Announcement

Collapse

Announcement

Welcome to the NEW iPad Rehab Forum! Everyone is welcome to read posts and learn for free. If you'd like to post your own question on the forum, please click "register" above or go here: http://forum.mendonipadrehab.com/register to enroll as a paid subscriber for $29/mo for unlimited access to our forum support and private signature failure section.
See more
See less

iPad Air 1st PMIC is it really failing that much lately?

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • iPad Air 1st PMIC is it really failing that much lately?

    I had 1 iPad Air which the only history is small drops here and there but the logic board looks perfectly dead

    Had too many voltages missing during charging to even name, but the 5V were coming from the charging port so tried tristar as good measure and still same result.

    So the other day another came by with the same symptoms.

    What's do you guys think? is this the next big thing?


    BTW loved how tristar goes directly to the store
    LastDeuS
    Friendly Contributor
    Last edited by LastDeuS; 11-26-2017, 08:32 PM.

  • #2
    Yes "tristar" goes directly to LOUIS's store---a small price to pay for his enormous help setting up this forum.

    Let's get out of the habit of "all roads lead to PMIC" on any board problem. That is rarely the case.

    So your problem is iPad Air is not charging. First question---does it boot? An iPad that can't boot obviously can't charge, so let's make sure that we start with rule #1--this iPad Air can boot in a known good housing, yes? After that--what makes you think that it can't charge? We need to differentiate two important things. "Not charging" and "not reporting charging correctly"

    Comment


    • #3
      Originally posted by Jessa_the_Professa View Post
      Yes "tristar" goes directly to LOUIS's store---a small price to pay for his enormous help setting up this forum.

      Let's get out of the habit of "all roads lead to PMIC" on any board problem. That is rarely the case.

      So your problem is iPad Air is not charging. First question---does it boot? An iPad that can't boot obviously can't charge, so let's make sure that we start with rule #1--this iPad Air can boot in a known good housing, yes? After that--what makes you think that it can't charge? We need to differentiate two important things. "Not charging" and "not reporting charging correctly"
      Oh sorry my bad, ok yes before posting I always make sure to test the device on a know good housing with a known good battery, so yeah it does not boot and it does not get recognized by pc
      haven't tried dfu on this one
      To be honest I just mentioned PMIC because there is a lot of hype on the group lately about it and since in my case so many voltages were missing that I assumed this was actually a thing now

      I will measure tomorrow and be more specific

      Comment


      • #4
        So this isn't "not charging" this is "not booting". Let's forget about charging until it can boot. Your first step toward a not booting problem is to determine what the overall current consumption in the device is---does it have some big short? Is it brain dead? These are two very different problems--heart and brain. Both power (heart) and brain (data) are required for the device to turn on.

        You mention "missing voltages" and are jumping to "PMIC is bad". My question is "how do you know the PMIC is being told to turn on?" What tool can we use to assess whether a device has a bleeding heart with a short vs one that is brain dead?

        Comment


        • #5
          OK when I mentioned "charging" was only to point that my tests were performed while connected to a charger (0 current draw on ampmeter btw)

          Not really sure could have cold solder on under CPU as well so tomorrow I will show the specific voltages and some diode measurements

          So this is still not considered a signature fault just yet then

          Comment


          • #6
            Be wary of introducing variables into a troubleshooting problem. That is when things get complicated. The first step is "Identify the problem you are trying to solve" A usb ammeter asks the question 'does this device charge normally?" Of course the answer is no on a device that can't boot---so plugging a device into a usb ammeter gives us no useable information and just muddies the post.

            "I changed tristar" Why? What problem were you trying to solve? That isn't necessarily a bad first step, but only if you had a theory. "This device is consuming low current on DC power supply at prompt to boot, it does not have any short circuits, and no physical damage or history of drop/failed update etc, so therefore I made the hypothesis that tristar could be preventing the device from booting by scrambling i2c line communications from CPU after electrical damage to tristar" But that only make sense if you knew that A, B, and C in that theory were true. You're not there yet. Changing tristar 'randomly' or 'just because' is introducing a variable that is now part of the problem.

            There are a couple of signature failures for no power iPad Air. Tristar is not one of them. First we need to do the same diagnostic test that we do with any no power device---what is that test?

            Comment


            • #7
              in my case, the one i have in front of me shows no life. Amp meter hangs out at .04/.05 and sometimes jumps all over. I hooked up DCPS and goes to .08 on boot and hangs there. Responds to power button boot and charge port connection.

              Comment


              • #8
                Originally posted by Allan View Post
                in my case, the one i have in front of me shows no life. Amp meter hangs out at .04/.05 and sometimes jumps all over. I hooked up DCPS and goes to .08 on boot and hangs there. Responds to power button boot and charge port connection.
                There is another similar post that you can check regarding this issue and the tech could test further my customer just took the iPad since he could not wait any longer.
                It looks like his problem was Nand Related

                Comment


                • #9

                  "There are a couple of signature failures for no power iPad Air. Tristar is not one of them. First we need to do the same diagnostic test that we do with any no power device---what is that test?"


                  I would check the voltage at the battery connector with a meter??

                  Comment


                  • #10
                    Originally posted by eDigitCom View Post
                    "There are a couple of signature failures for no power iPad Air. Tristar is not one of them. First we need to do the same diagnostic test that we do with any no power device---what is that test?"


                    I would check the voltage at the battery connector with a meter??
                    What I'm fishing for with "what diagnostic test do we do on any no power device" the answer is "connect to DC power supply and prompt to boot" this shows us what category of failure we are in. For those of you that have been reading every post, you can see that multiple devices are all coming up in the same category of "it consumes 0.09A after prompt to boot" either in a loop or steady. Right now there are a few different threads that have arrived at this diagnostic result, and we are waiting on them to answer questions to move forward. For example, Allan ^ above is commenting on this post with a similar observation on his iPad Air.

                    Comment


                    • #11
                      Jessa could you explain to me what is meant by "prompt to boot" and how you carry out this procedure. Is it where you connect a charging cable to a computer and connect it to DCP??

                      Thanks
                      eDigitCom
                      Friendly Contributor
                      Last edited by eDigitCom; 12-03-2017, 02:54 AM.

                      Comment


                      • #12
                        Originally posted by eDigitCom View Post
                        Jessa could you explain to me what is meant by "prompt to boot" and how you carry out this procedure. Is it where you connect a charging cable to a computer and connect it to DCP??

                        Thanks
                        Yes. At rest, a phone should consume 0amps--thus saving the battery. It will only come alive and begin the symphony of current consumption after it is prompted to boot, aka turned on. This can be done by inserting usb and pulling it back out, or by pressing the power button, or simulating the press of a power button.

                        Comment


                        • #13
                          thanks Jessa

                          Comment

                          Working...
                          X