What to do if the motherboard power point is not lit

Solution for motherboard Power point is not lit:

1. Judge the computer power supply or bad

The 1th step, first connect the host power (ATX), press the host switch button, if not power, and then the power to connect the motherboard power plug off.

The 2nd step, using tweezers to power the green Line and black lines short-circuit, check to see the power supply fan does not turn. If the power supply fan turns, the power is good and the fault is in the host.

The 3rd step, Judge computer mainframe switch good or bad. ATX Power Cord and motherboard connection, 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.

The 4th step, if the short-circuit switch needle trigger power or not boot, that the motherboard really can not trigger the boot, the motherboard from the reed _. Remove and overhaul.

The 5th step, the motherboard removed, first the dust on the board clean, so as not to prevent obstruction maintenance. First, see if the motherboard has no components burned, drum kit, the circuit board has no burnt, disconnected.

The 6th step, put the motherboard, plug in the CPU false load, plug good power. Plug in the motherboard test card to prepare for overhaul.

2. Check the trigger Circuit

When the motherboard does not power up, first of all, through the imposition of electricity to locate the motherboard small power of 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 possible reasons are: the motherboard 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. Measured 5VATX data or power supply tube to the number of the eulogy 穸 margin fontanel, u5 mu margin jue  stool 380U or so, if the obvious power supply pipe to the ground 0 trillion euro or nearly 0 trillion, indicating that the motherboard chip on the ground short-circuit phenomenon caused by the 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 after the motherboard, the main power supply short-circuit CPU may also be the North bridge short circuit. Detect the ATX power cord to the pool short circuit, and then follow the line run circuit to find the related damaged components for the swap.

3. Check the soft boot circuit

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

(1) COMs battery. Some motherboards, battery power is not enough to boot, tantric most of the motherboard does not have the battery does not affect the boot. Under normal 愔 conditions, the COMs battery provides voltages above 2.6V (2.6~3.3v).

(2) coms® practise. COMs jumper is not correct and can not boot, generally jump on the one or two-pin is correct, the third pin is grounded. If you jump on the second and third pins, you will not be able to boot. Argon some of the main line jump after the wrong, you can boot, because the real-time crystal power supply is provided by the Purple Line.

(3) measuring power switch needle has no 3.3V or 5V voltage, the electric switch needle is grounded, a needle from the purple 5V supply, the middle will pass some electrical circuits, resistors and other electronic components. If there is no 5V or 3.3 voltage to the switch needle, run the circuit, from the ATX power supply purple 5V to the components between the two look at the damage, find the damaged and then replace.

(4) Measuring the crystal of the next bridge chip to see if the vibration. The starting voltage is about 0.5V and 1.6V, if not, replace the filter capacitor next to the crystal oscillator and the crystal oscillator element. There is a hand to touch the real-time crystal vibration of the two pins, hand touch the motherboard can be added power, you can work. Tantric is real-time crystal damage, you touch the real time after the crystal can be added power, Tantric is not working CPU. At this time or continue to touch with the hands of real-time crystal two pins, so that the power and memory, and then used to touch the real time crystal vibration of the two pins, voltage 乂 memory. This is the typical real-time crystal oscillator peripheral circuit damage phenomenon. Such motherboards are more difficult to repair. Real-time crystal vibration of the electric buckwheat circuit requirements are very strict, after the damage to the same color and size of the same real-time crystal, and Kai Vibration capacitor to replace, otherwise it will not be successful replacement.

Cause analysis of motherboard power point is not lit:

1, Power switch failure

When the power switch button because the aging can not be reset or chassis front panel because of the deformation caused by the power switch button can not be reset in time, using the switch is always in the state, then the power switch will appear after the main engine to start, but after 4 seconds automatically shutdown.

If the relevant line of the power switch appears short, when we connect the host power plug, the host will be powered up, 4 seconds after the automatic shutdown.

Check the method to unplug the board with the motherboard pw_on interface connected to the panel switch, directly with a small screwdriver short patch jumper, observe whether the host still 4 seconds shutdown failure. If the failure disappears, you can conclude that there is a problem with the switching circuit.

2, reset switch or jumper is shorted

Although this type of failure occurs, but with the increase in the use of computer time, the reset key use of the non-self-locking button switch will be due to the elastic failure of the press can not bounce, resulting in always connected state; or because the buttons on the front panel of the chassis are not installed or deformed, Cause reset switch button can not be reset in a timely manner, long time in the state; again, because of our overhaul process, pull, pull plug inadvertently caused reset line short connection. At this point, when we press the power switch, because the motherboard is always in the reset state, although the mains has been connected, the CPU fan and Power fan, video card fan, the motherboard fan has started to work, but the host does not have any boot traces.

If we have the debug card inserted into the PCI slot, we will immediately find that the reset light is always bright, you can immediately determine the power of the reset related to the phenomenon of short connection.

3, the memory is faulty

Memory of a chip or capacitance failure, sometimes will be able to power up after the host can be added, but there is no normal start "beep" sound, there is no memory alarm sound, long time can not start. Another situation is that if the CMOS settings when the frequency of memory or related parameters are set incorrectly, there will be power to add the host power, but is not to start and no alarm sound phenomenon.

Troubleshooting:

For such a failure we can first unplug the memory and then boot, if the host memory alarm, the CPU and host basic normal. Then try to clear the CMOS settings to see if the failure can be resolved, if the troubleshooting indicates that the cause of the fault is due to the memory parameter set in the CMOS error caused; if not, we need to use the replacement method, generally can be ruled out memory failure.

4. DMI data cannot be updated or ESCD data is not set to update automatically

The DMI (Desktop Management information) data is a collection of data stored in the BIOS chip to facilitate system calls and verifies that the DMI data is correct every time the system starts. I have not encountered a failure to boot the system because of DMI data errors.

ESCD (Extended System confirguation data) is stored in a CMOS chip to manage the collection of resource configuration data for a computer. With the rapid development of the computer and the application of Plug and Play technology, in order to avoid the conflict of resource occupancy, it is necessary to allocate limited system resources (such as address, IRQ,DMA, etc.) due to the rapid increase of computer peripheral resources, such as ACPI,APM,USB,MODEM,INC,VGA card, etc. Will cause the computer self-test time increases, causes the startup time to be too long.

In fact, most of the time, the computer board is not frequent, does not need to be a detailed self-test every time, so the computer designed ESCD data to simplify the start-up process of the computer, if the computer does not change the hardware, at the start of the computer directly call the ESCD data to allocate system resources to control the operation To save your computer's startup time.

However, when we change the hardware of the computer, such as changing the CPU type, replaced the memory, increased memory, acquired the optical drive, changed the graphics, etc., if we do not force the update ESCD data, then the computer will still be in the old configuration to allocate system hardware resources, At this point, there will be a failure to start properly or not recognize the newly acquired hardware. The solution we only need to enter the CMOS setup "Pnp/pci CONFIGURATION", the "reset ESCD" set to "Enabled" (after the computer is restarted, this option will automatically convert to disabled) but.