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ASUS K8N MOTHERBOARD REPAIR WITHOUT RESET INSTANCE

Lay before this board for a long time, and we have no CPU can be measured, naturally do not know good or bad, online auction to buy the CPU, the CPU is repaired, ready to test Hello!





Repair this board, learned the geography of some powerbecause there is no process taking a lot of costly mistakes.
Is a power failure situation, there is no reset, the system continues to remain reset state, master P, C, R principles repair.






Saw the unconscious is not reset immediately check the CPU working conditions, digging miles! CPU is not powered, also check the CPU power supply of the relevant line, did not send EN to the PWM chip, no wonder no Vcore, and there is no VID signal, obviously the first hurdle (North Bridge) hung up, K8 architecture since there is no northbridge ( actually integrated within the CPU), memory, first check the power supply, after investigation did not, went to the CPU VDDQ also found no problem, some are originally went to the North Bridge voltage CPU, the checked , some are normal, but some did not supply the associated, these non-voltage power supply with the South Bridge (integrated bridge), a common share, and truly suffered. South Bridge Voltage 1.2V No, there are 1.6V, and also did not, did not get.





G had to say off the voltage so lowmiddle resistor is larger, the result is still the same(Not seriously run the linesimply has noresistance)Would like to break it up ...... for the one, the result is still the same.

Grew more and more strange, so he changed back.
Read the nexteven with transistors(Lost time did not knowwhere the transistor is doing.)
Volume a bit reference voltage of 3.3V down the topbut through the resistor divider, the voltage actually gone!


 The other was a resistance to ground, figured, there mustobviously 1.2V ah! How not.

 Way to play a little resistance, and no case of low impedance ah!
 Simply removed the transistor ..... really amazing, 1.2V there!
 Later, after inspection, not a bad transistor ...........
Then check the other one for MOS, Fengyun MOS, is to provide1.6V power supply to the South Bridge, but it did not even out?
D voltage

                                         
                          S voltage


 G is the voltage again, to the side, has been suspected of MOSdestroyed.


 Altogether removed, really, bad!
 MOS checked, confirm that it is bad.
As sure is bad, and from the waste board put to find a good product.
 Power on again, and she ran yards
 Measure the voltage.
1.2V appeared.
 1.6V is also normal.
 Previously suspected transistor voltage, good, also pulled down,this is correct,
0.032V (hit 2000mV stalls)


To the side, complete repair Hello!

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