Troubleshooting of the monitoring system When operating and maintaining the monitoring system, you may encounter various failures that affect the normal operation of the system. This article is written by PHP editor Xiaoxin to bring you common faults in monitoring systems and corresponding troubleshooting methods. The following details the causes, symptoms, and resolution steps of these failures to help you quickly identify and solve problems and ensure that the monitoring system operates efficiently.
A large-scale video surveillance system that operates in conjunction with an anti-theft alarm is a system with high technical content and complex structure. When a surveillance system enters the debugging stage, trial operation stage, and delivery, equipment caused by incorrect power supply Failure, equipment damage due to power supply errors or instantaneous overvoltage, poor equipment connection, etc. may cause various failures, such as: failure to operate normally, the system failing to meet the technical specifications required by the design, and the overall performance and quality being unsatisfactory. , that is, some "soft problems". These problems are inevitable for a monitoring project, especially for a complex and large-scale monitoring project. Below we will elaborate on the corresponding problems and solutions.
1. Deep and chaotic large-area mesh interference occurs on the monitor, so that the image is completely destroyed, and no image and synchronization signal can be formed. · The fault is caused by short circuit or open circuit between the core wire of the video cable and the shielding network. This is This kind of fault often occurs on BNC connectors or other types of video connectors. That is to say, when this kind of fault occurs, it is often not a problem with all signals in the entire system, but only in those channels with bad connectors. As long as you carefully check these connectors one by one, you can solve the problem.
2. Equipment failure caused by incorrect power supply. Incorrect power supply generally has the following possibilities. · Incorrect power supply line or supply voltage. · Insufficient power (or a certain power supply The wire diameter of the line is not enough, the voltage drop is too large, etc.). · Short circuit, open circuit, instantaneous overvoltage, etc. occur in the transmission line of the power supply system. · In particular, equipment damage occurs due to power supply errors or instantaneous overvoltage. Therefore, Before system debugging and power supply, careful and strict verification and inspection must be carried out. Never take it lightly.
3. The three-variable lens camera and pan/tilt do not rotate/the lens does not move. There are many conditions for the connection of these devices. , problems such as open circuits, short circuits, poor insulation between wires, miswiring, etc. often occur, leading to equipment damage and performance degradation. · It is particularly worth pointing out that cameras with pan/tilts move in all directions over time, causing wiring problems. It is common for the equipment to fall off and break. 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.
4. Quality problems of the equipment or components themselves. · Theoretically speaking , various equipment and components may have quality problems. But from experience, it is purely a quality problem of the product itself, which mostly occurs in decoders, electric pan/tilts, transmission components and other equipment. It is worth pointing out that some The overall quality of the equipment may not cause unusable problems, but some technical indicators cannot meet the indicators given in the product manual. Therefore, necessary sampling testing must be carried out on the selected products. If it is indeed For product quality problems, the best way is to replace the product instead of disassembling and repairing it yourself.
5. Problems caused by improper adjustment of the equipment. · For example, the adjustment of the rear intercept of the camera is a very detailed and precise work, such as If you do not adjust it carefully, problems such as poor focus or defocusing may occur during various operations of the three-variable lens. · Whether the positions of some switches and adjustment knobs on the camera are correct, and whether they meet the technical requirements of the system, and whether the decoder encoding The correct setting of switches or other adjustable parts will directly affect the normal use of the equipment itself or the normal performance of the entire system.
6. Caused by incorrect connections between equipment (or components) and equipment (or components) Problems generally occur in the following aspects: · Impedance mismatch. · Communication interface or communication method does not correspond. · Insufficient driving capability or exceeding the specified number of device connections.
7. A black bar or a black bar appears on the monitor screen. The white bar slowly scrolls up or down. The fault may be caused by two different reasons. · To distinguish whether it is a power supply problem or a ground loop problem, a simple method is to connect the Input the output signal of a camera with no problem with the power supply. If the above interference phenomenon does not appear on the monitor, 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 nearby, and the video output of the front-end camera can be connected one by one. Check each camera. If yes, deal with it. If not, the interference is caused by ground loops and other reasons.
