Microcomputer is a high-precision equipment, in addition to correct use, daily maintenance is also very important. In the long-term maintenance work, the author found that a large number of failures were caused by insufficient daily maintenance or improper maintenance methods. This series of articles comprehensively introduces the disassembly and daily maintenance methods of each part of the microcomputer system, aiming at helping microcomputer users to maintain their own computers and prevent problems before they happen. This paper, the first in this group, mainly introduces the common maintenance tools, maintenance precautions, the removal of wiring in various parts of the main chassis, the dust removal inside the chassis and the daily maintenance methods of the board.
A, maintenance tools:
Computer maintenance does not need complicated tools. Generally, dust removal maintenance only needs to prepare a cross screwdriver, a word screwdriver and a paint brush (or a paint pen, which is easy to shed and not suitable for use). If you want to clean the inside of floppy drive and CD-ROM drive, you need to prepare lens wipes, hair dryer, anhydrous ethanol (analytical pure), absorbent cotton balls, a set of clock screwdrivers, tweezers, balloon blowing (leather tiger), paper clips, clock oil (or sewing machine oil) and butter. If further maintenance is needed, please prepare a needle-nosed pliers, an electric pen and a multimeter.
Second, the maintenance precautions
Some original and branded computers do not allow users to open the chassis by themselves. If you open the chassis without authorization, you may lose some warranty rights provided by the manufacturer. Please pay special attention.
All parts should be handled with care, especially the hard disk, which will kill people if it falls;
Pay attention to the orientation of each jumper, such as hard disk cable, floppy drive cable, power cable, etc. In the process of disassembly, in order to recover correctly;
When fixing all parts with screws, align the parts first, and then tighten the screws. Especially the motherboard, a slight position deviation may lead to poor card contact; The uneven installation of the motherboard may lead to poor contact or even short circuit between the memory module and the adapter card, and even deformation and failure over time;
Because the integrated circuit devices on the computer board are mostly manufactured by MOS technology, this semiconductor device is quite sensitive to electrostatic high voltage. When people or things with static electricity touch these devices, they will release static electricity, and the released static high voltage will damage these devices. Static electricity is everywhere in our daily life. For example, when you take off some chemical fiber clothes, you may hear a sound or see a flash. At this time, the static electricity is at least 5kV, which is enough to damage the components of the microcomputer. Therefore, special attention should be paid to electrostatic protection when maintaining computers. Therefore, before disassembling and maintaining the computer, you must do the following:
Disconnect all power supplies;
(2) Before opening the chassis, touch the ground or wall with both hands to release static electricity. When holding the motherboard and card, try to hold the edge of the card and don't touch the integrated circuit of the card with your hands. If you must touch the internal circuit, it is best to wear a grounding ring;
(3) Please don't wear rubber shoes that are easy to rub with the floor and carpet to generate static electricity. Wearing metal shoes can release static electricity on people, and anti-static floors should be used in qualified workplaces;
(4) Maintain a certain humidity, which is easy to generate static electricity when air is dry, and the ideal humidity should be 40%-60%;
(5) When using electric soldering iron and electric fan, the grounding wire should be connected.
Third, the removal of the microcomputer host
Unplug the peripheral connection.
After turning off the power switch and unplugging the power cord, you can begin to disassemble the host. The first step in removing the host is to unplug all peripheral connections on the back of the chassis.
There are two main ways to disconnect the connection between the peripheral and the computer. One way is to directly unplug the plug, such as keyboard cable, PS/2 mouse cable, power cable, USB cable and so on. Another kind of plug needs to loosen the screws on both sides of the plug to fix the handle, and then pull it out horizontally, such as the signal line plug of the monitor and the signal line plug of the printer. In the early days, some signal cables did not have screws to fix the handle, so it was necessary to unscrew the screws on both sides of the plug with a screwdriver.
Open the case cover.
After unplugging all the peripheral wires, you can open the chassis. Whether it is a horizontal or vertical chassis, the fixing screws of the chassis cover are mostly at the rear edge of the chassis. You can unscrew a few screws with a Phillips screwdriver and remove the chassis cover.
