Checking the problem by the Symptom in laptop motherboard
Checking the problem by the symptom and make service log measurement service log is made by technicians to make a record of faulty
motherboard electricity and signal system, every single voltage and signal measurement are notice in this
log.To narrow the search of missing voltage and signal, divide by checking symptom of faulty to be :
1.
Dead motherboard
No led indicator at all,no fan moving ,no power .This motherboard
require an adapter
voltage(12V_15V_16V_18.5V_19V_20V) also 3V and 5V to completely VALW power
supply need without this impossible motherboard to a life.Starting with checking power jack to ensure adapter continuity supply P channel mosfet transistor(adp fet's) ended to P channel mosfet transistor for battery
fet.This line power
contribution called Main circuit line of VALW power supply.Open
schematic (ensure
match motherboard and schematic code)for charger IC page and trace started
from DC jack to adp P
channel mosfet (or same motherboard using Inductor or Diodes to replace
transistor on circuit)
make sure continuity supply for charger IC VCC,DC/DC main supply IC VCC
and each Upper N channel SOURCE to produced 3V and 5VALW. Signal confirmation EC Bios working name is RSMRST# for 3.3V
2.
No display motherboard
led indicator on,switch on but no internal or external display.There are 3 boot strap device supported to make motherboard load to
display of course after Bios system working properly :
A.Processor Without this motherboard will not be able to display.power name by
VCCORE and
enable signal called VR_ON or V_RON as a trigger from Embedded controler(EC) to enable
or
disable VCCORE IC.Processor need power supply greater than 1.05V but some AMD processor only
need power greater than 0.9V. B.SODIM SoDim power called VCCRAM.There are 2 VCCRAM need to make sodim working:1.5V and 0.9VTT for DDRIII and 1.8V_0,75VTT for DDRII.Get the schematic and find
VCCRAM/VTT measuring point to ensure sodim powered well. C.CHIP's(SB/NB/VGA) Chip Power called VCCP.There are very complex power supply system.Chip
need 19VALW5/ 3VALW5/ 3VS1.2VS1.05VS.
Chip also have they own RAM and need power supply to working.Finding measuring point on chip by opening chip page on
schematic or by checking Voltage rail for specific motherboard.Signal confirmation chip was ok on chip PWRGOOD for 3.3V or tolerance
10% Note every missing power and replace damage component.
The Technical Junction |
3.
Power Drop
Led Indicator on ,switching on,on for few second after that back off.This symptom happen because power spike or there is shortage on VS line.Processor and Chip are most which can cause power spike,look at VCORE
and VCCP circuit line ,circuit has provide stockpile empty pad to add some more capacitor
to anticipate power spike during boot up process. The other problem of power drop are some shorted on VS line so after
switch on VS active 1 or more VS line got a feed back caused power down and shutdown the system.
4.
VALW SHORTED
Adapter led Blinking or drop,Current high Voltage down,no movement at
all(Dead shorted motherboard)
This feed back comes from VALW main power supply line.Checking this on schematic by opening Charger IC page and trace any sorted component on VIN and VBAT+line.Finding shorted by checking all component having Cathoda and anoda .this are
most potential component conduce shorted.
5.
No switch/Can not Switch on
There are few system switch found for different circuit
manufacture. measuring switch voltage on one of switch button pin,before switch standby power available for 17~19V
comes from 51_ON#and after switch on power switching vcc 3.3V replace 51_ON# supply
than EC_ON# one of pin Embedded controller reacted for on/off mode. Switching system shorted power switch to the ground,while shorted vcc
become zero volt than
3,3V_vcc replace 51_ON# 17~19V become 3.3V.this signal read by Embedded controller to switch on
or switch off the system. The other system used 3 or 5V switch button VCC.this system using curve
signal
reading .when 3or5V shorted to the ground by switching button ,3V will drop to zero
volt(for 1 second) EC will
reacted to power on the system and when 3or5V shorted for more than 3
second ,EC will reacted to power off the system. Make sure this system running properly beside checking for spi flash
running on this EC and EC
powered well. Can not switch also will happen if NBPWR_BTN# or what ever pin called.if
this signal
missing event all system above checked well,the switching power on
system will not work.
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