Computer No boot failure repair method

Computer can not boot is a lot of friends have encountered problems, the general computer can not boot with the power and the motherboard power-on circuit, today we say that the computer can not boot troubleshooting methods and procedures:

Judge the power of a computer

First, the power supply, press the switch, if not power, and then unplug the main engine power, with tweezers to the Green Line and black lines short-circuit, look at the power supply fan does not, if the turn, indicating the power is good, failure in the host.

Determine the computer mainframe switch is good or bad: and then the ATX power cord and the motherboard, the motherboard on the switch needle, reset needle, such as pull up, with tweezers short-circuit switch needle trigger power switch, see can boot, if you can, it is the main engine box switch bad, the main box switch to remove the cleaning. If the short-circuit switch needle trigger power or not boot, the motherboard really can not trigger the boot, the motherboard from the chassis to be removed from the overhaul. Remove the motherboard and clean the dust off the board before it prevents maintenance. First, see if the motherboard has no components burned, drum kit, the computer board has no burnt, disconnected. Put the motherboard, plug the fake load, plug the power, test card, do a good job overhaul preparation.

When the motherboard does not power, first by imposing electrical method to locate the motherboard does not power the specific fault circuit.

That is, a direct short circuit to connect the green and black lines. If this can be powered up at this point the fault in the soft boot circuit itself. If you can not add electricity at this time, indicating a serious short-circuit phenomenon. ATX Power supply internal protection, it does not allow itself to output voltage to the ground, so the power supply is automatically protected.

There may be short circuit, yellow line short circuit, Purple Line short circuit or the main power supply side of the CPU short-circuit. The above short-circuit phenomenon, in the actual motherboard failure occurred in any one will appear forced to add electricity and not power.

For the red line short circuit may be the main board of a field effect tube short-circuit or Power Manager short circuit, there is a door circuit short-circuit or I/O short-circuit, as well as a bridge short-circuit, there may be a 5V filter capacitor short-circuit. Take a look at the 5V ATX Value or the value of the power supply tube to see if the ground shorted out. The normal ground value is about 380 ohms, then you obviously measure the power supply tube to the ground 0 ohms or nearly 0 ohms, this time must be said that the motherboard chip to the ground short-circuit phenomenon caused by ATX protection.

For Yellow Line 12V short circuit is usually the power management itself and 12V filter capacitor short-circuit, for 12V short-circuit also may be a serial chip problem.

For the Purple Line short circuit may be the South Bridge, I/O, Fet and gate circuits, as well as the Purple Line filter capacitor and violet line voltage regulator diode caused.

For the CPU main power supply short-circuit may be FET, Power Manager and main power filter capacitor. For P4 motherboard, the CPU main power supply short circuit may also be the North bridge short circuit. Detect the ATX power cord to the ground short circuit, and then run the circuit along the line to find the related damaged components replaced.

If the power can be powered by force, the fault in the boot fault itself, at this point should be focused on the soft boot circuit itself and the soft boot circuit has links to other circuits.

1, COMs batteries, some motherboards, battery power is not enough to boot, but most of the motherboard does not have a battery does not affect the boot. Under normal circumstances COMs battery it is a voltage of more than 2.6V, sometimes 2.6v-3.3v about the voltage, this should also pay attention to.

2, COMs jumper, COMs jumper is not correct also can not boot, is generally jumping on the one or two is correct, the third is grounded, if the jump on the second third needle can not boot, attention. Some of the motherboard jumper jump wrong, you can boot, because the real crystal oscillator power supply is provided by the Purple Line.

3, Measuring power switch pins have 3.3V or 5V voltage, power switch needle is grounded, a needle by the purple 5V power supply, the middle will pass some door circuits, resistors and other electronic components, if there is no 5V or 3.3 voltage to switch needles, run the circuit, from the ATX supply of purple 5V to the electricity between the components to see the damage, replace.

4, measuring the crystal near the bridge, to see if the vibration, starting voltage of 0.5 and about 1.6V, if not, replace the crystal next to the filter capacitor and crystal oscillator itself. There is also a hand to touch, when the real crystal vibration of the two pins, hand touch motherboard can be added electricity, you can work. But when the real crystal vibration damage, you touch the real crystal oscillator you can add electricity, but the CPU does not work. At this time still continue to touch with the hand, so that when the real crystal two pins it is not memory, and then touch the hand when the real crystal vibration of the two pins, and will be over memory. This is the typical time the real crystal oscillator peripheral circuit damage phenomenon.