Take out the adapter card.
The video card and sound card are inserted into the expansion slot of the motherboard and fixed on the bar window on the back of the chassis with screws. When removing the interface card, first unscrew the screw fixing the card on the upper edge of the bar window with a screwdriver, then hold the upper edge of the interface card with both hands and pull it straight up.
Unplug the drive data cable.
One end of the data cable of the hard disk, floppy disk drive and CD-ROM drive is plugged into the driver, and the other end is plugged into the interface socket of the motherboard. Hold both ends of the data cable plug and pull it out smoothly in the horizontal direction.
Pay attention to two points when unplugging the drive data cable. First of all, don't pull down the data cable to avoid damaging it. Second, pay attention to the direction of pulling and inserting to restore. There is a red line (line 1) on the edge of the data line of the driver, which corresponds to the 1 pin on the interface between the driver and the motherboard, and most of them are marked with 1 next to the interface socket of the driver and the motherboard.
Unplug the power plug from the drive.
Hard disk and CD-ROM power plugs are big four-pin plugs, and floppy drive power plugs are small four-pin plugs. Just pull them out horizontally. Please pay attention to the direction when installing and restoring. Generally, you can't insert it in the opposite direction. After the power supply is connected, the reverse forced insertion will damage the drive.
Remove the drive.
The hard disk, floppy disk drive and CD-ROM drive are all fixed on the drive bracket on the chassis panel. When removing the drive, please unscrew the screws that fix the drive on both sides of the drive bracket (some fixing screws are on the panel), and then pull the drive forward. When unscrewing the last screw on the hard disk, please hold it by hand. Be careful when the hard disk falls, it will be damaged if it falls lightly. In some cases, the driver is not fixed with screws, but clamped with spring plates. In this case, the driver can be pulled out of the slide rail by loosening the spring leaf.
Unplug the motherboard power plug.
The power plug is plugged into the motherboard power socket. ATX power plug is a double-row 20-pin plug with a small plastic card. You can pull it out by pinching the power plug of ATX. AT power plugs are two six-pin plugs P8 and P9, which can be pulled out smoothly. Finally, please pay attention to the direction when restoring the AT power plug. The black wire between the six-pin plugs P8 and P9 should be inserted together, and the wrong direction will lead to short circuit of power supply.
Other plugs
Other plugs that need to be unplugged may include CPU fan power plug, audio cable plug between optical drive and sound card, motherboard and chassis panel plug, SB-LINK plug between sound card and motherboard, etc. When unplugging these plugs, records should be made, such as the color of plug wires, the location of sockets, the arrangement of pins of sockets, etc. So that it can be repaired.
Fourth, clean the dust on the inner surface of the chassis.
For a large area of dust accumulated on the inner surface of the chassis, you can wipe it with a wringing wet cloth. Dry the wet cloth as much as possible, wipe the water stains and blow dry with a hair dryer. Generally, all kinds of plugs, sockets, expansion slots, memory sticks and boards should not be wiped with water.
Five, clean the slot, plug and socket.
The slots to be cleaned include various bus (ISA, PCI, AGP) expansion slots, memory card slots and various driver interface plugs and sockets. The dust in all kinds of grooves is generally cleaned with oil painting pen first, and then blown out with balloon or hair dryer.
If there is oil stain on the metal pin in the slot, it can be removed with absorbent cotton balls dipped in special cleaning agent for computer or anhydrous alcohol. Most special cleaning agents for computers are composed of carbon tetrachloride and activator, which can volatilize automatically after smearing and decontamination. When buying a cleaner, first, check its volatile performance. Of course, the sooner it volatilizes, the better. The second is to check its acidity and alkalinity with PH test paper, and the requirement is neutral. If it is acidic, it will corrode the plate.
Six, clean the CPU fan
PII and Celeron CPU are still relatively new at present, so fans generally don't need to be removed, just clean them with a paint brush or oil painting pen. There is a lot of dust on the older CPU fan, which generally needs to be removed and cleaned. Taking the CPU of Socket 7 as an example, this paper introduces the dust removal of CPU fan.
