding, the broadcast sound can be removed, the howling balance, the potentiometer should miss the critical value, that is, adjust to a little when not whistling.
Principle analysis: This area is too close to the radio and television tower. If the wiring is unreasonable, it will be easy to receive the broadcast sound. Therefore, it is necessary to consider the input impedance of a power amplifier at the farthest end of the “T†line. If you don't miss the threshold, it may happen that the extension does not scream, and the other extension screams because the length of the line varies.
X. Zhengzhou Shangdu International Apartment Site <br> Fault phenomenon: The coded intercom network system has 28 floors on each floor of 28 floors. If the first house number is called, then immediately hang up and then call the second house number, but it is still the first one. The room number is ringing.
Solution: Connect a 1K resistor to the ground on the “V†line. The 1K resistor is added to discharge the "V" line, so the line of the system "V", "T" and "G" is too long. When the call is made, the "V" line will have 5V, and the second party will be called immediately. The power of the "V" line has not been exhausted, so the first household is ringing.
Principle analysis: Because the situation of the community is special, each unit has 16 layers, each floor has dozens of households, and one unit has 700 households! So many extension line wires cause the V line voltage not to be completely discharged immediately, thus making the host software Misjudged.
XI. The scene of the family building of the Henan Provincial Inspection Institute <br> Fault phenomenon: The coded intercom system, the whole unit host gives the extension a small voice.
Solution: The microphone hole of the host is blocked by the bug, and it is cleared and returned to normal.
Principle analysis: The microphone hole on the main unit casing is only 1 mm in diameter, and any foreign matter blocking the small hole will weaken the sound transmitted to the microphone.
Twelve, the traffic police brigade family hospital <br> Fault phenomenon: coding intercom system, the host whistling, adjust the volume potentiometer can not be resolved.
Solution: After opening the host, I found a dead moth inside the board, causing a short circuit.
Principle analysis: The moth is drilled into the host, causing the pins of the electronic components on the circuit board to be short-circuited.
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