8. There is wood grain interference on the monitor. This kind of interference occurs only when it is slight. It will not flood the normal image, but in severe cases, the image will not be able to
Electrical equipment faults can be roughly divided into 3 major categories:
1: Open circuit fault
2: Short circuit fault
3: Electromagnetic interference
The classification method is very general but can cover almost all faults:
For example : Poor contact has a small contact resistance, which can be regarded as a slight open circuit in the circuit
; a large contact resistance indicates a moderate open circuit; if the resistance
Infinity is a complete circuit break. Contact resistance can cause failure. Short circuit faults can also be divided into slight short circuit, moderate short circuit and complete short circuit. If the cable ignites or is grounded but does not cause the circuit breaker to operate, it is a mild or moderate short circuit. The short circuit point will ablate and heat to the point of breaking the circuit. Breakdown of an electronic device is considered a short circuit. The degradation of component performance is understood as a slight circuit break, which is a major cause of failure of electronic equipment.
Diagnosis and troubleshooting of common electronic throttle faults
01; The throttle valve of a vehicle equipped with an electronic throttle valve is too dirty, usually due to excessive carbon deposits on the inside of the throttle valve, which will cause the EPC light to light up frequently and the vehicle It suddenly stalled while driving and kept vibrating. The fault can be eliminated by removing the throttle, cleaning it thoroughly, and then rematching it.
02; Once the electronic throttle control system fails and the engine enters the "limp home" state, the throttle valve plate can return to the high idling position under the action of the spring, allowing the engine to always maintain high idling speed.
03; The plug on the accelerator pedal position sensor or throttle position sensor of the electronic throttle system is loose or has poor contact, which will interrupt the signal transmission between the computer and the accelerator pedal position sensor or throttle position sensor, thus lighting up the electronic The throttle system warning light (EPC) comes on, and the accelerator pedal also feels empty.
04; When one throttle position sensor is damaged and the system uses the signal from the other sensor and the response to the accelerator pedal remains unchanged, only weak acceleration, shifting shock, cruise system shutdown, EPC light on, and fault codes will be stored.
05; When the two throttle position signals are interrupted at the same time, the engine is running at about 1500r/min, there is no response when pressing the accelerator pedal, the EPC light comes on and the fault code is stored.
06; The signal of one accelerator pedal position sensor (potentiometer) is distorted or interrupted. If the other sensor is in the idle position at this time, the engine will enter the idle condition.
07; If the signal of an accelerator pedal position sensor is distorted or interrupted under load conditions, the system will automatically enter the emergency operation state. At this time, the engine speed will rise slowly and the maximum vehicle speed will be limited to 120km/h.
08; For V-type engines, if the DC motor responsible for controlling the opening angle of the right throttle valve is ablated, it will cause unstable idle speed and poor acceleration. Gently cover the left and right air intake pipes with your hands respectively. When accelerating, you can clearly feel strong suction on the left side, but no suction on the right side.
09; For vehicles using electronic throttles, if the driver depresses the accelerator pedal and the brake pedal at the same time, the braking function will override the throttle control function and return the engine to idle operation mode. Although this situation will not remain DTC, but the vehicle cannot drive.
10; After starting the engine, touch the throttle valve with your hand. You can feel whether the throttle valve is open during rapid acceleration. If it is not open, it means that the electronic throttle valve has entered the fail-safe mode.
11; For engines equipped with electronic throttle valves, after turning on the ignition switch, do not open the throttle valve manually. Be sure to use a diagnostic tool to open the throttle valve.
12; Unplug the two-terminal connector from the clutch switch and check the continuity between the clutch switch terminals. When the clutch pedal is depressed, it should be conductive; when the clutch pedal is released, it should not be conductive. 4. Common faults and troubleshooting methods of the accelerator pedal?
