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Iphone 6s - Tristar issue

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  • Iphone 6s - Tristar issue

    Right now, I am stuck with my thinking process having an iPhone 6s that had no water damage, but had a previous history of fake charging and it was used to charged with no MFI_charger.

    When I plugged into DCPS, It started from 0.250A which is not normal, and it got very hot while and after booting. I did a freeze spray test and the Tristar was getting hot first, confirming my guessing of a bad Tristar.

    Then, after changing Tristar, the phone booted normally (from 0A up to 1A), although had a weird behavior: just for a second it blanked the apple logo in the very begining. I am still wondering what should this indicate?

    Using the USB cable and a known good battery, the phone booted up althought there was no consumption on the USB amp. So, I did a microscope inspection onTristar IC and I realized one of the balls was not melted and did not have a contact with one of the pads (D1 - which is NC) and I assumed probably there were some other pads with the same issues.

    Then, I reflowed the Tristar and the phone booted up normally and showed and sounded a charging battery porcentage when USB was plugged in and the USB meter was showing normal consumption charging.

    For making sure everything was okay with charging, I had the battery gone from 100% to 0% - running Youtube videos - and I got the phone off then.

    Here is where I am getting stuck with my Tristar troubleshoting:

    Now, with a battery completly died, when plugging the USB cable, Apple logo shows up and the USB meter reading goes apparently normal for a booting phone. It blinks for a second (as a weird behavior described before), the phone boots up, I can see the 1% battery icon, then, after a while, the phone turns off (0A at the USB meter) and restarts the process.

    I retried a couple times, and once I got the baterry reached to 2%, it charged normally going up the porcentage (USB amp from 0.76-0.78A). So, once the battery porcentange reaches up 2%, the charging process goes normally. I had this situation twice.

    I also tried with a known good but not fully battery (80%), and it charges up normally. With another battery reading 3.5v, I got stuck in 3% not charging up.

    Another observations:

    Without the USB cable plugged in: I saw the battery charging icon with the USB cable on the screen just once in the several attemps tried. And that is also confunding me. When the phone turns off because of the 0% battery, and when I pressed the power button, instead of appearing the charging battery icon, it shows up directly to the Apple logo and gets stuck there for a while until tried to restart.

    With the USB cable plugged in: it does not show the charging battery icon, it starts straight to Apple logo and after a while boots up.

    By all that has been said, my assumption is that the phone has not been able to recognize when the battery is 0% and then is not giving the proper instructions toTigris saying "starts the charging", even though the Apple logo appears.

    My troubleshoting thinking process, there are only 3 possibilities to this fault:

    1) a bad Tristar which is responsable for the fake charging
    2) a bad Tigris which is not able to read the information sent saying: "the battery is 0%, than starts to charge it"
    3) a missing dataline in any of those IC's, which is not sending/receiving the info to let the Tigris does his job when the battery is 0%

    So, before going to blindly replace any of both IC's, and take the risk to change an unecessary chip, I would like to understand how they actually work and could be relaterd to the issue.

    Looking at the schematic, in my guessing, there are just two data lines that should be involved in the problem:
    - VBATT_SENSE
    - TRISTAR_TO_TIGRIS_VBUS_OFF

    Assuming the problem is not related to a dataline, then, I would change Tigris first since I already changed the Tristar and I know a bad Tigris can damage Tristar. And if this does not fix the problem I would change again the Tristar.

    Please, help me out!

  • #2
    I changed again the Tristar and also for the first time, the Tigris. I still have the issue. I found out I just had 4.2V-4.7V fluctuacting, instead of having the 5V in the cap C4503 (PP_TRISTAR_PIN).

    Then I removed the Q4500 and made a jumper from its pin#2 to the cap C4503. Still the same results. Iphone is charging, but when the battery reaches zero, there is no red battery sign when plugging the USB cable and it has that weird behavior. But for just once when I plugged the usb cable, the battery went up to 100%. But, when I unplugged and plugged it back, it started from 1% normally. Will the tristar be damaged again? (I dont think so, until I can rule out the questions below and fix the 5V to be back again...)

    I put the Q4500 back and I measured the resistance to ground of the PP5V0 and I got 2200mV instead of 2480mV from a known good board. So, I think there is a partial short on that line.

    I just removed the C4503 and it was not shorted. Of course the resistence in DM went down to 667mV. I will put it back and tomorrow, will remove the other caps in that line. Unless you tell me for not doing that. I am really afraid of messing it up...

    Should I change the Tristar Again?

    Is the Q4500 the real problem?

    Is there a real partial short on that line?

    My guess, I should clear the partial short and replace the Q4500 harvesting it from a donor board because I don't have a new Q4500 IC...
    Last edited by Alber_the_Learner; 02-06-2018, 10:40 PM.

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    • #3
      When you remove the active diode / mosfet it does weird stuff like jump around charge percentage when the charger is plugged in. This blinking you're talking about, that's normal for iOS 11 and above,most devices tend to do it.

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      • #4
        In some cases Tigris and Tristar get damaged because of imitation chargers/cables. There is one vid where Jessa explained after replacing Tristar still the phone would not behave 100%. In the end it turned out that a bad Tigris was affecting Tristar function, so the solution was to replace Tigris first and then Tristar.

        Your 1st Tristar might be damaged by the bad Tigris. Now that you replaced Tigris, I would replace Tristar again and then test the phone.

        As to your other quesions about the exact interplay between Tigris and Tristar....I dont know and unfortunatly we don't have the datasheets

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        • #5
          Hey Albert,
          Did you make any headway with this device?

          Like crea2k said, Apple logo blinking once has become a normal occurrence since iOs 11.

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          • #6
            TKS crea2k and Sly I Will be back to this board soon... It seems the only issue to solve is the missing "red low battery ícone" that is supposed to be shown when the battery is low and the USB cable is plugged in. This is the only thing is not working...

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            • #7
              Originally posted by Mohammed View Post
              In some cases Tigris and Tristar get damaged because of imitation chargers/cables. There is one vid where Jessa explained after replacing Tristar still the phone would not behave 100%. In the end it turned out that a bad Tigris was affecting Tristar function, so the solution was to replace Tigris first and then Tristar.

              Your 1st Tristar might be damaged by the bad Tigris. Now that you replaced Tigris, I would replace Tristar again and then test the phone.

              As to your other quesions about the exact interplay between Tigris and Tristar....I dont know and unfortunatly we don't have the datasheets
              I will give that try as well - change again the Tristar - tks, Mohammed!

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