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820-00164 PP5V_S5 1.57v no PCH power

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  • 820-00164 PP5V_S5 1.57v no PCH power

    I have this board that was liquid damaged around by the SMC U6100, and U7501 mostly. I have UC'd the board and replaced U7501 as well as some resistors that were damaged by the SMC.
    I am now getting 1.57v on PP5V_S5. I checked for PM_SLP_S4_L and it is showing 0v and not even a pulse when the machine turns on.

    Here are some other measurements I got.

    SMC_ADAPTER_EN - 0v
    SMC_S5_PWRGD_VIN - 3.4v
    PM_PWRBTN_L - 0v
    PPVRTC_G3H - 3.4v
    SMC_RESET_L - 3.4v
    PM_SYSRST_L - 0.06v
    PM_PCH_SYS_PWROK - 0v
    PM_PCH_PWROK - 0v
    PM_RSMRST_L - 0.02v
    PM_SLP_S5_L - 0v

  • #2
    Start checking resistance to ground at 5V_S5.
    Post voltages for U7501, pins 23, 12, 13, 22, 29, 21.

    Comment


    • #3
      Yeah we need more things before PCH power. What is your exact voltage on PPBUS? VRTC_G3H and SMC_PM_G2_EN present?

      Comment


      • #4
        Sorry I forgot to mention those voltages but I get 8.58v on ppbus and 3.4v on ppvrtc_g3h. I will give you the voltage for smc_pm_g2_en in a couple of hours.

        SMC_PM_G2_EN - 3.45v
        Last edited by ytesfay80; 03-20-2019, 08:12 PM.

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        • #5
          Ok so something is wrong near the TPS as you need PP5v_S5. Post voltages for the pins 2informaticos asked for.

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          • #6
            Sorry I was on my phone and didn't see 2informaticos' post. I did replace the U7501 chip but here are some of the measurements.
            Resistance to ground on PP5V_S5 is around 50kohms.
            U7501
            Pin 12 - 3.45v
            Pin 13 - 2.00v
            Pin 21 - 3.4v
            Pin 22 - 3.3v
            Pin 23 - 8.57v
            Pin 29 - 1.58v

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            • #7
              Remove C7505, C7400 and C4810; still the same?
              Also remove L4820; to discard trackpad connector.
              Finally remove U7400 AND Q7430; you can cut off trace from pin 12/U7400 instead.
              Do NOT power up the board without U7400, when Q7430 is still soldered!!!

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              • #8
                So after I remove C7505, C7400 and C4810 I should power on the board and see if PP5V_S5 goes to 5v?

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                • #9
                  Better to remve them one by one.
                  Be carefull about U7400...

                  Comment


                  • #10
                    Yeah you can try with those caps removed. Just don't power it on with U7400 off the board. Or U7501 for that matter.

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                    • #11
                      Okay I figured out that C7505 was issue had some solder connecting it to the probe point in front of it. I figured they were connected so I didn't bother separating the solder but it is all fixed now.

                      Thanks guys!

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