Motherboard not powering up what's going on

Motherboard not powering up what's going on

Why the motherboard does not power on and how to fix it:

Connect the power button, no reflection (CPU, Power fans do not turn, the host power LED is not lit);

Probably the reason for this result is:

1, the power itself has problems;

2, the battery has the problem;

3, clock frequency control is not normal;

4, CMOS jumper error;

5, the CPU burned out;

6, other accessories problems.

So how to solve it?

A. Power check

1, first, check the power to confirm its good or bad. Practice: Verify that the power supply interface is connected to the motherboard, if there is no problem, replace the old power supply with a new power supply to see if the motherboard can be lit (the old power supply to other machines to confirm its integrity, such as the power supply on other computers working properly, directly excluding power damage may be the power supply on other computers working properly, Directly eliminate the possibility of power damage, fully automatic BGA disassembly pad If you still do not make the motherboard power on the power failure to troubleshoot, proceed to step 2;

2, check the motherboard instructions to verify that the CMOS jumper is correct, such as the exclusion of this situation, proceed to step 3;

3, replace the motherboard battery (we all know, if the motherboard battery short-circuit, the same as the motherboard of the CMOS has been in the "clear" state, the motherboard will not be able to work on the power), such as the elimination of battery problems, proceed to step 4;

4, to see whether the CPU inserted in place, whether there are burned traces, replace and try again;

5, direct observation of the motherboard, the entire motherboard without obvious cracks, to see whether the power control chip overheating and burned traces;

6, the power supply Plug and the motherboard socket connection, measuring the motherboard "Pw on" the pin voltage, very normal; 3, with universal table Test crystal oscillator Y4 ends, no current, 4, remove the motherboard CR2032 3V battery, measuring the voltage between the two ends of 0V, and then use Ω file test, found that its positive and negative has shorted out.

Two. Watch the motherboard:

For a few reasons above, we can first eliminate this failure due to power supply damage because new power has been replaced in conventional detection. So we should consider from other aspects, such as not in the time drive, hard drive screws are not tightened, in the transport or collision screws loose fall to the motherboard, or the motherboard itself is not installed and so on, and chassis a screw contact. These may cause the motherboard to short-circuit, resulting in the protection State, unable to boot. IR BGA back soldering station

Three. Analysis Circuit

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 you can add power at this point the fault lies in the power-on 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. Test 5V? ATX Value or power supply tube to the number of the eulogy 穸 margin fontanel, u5 mu margin jue  stool about 380 ohms, then you obviously measured power supply pipe to the ground 0 ohms or nearly 0 ohms, this time must be said that the motherboard chip on 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 relevant damaged components, replaced. It is recommended to use professional hot air drawing and soldering station.

Summarize:

1, the motherboard does not supply a lot of reasons, this motherboard has no obvious damage traces, so should first suspect CMOS battery power supply or short circuit.

2, with the help of the voltage, current, resistor file with the use of multimeter, can be more than twice.