A large CPU fan is stuck on the buckles on both sides of the CPU socket. Gently press the fan button to remove the CPU fan. After removing the CPU fan, the dust on the fan can be removed. Note that there is a lot of dust in the cracks of the radiator.
The original CPU fan is connected with the CPU as a whole. It is necessary to gently pull out the handle next to the socket 7 to separate the handle from the handle positioning card, then push it up to a vertical position of 90 degrees, and then remove the CPU upward. When cleaning the CPU fan, be careful not to dirty the heat-conducting silica gel between the joint surface of CPU and radiator.
Seven, clean the memory and adapter card.
Cleaning of memory sticks and various adapter cards includes dust removal and cleaning of gold fingers on circuit boards. Just use an oil painting pen for dust removal. The gold finger is the connection point between the circuit board and the socket. If there is dust, oil pollution or oxidation, it will cause poor contact. A large number of failures of old microcomputers come from this. The gold fingers of advanced circuit boards are gold-plated and are not easy to oxidize. In order to reduce the cost, the gold fingers of general adapter cards and memory chips are not plated with gold, but only plated with a layer of copper foil, which will oxidize after a long time. Eraser can be used to wipe the dust, oil stain or oxide layer on the surface of gold finger. Never use sandpaper to wipe the golden finger, otherwise it will destroy the extremely thin coating.
Removal and maintenance of optical drive-cleaning focusing lens, laser head and laser power adjustment
Optical drive is an essential basic configuration of multimedia computer. In actual use, the optical drive often fails. When the CD-ROM drive first broke down, it usually picked the disk, and then it became more and more serious until it was impossible to read the disk. This kind of fault is usually caused by dust accumulation on the focusing lens and laser head or aging of the laser tube. Therefore, after the disk reading fails, the optical head can be cleaned first, including general dust removal and cleaning of the focusing lens and laser head. If the fault cannot be eliminated, it may be caused by poor contact of the laser current adjusting potentiometer or aging of the laser diode, which can be solved by adjusting the potentiometer. Most of the failed CDs handled by the author are repaired by the above methods. Taking Sony CDU3 1 1 eight-speed optical drive as an example, this paper introduces the methods of disassembling the optical drive, cleaning the focusing lens and laser head, and adjusting the laser power.
CD-ROM drive is a high-precision device integrating optics, electricity and machinery. Disassembly and cleaning should be carried out according to certain steps, otherwise it will be easily damaged. Usually, you can disassemble the optical drive as follows.
1. Remove bottom plate.
Turn the bottom of the CD-ROM drive upward, unscrew the screws fixing the bottom plate with a Phillips screwdriver, and then remove the metal bottom plate upward. At this time, you can see the circuit board at the bottom of the CD-ROM drive. Some CD-ROM drives have a lock on the bottom plate, and the lock is buckled on the corresponding buckle of the shell (concave metal upper cover). To remove this type of optical drive backplane, you must gently push the backplane to the back of the optical drive to separate it from the latch, and then remove the backplane upward.
2. Pull out the CD holder
There is a forced disc ejection hole with a diameter of 1.0 ~ 1.5 mm on the left side of the CD-ROM drive in and out button. Straighten a paper clip, insert it into the emergency disc ejection hole and push it hard for about 2.5cm. The disc tray will pop forward and then pull it out by hand. Some CD-ROMs don't have forced ejection holes. You can turn on the power, press the in and out disk key to make the disk tray slide out, and then turn off the power. If the CD is jammed when entering, check the lubricating oil on the slide of the CD carrier after taking out the movement. If it is too dirty or solidified, wipe off a drop of oil or high-grade butter. Of course, the chuck may also be caused by mechanical failure, so check the mechanical part at this time.
3. Remove the front panel of the optical drive.
There are buckles on both sides and top of the front panel, which are stuck in the holes of the metal shell (concave metal upper cover). Gently push the buckles inward to disengage them and pull the front panel forward.
Step 4 take out the movement
The movement (including circuit board) of Sony CDU 31KLOC-0/CD-ROM drive can be taken out of the housing after the front panel is pulled out.
