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820-3115 must short power pads

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  • 820-3115 must short power pads

    Hi Team,

    I have a 3115 board that missing S4 state, after following the schematic I've seen that PM_SLP_S5_L was missing, and this one is provided by the PCH.
    At this point we now that it could be many things:
    I've mesured
    PM_BATLOW_L: 3.307V OK
    SMC_ADAPTER_EN: 3.446
    PPVRTC_G3H: 3.31
    Then I checked SMC_ONOFF_L to be sure that it is NOT always low and keeps the SMC in reset mode: solid 3.483V , never pulsing down.
    I decided to short the power pads at R5015 or R5016 and suddenly it starts.

    could some one please explain me the sequence/ conditions for the SMC to start: does it only needs SMC_RESET_L to start or something else? (of course if all the PWR and SLP rails present).
    Should I try to put back the board in the MBP and try an SMC + PRAM Reset?

  • #2

    After a full night rest , now the board doesn't boot when i short the power pads but only a quarter fan spin.

    PPBUS_G3H: 12.60V
    PP3V42_G3H: 3.485V
    PPVRTC_G3H: 3.313V
    PP5V_S5 : 5.020V
    PP3V3_S5 : 3.313V
    PP5V_SUS : 5.020V
    PP3V3_SUS : 3.311V
    PP3V3_S4 : 0.40V
    PP5V_S3 : 0V
    PP3V3_S3 : 0.011V

    P3V3S4_EN: 0V
    PP3V3_S4_P3V3S4FET : 3.313V

    PP3V3_S5_PWRCTL: 3.313V
    PM_SLP_S5_L: 0V but pulsing when short power pads to gnd.
    SMC_S4_WAKESRC_EN: 0V but pulsing when short power pads to gnd.

    ALL_SYS_PWRGD: pulsing

    PPVCORE_S0_CPU: 0V resistance to gnd: 1.5 Ohm

    then I removed R7510 and mesured the resistance to gnd on both sides:
    L7510 side: infinite
    C1657 side: 0.8 Ohm
    Without R7510 it quarter fan spins in loop.....
    So my short to ground is for sure on the CPU side, any clue where to start by as there's a bunch of critical condensators in parallel at he CPU VCORE DECOUPLING level.....
    I've removed the 4 easiest and checked : C1680, C1681, C1682, C1683 .....not OK that would be too easy....
    Maybe the CPU ?

    I've also replaced the bios chip: NOK
    Dumped the original one cleaned the ME Region and re writed in: NOK ( Thanks for Duke for his quick tutorial here: )

    Sometimes it do 2 quarter fan spin, sometimes 1 and sometimes none.

    Waiting for your feebacks......thanks in advance.....
    Last edited by Bouba148; 09-15-2018, 10:18 AM.


    • #3
      There is very low resistance to ground as normal value for i7-3xxx CPU...

      L7510 pulses too?
      Check R7402/03.


      • #4
        at L7510 with R7510 the DVM can barely see the pulse but without R7510 it's 0.6V pulsing to 1.3V
        Checked R7402/03: OK


        • #5
          Hi, I'm back with that board after several weeks......

          So I took again the main voltages:
          PPBUS_G3H: 12.30V
          PP3V42_G3H: 3.479V
          PPVRTC_G3H: 3.313V
          PP5V_S5 : 5.018V
          PP3V3_S5: 3.313V
          PP5V_SUS: 5.015V
          PP3V3_SUS: 3.312V

          I've found out that R5123 was missing ( Directly attached to Pin 2 of of the U6100) so I've put a new one now the board still have a dimm green light but with PPBUS_G3h and PP3V42 OK

          And sometimes it starts with fan at full speed but delayed from the dimm green light from 5 sec, chime, load the OS at almost 75% then stops. The board is NOT heating.
          When I mesured SMC_ONOFF_L this one is always 0.108 meaning for me ( correct me please ), that MAYBE the board is always in SMC Bypass mode......
          Also the BIL lights stays always off with charged battery, that's why all my suspicious is going to the SMC, please confirm.
          Thanks in advance


          • #6
            Seems that SMC is not running, is this water damage??


            • #7
              "PPBUS_G3H: 12.60V
              PPBUS_G3H: 12.30V"
              You had correct PPBUS_G3H.
              Now you have problem with SM Battery Bus.
              SMC works, if board starts (even get image), but that bus can be damaged, or affected by external component.

              "SMC_ONOFF_L to be sure that it is NOT always low and keeps the SMC in reset mode: solid 3.483V , never pulsing down
              SMC_ONOFF_L this one is always 0.108"
              Your values change drastically...
              Is the board liquid spilled?
              Board cannot stay on more than 4s if SMC_ONOFF_L is low.

              You alse have SYS_ONEWIRE circuit affected, possibly crap under SMC.
              Reball it...


              • #8
                SMC_ONOFF_L was shorted to gnd because of the SMC, I replaced it now the short is gone.

                PPBUS_G3H: 12.60V green light present

                Sometimes it's pulsing once up to CPU_Vcore and when it's not pulsing I have to short the power pads to make it pulse once in both cases after that pulse I'm loosing S5 state, SMC_ADAPTER_EN

                It turned ON once with only the battery to Fall full speed then stopped like V or I Sense issue, since then no way to turn it again from battery.

                At the pulse SMC_CPU_HI_ISENSE pulses to 1.2V,
                Then I've removed R5400, it's rising to 3.3V

                Is the CPU dead?


                • #9
                  Did you try SMC bypass?
                  Check Power FETs output on page 72.
                  Also check U6200.


                  • #10
                    Yes of course I've already tried, I didn't post it because it's acting exactly the same : fan pulses at full speed once then stops.
                    Regarding page 72, sorry but I didn't got you, because everything is pulsing there, and when it's not, it's because PM_SLP_S5_L is missing.
                    U6200???? are you sure? you didn't meant U7200?



                    • #11
                      Yeah, do you get a pulse on U6200 output too?
                      A short there will block the power on sequence.


                      • #12
                        On Pin 1 of U6200 it's also pulsing and there's no short there as in diode mode I'm mesuring 0.497V on pin 1 of C6203.


                        • #13
                          Reball/change SMC...


                          • #14
                            ok, I will ........I was excatly supecting the SMC again....
                            I will let you know



                            • #15
                              could you please confirm that those 4 pads are not connected any where.......if not that's the reason of my issue....

                              3115 SMC.jpg


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