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

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  2. Am greatful sir, it informative enough

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  3. Very good tutotial, thanks you!

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

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  5. 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

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  6. 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

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  7. 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

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  8. 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 ??

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

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  10. 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

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  12. terimakasih pak sudah berbagi.ijin yontek.

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

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

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  16. 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

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  18. 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.

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