Step 5 clean the focus lens
Turn the front end of the movement upwards and pull out the optical disc holder, and you can see the optical head assembly. The glass spherical transparent body with the size of soybean at the top is the focusing lens. Now you can clean the focusing lens with a cotton swab dipped in anhydrous ethanol. Before cleaning the focusing lens, you can carefully observe the surface of the focusing lens with a magnifying glass. You may see a piece of dust or fog. Wipe the dust off the lens surface with absorbent cotton or lens paper, and then wipe it several times to get a clear and transparent mirror. The focusing lens is installed on the elastic body, and a little force can be applied when wiping, but the lens displacement or deflection caused by excessive force will affect the reading disk. Do not use tweezers to avoid scratching the lens surface. Do not touch the focusing coil on one side of the focusing lens.
Whether cleaning the optical head needs cleaning solution and what cleaning solution to use has been debated in the industry. I don't think it's necessary to use cleaning solution in general. If drying can't remove the dirt, please consider using the cleaning solution again. Washing with water is absolutely not acceptable. Whether the laser head can be cleaned with alcohol is also controversial. The author thinks that it is entirely possible to use high-purity anhydrous ethanol. The so-called alcohol usually refers to an ethanol solution containing water and impurities. So alcohol is really not suitable for cleaning laser heads. Anhydrous ethanol is a weak organic solvent, and its purity can be divided into industrial purity, chemical purity, analytical purity and spectral purity from low to high. The higher the purity, the less water and impurities it contains. The optical head of CD-ROM drive consists of laser generator, photodetector, focusing lens, laser beam splitter and servo motor. The focusing lens located under the optical disc is the most prone to dust. Generally speaking, cleaning refers to cleaning the surface of this lens. The lens surface is coated with a thin film called antireflection film, and its material is magnesium fluoride. The main function of antireflection film is to reduce refraction and increase transparency. Magnesium fluoride is insoluble in ethanol, but it is easy to absorb moisture and deform.
Because of the analytical purity of anhydrous ethanol, the water content and impurities are already very low, and the volatility is very strong, which can dissolve organic impurities without damaging the antireflection film. Therefore, the author thinks that it is possible to clean the optical head lens with high-purity anhydrous ethanol. In the actual maintenance work, this did not damage the film on the lens surface. It is not suitable to clean with clean water, because magnesium fluoride is easy to deform after absorbing moisture, and there are many impurities in the water, which may damage the antireflection film and make the optical drive unable to work normally. Similarly, alcohol with more moisture and impurities is not suitable for cleaning the laser head.
6. Remove the laser head assembly.
If cleaning the focusing lens cannot eliminate the fault, the laser head assembly can be further disassembled for further processing. One side of the laser head assembly is sleeved on the cylindrical metal sliding bar, and the other side is connected with the stepping motor transmission mechanism.
The fixing point of the laser head assembly of Sony CDU3 1 1 CD-ROM drive is at the upper part of the CD-ROM drive. Just unscrew the screwdriver, unplug the flexible cable and take down the laser head assembly upwards. Before unplugging the cord, it is recommended to draw a straight line at the interface between the cable and the socket, and mark it well, so as to judge whether it is correctly returned when restoring. Do not disconnect the flexible cable when unplugging or plugging it in. Gently pull and insert, which is extremely difficult to maintain after damage.
7. Clean the laser head
The laser head (laser emitting tube and photoelectric receiving tube) is installed on a small circuit board, and there are generally eight outgoing lines, which are led out by flexible flat cables. The laser head circuit board is mainly installed on the side of the laser head assembly. The laser emitted by the laser emitting tube passes through the right-angle splitting path formed by the prism, and after being reflected by the focusing lens and the optical disc, it returns to the original path and is received by the photoelectric receiving tube. The circuit board of the laser head is fixed on the optical head assembly. When the circuit board is removed, the laser emitting tube and the photoelectric receiving tube can be cleaned, and the prism in the cotton wiping hole can also extend from the corresponding hole of the circuit board.
