Computer Power Maintenance And Repair
In general, the computer work the sound is very small
, in addition to the sound of the hard disk read and write data, the main cooling fan is the sound, especially in the switching power supply fans the loudest sound. Some switching power supply long-term use, at work will produce some noise, mainly due to poor power supply fan rotation caused. Caused by poor power supply fan turn many reasons of noise, mainly in the following areas:
- Fan motor bearings connected sets the axial deviation, causing the fan blade is stuck or grazing, issued a "chug" sound.
- Fan motor bearings loose, making the blades in the rotation issue "buzzing" sound.
- Fan motor axial movement, the pads wear, the axial gap increases, after power was given a "chug" sound.
- Fan motor bearings are used in low-grade oil, the lower temperature in the environment with easy access to the fan bearing dust stick together, increase the resistance of the motor rotation, the motor was given a "buzzing" sound.
If the fan is not working properly, it is possible to burn a long time, the motor, causing damage to the switching power supply. Above the power supply fan for sound reasons, usually require the following maintenance work.
Power Box is the easiest place to gather dust, if the power supply fan sounds large, generally every six months, the fan removed, wash the dust and processing point oils, simple maintenance. As the power supply fan is enclosed in a box, the removal is not easy, so be sure to pay attention to methods of operation.
(1) demolition of the host disconnect the fan, unplug the power behind the input and output cord. Then unplug the power connector and plug all the accessories and connection, remove the power box mounting screws, remove the power supply box. Observe the power supply box appearance of the structure, remove the screw with reasonable accuracy, remove the cover. When wire should take cover from the gap at the same time pry out. Remove the four screws fixed the fan, remove the fan, you can temporarily under the two welding power cable.
(2) The cardboard dust cleaning isolation in the power circuit board and fan, the used a small brush or damp cloth to wipe dust, wipe clean. Paper Tiger can also use the fan blades and bearings blowing the dust.
(3) lubricating tear stickers, rubber seal with needle nose pliers pick out pieces. Find the motor bearings, while lubricating the fan struck the side of his hand, so that oil flows evenly along the bearing, usually add a few drops can be. Pay attention to whether there are two ball bearing fan bearings, do not ignore the inlet side of the bearing to the oil, oil not only on the spindle.
Lubricants special lubricants must use a computer or high light sewing machine oil, do not use the general use car oil. Finally, the rubber seal fitted sheet, labeled.
(4) plus pads If the fan is the larger issue of "chug" noise, dust cleaning and processing of light lubricant normally can not solve the problem, then open the fan blades will find more in the axial sliding distance large. Remove the rubber seal piece, the use of needle nose pliers clasp separate axis, the following is the gasket, then you can remove the fan rotor (with fan Ye Liancheng line) to the original gasket as the standard, with the thickness of the thin plastic film made moderate as a gasket. To make a good gasket placed between the original pads, note pads not too thick, axial to maintain a certain distance. Hand struck blades, fan run smoothly on it. Finally loaded clasp, rubber seal piece, labeled. Remember the spindle on the gasket, rubber sealing film, spring and other small parts, so I do not know how to reset after scattering.
In short, power is the computer the incentive to work out if the power supply fan fails, the consequences are serious, and therefore the power to carry out regular maintenance and repair.
According to the data that caused the power failure about various parts of the computer machine 20% of the total number of failures to 30%. The various parts of the host failure detection and repair, but also must be established on the basis of the normal power supply. Let the power of the common failure to do some discussion. Computer power generally susceptible to failure are as follows: blown fuse, power supply without input or output voltage instability, power output, but there is no display power, poor power supply load. The repair methods are introduced below:
1. Troubleshooting blown fuse
Recurrence of such failure, the first turn on the power shell, check the power fuse on the fuse, whereby you can initially set the inverter circuit is down. If so, the following three conditions are not caused by outside: the input diode bridge rectifier circuit is a breakdown; high-pressure filter electrolytic capacitors C5, C6 is the breakdown; inverter power switches Ql, Q2 damage. The main reason is because the DC filter and transform the work in the high-voltage oscillator circuit for a long time (ten 300V), high current state, especially because of the larger AC voltage, output load is heavy, is easy to fuse failure occurs. DC filter circuit consists of four rectifier diodes, two current limiting resistor of about 100k and two 330uF electrolytic capacitors around the composition; transform oscillator circuit is mainly composed of the same heat sink mounted on the two models of the same high-power switch tube.
AC fuse blows, unplug the power plug off, the first circuit board carefully observed the appearance of the high voltage components have been burnt or breakdown traces of the electrolyte overflow. Without exception, with a multimeter to measure the value of the input: If less than 2OOk, shows a partial short circuit back then were measured in two high-power switch tube e, c resistance among most; if less than 100k, the description of switch tube is damaged, measuring four rectifier diodes, the reverse current limiting resistor and two resistors with a multimeter to measure the charge and discharge conditions to determine whether it is normal. Also when replacing the switch, if you can not find the same types of products to choose alternatives, they should pay attention to the collector - emitter breakdown voltage Vceo, the maximum allowable collector power dissipation Pcm, the collector - base hit reverse through voltage Vcbo parameters should be greater than or equal to the original transistor parameters. Another to note is that: a component must not be damaged in the identified, direct start after replacing, this is likely due to other high voltage components are still failures, in turn replace the damaged components. Must be on the circuit components conduct a comprehensive inspection of all high-voltage measurements, to completely rule out the blown fuse fault.
2. No DC voltage output or voltage output instability
If the fuse intact, in a load case, no output DC voltage levels, the possible reasons are: power appears open, short circuit; over voltage, over current protection circuit failure; oscillator circuit does not work; power overload; high-frequency filter circuit in the rectifier diode rectifier is the breakdown; filter capacitor leakage and so on.
Processing methods; system board with a multimeter measuring ten 5V power supply to ground resistance, if greater than 0.8, it indicates the system board without short circuit. The computer configuration to minimize the machine, leaving only the motherboard, power supply, buzzer, measuring the output DC voltage, if still no output, indicating a fault in the computer power supply control circuit. Controlled mainly by the integrated circuit switching power supply controller (TL-496, GS3424, etc.) and over-voltage protection circuit, control circuit is working properly is directly related to whether the output DC voltage. Over-voltage protection circuit mainly by the low power transistors or SCR and related components, the transistor can be used whether the multimeter to measure the breakdown (if you need to weld measured SCR), related resistors and capacitors for damage.
3. Power supply output, but no display power
When this failure may be due to "POWER GOOD" Reset the input delay time is not enough, or "POWER GOOD" no output. Boot, with the voltmeter "POWER GOOD" the output of the (then host of the power plug pin 1), if there is no +5 V output, then check the time delay components; if +5 V output, replace the extended delay circuit when the capacitor can be.
4. Poor power supply load
Power supply only to the motherboard, floppy drive to work when power when connected to the hard drive, optical drive, or plug in memory, the screen was not working properly since the change. The possible reasons are: the transistor operating point does not choose the good, high-voltage filter capacitor leakage or damage, leakage heat regulator diode, rectifier diodes and other damage.
Exchange of each transistor oscillator circuit, to increase the gain, or transfer large transistor operating point. Detected a problem with a multimeter parts, replace the SCR, voltage regulator diode, high voltage filter capacitor or rectifier diode can be.
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