LAPTOP MOTHERBOARD SYSTEM SWITCHING


Laptop requirements in order to switch on first are the availability of 3V and 5VALW. Careful when finding 5VALW missing , switched on first cause of several motherboard, 5VALW appear after switch on .Than 3V_ALW or 3VPCU provide power supply to the EC , BIOS IC , South Bridge ( SB ) , clock generator and oscylator on ALW voltage .
VSB or swuitch voltage button (3.3V) will appear after Bios and EC powered. some of laptop motherboard will found 17V switch voltage on one of pin switch button but after switch -on voltage is changed to be 3.3 V.This is normal. Press power button ( short to ground ) then 3.3VSB will turn into 0V and back to 3.3V.and if standby VSB 17V press power button VSB become 0V and back to 3.3V. than power button is a good sign . steps further is the signal being sent to the EC ( Embedded controller NPCE 885LAODX ) signal names is NBSWON # most other brands of EC signal name may SW_ON, EC_ON or whatever name of the signal as long as signal coming from SW1 sent to EC , this voltage must respond in the same manner of testing power button , BIOS IC and firmware connected to SPI interface to the EC .Signal confirmation to ensure EC BIOS working properly is RSMRST # for3.3V.RSMRST# signal sometimes appear after switch on and other motherboard without switch on 3.3 V already present .Modern Motherboard has 2 or 3 IC BIOS. Identified EC BIOS which is usually one-page schema with EC names EC BIOS.

Other important signal from EC is DNBSWON # ,this is PWR_BTN signal to switch on South bridge sent by the EC after receiving NBSWON # signal from power button . DNBSWON # 3.3V must be present otherwise it would not switch on , after this signal appears then the SB will sent SUSCLK # signal back to the EC and turn on VS as trigger for all switching gate driver as VR_ON , Suson , MAINON , S5_ON or SLP_S3 , SLP_S4 and SLP_S5 . and for all the Vs voltage to the Device .

21 comments:

  1. UnknownSeptember 23, 2015 at 4:56 AM

    Very good sir I was searching for this tutorial please share more details if you have arjunadval

    ReplyDelete
  2. UnknownOctober 23, 2015 at 12:08 AM

    Am greatful sir, it informative enough

    ReplyDelete
  3. pcp04December 27, 2015 at 5:07 AM

    Very good tutotial, thanks you!

    ReplyDelete
  4. tuyetkiemApril 5, 2016 at 11:21 AM

    Vr Good, thank U ! Wish U peace, success & happiness

    ReplyDelete
  5. UnknownApril 18, 2016 at 11:05 PM

    thanks.
    thanks..
    thanks...

    ReplyDelete
  6. UnknownJune 22, 2016 at 2:33 PM

    Thanks for the FANTASTIC post! This information is really good and thanks a ton for sharing it :-) I m looking forward desperately for the next post of yours..
    Laptops for sale

    ReplyDelete
  7. nagarajuAugust 30, 2016 at 1:38 PM

    how to update this type of EC bios and which type of bios copier is use full . please mention the name of the bios copier

    ReplyDelete
  8. AnonymousOctober 22, 2016 at 8:10 AM

    sir, each time i plug in my charger to my laptop it will just go off immediately even when there is a tight contact with power source and the laptop wont ON. what could be the problem

    ReplyDelete
  9. UnknownNovember 26, 2016 at 12:30 AM

    wow its help a lot master

    ReplyDelete
  10. UnknownFebruary 25, 2017 at 3:54 AM

    thank's a lot sir .just a question what did you mean by EC and turn on VS
    I know EC is embedded control but what is VS ??

    ReplyDelete
  11. UnknownApril 22, 2017 at 6:50 PM

    THANK'S A LOT SIR..........................

    ReplyDelete
  12. UnknownJuly 3, 2017 at 6:36 PM

    My Dell xps m1530 when I pressed power button, it will on for 4seconds and CPU fan rotate for 4swconds and stop ... Where is the problem I am getting 3v3, and 5v from power IC

    ReplyDelete
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    this is the only man who is not selfish in sharing. only a few details and you're fully aware! We love you from Nigeria.

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  14. UnknownJanuary 16, 2018 at 4:53 AM

    terimakasih pak sudah berbagi.ijin yontek.

    ReplyDelete
  15. UnknownJanuary 28, 2018 at 3:39 AM

    thanks sir

    ReplyDelete
  16. AnonymousApril 14, 2018 at 9:46 AM

    Hi I have mbx-247 no power on
    After press power button rsmrst OK
    Slp s4 and s5 OK but no run_on ..

    ReplyDelete
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  18. kianJanuary 6, 2020 at 5:09 PM

    hi
    laptop 1564 no display and not turn off whith button key
    5v is key button

    ReplyDelete
  19. georgeMarch 10, 2021 at 9:52 PM

    great post, however, looking at the diagram I'm confuse what is the difference between 3V and 3VPCU, +A3VPCU... are they the same? do they come from same power supply? are they present when charger connected and laptop poweroff? if you can explain this? thanks

    ReplyDelete
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  21. AnonymousAugust 24, 2022 at 10:46 PM

    Sir i am facing problem with 5valw and 3valw on lenovo g400s motherboard. The 5valw regulator sy8208c is short afiter removing regulator short is gone l injected 5v to 5valw line fan turn on without power button but no presence of 3.3valw. The board was water damaged. What should i do where to check for fault? No ic is heating up . power consumption is 200 mili amps.

    ReplyDelete

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