The optical head of Sony CDU3 1 1 optical drive cancels the reflective prism and directly emits and receives the laser beam through the focusing lens. You can use the cleaning method without disassembling the circuit board.
To clean the laser head of Sony CDU3 1 1 optical drive, you must first remove the black plastic dust cover covering the focusing lens. There are two buckles on both sides of the plastic dust cover, which are clamped at the bottom of the optical head assembly through two clamping holes in the metal casting, and bonded by adhesive, so that the bottom of the laser head faces upwards. Remove the adhesive on the buckles at both ends of the dust cover with the tips of tweezers, and then loosen the buckles and pull out the dust cover upwards.
After pulling out the dust cover, you can see that there is a round hole directly below the focusing lens, and the lower part of the round hole is facing the laser head. It is made of a thin copper wire into an L-shape, wrapped in cotton, carefully put the cotton into the bottom of the hole and wipe the photoelectric device of the laser head. When wiping, be careful not to scratch the surface of photoelectric device by laser, and don't break the elastic metal wire hanging the focusing lens, which not only plays a hanging role but also is the lead-out wire of the focusing coil, otherwise it will damage the focusing coil loop. It should be noted that the sealed cavity of the laser head of most optical drives is not easy to get dust, and it is not convenient to disassemble and clean. Careless operation is likely to cause the CD-ROM drive to be scrapped. It is strongly recommended that ordinary users do not implement this top operation.
8. Adjust the working current of the laser tube.
If the cleaned CD-ROM drive still doesn't work, it means that the laser tube has a certain degree of aging. Try to adjust the working current of the laser tube and increase the output power.
Sony CDU3 1 1 The potentiometer for laser working current of CD-ROM drive is on the side of the laser head assembly, which is only the size of mung bean. Many early laser power fine-tuning potentiometers are located on the side of the laser head assembly, and it is necessary to remove the laser head assembly to facilitate adjustment.
Before adjustment, mark the potentiometer with a colored pen and record the initial position; Turn the potentiometer by a small angle in a certain direction with a clock screwdriver. According to the author's experience, the poor contact of the fine-tuning potentiometer itself is also one of the reasons for the failure, and sometimes moving the potentiometer slightly can solve the problem. Therefore, it is strongly recommended that each adjustment should not exceed 10 degrees. Conditional users can use a multimeter to measure and adjust in the direction of decreasing resistance. Try the installation once every time you adjust the machine until you can read the disk correctly. The total adjustment range should not be too large to prevent the laser tube from being burned by excessive current.
After reading this article, you may want to clean your CD-ROM drive. But a little carelessness may lead to the scrapping of the CD-ROM drive. Because the current CD-ROM drive is not cheap, I think the following precautions should also be explained.
1, don't turn on the CD-ROM drive unless there is a fault. The CD-ROM drive is a precision device, which will be damaged if it is disassembled at will. Many irreparable faults of optical drive are caused by improper disassembly and maintenance. The implication is that as long as your CD-ROM drive works normally, don't bother.
2. Some optical drives can't read discs normally, which may be caused by poor disc quality, circuit failure, mechanical failure and even software factors. It is suggested to rule out other factors first.
3. When removing the optical drive, please pay attention to save all the removed parts. The loss of any small parts may cause the CD-ROM drive to be unrecoverable.
4. Since many parts of the CD-ROM drive are plastic, the operation should be moderate, otherwise the plastic parts will be damaged. Besides, don't use a hair dryer. Hot air may not only cause deformation of plastic parts, but also affect the normal performance of other parts.
5. Different models of optical disk drives have slightly different structures. This paper mainly introduces Sony series CD-ROM. How to disassemble and clean your CD-ROM drive mainly depends on your own exploration.
Clean maintenance and repair of floppy drive
Floppy drive is one of the external devices that need to be maintained in microcomputer system. Excessive dust accumulation is the most common cause of soft drive failure, and the key points of soft drive cleaning and dust removal are magnetic head, photoelectric detector and stepping motor drive screw. When cleaning and removing dust, be careful not to damage or displace the magnetic head, otherwise the damage and displacement of the magnetic head caused by human beings will be extremely difficult to handle. If the magnetic head is not too dirty, you can clean it with a cleaning disk without disassembling the floppy drive. If the cleaning effect with the cleaning disk is not good, you must disassemble the floppy drive and clean it manually. The processing procedure is described in turn below.
