HP G62 star reverer - missing +V5A rail

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  • mhd_mahad
    Senior Member
    • Jun 2016
    • 54
    • egypt
    #1

    HP G62 star reverer - missing +V5A rail

    hello friends,

    I have hp g62 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

    EC_ALW_EN missing

    IT8502 vcc= 0v
    +V3.3S=0v
    can any one help me urgently
    Tags: None
    • Tom_avia
      Member
      • Jan 2020
      • 26
      • Lithuania
      #2
      Re: HP G62 star reverer - missing +V5A rail

      Did you try to use laboratory power supply? How much Amps the motherboard is consuming?
      Also do some elements are heating?

        Comment

        • jasko_jacker
          Badcaps Legend
          • Oct 2014
          • 1137
          • italy
          #3
          Re: HP G62 star reverer - missing +V5A rail

          In this motherboard the +5alw are present only after pushing the power button.

            Comment

            • mhd_mahad
              Senior Member
              • Jun 2016
              • 54
              • egypt
              #4
              Re: HP G62 star reverer - missing +V5A rail

              thanks all
              No elements are heating or shorting.
              IT8502 IO vcc= 0v how can i check missing volt?

                Comment

                • Tom_avia
                  Member
                  • Jan 2020
                  • 26
                  • Lithuania
                  #5
                  Re: HP G62 star reverer - missing +V5A rail

                  I would check this area of board. I think this is an origins of +v3.3s voltage.
                  Attached Files

                    Comment

                    • Tom_avia
                      Member
                      • Jan 2020
                      • 26
                      • Lithuania
                      #6
                      Re: HP G62 star reverer - missing +V5A rail

                      SN0608098 (PU11) is forming +v3.3al and then +v3.3s. Check there.

                        Comment

                        • Sametbey
                          Badcaps Veteran
                          • Jan 2021
                          • 229
                          • Turkey
                          #7
                          Re: HP G62 star reverer - missing +V5A rail

                          Do you have 7 pin LDO, 14 pin and 27 pin ENL voltages. System does not start without 13 and 28 PWGOD signals.
                          I'm not happy to be so strong. because it's not humanly

                            Comment

                            • mhd_mahad
                              Senior Member
                              • Jun 2016
                              • 54
                              • egypt
                              #8
                              Re: HP G62 star reverer - missing +V5A rail

                              pin 14 EN1=0v
                              pin 27 EN2=5v
                              13&28=0vi only have enable and signals for 3.3v

                                Comment

                                • Tom_avia
                                  Member
                                  • Jan 2020
                                  • 26
                                  • Lithuania
                                  #9
                                  Re: HP G62 star reverer - missing +V5A rail

                                  Originally posted by mhd_mahad
                                  pin 14 EN1=0v
                                  pin 27 EN2=5v
                                  13&28=0vi only have enable and signals for 3.3v
                                  EC_ALW_EN to pin 14 is going from EC.

                                    Comment

                                    • Sametbey
                                      Badcaps Veteran
                                      • Jan 2021
                                      • 229
                                      • Turkey
                                      #10
                                      Re: HP G62 star reverer - missing +V5A rail

                                      AD_ID activates the charge control chip when the adapter is installed. Then the charging chip generates the signal AC_OK + 19V is supplied to the system. PU850 STBY chip generates +3.3 V LDO voltage. IO works, BIOS gets the program. It sends the signal to PU850 and output 3.3 VALW to 5VALW. PU850 pwrgood sends signal to IO. IO waits, the SYS opens when the POWER button is pressed.
                                      Attached Files
                                      Last edited by Sametbey; 05-12-2021, 05:46 AM.
                                      I'm not happy to be so strong. because it's not humanly

                                        Comment

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