2. Unplug the connector of the accelerator pedal position sensor on the wiring harness, and use a multimeter to check whether there is about 5V between pins 1 and 2 on the connector and the ground wire. Voltage signal;
3. Unplug the connector of the accelerator pedal position sensor on the wiring harness, and use a multimeter to check whether there is a short circuit or open circuit between pins 1 and 2 on the connector and ECU32# and 33#;
4 , Unplug the connector of the accelerator pedal position sensor on the wiring harness, and use a multimeter to check whether there is a short circuit or open circuit between pins 3 and 5 on the connector and ECU36#, 35#;
5. Unplug the connector on the wiring harness For the connector of the accelerator pedal position sensor, use a multimeter to check whether there is a short circuit or open circuit between pins 4 and 6 on the connector and ECU16# and 40#;
6. Use a diagnostic tool to read the signal of the accelerator pedal position sensor. output, check whether signal 1 increases as the accelerator pedal opening increases;
7. Use a diagnostic instrument to read the signal output of the accelerator pedal position sensor, and check whether signal 2 increases as the accelerator pedal opening increases.
5. How to troubleshoot common faults of the relief valve?
(1) Noise and Vibration
The components that are prone to noise in hydraulic devices are generally considered to be pumps and valves. Among the valves, relief valves and electromagnetic reversing valves are the main ones. There are many factors that produce noise. There are two types of noise from the relief valve: flow velocity sound and mechanical sound. The flow velocity sound is mainly caused by oil vibration, cavitation and hydraulic impact. Mechanical sound is mainly caused by the impact and friction of parts in the valve.
(1) Noise caused by uneven pressure
The pilot part of the pilot-operated relief valve is a part prone to vibration. When overflow occurs under high pressure, the axial opening of the pilot valve is very small, only 0.003 to 0.006 cm. The flow area is very small and the flow velocity is very high, up to 200 meters/second, which can easily cause uneven pressure distribution, causing the radial force of the poppet valve to be unbalanced and causing vibration. In addition, the ovality produced during the processing of the poppet valve and poppet valve seat, dirt sticking to the pilot valve port, and deformation of the pressure regulating spring can also cause vibration of the poppet valve. Therefore, it is generally believed that the pilot valve is the source of noise.
Due to the existence of elastic elements (springs) and moving masses (poppet valves), a condition for oscillation is formed, and the front cavity of the pilot valve also acts as a resonance cavity, so the vibration of the poppet valve can easily cause the entire The resonance of the valve causes noise. When noise occurs, it is usually accompanied by violent pressure jumps.
(2) Noise generated by cavitation
When air is sucked into the oil for various reasons, or when the oil pressure is lower than atmospheric pressure, part of the air dissolved in the oil will precipitate to form bubbles. These The bubbles have a larger volume in the low-pressure area. When the oil flows to the high-pressure area, they are compressed and the volume suddenly becomes smaller or the bubbles disappear. On the contrary, if the volume is originally small in the high-pressure area, but when it flows to the low-pressure area, A sudden increase in volume, a phenomenon in which the volume of bubbles in oil changes rapidly. The sudden change in bubble volume will produce noise, and because this process occurs in an instant, it will cause local hydraulic shock and vibration. The pilot valve port and main valve port of the pilot relief valve have large changes in oil flow rate and pressure, and cavitation is prone to occur, resulting in noise and vibration.
(3) Noise generated by hydraulic shock
When the pilot relief valve is unloading, pressure shock noise will occur due to a sudden drop in pressure in the hydraulic circuit. The more high-pressure and large-capacity working conditions the greater the impact noise. This is caused by the hydraulic impact caused by the short unloading time of the relief valve. During unloading, the oil flow rate changes sharply, causing a sudden change in pressure, causing The impact of pressure waves. The pressure wave is a small shock wave, which itself produces very little noise. However, when the oil is transmitted to the system, if it resonates with any mechanical part, it may increase vibration and noise. Therefore, when hydraulic impact noise occurs, it is usually accompanied by system vibration.