Eight, use the cleaning disk to clean the magnetic head.
Due to the frequent contact between the magnetic head and the floppy disk, all kinds of dirt on the disk will pollute the magnetic head, and too much dust will lead to the floppy drive.
The magnetic head can't read and write normally, which is the most common floppy drive failure. It is very simple to clean the floppy disk head with the floppy disk cleaning disk. Spray cleaning agent or anhydrous ethanol (analytical grade required) evenly on the surface of the cleaning disk, and turn on the power supply of the microcomputer. After the system is successfully started, insert the cleaning disk into the floppy drive, and the floppy drive will rotate by itself, and the cleaning disk will absorb the dirt on the magnetic head and the surrounding dust.
X. remove and clean the floppy drive.
1. Remove the upper cover.
The concave thin iron cover of the floppy drive is fixed on the cast aluminum base with screws. When cleaning manually, first unscrew one or two screws for fixing the upper cover with a cross screwdriver (some floppy drives have no screws, so this step can be omitted), and then gently pull the upper cover to both sides to separate the upper cover from the convex buckle on the cast aluminum base, and then remove the upper cover of the floppy drive.
Step 2 clean the magnetic head
The No.0 and 1 magnetic heads of the floppy disk drive are fixed on the top and bottom of the seek trolley respectively, and the lower magnetic head is stuck on the lower fixed arm of the plastic magnetic head trolley, so it can not move and is convenient for cleaning. The upper magnetic head is attached to the movable arm of the plastic magnetic head trolley through an elastic piece, and the other end of the upper movable arm is a spring piece fixed by a screw. When cleaning the upper magnetic head, you can use a little force, but if you pay too much attention, it will cause the magnetic head to deviate. It is extremely difficult to adjust the artificial magnetic head deviation fault, so you must be careful when cleaning.
When cleaning the magnetic head, dip the medical absorbent cotton in absolute alcohol or special magnetic head cleaning agent, gently scrub the magnetic head and wipe it for several times, then the stubborn attachments can be wiped off. When cleaning the upper head, gently press the head down by hand to avoid the head moving. After alcohol dissolves the dirt on the magnetic head, gently wipe the dirt.
3. Clean the spindle screw of the stepping motor.
In the process of reading floppy disk, if the system often gives the prompt that the file is read incorrectly or the sector cannot be found, it is mostly the phenomenon that the rotating shaft of stepping motor is poorly connected with the head car. Please check the lubricating oil on the spindle screw of stepping motor. If it is too dirty or solidified, you can scrub it with alcohol and add a little oil or high-grade butter. You can also turn the screw by hand to move the head carriage, thus cleaning the whole screw.
4. Clean the photodetector
In the old floppy drive, write protection detection, disk density detection, disk change detection and track 0 detection are all completed by photoelectric detectors, and the surfaces of photoelectric emission tubes and photoelectric receiving tubes can be wiped with cotton swabs dipped in a little anhydrous ethanol. The detectors of the new floppy drive are all microswitches, so they don't need to be processed.
Cleaning, maintenance and repair of mouse
The mouse is an indispensable input device for today's computers. When you find that the mouse pointer doesn't move smoothly on the screen, you should dust off the mouse. Cleaning and maintenance of the mouse can be carried out according to the following steps.
1, basic dust removal
The bottom of the mouse is in contact with the table for a long time, and it is the easiest to be polluted. Especially the rolling ball of mechanical and optical mechanical mouse, it is easy to bring dust, hair and fine fibers into the mouse. Taking the photoelectric mouse as an example, the method of disassembly and dust removal is explained.
