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iPhone 7 random restarts and battery % jumps after audio ic replacement?

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  • iPhone 7 random restarts and battery % jumps after audio ic replacement?

    Hi everyone, new to this forum and fairly new to microsoldering, but have done phone repairs as a business for many years, won’t bore you with my back story but have all the equipment I need (I think) and have been practicing board repairs (properly) for about 6 months with pretty good success, learning a lot.

    I dropped my own iPhone 7 and broke the screen then lost sound in calls, after that my phone had problems charging, then lost voice notes, after 24 hours charging came back fine and used the phone for a couple of weeks on holiday on WiFi only fine.

    i have done my first audio ic repair (no jumpers) on my own iPhone 7, fudged it up first time so reballed and second time worked well. After start up all works fine, voice memos, sound in WiFi calls but had no service. I looked under the edge of the shield and found something knocked out of place and some damage to the end of one cap so removed the edge of the shield, refitted it and replaced the cap then that sorted the signal problem. I then put the phone back together thinking I had cracked it and now the phone will randomly restart and battery percentage jumps up and down, I can’t tell if the phone is charging properly (it says it’s charging) but this issue wasn’t here before I replaced the audio ic? Is it likely I have damaged something whilst replacing audio ic or maybe the charging issue has re-appered?

    I’ve been stupid probing around looking for a possible short, found PP_GPU/CPU and PP_SOC short thinking what the hell have I done to this phone! until I researched tonight and found that they have low resistance anyway.... so basically now looking for advice for what to look at next when I’m back in the office tomorrow?

    any help would be much appreciated, this is my first attempt at an iPhone ic after building up confidence on the older models.

  • #2
    The key words in all of this are "battery %" which is diagnostic for batt_swi (battery data) problems. Either the phone can't hear or it cant understand batt_swi. Take a look at the schematic and see if you can find a relationship between BATT_SWI and audio ic. If not, then think more broadly about the larger process of doing that audio ic job, starting with an intact phone. What is MOST LIKELY about how BATT_SWI got damaged? (also, stop using that phone until you fix it)


    • #3
      Thanks I’ll take a look into this I’m not using the phone just tested over the weekend as I thought I had fixed it but unfortunately not /(


      • #4
        What I am seeing is that PP_1V8_SDRAM is linked into BAT_SWI THROUGH Q2102, is this maybe where the issue is. Don’t see any problems with the components near the audio ic on PP_1V8_SDRAM is this what I should be looking at do you think or more likely a component near audio ic? There are 2 pads for this line under audio ic so maybe I need to reball? No shorts on these circuits.


        • Jessa_the_Professa
          Jessa_the_Professa commented
          Editing a comment
          What i think is that you fucked up the battery flex. Until ruled out, that is MOST likely. Remember BATT_SWI has to travel from the board within the battery to the battery connector and beyond.

      • #5
        i wouldnt rule this out but it does the same thing on dc power from my desk power supply so not sure it is battery related... although i will try a new one and see where i go from there


        • Jessa_the_Professa
          Jessa_the_Professa commented
          Editing a comment
          DCPS does not provide any battery data, so if anything this confirms the problem, not rule it out!

      • #6
        Jessa_the_Professa thank you.
        update on this issue! I replaced battery and checked the original, original had a tiny scuff on the flex (probably from when board was removed) although this didn’t resolve the issue
        disconnected front camera and it worked for hours. Then replaced it and same problem is happening. Also just noticed that when plugged in through my ammeter amps jump from 0.19 up to 0.49 and jumping constantly, also when powered off amps show 0.02 so wondering if this is a Tristan/Tigris issue now, what do you think?
        thanks in advance


        • #7
          Time to clarify the problem.
          This is what you've told us.
          You had a phone with classic audio ic fault.
          It had "a charging problem that spontaneously resolved" --this is a question mark now--the only measure of charging problems is usb current consumption. When you said that charging was fine, did this actually mean that you confirmed that the phone would consume normal charging current on usb, therefore ruling out tristar/tigris problems (which are electrical damage and would be totally unrelated to drop, flexion and audio ic problems).

          Then you had gas gauge problems in the absence of charging problems---this can only be batt_swi. batt_swi problems in the absence of charging problems points to battery flex. However, batt_swi problems IN THE PRESENCE of charging problems (low, zero, or erratic usb current consumption) points to tigris. When tigris fails then by default you can expect that tristar was also damaged. It is possible for batt_swi problems to be neither the battery flex, or tigris but instead to be damage to the CPU at batt_swi although this is less common.

          If you are having erratic charging as well as batt_swi problems AND YOU ARE SURE this has passed rule #1 (you don't have a board problem until you KNOW you don't have a parts problem) then change tristar and tigris.

          I am concerned here, since i have never seen you operating on a device in person. Your story has a lot of inconsistencies that seem to be parts/assembly/disassembly related. For example--a bona fide tristar/tigris electrical damage problem does not have the same mechanism as audio ic failure. To have them present at the same time is rare. More likely is assembly/disassembly battery/charge port problems, poor connection etc, especially when charging spontaneously resolves (i.e. you took apart and reconnected and now it works). You are finding that you have different batt_swi results depending on whether or not fcam is connected--these are unrelated. More likely this is poor connection at battery/charge port between tests.

          Clear up any parts and assembly problems by connecting things under the microscope and scanning your connectors and surrounding area for any minuscule problems before deciding this is tristar/tigris.


          • #8
            I do see your concern Jessa, believe me I’m good at phone repairs (I suppose as I’m in uk and your in America all I can do is give you my word for that.) have been doing it for years since a teenager and have always taken pride in being the only local repairer to actually do a decent job, I’m just reasonably new to board repairs. The charging issue originally appeared a few days after audio ic problem so not necessarily from the drop also used abroad for 3 weeks before so could be from use on different cables over there, the issue resolved itself I never had to open the phone to fix it so maybe it was just intermittent but yes charging current through my ammeter seemed absolutely fine compared to other known good iPhone 7.
            Have checked that it isn’t the charging port or battery so I know parts is ruled out and the only reason I thought to remove the front camera was because I have seen a non original front camera cause random restarts in the past, bizarre I know and I couldn’t figure out why but the proof is that after replacement it stopped restarting itself.
            I’ll re-check everything tomorrow and decide if Tigris and Tristar are the way to go.
            gutted, I’m desperate for this phone back as currently using a ‘limited edition’ red one which is like new. You would understand my worry if you saw the one I’m trying to fix,my phones go through the wars and get very beat up over the years


            • #9
              One of the first that comes to my mind after reading all this is what shield had a component knocked out under it? What was that component and what do you mean by removing "the edge of the shield" ?


              • #10
                These are all very unrelated problems. I would not be surprise if you suffering from having too many variables to make sense of it at this point. But if I was in your shoes, I would start by understanding and eliminating your first variable in here which is the no signal leading to finding physcal damage, Can you clarify what happened?

                I would recommend to refraim from using any hot air for moment, as it will most likely blur the image even more by introduce bunch of new variables.

                Charging IC maybe the problem, but when I start to notice new, or odd behaviours, I usually examine everything I did and ask myself what could of reasonably been affected by my previous.
                Last edited by Sly; 07-06-2018, 02:20 AM.