(4) Mechanical noise
The mechanical noise emitted by the pilot relief valve generally comes from the impact of parts and the friction of parts due to machining errors.
Among the noise emitted by the pilot relief valve, there is sometimes mechanical high-frequency vibration sound, which is generally called self-excited vibration sound. This is the sound caused by high-frequency vibration of the main valve and pilot valve. Its occurrence rate is related to factors such as the configuration of the oil return pipeline, flow rate, pressure, oil temperature (viscosity), etc. Generally speaking, when the pipeline diameter is small, the flow rate is small, the pressure is high, and the oil viscosity is low, the occurrence rate of self-excited vibration is high.
Measures to reduce or eliminate the noise and vibration of the pilot relief valve are generally to add a vibration damping component to the pilot valve part.
The vibration-absorbing sleeve is generally fixed in the front cavity of the pilot valve, that is, in the resonance cavity, and cannot move freely. Various damping holes are provided on the damping sleeve to increase damping and eliminate vibration. In addition, due to the addition of parts in the resonant cavity, the volume of the resonant cavity is reduced, and the stiffness of the oil increases under negative pressure. According to the principle that components with high stiffness are less likely to resonate, the possibility of resonance can be reduced.
Vibration-absorbing pads generally cooperate with the resonant cavity and can move freely. There is a throttling groove on the front and back of the vibration-absorbing pad, which can produce a damping effect when the oil flows to change the original flow situation. Due to the addition of the vibration-absorbing pad, a vibrating element is added, which disrupts the original resonance frequency. A vibration-absorbing pad is added to the resonant cavity, which also reduces the volume and increases the stiffness of the oil when it is under pressure to reduce the possibility of resonance.
There are air storage holes and throttling edges on the vibration-absorbing screw plug. Because there is air in the air storage holes, the air is compressed when it is under pressure. The compressed air has a vibration-absorbing effect, which is equivalent to a micro-vibration absorber. When the air in the small hole is compressed, the oil is filled in, and when it expands, the oil is forced out, thus adding an additional flow to change the original flow situation. Therefore, noise and vibration can also be reduced or eliminated.
In addition, if the relief valve itself is improperly assembled or used, it will also cause vibration and noise. For example, the three-section concentric relief valve has improper coordination of the three concentric sections during assembly, the flow rate is too large or too small during use, and the poppet valve is abnormally worn, etc. In this case, the adjustment should be carefully checked, or the parts should be replaced.
How to troubleshoot common faults of the relief valve
(2) Radial clamping of the valve core
Due to the influence of machining accuracy, the main valve core is radially clamped, causing the main valve to open and not pressurize or the main valve not to close. Relieve pressure, and cause radial clamping due to contamination.
(3) Pressure regulation failure
Pressure regulation failure may sometimes occur in the relief valve during use. There are two situations when the pilot relief valve fails to regulate pressure: one is that the pressure regulating handwheel cannot build up the pressure, or the pressure cannot reach the rated value; the other is that the pressure of the regulating handwheel does not decrease, or even continues to increase. When pressure regulation failure occurs, in addition to the radial clamping of the valve core due to various reasons, there are also the following reasons:
The first is that the damper of the main valve body (2) is clogged, and the oil pressure cannot be transmitted to the upper chamber of the main valve and the front chamber of the pilot valve, and the pilot valve loses its ability to regulate the pressure of the main valve. Since there is no oil pressure in the upper chamber of the main valve and the spring force is very small, the main valve becomes a direct-acting relief valve with a very small spring force. When the pressure in the oil inlet chamber is very low, the main valve opens the relief valve. flow, the system cannot build up pressure.
The reason why the pressure cannot reach the rated value is that the pressure regulating spring is deformed or incorrectly selected, the compression stroke of the pressure regulating spring is insufficient, the internal leakage of the valve is too large, or the poppet valve of the pilot valve part is excessively worn, etc.
