A1502 Macbook Pro 13" liquid damaged 820-3476, orange light no power

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  • meantomatoes
    Member
    • Jun 2018
    • 28
    • United States

    #1

    A1502 Macbook Pro 13" liquid damaged 820-3476, orange light no power

    I'm new to board repair so bear with me. Just my luck that this is my first.

    This board likely had work done before. It was probably ultrasonic'd because it's pretty clean. The SMC had its underfill removed so someone probably reflowed or replaced (doubt) it. Pictured: Near the SMC the traces of Q5490 for pins 4 (PPDCIN_G3H_ISOL) and 2 (PP_SLP_SUS_L) are somewhat exposed.

    It's stuck in S5 and missing PM_SLP_SUS_L (shorted) although I don't think that exposed trace is the problem, may have been the last person being lazy for a reading? Anyway, is this a dead CPU? As I'm a beginner I don't have an oscilloscope

    From other threads, I measured
    PP3V3_S5
    PPVRTC_G3H
    PM_BATLOW_L
    PM_DSW_PWRGD
    PM_PWRBTN_L
    SMC_ADAPTER_EN
    PCH_SRTCRST_L
    PCH_INTVRMEN
    PCH_DSWVRMEN
    PCH_INTRUDER_L
    RTC_RESET_L
    which are all normal afaik.

    PM_RSMRST_L is 0 because PP3V3_SUS is 0, because P3V3SUS_EN is 0 and is short, but since EN comes from SLP_L through R8190 (0 ohms) is SLP the short and therefore the CPU? Or maybe a short trace?

    Edit: I'm editing as I go along. I found that PM_PCH_PWROK is 0 but isn't short. I don't think this explains the SLP short though.

    Not sure if this is related but S5_PWRGD is only 2v.

    Also please give me tips in general if you're willing!
    Attached Files
    Last edited by meantomatoes; 10-06-2020, 12:33 AM.
  • meantomatoes
    Member
    • Jun 2018
    • 28
    • United States

    #2
    Re: A1502 Macbook Pro 13" liquid damaged 820-3476, orange light no power

    Not sure who came up with that rule but here's my second edit:

    I think PM_PCH_PWROK is 0 because ALL_SYS_PWRGD is 0. Not sure why. Not short. So it's probably not an issue with U1950 as is common with this model.

    Comment

    • piernov
      Super Moderator
      • Jan 2016
      • 4435
      • France

      #3
      Re: A1502 Macbook Pro 13" liquid damaged 820-3476, orange light no power

      PM_PCH_PWROK and ALL_SYS_PWRGD are irrelevant when not even getting to DeepSx state.
      S5_PWRGD should be 3.42V. PM_SLP_SUS_L should not be 0ohm to ground.
      With issues on both of these and work done around SMC, SMC is the first suspect.
      OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

      Comment

      • meantomatoes
        Member
        • Jun 2018
        • 28
        • United States

        #4
        Re: A1502 Macbook Pro 13" liquid damaged 820-3476, orange light no power

        Originally posted by piernov
        PM_PCH_PWROK and ALL_SYS_PWRGD are irrelevant when not even getting to DeepSx state.
        S5_PWRGD should be 3.42V. PM_SLP_SUS_L should not be 0ohm to ground.
        With issues on both of these and work done around SMC, SMC is the first suspect.
        Hi piernov, thanks for replying

        So should I try replacing or maybe reflowing smc? I don't have a donor board

        Also thanks for the software in your sig! I've been using phoneboard

        Comment

        • piernov
          Super Moderator
          • Jan 2016
          • 4435
          • France

          #5
          Re: A1502 Macbook Pro 13" liquid damaged 820-3476, orange light no power

          Someone already tried to reflow it. If it didn't go well, the balls are probably damaged, so it needs to be reballed at least, and most likely replaced.
          Either 820-3476 or 820-3536 can be used as a donor for the SMC.

          But after that there may still be something else wrong with the board, since the issue right now could've been caused by the prior repair attempt and the real issue is hiding somewhere else…
          OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

          Comment

          • meantomatoes
            Member
            • Jun 2018
            • 28
            • United States

            #6
            Re: A1502 Macbook Pro 13" liquid damaged 820-3476, orange light no power

            Originally posted by piernov
            Someone already tried to reflow it. If it didn't go well, the balls are probably damaged, so it needs to be reballed at least, and most likely replaced.
            Either 820-3476 or 820-3536 can be used as a donor for the SMC.

            But after that there may still be something else wrong with the board, since the issue right now could've been caused by the prior repair attempt and the real issue is hiding somewhere else…
            Okay, thanks. It actually looks like some of the underfill stuff got under the balls. Will probably try cleaning and reballing but I need to get the stencil. Will report back

            After removing smc SLP_SUS short should go away right?
            Last edited by meantomatoes; 10-07-2020, 02:53 PM.

            Comment

            • meantomatoes
              Member
              • Jun 2018
              • 28
              • United States

              #7
              Re: A1502 Macbook Pro 13" liquid damaged 820-3476, orange light no power

              Wait--after checking S5_PWRGD again it's actually 3.42 as normal. Not sure what I was measuring before...

              So, short on SLP_SUS is either CPU, R1464, Q5490, or on P3V3SUS_EN etc. I don't see where it would be tied to SMC?

              Comment

              • piernov
                Super Moderator
                • Jan 2016
                • 4435
                • France

                #8
                Re: A1502 Macbook Pro 13" liquid damaged 820-3476, orange light no power

                My bad, I check the schematics and indeed SLP_SUS# doesn't go to SMC whereas all other SLP_S*# do.
                You can remove Q5490 and R8190 and see if the resistance to ground on PM_SLP_SUS_L goes up.
                OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

                Comment

                • meantomatoes
                  Member
                  • Jun 2018
                  • 28
                  • United States

                  #9
                  Re: A1502 Macbook Pro 13" liquid damaged 820-3476, orange light no power

                  Sorry for the slight necro but I wanted to update you. I removed R8190 first and found the short on PP3v3sus_en, which could only be U8020. SLP_SUS is now 3.3v, yaaay. The other rails connecting to U8020 are fine. I ordered a donor on aliexpress so hopefully it will have a working U8020 I'll post a final update once it arrives.

                  Comment

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