Checking the problem by the Symtom and make Service log measurement

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 19VALW-5/3VALW-5/3VS-1.2VS-1.05VS.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# 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.

Copyright~Adie Dkhaz

Link Ref  : http://adiedkhazbook.blogspot.co.id/p/blog-page_15.html