Computer Power detection method

1 People for Wake Power detection

In short, it is to connect the computer motherboard 20 pin plug, with a wire (such as a thin wire, the specific people to play the imagination) a green line, a black line (there are 8), if the power supply fan turned on the power is good.

With a thin wire to the ATX plug 14 feet ps-on and the other end of the 3rd, 5, 7, 13, 15, 16, 17 feet of any short foot connection, this is the ATX power supply in standby state of artificial wake-up start, when the ps-on signal should be low level, PW-OK, +5VSB signal should be For the high level, the most important thing is whether the switching power supply fan will rotate, if the rotation indicates that the power should be no problem (in the absence of a multimeter this is the most direct way to determine whether the power supply is damaged).

2 Offline Live detection

Under normal circumstances, in standby state of ps-on and Pw-ok two power signals, one is high, the other is low level, plug 9 feet only output +5VSB voltage, as long as the meter to measure the voltage to the parameter value, you can determine the result of the problem.

Computer power Maintenance common sense of power maintenance one, the type of failure: power supply no output such as the most common fault, mainly performance is not working power. When the host confirms that the power cable is connected (some of which have a power supply to be switched on), no response is turned on, the monitor does not display (the monitor led flashes). No output fault is divided into the following: ①+5VSB no output before the +5VSB in the main power supply AC power should be normal 5V output, and the motherboard to start the circuit power supply. Therefore, +5VSB no output, the motherboard boot circuit cannot act, will not boot. This fault-making method is: the power supply from the host removed, connect the host power AC input line, using a multimeter to measure power output to the motherboard of the 20-pin Purple Line (+5VSB) of the voltage, such as no output voltage, the +5VSB line is damaged, need to replace the power supply. For some motherboards with the standby indicator, no multimeter, you can also use the light to determine whether the +5VSB has output. This kind of fault indicates that there is a device damage inside the power supply, and the insurance is likely to fuse. ②+5VSB has output, but no output of the main power supply this situation standby indicator light, but press the power-on key after no response, Power fan does not move. This phenomenon shows that the fuse is not fused, but the main power supply does not work. The Fault judgment method is: the power supply from the host, the 20-core Green Line (PS On/off) to the ground short-circuit or a small resistor to the ground to make its voltage below 0.8V, at this point, the power supply is still no output and no indication of the fan rotation (note: A very small number of power supply in the no-load when not working, except in this case), then the main power has been damaged Bad, need to replace the power supply. ③+5VSB has output, but the main power supply protection This situation is also more, because the manufacturing process or device early failure will cause this phenomenon. The difference between this phenomenon and ② is that the fan will wobble when the power is on, that is, there is output, but due to failure or external factors to protect. In order to eliminate the power load (motherboard, etc.) damaged short-circuit or other factors, power supply can be removed from the host, the core Green Line to the ground short-circuit, such as the power output is normal, it may be: I. Power load corruption causes

Power protection, replace the damaged power load; Ii. power supply internal abnormal cause protection, need to replace power supply; Iii. power supply and load coordination, poor compatibility, resulting in a specific load protection, this situation needs to be further analyzed. ④ power supply is normal, but the motherboard does not give the boot signal in this case also performance for power supply without output, can be measured through the multimeter 20 core in the Green line to the ground voltage in the host after the boot down to 0.8V below, if not down or not below 0.8V, may lead to power failure to boot. Two fault type: The power supply has output, but the host does not display. This situation is more complex, it is difficult to determine, but can be considered from the following aspects: 1 power supply of the output of all the way or multi-channel output voltage is not normal, available multimeter test; 2 No P.G signal, that is, to measure whether the gray line in the 20 core line is a high level, if the low level, the host will always be in a reset state, can not start. 3) Power output rising along or abnormal timing, or the motherboard compatibility is not good, can also cause the host does not show, but this kind of situation is more complex, need to rely on storage oscilloscope can be analyzed.

Practical manual: Power output conductor corresponding function full contact practical manual power output conductor corresponding function full contact power supply is the heart of the mainframe, the steady flow of the computer to provide energy. Is not everyone thought that the wood will also recommend the power, haha, today we do not talk about products, mainly chat about each power supply has the output wire. For different positioning of the power supply, the number of its output conductor is different, but can not be separated from the colorful 9 kinds of colors: yellow, red, orange, purple, blue, white, gray, green, black. A sound PC power supply in these 9 colors of the wire (the current mainstream power is omitted white line), their specific functions to believe that there are many netizens do not know, today's wood to give you a detailed explanation.

