Troubleshooting Laptop Power System

This tutorial shows you how to check and troubleshooting Laptop Power System. The first thing that must be understood is how the system works to enable/disable Power on VS.

The laptop requirements in order to turn on first are the availability of  VALW / Power Always or MAIN DC POWER SUPPLY CIRCUIT LINE  (ADP+ = 12V, 15V, 16V, 18.5V, 19V or 20V adapter range voltage used depend on laptop brands),  3V and 5V. Careful when finding 5VALW missing, switched on first cause of several motherboard, 5VALW appear after switch on .

Before starting check electronics components take a look at the motherboard for burn component.

Laptop Power System sequence check

Check +PWR_SRC/DC_IN 19.5V=19.5V
Check +DC_IN_JACK and electronics components directly after DC_IN_JACK
Check +3.3V_ALW =3.3V
On IC Power-Supply Output
Check Power-Supply IC
Check PWR_SW#=Low pulse
Power Switch
Check +3.3v_ALW on Power Switch


Check ON/OFF Power Switch
Check +5V_ALW2=5V On IC Power-Supply Output No
Check Power-Supply IC
Check SUS_ON=H No Check SIO (super input/output) IC

(Example IC: ITE8512)

Check +3.3V_SUS No Check +3.3V_SUS  MOSFET on Motherboard
Check +5V_SUS No Check Power-Supply IC

(Example IC: MAX17020ET)

Check 1.8V_SUS No Check Controller, DDR Voltage Regulator IC
Check SLP_S3# No Check I/O Controller Hub 9 (ICH9) SLP_S3# Pin
Check RUN_ON1 No Check SIO (super input/output) IC

(Example IC: ITE8512 Pin123)

Check RUN_ON
Check RUN_ON MOSFET on Motherboard
1.Check +5V_RUN
2.Check +3V_RUN
3.Check +1.5V_RUN
4.Check +1.5V_SUS(UMA)
5.Check +1.8V_RUN
Check +V5_RUN, +3V_RUN, 1.5V_RUN, 1.5V_SUS(UMA),  1.8V_RUN MOSFET pass through and IC source


Check CPU and GPU Power-Supply IC
(Example IC: MAX8632ETI+)
Check HWPG
Check HWPG MOSFET pass through and IC source
(Example IC:  SN74AHC08PW)
Check SIO IC and CPU and GPU Power-Supply IC (Example IC: ITE8512 Pin95 and ISL6262ACRZ-T Pin44)
Check  CPU and GPU Power-Supply IC (Example IC: ISL6262ACRZ-T)
Check PCI_RST#
Check PCI_RST# MOSFET pass through and IC source
(Example IC TC7SZ32FU Pin4)
CPU_RST Check Northbridge IC (MCH)

Check electronics components Voltage, Continuity and temperature. Replace the failure one.

How to test Integrated Circuit (IC) in Laptop Motherboard in safe way

This article will be update with the time to make it easy to understand.

19 thoughts on “Troubleshooting Laptop Power System

  1. AGmR

    Hello helppard ^_^,

    Thank u for this awesome guide and this helpful website 🙂

    if u can in >> Laptop Power System sequence check table <> +PWR_SRC/DC_IN << what is this called in my schematic

    to make it easy for me to test 🙂

    My Kind regards,

  2. helppard Post author

    first replace the rom chip even if it readable

    +PWR_SRC/DC_IN is the Courant/voltage in the power jack pin

  3. AGmR

    Now i understand,

    so i have now Voltage drop on pin 1 from dc jack (PJPDC9) = 0.6v

    so what can cause this problem ? i tested all components after this pin from schematic its all good !

  4. helppard Post author

    there is a burn component after power jack, test electronic component temperature with your finger or there are a bad solder between power jack and motherboard.

  5. Pradeep


    My motherboard dell 3330.
    The super io chip is getting heated on adapter plug in. No other components are heated. Please advise

  6. helpmate

    with multimeter check countinuity on SMD capacitor and mosfet beside the I/O chip, the short capacitor or mosfet can make IC get hot, if there is no short capasitor or mosfet, thats mean the IC is burn you need to replaced or you need a new motherboard.


    I am facing a strange problem in my dell E6430 used laptop, often my laptop does not boot. I replaced and checked ram and also checked in different slots. When i restart it, it works but when i shut down it and then try to start again by pressing power button, it does not boot. only power light comes on and fan works with supply to cd drive and hard disk only motherboard light comes on for 1 sec at the time of pressing start button. If i place the laptop for few hours in shut down position then it boot up at that time only. Moreover I tried to update bios but after restart during bios upgrade, it does not show any thing on the screen and just power led on and fan runs. please any expert opinion on my email

  8. paolopanini

    Hello and thanks for this guide!

    I found a burned capasitor on my motherboard. It says PL100 does anyone know which capasitor it is so that i can get a spare one and replace it?

  9. paolopanini

    sorry i thought this post is about the dell latitude 6430u, which i am using. It looks like a ceramic decoupling capasitor (see picture).


  10. Acquah Daniel

    pls I have hp elitebook 2530p, it switchs on immidiately I plug in the power AC and turn off within 2 seconds. Without me pressing the power button. nothing displays on the screen and all that I can see is the lights in line with the power button turns on and I can hear the fan working and after two seconds everything goes off and start again. This process will continue untill I disconnect the AC and the machine goes off.

  11. matthew

    Hello. Thank you for this detailed guide. I however cannot follow it because none of the component names match with the components on my motherboard. I have the hp probook 650 g1, and your schematics have component codes different than mine. Also, the power input jack on my motherboard has 8 pins but your guide only shows 4 pins.

    Can you put up the power system diagnostc guide for my motherboard? The hp 650 g1 motherboard is 744016-001. Thank you.

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