The second is that the damper (3) is clogged and the oil pressure cannot be transmitted to the poppet valve, so the pilot valve loses its ability to regulate the pressure of the main valve. After the damper (small hole) is blocked, the poppet valve will not open to overflow oil under any pressure. There is always no oil flow in the valve. The pressures in the upper and lower chambers of the main valve are always equal. Since the annular pressure-bearing area at the upper end of the main valve core is larger than The lower end has an annular pressure-bearing area, so the main valve is always closed and will not overflow. The main valve pressure increases as the load increases. When the actuator stops working, the system pressure will increase indefinitely. In addition to these reasons, it is also necessary to check whether the external control port is blocked and whether the poppet valve is installed properly.
(4) Other faults
During assembly or use of the relief valve, due to damage to the O-ring seal, the combined seal ring, or the loosening of the mounting screws and pipe joints, undue leakage may occur.
If the poppet valve or main valve core is too worn, or the sealing surface is in poor contact, it will cause excessive internal leakage and even affect normal operation.
Common faults of electromagnetic relief valves include failure of the pilot solenoid valve, failure of pressure regulation of the main valve and impact noise during unloading, etc. The latter can be reduced or eliminated by adjusting the added buffer. If there is no buffer, a back pressure valve can be added to the main valve overflow port. (The pressure is generally adjusted to about 5kgf/cm2, that is, 0.5MPa).
Common faults of electric valves. Generally, there is a foreign object in the fluid in the pipeline equipment that blocks the valve center seal and the core, causing the electric valve to malfunction. The solution is to disassemble the valve, check and clean the blocked foreign objects, and the fault can be eliminated. If there is another fault, The valve control shaft electronic control solenoid coil is burned out. After troubleshooting and replacing the solenoid coil, it will be normal.
Computers have become an indispensable tool in our daily lives, but when using computers During the process, we often encounter various problems. This article will introduce several common computer failures and provide corresponding troubleshooting methods to help readers better solve computer problems.
Computer startup problems are one of the most common computer failures. When the computer won't start, we can try the following solutions:
Check the power connection: Make sure the computer's power cord is connected correctly and there is no problem with the socket. Check hardware connections: Make sure all hardware devices are connected correctly and are not loose or damaged. Restart the computer: Sometimes the computer only has a temporary fault, and restarting can solve the problem. Enter safe mode: If your computer still won't start, you can try entering safe mode and troubleshooting.A blue screen problem means that the computer suddenly appears with a blue screen during use and automatically restarts or becomes unresponsive. To solve the blue screen problem, you can try the following methods:
Check the error message: When the computer has a blue screen, there will be an error code or error message displayed, and you can search for solutions through this information. Update drivers: Sometimes blue screen problems are caused by outdated or incompatible drivers, and updating drivers in time can solve the problem. Check the hardware device: The blue screen problem may also be related to the hardware device. You can check whether the hardware device is connected stably and whether there is a fault. Scan for viruses: Sometimes the blue screen problem is caused by a virus infection, running a virus scan and removing the virus can solve the problem.When using computers to access the Internet, we sometimes encounter network connection problems. Here are some ways to troubleshoot network connection issues:
Check network devices: Make sure your router, modem, and other network devices are connected properly and that the network cables are not damaged. Restart the network device: Sometimes the network device fails and restarting can solve the problem. Check network settings: Check whether your computer is set up with the correct network connection, such as IP address, subnet mask, etc. Reset network: In some cases, resetting network settings can resolve network connection issues.During the process of surfing the Internet, our computers may be infected with viruses. Here are some ways to solve the problem of virus infection:
Install anti-virus software: Install anti-virus software promptly and conduct virus scans regularly. Update your antivirus software: Make sure your antivirus software is always up to date to get the latest virus databases. Be cautious when opening attachments: If you receive an unknown email, try not to open or download the attachment. Regular backup: Back up important files and data to prevent data loss caused by virus infection.The above is the detailed content of Common faults and troubleshooting of monitoring systems?. For more information, please follow other related articles on the PHP Chinese website!
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