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HP G62 - Foxconn star reverer - missing +V5A rail

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    #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
    #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

      #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

        #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

          #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

            #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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