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820-3662 - Sudden power off

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  • 820-3662 - Sudden power off

    Hey everyone,

    A Macbook 15" Late 2013 model here with no visible signs of water damage. The device suddenly powers off after using it for somewhere between 10 to 40 minutes.
    Having a high load running on it won't charge the issues (Furmark + Prime95 for 20 minutes would not cause the device to shutdown) but just idle running a youtube video made it crash at one point.
    The power off is not registered by the system as a kernel panic and does not show signs of the keyboard incorrectly pressing the power button. (The Shutdown window does not appear, as it would when the power button is being held down). The system does not reboot after the power off has occurred but would stay in S5

    Is this model also affected by bad soldering? If so what chip would be the cause of this?
    Any idea where to look?

    Last edited by smiba; 01-15-2018, 02:53 PM.

  • #2
    Duke helped me with one of these a while back. It seems the 3662 and 3787's have unexpected shutdown issues, and that there isn't a solution yet.


    • #3
      The usual 3662 issue. I have one here to right now. I really have no time to dig into this problem at the moment.


      • #4
        Hey duke,

        Is there any information or speculation about this issue so far? I have some free time on my hands this week so I woudn't mind experimenting around, who knows what I might find.
        (I tried to DM you about this but it seems your "Quota" has been reached and it won't let me send)

        Thanks in advance!


        • #5
          It must be something is the power rails to the CPU. I have 0 time to deal with this at the moment as repairs are stacked up here.

          First to see which rail causes this hook up your 2 channel scope to both CPUVR_PGOOD and ALL_SYS and trigger on the falling edge to see which one drops off first.


          • #6
            ALL_SYS_PWRGD drops before CPUVR_PGOOD drops.

            I guess at this point its just a matter of going through a whole bunch of power signals to hopefully see which one goes first? CPUVR_PGOOD would be much easier
            Last edited by smiba; 11-21-2017, 11:44 AM.


            • #7
              Try retinning all the pads on U7200. I am currently experimenting with a board like this and after checking the chip at all 4 angels and making sure each joint was solid it seems to have stopped happening.. I am still testing however just figured it was worth putting out there for someone else to try as well... If It continues to work for over 24 hours I will report back.


              • #8
                Don't heat anything up on the board as this may mask the problem again for weeks.

                Now comes the shitty part in separating the ALL_SYS signals and see which one falls first. It seems like ALL_SYS is not a "hard" drop and it gradually drops to zero. What is your time base in that picture?


                • #9
                  Let me know if it works for you. I'm currently keeping track of any power lines dropping just before ALL_SYS_PWRGD does before I solder anything

                  I'm sceptical about it being a contact issue as the problem gets more frequent once it keeps crashing and you keep rebooting it. But I'm hoping
                  820-3662 board as well?

                  Last edited by smiba; 11-21-2017, 02:37 PM.


                  • #10
                    Yep same board 820-3662. Also I didn't use hot air duke, just my micropencil to connect the joints with fresh solder.. shouldn't have a large impact. So far I've been able to run migration assistant, complete an external drive restore, and an internal in-place software upgrade without problem. I have this thread bookmarked however and if for some reason it does come back in the future for anything I will be sure to keep everyone in the loop.


                    • #11
                      Originally posted by dukefawks View Post
                      What is your time base in that picture?
                      4μs/div by the way

                      The wait is the worst, at this rate its going to take a couple of days...I already confirmed PP1V35_S3RS0_CPUDRR not being at fault and I'm currently testing PP3V3_S0.

                      Are there any power lines you recommend taking a look at first?

                      (On the picture the voltages you see on the side are for Probe A and I didn't align B. Sorry for the unclarity. Probe B is seeing normal 1.35V)
                      Attached Files
                      Last edited by smiba; 11-21-2017, 02:44 PM.


                      • #12
                        U7200 is on my suspect list but I would have expected CPUVR_PGOOD to drop before ALL_SYS. Resoldering it with an iron can not hurt, just don't use hot air or it may disturb the actual problem.

                        Do remember that this issue only happens when the machine is "idle" or light load. As soon as you hammer the CPU it keeps running fine. So no use is stress testing with this problem.


                        • #13
                          In the situation with the machine I have, it seems to happen when firefox is opened (usually playing a youtube video) and then there is graphical activity on the dock from the magnification feature.. a few swipes back and fourth with the cursor and it'd crash out. Tried that for about an hour on a cold boot. doing the more extensive stuff now.. I'll probably let it idle overnight tonight on a video or something and retest everything out in the AM tomorrow.


                          • #14
                            Can confirm that low load is more likely to let it crash. In my case I often make it stream some music from my local library and thats been pretty effective at making it crash. Stuff like YT also works alright
                            Stress testing the device will not make it crash at all.

                            Trick seems to be not to blast the CPU but just keep it at a couple of cpu%. But this is purely speculation based on just a couple of samples so far though

                            EDIT: Its also not PP3V3_S0. Testing it with PP3V3_S5 now
                            Attached Files
                            Last edited by smiba; 11-23-2017, 04:32 PM.


                            • #15
                              Got it. I have it off and will let it cool off for the next 2 hours and retest cold before i leave the office.


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