The port of a computer is divided into two parts: the host and the peripheral. Below I will introduce the common faults and maintenance methods of host and peripheral ports one by one.
1. The 15-pin VGA port of the monitor.
Under normal circumstances, once the monitor is connected to the 15-pin VGA port of the host graphics card, it does not need to be replaced frequently, and problems are unlikely to occur. But in some special cases, such as: DIY enthusiasts often disassemble and replace the graphics card; Plug and unplug the port with brute force when disassembling the mobile computer; Metal oxidation will occur when computers are used for a long time. It is possible that the VGA port is in poor contact, and the metal pin is bent or even broken, resulting in port failure.
There are usually two manifestations of VGA port failure: the display is not displayed at all and the picture display is color cast. There is no fault at all, which is generally caused by the bending and fracture of the pin responsible for synchronous transmission or information interactive communication between the pins of 15, and this situation has different specific manifestations according to the motherboard used. For example, some computers will give an alarm and give a prompt during the self-check, while others simply do not display a black screen. The color cast problem is caused by bending, breaking or poor contact of three pins responsible for R, G and B transmission.
Generally, computers with the above situation need to carefully check the disconnection of VGA plug, socket and cable, and the pins are mostly bent and poorly contacted, so it is generally easier to eliminate the faults after corresponding adjustment.
2. Keyboard and mouse ports
Keyboard port failure, computer self-test will generally give an error prompt? Keyboard interface error? After the car accident. At this time, if you turn off the phone, unplug the keyboard and plug it in again, some of them can start normally, but after using it for a period of time, the buttons will not respond. This phenomenon is mainly due to frequent hard plugging and unplugging of the keyboard, which leads to the loosening of five solder joints of the keyboard port signal line on the motherboard. In addition, the fracture of two iron plates connected to the motherboard on the keyboard port socket will also cause unstable port connection, so the motherboard can be removed and soldered again with an electric soldering iron. In addition, fuses are usually installed in. +5V keyboard power supply and keyboard port on motherboard. If it blows, there will be similar fault performance. At this time, we must carefully look for the short-circuit point of the keyboard line or the internal +5V power supply circuit, and the fuse with the same specification can only be replaced after the short-circuit hidden danger is eliminated. If you can't find a variety of the same specification, you can temporarily replace it with an ordinary 0.5A fuse.
When the mouse with PS/2 port fails, it is somewhat similar to the keyboard failure above, and the system will give corresponding prompts after self-checking. But it generally does not affect the computer startup, but the mouse cannot be used after entering the desktop. Therefore, the method of checking and handling keyboard faults is also applicable to the mouse. However, due to the low probability of failure of the PS/2 port drive circuit on the motherboard and the port circuit inside the mouse, the contact problem between the connecting cable and the plug and socket is the most common. Therefore, as long as the cable and socket are carefully checked, the fault can be easily found and finally eliminated.
3. Audio port
The audio port consists of standard dual-channel plug, socket and audio cable with shielded grounding layer. If the plug of this port is plugged and unplugged frequently, it may also cause poor contact between the plug and the cable, thus affecting the transmission of the sound card output signal. However, it is not common that the two audio signals disappear completely at this time. Generally, there will be a phenomenon that one channel has sound and the other channel is silent. In this case, as long as you check the connection and disconnection of the elastic metal contact piece of the plug and socket and the audio cable, you can quickly find the problem and deal with it. However, it must be noted that the shielding grounding layer in the audio cable must be reliably grounded, and only one end of the shielding layer can be grounded (generally at the amplifier end of the speaker), otherwise there may be various interferences in the playback of the speaker, especially AC acoustic interference.
4. Serial ports and parallel ports
Due to the continuous improvement and wide application of USB port, more and more peripherals use this high-speed port. Therefore, the ancient serial port and parallel port began to be gradually forgotten by people. However, some old peripherals, such as pin printers, external modems using COM port, especially serial programmers equipped with some industrial control computers, still need the support of serial port or parallel port to work. Relatively speaking, the parallel port has as many as 25 pins. Therefore, the possibility of poor contact, bent needle and broken needle is greater, and it is relatively complicated to handle. If there is a problem with the parallel port, you can use another method to confirm it. After the fault is found, methods such as adjusting the pin and welding the exposed cable connection point can be adopted to eliminate it.
The inspection and handling methods of serial port and parallel port faults are basically similar, so I won't introduce them here. However, we must pay attention to one thing. After the peripheral is inserted into two ports, the two-handed screw fixing bolts on the ports must be tightened as much as possible, which can effectively avoid poor contact between the peripheral and the ports. On the other hand, when using an industrial programmer, we must pay attention to the current parameters of the programmer and must not exceed the current supply capacity of the serial port, otherwise it is very likely to burn out the components or fuses of the serial port power supply circuit of the motherboard.
5. Universal serial bus interface
The transmission speed of USB port is much higher than the traditional serial port and parallel port, and it also has the advantages of simple connection, convenience and hot plug support, so it has been widely used soon. However, the current supply capacity of its +5V power supply is generally less than 500mA or even per channel 100mA, which may not support some USB devices with large current consumption, such as mobile hard disks. When some devices are plugged into the USB port, the system can't find the fault of the device, which is generally caused by the insufficient current supply capacity of the USB port of the motherboard. The solution is: if the current consumption of USB devices is high, be sure to provide additional power for the devices, or use an independent USB HUB. On the other hand, when installing the USB2.0 driver of the motherboard, you must upgrade and install the Service Pack 1 of Windows XP before installing the USB2.0 driver.
6. Some special ports
(1) Cable port: This year due to? Asian Cup? And then what? Olympic Games? One by one, TV card sales are extremely hot. However, some people buy and install TV cards, only to find that the displayed pictures are all chaotic or black and white stripes, and some TV cards can't even work normally. Among them, the problem of low image quality is closely related to the connection of wired ports. Therefore, in this section, we will discuss the selection of TV card port components in detail.
① Device selection: The coaxial cable must be a 75 ohm oxygen-free copper core coaxial cable. It is best to use gold-plated varieties for connecting plugs of wired cable ports, and the cable length should be as short as possible.
② Be sure to install the TV card away from other cards, especially the graphics card. When connecting the cable port of the TV card, it is necessary to check whether the single-layer copper mesh shielding layer in the plug is grounded reliably and there can be no resistance between it and the core wire. If there are multiple televisions and TV cards in the room using the same coaxial signal line, a demultiplexer must be installed as required. Only by following the above methods can we get a satisfactory TV picture on the monitor.
(2) NIC ports: NIC ports and? Urgent? The crystal head of the network cable is generally not easy to contact badly. Therefore, when installing the software and hardware of the network card and plugging in the crystal head, if there is a fault that the network card works normally but cannot communicate with the ADSL modem. On the premise of ensuring the normal connection between ports and network cables, resource conflicts usually occur between network cards and other hardware devices. As long as the interrupt number is redefined for the device, the network card can be restored to normal.
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