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iPhone not Charging.

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  • iPhone not Charging.

    Hi! I do have a couple of iPhones that is not charging one is an iPhone 5s and the other is an iPhone 7 Plus,

    iPhone 5s, (NOT CHARGING) Fake charging. indicates charging but 0 on amp meter.
    - Replaced tristar,
    - made a Q2 & Q4 jumper
    - connected with a known good dock ang battery
    - still 0 amps on amp meter.
    - 5v is pressent on pp_bat and 3v on vcc main
    Still not charging....

    iPHone 7 Plus,2 units
    * 1st unit not charging
    -Replaced Tristar and Tigris
    - still not charging

    * 2nd unit iPhone 7 Plus (Boot looping )
    -Found there is a short on PP1v8_SDRAM
    - short was on Tristar
    - Replaced tristar ( no more boot loop, back to normal)
    but the iPhone now is Fake charging, at boot it will charge normally at from 0.100 to .900a but after a while it will drop to slowly even up to zero at times and will only go up if you use the phone (if the lcd is on)
    the iPHone indicates its charging but amp meter says 0amps if its on sleep and will just go up if you use the phone 200-400a. then back to zero if you lock the phone,

    I'm not looking for a Hey bro solution here, I would like to understand the iPhones charging circuit better, but I think my knowledge about iPhones charging circuit is lacking, Really banging my head on the wall here.

    This is what I my understanding so far..

    Tristar is the data chip that controls charging but trigis is the on who really charges the iphone since PP_bat, vcc main and pp5v0_usd is there, and theres an LDO that acts like a switch to connect PP_bat and VCC_main. but my current situation is all the voltages are present and there is no shorted caps, I seem to be on a dead end. don't know what to diagnose next.... Wish there was a video or an topic on a forum that explains the iPhones charging circuit.

  • #2
    Can you do me a favor, and remove the logic boards from the frames. After they are out, plug a known good charger port and screen into them, and then plug them into a charger with an ampmeter. See if you get an Apple logo when plugged in. Also let us know how many milliamps they consume, when plugged in.

    I was banging my head against an iPhone 7 that was fake charging. I forgot the critical step of checking for Apple logo with only a charger port, and wasted about 8 hours trying to figure it out.

    If you don't see an Apple logo when plugged into a charger with no battery, I am 85% sure it is a Tristar fault. I could be wrong though, and I am sure someone will chime in and correct me.

    EDIT: I guess you could do this with the logic board still in the frames. Just unplug the battery and charger port, and use a known good charger port to test with. I usually do all my testing with the logic boards out of the frames, for convenience.
    Last edited by SquidBilly; 08-23-2018, 05:47 AM. Reason: I forgot something.


    • #3
      SquidBilly Apple Logo Apears , East about 160-400 then turns off< then apple Logo again.


      • #4
        Then I am less sure it is your Tristars at fault.

        When you talk about unit 2

        it will charge normally at from 0.100 to .900a but after a while it will drop to slowly even up to zero at times
        I thought that was normal behavior. Albeit, all the iPhone 7s I have dealt with, charge at around 1.5 to 1.6 amps, and then when they reach about 90% they start trickle charging at around .3 amps. When they reach 100% they drop to near 0, unless I turn on the screen.

        Are you using a 2 amp charger? I would expect a 1 amp charger to output around .9 amps.

        I am assuming you are using new, good quality chips for your Tristar replacements. I made the mistake of reballing parts from scrap phones. I have since started ordering new chips.


        • #5
          SquidBilly Yes brand new tristar a3b for iPhone 7, and Yes the normal is .9a using my 1am charger.


          • #6
            Let’s not try to boot phones with no battery! I see this advice from time to time on here—where is this coming from?

            Iphone 5s—stare at the schematic and tell me where does charging happen? Hint: it’s not Tigris.

            iPhone 7p #1–if you are sure that you have 5v getting to tristar and Tigris, and you are sure about your replacements then I’d look for shorts at Tigris pmid caps, and I’d worry that you floated the charging coil within trinity. There’s really not much to the charging circuit and everything there is you can see on the schematic. Look at the schematic without worrying about exactly how does the system work, but instead just look for failure points. Follow your charge port lines that look important for charging—where do they go, how might they fail? Then you get to the chips...are they powered on? Are they told to turn on? Do they have helpers (like the charging coil) that are missing/damaged/not working. Etc

            second one with the SDRAM short—that should have definitely been tristar if pulling tristar relieved an SDRAM short (which is really odd, that short is almost always within the RAM). For “state specific charging” this can sometimes be the battery/main mosfet. To test, I jump across it and then replace if that solves.


            • #7
              Let’s not try to boot phones with no battery! I see this advice from time to time on here—where is this coming from?
              I thought that was the test for tristar. If you plug a charger port into a logic board and you don't see an Apple logo, I thought that was a sure sign. I don't know where I got that from, but I have seen in other posts on this forum that was the test. Something similar to plugging in a charger port and testing the battery terminal for over 3volts.

              From now on, I will plug a battery and charger port in and watch the charger port power for normal current.

              Iphone 5s—stare at the schematic and tell me where does charging happen? Hint: it’s not Tigris.
              When we are looking at schematics for information such as this, where do we start. Do we look at where the 5 volts from the charger port is going, or do we look for where it is being sent to. I am not sure I worded that right. If in this instance we are looking for what charges a battery, I feel like I would start at the battery connector and work back, am I wrong here?


              • #8
                I have never advised anyone to test tristar like that, and I, too, have seen it mentioned from time to time. I am curious where the source of that idea is.

                i consider usb 5v a variable to be eliminated when studying a phone that doesn’t boot. Boot is battery. A phone can NOT boot on usb, and also can NOT boot WITHOUT battery—so when a phone doesn’t boot I eliminated usb from the equation to simplify the system and see what happens at battery.

                if you’re interested in charging—start at charge port. If you’re interested in booting, start at battery connector.


                • #9
                  Power comes from pp5v0_usd_conn from the dock flex then goes to Q2 which acts like a switch to PP5v0_USB_Prot that is connected to Tristar (data) and pmic (power)

                  So I think Q2 is where the power comes from needed for charging

                  and (not sure here) Pmic is the one will charge the battery via Q4 using VCC Main?


                  • #10
                    Yes—for the 5s, tristar talks to Charger and give thumbs up to PMIC for charging (instead of Tigris). PMIC checks battery data and begins charging. If you have changed tristar and verified the tristar side of charging and battery data swi line is okay, then that leaves the “business” of charging which in the 5s is the pmic and its charging coil.
                    you can check for short caps on the lines that help the pmic charge, but replacing the pmic is the likely problem—just like some iPhone get Tigris damage in addition to tristar, in phones with no Tigris this happens at the pmic


                    • #11
                      That clears things up alot. Thanks Jessa!