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iPhone 6s stuck on 0.09A

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  • iPhone 6s stuck on 0.09A

    I have an iPhone 6s pcb, Its has a prior tristar replacement, no water damage and no major dents on the housing.
    When prompt to boot its stuck on 0.09A. I replaced tristar to rule it out, still stuck on 0.09A when prompt to boot. I also probe around to find a short but i cant seem to find one. I cant detect any heat when its stuck on 0.09A too.

    I cant seem to figure out whats the fault.
    Last edited by GHI888; 11-29-2017, 10:08 AM.

  • #2
    Does it boot with a known good charged battery? I tend to get .09A on shorted 6 boards at least.

    Comment


    • GHI888
      GHI888 commented
      Editing a comment
      doesn't boot,

  • #3
    "prompt to boot is stuck on 0.09A".

    Are you saying "I have a dead phone that doesn't boot and is not detected by iTunes with nothing on the display in a known good housing with known good battery. There is no water damage and there is a history of prior Tristar replacement." ??

    assuming so, then it sounds like you are saying "so I decided to ask this dead phone if it could charge by connecting it to a USB ammeter. And of course it can not charge because it can't power on, so I found that it consumes low charging current"

    Put away your USB ammeter when you are troubleshooting a no power phone. You already know a dead phone can't charge so this isn't the right tool to troubleshoot no power phones.

    what can make a phone not boot? One thing would be a short circuit on a power rail. But what are other reasons that a phone can't boot?

    answer that question with some ideas.

    Comment


    • GHI888
      GHI888 commented
      Editing a comment
      Sorry I failed to clarify, I plug it on a DC power supply and when I prompt it to boot the dc power supply shows 0.09A only. I'm pretty sure its a short somewhere, but I cant seem to figure out where, ruled out VCC main, and GPU lines on continuity mode beeps but I'm pretty sure it normal because I've compared it to my known good. The next might be to check all the power rails for a short?

  • #4
    Use continuity mode to quickly narrow down possible lines that can be shorted. Use diode mode to actually measure them and compare to a known good. CPU, soc, and gpu lines always beep because they naturally have low resistance to ground.

    Does iTunes detect the board in dfu or recovery mode?

    Comment


    • GHI888
      GHI888 commented
      Editing a comment
      iTunes does not dettect it on DFU mode.

  • #5
    Originally posted by Jessa_the_Professa View Post
    "prompt to boot is stuck on 0.09A".



    what can make a phone not boot? One thing would be a short circuit on a power rail. But what are other reasons that a phone can't boot?

    answer that question with some ideas.
    ^^Answer that question. Forget about a short. What OTHER THAN a short circuit can make a phone not boot?

    Comment


    • GHI888
      GHI888 commented
      Editing a comment
      Maybe corrupted software or data lines that it cant read the instructions on what to do.

  • #6
    It cant be detected by iTunes, is there other ways to fix faulty software?

    Comment


    • #7
      Have you considered looking for an open line, or a line with a wrong voltage drop instead of only looking for a short?

      Comment


      • #8
        "Maybe corrupted software or data lines that it cant read the instructions on what to do."

        yes. Software corruption is a possibility, or "can't hear instructions from CPU" or "CPU cant talk to NAND".

        Next question--examining your D.C. Power supply result of steady 0.09---does that seem high or low to you? If there was a short circuit--would you predict D.C. Power supply reading to be high or low?

        Think about that and tell me what is MOST LIKELY--a short circuit somewhere, or a software/CPU data line problem?

        Comment


        • GHI888
          GHI888 commented
          Editing a comment
          Its most probably a short on a CPU power rail, since DC power supply has a low amperage short?..
          My thinking is its stuck on 0.09A so its a short, and if its a "cant hear instructions it would probably fluctuate nott stuck on 0.09A

      • #9
        Keep in mind that a short on any power rail is a "free path to ground" for electrons. This means current will rush to ground through this path as fast as possible. You will rarely see a shorted line consume less than 150ma in an iPhone. In other devices it can be different, samsungs will pull 40ma with a full short to ground on VCC main, but that's getting a bit of topic.

        Your guess is that a phone with a data line problem will pull fluctuating current. Try an experiment to verify this. Pull a resistor off an i2c0 data or clock line on a working board and see what results you get.

