Checking the problem by the Symtom

Checking the problem by the Symtom
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.
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.measurung 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# 1719V
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.