There is a round plastic cover on the outer ring of the roller ball at the bottom of the mouse. Gently press the plastic cover, rotate counterclockwise, remove the plastic cover and take out the ball. Clean the dirt on two rotating shafts and one wheel inside the mouse with your fingers. When cleaning, avoid dust falling into the mouse. The ball can be cleaned with neutral detergent.
2. Open the lid to remove dust.
If the pointer is still not very active after the above treatment, especially the mouse pointer is not very active in a certain direction, it is mostly because dirt blocks the light of the photodetector. At this point, please use a Phillips screwdriver to remove the screws on the mouse bottom cover and the mouse top cover, and use a cotton swab to clean the dirt in the middle of the photodetector.
3, button troubleshooting
Wear of mouse buttons is a common failure that leads to button failure. The worn part is usually the small button on the mechanical switch of the button, or the plastic cover in contact with the small button. Emergency treatment can be solved by sticking a self-adhesive paper or brushing a layer of dry glue. A better solution is to change a button. Mouse buttons are generally available in electrical accessories companies, and the exchange of middle and left buttons that are not commonly used is also a common way.
The key failure of inferior mouse with miscellaneous brands is mostly broken reed, which can be replaced by small copper sheet in the microswitch of discarded electronic lighter. Poor soldering of components on the mouse circuit board may also lead to failure. The most common fault is that the solder joint at the bottom of the mechanical switch is broken or desoldering.
Cleaning and maintenance of keyboard
Keyboard is one of the most commonly used input devices. Even if one key fails, it is inconvenient to use. Because the keyboard is a kind of electromechanical equipment, it is used frequently, and the gap between the keyboard base and the keys is large, so dust is easy to invade. Therefore, it is necessary to clean and maintain the keyboard regularly.
The simplest maintenance is to tap the keyboard in turn to let the dust fall out; Second, clean the keyboard surface with a wet cloth, but be careful that the wet cloth must be wrung out to prevent water from entering the keyboard.
The long-used keyboard needs to be disassembled for maintenance. Disassembling the keyboard is relatively simple. Unplug the cable plug connecting the keyboard and the host computer, then put the keyboard face down on the workbench, unscrew the screws on the bottom plate, and remove the keyboard back cover. The disassembly and maintenance methods of mechanical key keyboard and electric contact key keyboard are introduced below respectively.
First, the mechanical key keyboard
You will see a circuit board when you remove the bottom plate of the mechanical key keyboard. The circuit board is fixed on the front panel of the keyboard by several screws, and the circuit board can be removed by unscrewing the screws.
Unplug the plug connecting the cable to the circuit board, and you can clean the dust on the circuit board and keyboard keys with a paint brush or oil painting pen. In general, it is not necessary to clean with a wet cloth. The key switch is welded on the circuit board, and the key cap is clamped on the key switch. If you want to remove the key cap from the key switch, you can gently pry the key cap with a flat screwdriver and pull it out. Generally speaking, the keycap does not need to be removed, and some keyboards are difficult to recover after the keycap is removed.
If a key fails, it can be repaired by welding the key switch. However, because the parts that make up the key switch are very small, it is inconvenient to disassemble and maintain. Due to mechanical failure, the service life of the repaired key is extremely short in most cases. The best way is to use the same type of keyboard keys or non-common keys (such as F 12) to weld the invalid keys and exchange positions.
Second, the electric contact key keyboard
After opening the bottom plate and cover plate of the electric contact keyboard, you can see three layers of films embedded in the bottom plate, namely, the lower contact layer, the middle isolation layer and the upper contact layer. The upper and lower contact layers are pressed with metal circuit wires and circular metal contacts corresponding to the keys, and the middle isolation layer is provided with circular holes corresponding to the upper and lower contact layers. All the keys of the electric contact keyboard are embedded in the front panel, and there is a rubber pad between the three layers of films on the bottom panel and the keys on the front panel. The protruding part on the rubber pad corresponds to the keys embedded in the front panel. After the key is pressed, the corresponding convex part on the rubber pad is depressed downward, so that the circular metal contacts of the upper and lower contact layers of the film contact each other through the circular hole on the middle isolation layer, and a key signal is sent out. There is also a small circuit board in the upper corner of the bottom plate, and its main components are keyboard socket, keyboard CPU and indicator light.