        Comment


        • GHI888
          GHI888 commented
          Editing a comment
          WOW! Just removing R0302 on my known good ip6 PCB made it not boot, and its stuck on a loop on DC power from 0.09 then 0.01.
          So this is what it looks like if PCB doesn't read instructions Thanks Mark!

          but my iPhone 6s pcb is stuck on 0.09A, its not on a loop so its a short on a data line then? maybe ill just short one of the resistors to find out? EXCITED!
          Last edited by GHI888; 12-01-2017, 04:24 AM.

      • #10
        Shorted my knowd good ip6 pcb on C0511 to ground and DC power is stuck on 0.53A. So i wonder what line would give a short of 0.09A its to low., If I'm right if its a short that causes my pcb to be stuck on 0.09A on DC power in the first place.

        Comment


        • #11
          I like where you're going with your thought process. Intentionally causing faults in a working phone really helps gather a knowledge base of what different faults will do on dcps.

          Now tell me if c0511 is on a data line or a power rail.

          Comment


          • GHI888
            GHI888 commented
            Editing a comment
            since its connected to other resistor for data its most probably a data line,
            Last edited by GHI888; 12-01-2017, 01:52 PM.

          • Alber_the_Learner
            Alber_the_Learner commented
            Editing a comment
            GHI888, If I'm not wrong in my interpretation of your response, your assumption is "a resistor is used for data in a circuit...". That's is not true! A resistor can be used in both kinds of lines, data lines and power rails.

            To find out that, just take a look at the schematics. The cap C0511 is in the PP1V8 (data line or power rail?). How do you know the difference between a power rail and a data line just by looking at the schematics? Have you realized that in a iPhone schematics there are "Thick Lines" and "Thin Lines"? Besides that tip, what does the term "PP" mean? Now, go back and rethink about if your awnser to Mark_S is right or not?
            Last edited by Alber_the_Learner; 01-24-2018, 05:13 PM.

        • #12
          I keep seeing the word "short" in almost all of your responses. Let's get past the idea that all faults are shorts.

          My question was "what can cause a phone to boot that IS NOT A SHORT".

          You suggested a CPU/data line problem, (YES!) and that CPU power might be SHORT---that's back to shorts, forget shorts

          You did an experiment (GREAT!) where you pulled a resistor creating an OPEN LINE on a CPU data line and found that phone modeled the similar symptoms as your phone. An open line is not a short!

          but then you interpreted this to mean that your phone may have a SHORT---wait, what? How did "I have a short" get back on the list?

          Then you try intentionally creating a short to see if it matches your symptoms and it does not.

          Now answer my same question I left you with earlier.
          From what you know about short circuits and how your phone behaves on D.C. Power supply. DO YOU HAVE A SHORT? Yes or no.

          Comment


          • #13
            Sorry I might have the wrong assumption that " if the DC power supply reading is stuck on a certain current its a Short like my pcb is stuck on 0.09A so i ASSUMED it has a shorted data line since the reading is kinda low for a power line short, because when I shorted i2c0 line, DC pulled 0.53A.

            The other possibility is an open line but DC pulled a fluctuating current reading of 0.09A then back to 0.01A on a loop when I did the Open line experiment, my current PCB is just stuck on 0.09A.

            so it might be a software fault or a data line fault or just bad NAND?
            Last edited by GHI888; 12-01-2017, 03:30 PM.

            Comment


            • #14
              0.09 is really really low--almost zero. It is hard to imagine that something with a path to ground would just drip drip drip current at 0.09. In fact when you shorted the relatively low voltage 1v8 power line to ground you saw 0.53A--which is high.

              Two things I want you to think about:
              1--Marks question to you. In your experiment--did you short a POWER line or a DATA line to ground? Let's clear that up before moving on.

              2--this forum has only a handful of questions on it so far. Have any of the other questions discussed something that may be relevant to this case?

              let me know your thoughts.

              Comment


              • #15
                1. Its most probably a data line, So if I have a data line short DCPS will show a 0.53A not 0.09A which rules out short on a power line short on my case.

                2. Base on what I have read this is most likely software fault? and the best route is DFU mode on iTunes. but iTunes cant detect my iPhone on DFU.
                Last edited by GHI888; 12-02-2017, 01:30 AM.

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