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 Clock signal , will produce two-way 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
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