Because the keyboard with live contacts sends out key signals through the contact of circular metal contacts on the upper and lower contact layers, the circular metal contacts on the film need to be wiped clean with rubber. In addition, if there is oxidation at the outlet of the output interface, the oxide layer at the interface must be cleaned with an eraser.
There is generally no dust between the three layers of films embedded in the bottom plate. Just clean the film surface with a paint brush.
The rubber pad, the front panel and the buttons embedded in the front panel can be cleaned with water. If the keyboard is dirty, you can use cleaner. Some keyboards can remove all the keys embedded in the front panel, but it is very troublesome to recover more than 100 keys after removal. It is recommended not to remove them.
Clean all buttons, front panel and rubber pad, and you can install and restore. Pay attention to the following points when installing and restoring: first, pay attention to wait until the keys, front panel and rubber pad are dry before restoring the keyboard, otherwise the contacts in the keyboard will rust; Second, pay attention to the accurate alignment of the three layers of films, otherwise the bonds will not be connected.
Dust removal and maintenance of power supply
Switching power supply is the power supply of the whole host. Although the power of the power supply is only 200-350W, the output voltage is low and the output current is large, so the power switching transistor inside will generate a lot of heat. In addition to installing heat sinks on power transistors, fans are also needed to extract heat from the power box. When the fan exhausts air, a negative pressure is formed in the power box, which makes all parts in the power box absorb a lot of dust, especially on the blades of the fan. Dust accumulation on power transistors and heat sinks will affect heat dissipation, and dust accumulation on fan blades will increase fan load and reduce fan speed, which will also affect heat dissipation effect. When the room temperature is high, if the power supply cannot dissipate heat in time, it will burn out the power transistor. Therefore, the dust removal and maintenance of power supply is very necessary.
In addition to dust removal, the maintenance of power supply should also add lubricating oil to the fan. The specific operation method is as follows.
First, remove the power box.
The power box is usually fixed on the metal plate behind the chassis with screws. When removing the power supply, you can remove the power supply by unscrewing the fixing screws from the back of the chassis. Some cases have power supply fixing screws inside, which should also be removed. The power cord for supplying power to all parts of the main engine should also be removed, which has been introduced in "Chassis Dust Removal and Board Maintenance".
Second, open the power box.
The power box is made of thin iron sheet, and its concave upper cover is buckled on the concave bottom cover and fixed with screws. Remove the fixing screws and gently push the upper cover inward from both sides to take out the upper cover.
Third, the circuit board and heat sink dust removal
After the upper cover of the power supply is removed, the paint brush (or oil painting pen) can be used as the dust removal power supply. There is often a lot of dust under the circuit board fixed on the concave bottom cover of the power supply. You can unscrew the fixing screws at the four corners of the circuit board and remove it for dust removal.
Fourth, fan dust removal
The four corners of the power supply fan are fixed on the metal shell of the power supply with screws. When dusting the fan, first remove these four screws, and then remove the fan with a paint brush. You can also wipe the fan with a wet and dry cloth, but be careful not to let water enter the fan shaft or coil.
Five, fan refueling
After the fan has been used for one or two years, the rotating sound is obviously increased, mostly due to poor lubrication of bearings. When refueling the fan, first uncover the self-adhesive label on the front of the fan with a knife, and you can see the front bearing of the fan (and the domestic rubber cover needs to slide down to see it); There is a snap ring at the top of the shaft. Use tweezers to separate the clasp, then remove it, and then remove the metal washer and plastic washer respectively. Pinch the blade with your fingers and pull it out, and pull out the motor blade together with the rotor. At this time, the front and rear bearings are clear. Drop two or three drops of clock oil between the inner and outer rings of the front and rear bearings respectively (the oil should be immersed in the bearings), re-insert the shaft into the bearings, install plastic washers, metal washers and snap rings, affix self-adhesive labels, and then put the fan back into the machine. For bearings that have not been lubricated for a long time, the rotating sound is obviously reduced after refueling.