HP G62 - Foxconn star reverer - missing +V5A rail

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  • Atomdesign
    Member
    • Feb 2012
    • 19
    • The Netherlands
    #1

    HP G62 - Foxconn star reverer - missing +V5A rail

    Someone left me a G62-a13ED laptop to repair.
    Symptoms: Wont turn on.
    Some corrosion around PU850 (SN0608098RHBT)
    +V3.3AL OK
    +V5A is 0 volt.

    I've replaced PQ850 and PU850, no change.
    There is no short to ground on the +5VA rail.

    Measurements I've taken:

    PU850 pins:

    Pin 26 (DRVH2 +V3.3AL_UG_20) = 3.5V
    Pin 25 (LL2 +3_3V_AL_PHASE_20) = 3.3V
    Pin 24 (VBST2 +3_3V_AL_VBST_20) = 8.4V
    Pin 23 (DRVL2 +V3.3AL_LG_20) = 0.9V

    Pin 15 (DRVH1 DHI) = 0V
    Pin 16 (LL1 +V5A_PHASE_20) = 0V
    Pin 17 (VBST1 +5VA_VBST_20) = 4.8V
    Pin 18 (DRVL1 +V5A_LG_20) = 0V

    I've tried giving 5V to the +V5A rail through my lab supply, this doesn't heat anything up. The rail itself seems fine, and I'm not sure how to proceed. Any ideas would be welcome!
    Tags: None
    • piernov
      Super Moderator
      • Jan 2016
      • 4435
      • France
      #2
      Re: HP G62 - Foxconn star reverer - missing +V5A rail

      Can you give voltage on EC_ALW_EN line? And voltage on +V5AL?
      Can you upload a picture of corroded area?
      Are you on AC power without battery? Nothing after pressing power button?
      OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

        Comment

        • Atomdesign
          Member
          • Feb 2012
          • 19
          • The Netherlands
          #3
          Re: HP G62 - Foxconn star reverer - missing +V5A rail

          EC_ALW_EN is 0V
          AC power with no battery attached, and indeed no reaction after pressing the power button.

          Image of the area is attached.
          Attached Files

            Comment

            • Atomdesign
              Member
              • Feb 2012
              • 19
              • The Netherlands
              #4
              Re: HP G62 - Foxconn star reverer - missing +V5A rail

              EC_ALW_ON should be coming from UI2, I see. That chip is also getting a little warm.
              resistance between EC_ALW_EN and ground is infinite, so no short to ground there. Should I start ordering me a new IT8502E?

              Update: IT8502E no longer warming up. Also, +V3.3AL is now gone. I havent changed anything other than leaving the DC jack plugged in for a half hour or so.
              Last edited by Atomdesign; 08-07-2017, 07:39 AM.

                Comment

                • piernov
                  Super Moderator
                  • Jan 2016
                  • 4435
                  • France
                  #5
                  Re: HP G62 - Foxconn star reverer - missing +V5A rail

                  IT8502E shouldn't be getting warm in OFF (S5) state I think. It could be damaged. You could try to reflash the EC ROM at UI6 if you find the file. (make a backup before)
                  Still nothing on +V3.3AL? In that case measure pin 4, 6, 7, 25, 27 of PU850.
                  +V3.3AL is a required power rail for the IT8502E to turn on.
                  OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

                    Comment

                    • Atomdesign
                      Member
                      • Feb 2012
                      • 19
                      • The Netherlands
                      #6
                      Re: HP G62 - Foxconn star reverer - missing +V5A rail

                      +V3.3AL is back up after leaving the board alone for a while and plugging it back in.

                      just in case: PU850:
                      Pin 6 is 19.5V and fine
                      Pin 4 is 3.3V and fine
                      Pin 7 is 5V and fine
                      Pin 27 5V and fine

                      I'll see if I can find the bios file and whether my programmer supports the chip.

                        Comment

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