Color variety of power output wire yellow: + Yellow: +12v: + Yellow Line in the power supply should be a large number of one, with the addition of the CPU and PCI-E graphics power supply components, the role of +12v in the power supply important. +12V has been the hard drive, optical drive, floppy drive spindle motor and seek motor to provide power, and for the ISA slot to provide operating voltage and serial circuit logic signal level. If the +12v voltage output is not normal, often caused by hard disk, CD-ROM drive, floppy disk performance instability. When the voltage is low, the performance for the CD-ROM disk serious, hard drive logic is increasing, often bad way, the system is prone to panic, can not be used normally. On the high side, the speed of the optical drive too high, prone to runaway phenomenon, more prone to fry phenomenon, hard drive performance for stall, fly. At present, if the +12v power supply shortage will directly affect the performance of PCI-E graphics, and affect the CPU, directly caused the panic. Blue:-Blue: -12v:- -12v voltage is for the serial port to provide a logical judgment level, the need for a small current, generally under 1 amperes, even if the voltage deviation is larger, it will not cause failure, because the logic level of 0 levels to 3 to -15v, has a very wide range. Red: + red: +5v: + +5v wire number and yellow wire equivalent, +5v power supply is provided to the CPU and PCI, AGP, ISA and other integrated circuits operating voltage, is the main computer work power. At present, the CPU uses the hybrid power of +12v and +5v, and its requirements are not as high as before. It is only in the latest Intel ATX12V version 2.2 that it strengthens the power supply of +5v and strengthens the power of dual-core CPUs. It's power quality

The quality of the quantity is directly related to the system stability of the computer. White:-White: -5v:-At present, there are few power supply with white wire, -5v is also for the logic circuit to provide judgment level, the need for the current is very small, generally do not affect the normal work of the system, the probability of failure is very small.

Orange: +3.3v This is the ATX power supply specifically set up to provide power to the memory. The newest 24pin main interface power supply, the emphasis strengthens the +3.3v power supply. This voltage requirement is strict, output is stable, ripple coefficient is small, output current is big, want 20 amperes above. Some of the high-end motherboards in order to secure the use of high-power field tubes to control the power supply of memory, but also because the memory plug instead of the pipe burned. With +2.5v DDR memory and +1.8v DDR2 memory platforms, a voltage conversion circuit is installed on the motherboard. Purple: +5VSB (+5v standby Power) The ATX power supply provides +5v 720MA power to the motherboard via PIN9, which provides power to the WOL (wake-up on Lan) and the power-on circuit, USB interface and other circuits. If you do not use the network wake-up function, please turn off this type of functionality, jumper removal, you can avoid these devices from the +5VSB power supply end of the separation of current. This output of the power quality, directly affect the computer standby is the power consumption, and our electricity tariffs directly linked. Green: p-on (power switch end) to control the power supply through the level of the open. When the signal level of the port is greater than 1.8V, the main power supply is off, and if the signal level is less than 1.8V, the main power supply is open. Use a multimeter to test the output signal level of the foot, generally around 4V. Because the voltage of the foot output is the signal level. Here is a preliminary assessment of the power quality of the soil method: the use of wire short green port and any black port, if the power supply does not respond, indicating that the power supply damage. Now a lot of power to join the protection circuit, short power after the judge no additional load, will automatically shut down. Therefore, we need to carefully observe the power supply instantaneous start. Gray: P-ok (Power signal line) in general, Gray line P-ok output if above 2V, then this power can be used normally; if P-ok output is below 1V, this power supply will not guarantee the system's normal operation and must be replaced. This is also to judge the power supply life and whether the main means of eligibility. Understanding the role of wire types of DIY players is a compulsory course, is the only way to upgrade the novice users, we have mastered the type of power lines can be clearer understanding of the output specifications of power supply, convenient for everyone to buy power and troubleshooting.

The fault of the microcomputer is often on the power supply, and the fault caused by the power supply is approximately the 20%~30% of the total breakdown number of all kinds of parts. and the fault detection and maintenance of various parts of the host must be based on the normal supply of power supply. Below we have some discussion about the common problems of power supply.

