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Lanzado en Septiembre 16, 2016. Modelos 1660, 1778. Disponible en GSM o CDMA / 32, 128, o 256 GB / Oro Rosa, Oro, Plata, Negro Mate y Negro Brillante.

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Bootloop after tristar replacement

a customer came in with iphone 7 that wasnt charging. tried new battery and charge port, wasnt charging. so with the battery disconnected i plugged in charger and no apple logo. confirmed tristar was at fault, and proceeded to replace it with 1610a3b (the exact tristar model of iphone 7) after the replacement the phone was charging but only while it was powered down. so i though maby it was a bad chip placement and proceeded to remove and reball the chip i just put on. after that i reinstalled it and it was doing the same thing, only charging while it was off. so then i replaced tristar again this time with 1610a3 which as far as i know is fully compatible to substitute for the original. after that replacement the phone is charging at 1amp but is stuck in bootloop. i made sure i shielded the nand very well(quarter and nickle stacked on top) and there were no other underfilled chips near it, nor are there any chips directly on the opposite side of the board...ive done tristar replacements on older models at least 50+ i dont feel like i did anything wrong. the only thing ive done so far is inspect around the nand area for any oozing solder balls and there are none then i compared tristar lines and nand power rails to known good board and all seems im stuck, any insight would be greatly appreciated.

p.s. i tried to update the phone and get error 4013 and fails at 19% in 3u tools. the only thing i can think of is that the board may have flexed a bit at the audio ic/ bb pmu fault line and is causing this.

Hard to get a good close clear pic... But here's around the nand and TriStar itself after 2nd replacement.

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Update (06/13/2018)

i have found the issue, the bb cpu is internally shorted on PP_1V0_SMPS5 unfortunately there is no way to fix as far as i know.

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Don't you just hate these catch-22 situations!?!

First of all, regardless of how many times you replaced an IC before, you should never assume that you did it perfectly right. You probably did it right, and you most likely have a high rate of success. But the phone doesn't work so it would be silly to make the assumption that the problem is not there. Also, you used a different IC model and lastly, we all order these IC's from some gray market in China. It stands to reason that if these IC's are available, it's probably because they had an unacceptable rate of defects according to Apple's QC. So it's to be expected that some bad chips will be in those reels that we buy from.

Now for the charging issue, you could also have caused some problems with the Trinity coil package, which is almost directly opposite Tristar. Trinity contains the coil that is in the Tigris circuit so if that is damaged or the solder connections are affected in any way, you will not get proper charging. So I would go back and fully probe the Tristar/Tigris/Q2101/Trinity circuit to start.

As for the error 4013, it could be a BBPMU issue (check the voltages) or a BBCPU reball/jumper issue. Considering it wasn't there before the repair, I would focus on the charging and if 4013 is still there, then look at that separately.

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i order my chips from and haven't had any issues with them in the past, but i wont ever overlook a defective chip thats why i replaced it again. also the problem isnt with charging anymore, it charges just fine with the 1610a3 tristar chip. the only issue now is the 4013 error. and bbpmu is what i was thinking but i cant really test it because my tester phone has the intel version and the customers device has the qualcomm ic.

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You don't absolutely need comparison values, although that makes it much easier. Just probe in diode mode and look for anything out of place, like shorts or OL where they shouldn't be or disparate values on paired lines (like I2C).

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