Laptop boot process and how to determine fault current meter pointer

Description: When you press the power switch , such as the normal power supply (3.3V and 5V power
supply and CPU normal output) , power chip will produce a PG ( power good ) signals were sent to the north
and south bridge and CPU. When the South Bridge to the PG signal received , it will produce a two- way
clock control signal PCISTOP and CPUSTOP sent to the clock circuit, …
When you press the power switch , such as the normal power supply (3.3V and 5V power supply and
CPU normal output) , power chip will produce a PG ( power good ) signals were sent to the north and south
bridge and CPU. When the South Bridge to the PG signal received , it will produce a two- way clock control
signal PCISTOP and CPUSTOP sent to the clock circuit , clock circuit generates a clock signal , which sent
South Bridge Road, PCI clock , when the South Bridge received received Clock signal , will produce twoway
reset signal : PCIREST ( signal reduction ) and DRVREST ( device reset ) to reset the various parts of
the circuit board on which way to reset PCIREST North Bridge , when the North board received reset signal ,
the Will produce CPUREST to reset CPU, when the CPU reset signal received after the ( then CPU power ,
the clock reset conditions are available a ) indicates that the machine ‘s hard starting the process has been
completed , then the soft start .
POST CPU instruction execution process:
1: 12 cache and test the integrity of North and South Bridges
2 : Test 640K base memory is intact
3: test card , find the card ‘s BIOS, and call their initialization related equipment
4: Find other device BIOS, and call their initialization code to initialize the associated equipment .
5: Find complete BIOS other equipment , the system BIOS will display its splash screen , and began
testing extended memory and give the appropriate address .
6: testing a number of standard equipment, including hard drives, optical drives , serial , parallel ,
floppy , etc. .
7: After detection of standard equipment , support plug and play code within the system will start to
detect and configure the system Plug and Play devices , and distribution of these devices interrupt
addresses , DMA channels and I / O ports and other resources .
8: After all the hardware detection and interrupt addresses are assigned , that is all the hardware set
up a hardware system , then will generate a “ESCD” file ( the system BIOS and operating system used to
exchange information on hardware configuration A means of CMOS in these data there ), CPU will generate
the ESCD and the last of the ESCD were compared, the differences will update the data in the ESCD .
9: ESCD update , CPU also put POST and the interrupt service routine is finished , then the system
will be the bootstrap procedure .
How to judge the machine using the adjustable power supply failure
1 : Plug in the adjustable power supply , ammeter pointer may occur following changes:
a: ammeter pointer without any changes: the main power supply no output, check standby and
protection of the isolation circuit, the adapter interfaces
b: 1A ammeter pointer placed around from side to side to keep : the main power supply capacitor
leakage
c: ammeter pointer has been the biggest hit : the main power supply circuit , check capacitors , diodes,
and Xu Yong main power supply of all chips , charging unit , CPU power , etc.
d: ammeter pointer minor swing : Help to protect the normal and standby
2: standby to normal , press the power button :
a: current meter pointer does not move : typically 3.3V and 5V output without
b: 0.8A ammeter pointer placed down , then out to the original position (0.1A), shows poor
performance of the system power supply , ( such as the MAX1632, ADP3421), another possibility for the
start signal is not sustained, check terminals , that is, Start circuit is good or bad .
C: current meter pointer should be placed 0.8A, but not moved to a 0.4A ( check the clock circuit , the
components are not working , resulting in no current consumption .
d: ammeter pointer to play in the end , the voltage is pulled low (3.3V and 5V , or CPU power supply
output has short circuit , the first power , to play with a multimeter on resistance )
e: ammeter pointer hit 0.8A Department did not move (hard start normal, it says the first step in selftest
you have not seen )
f: ammeter pointer hit 0.8A , the swing is not moved a bit ( or a basic first step in self-test memory is
not too bad in parts)
g: ammeter pointer hit 0.8A , the swing twice and would not move the ( bad memory or graphics )
h: ammeter pointer hit 0.8A , the swing three times , the machine still does not light ( or the screen part
of the graphics are not bad work , try an external monitor

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