Micro-computer power supply generally easy to fault there are the following: fuse fuse, power supply without output or output voltage instability, power supply has output but no display, power load capacity is poor. The following is a description of the maintenance methods:

1. Fuse fuses

Failure analysis and removal: When such faults occur, first open the power supply shell, check the power supply fuse is fused, according to which can be preliminarily determined whether the inverter circuit has failed. If so, the following three situations result:

• A bridge rectifier diode is penetrated in the input loop

• High Voltage filter electrolytic capacitor C5, C6 is penetrated

• Inverter power switch Tube Q1, Q2 damage

The main reason is that DC filter and transform oscillation circuit work in high pressure (+300v), large current state, especially due to the change of AC voltage is large, the output load is heavier, easy to fuse failure. The DC filter circuit consists of four rectifier diodes, two 100kω and about two 330μf electrolytic capacitors, and the transformation oscillation circuit is mainly composed of two types of high-power switch tubes mounted on the same heat sink.

After the AC fuse fuses, power off the plug, first of all, carefully observe the circuit board on the surface of the high pressure components have been a breakdown of burning paste or electrolyte overflow traces, if no abnormalities, using a multimeter to measure the value of the input, if less than 200kω, the end of the local short-circuit phenomenon, and then measured two high-power switch tube E, C Polar resistance, if less than 100kω, then the switch tube has been damaged, measuring four rectifier secondary tube positive, reverse resistance and two current limiting resistance, using a multimeter to measure its charge and discharge situation to determine whether normal. In addition, if the replacement of the switch tube, if the same model can not find the choice of substitutes, should pay attention to the collector-emitter reverse breakdown voltage Vceo, collector maximum allowable dissipation power PCM, collector-base reverse breakdown voltage VCBO parameters should be greater than or equal to the parameters of the original transistor. Another thing to note is: Must not detect a component damage, replace the direct boot, this is likely because other high pressure components are still faulty and will replace the components damaged. It is necessary to the above circuit of all high pressure components of a comprehensive inspection and measurement, can completely eliminate the fuse failure.

2. No DC voltage output or voltage output instability

Failure Analysis and elimination: If the fuse is intact, in the case of load, all levels of DC voltage without output, the possible causes are: open circuit, short-circuit phenomenon in the power supply, overvoltage, overcurrent protection circuit failure, oscillation circuit is not working, power overload, high frequency rectifier diode is breakdown, filter capacitor leakage.

The processing method is:

• Use a multimeter to measure the system board +5v Power source of the ground resistance, if more than 0.8 ω, it shows that the system board without short-circuit phenomenon;

• The microcomputer configuration is minimized, that is, the machine only leaves the motherboard, power supply, buzzer, measuring the output of the DC voltage, if there is no output, indicating fault in the microcomputer power control circuit. The control circuit is mainly composed of integrated switching power supply controller (TL-496, GS3424, etc.) and overvoltage protection circuit, and whether the control circuit work is normal or not is directly related to the DC voltage and output. Overvoltage protection circuit is mainly composed of small power transistor or SCR and related components, can be used to measure whether the transistor is penetrated (if the SCR is required to be welded under the measurement), the relevant resistors and capacitors are damaged.

• Use multimeter static measurement of high-frequency filter circuit rectifier diode and low voltage filter capacitor is damaged.

3. Power supply has output, but no display on the boot

Failure Analysis and elimination: This failure may be due to the "power good" input reset signal delay time is not enough, or "power good" no output.

After the boot, the output of "power good" is measured with a voltmeter (1 feet of the plug of the main engine), if there is no +5v output, then check the delay components, if there is +5v output, then replace the delay circuit delay capacitor.

4. Poor power load capacity

Fault analysis and elimination: The power supply only to the motherboard, the floppy disk power supply can work, when the hard drive, the optical drive or plug in the memory, the screen will become white and not work properly. Its possible causes are: the transistor operating point did not choose good, high-voltage filter capacitor leakage or damage, voltage regulator diode heating leakage, rectifier secondary pipe damage.

Replace each transistor in the oscillating circuit to increase its gain, or to adjust the working point of the transistor. After detecting the defective parts with a multimeter, replace the SCR, voltage regulator diode, high voltage filter capacitor or rectifier diode.