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Released September 16, 2016. Models A1661, A1784, and A1785. Available in 32, 128, or 256 GB configurations in Rose gold, gold, silver, black, jet black, and (Product)Red.

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Device drawing 50ma in boot help

I’m having some issues with an iPhone 7 plus board number 820-00249-a. I bought this phone which was bootlooping and giving error 4013. The first thing i did was check the audio ic by reflowing it and giving it a litle nudge. After that the phone no longer worked and wasn’t recognized by pc. So I removed the ic and of course the c12 pad fell right of so i made a jumper reballed the ic and put it back on but no luck. All voltage lines are working no shorts. If I connect the board to a power supply and press the power button it’s draws about 50ma constantly. I’m guessing it is a data line problem but I don’t have new ic’s to test with. My question is if I were to let’s say remove the u3101 or any other ic that communicates with the cpu and try to boot the phone would it boot or boot loop or draw current in a different way or is this 50ma draw a thing that happens if a ic doesn’t respond. I’m quite new to this and would really appreciate any help.

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Error 4013 could be a Baseband issue. I would check the power rails (BBPMU_RF) going into the Baseband IC to see if there are any issues.

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Hi, thank you for your advice but unfortunately I have the intel version of the board for which I cannot find a schematic diagram.

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Yeah, I mostly see this version of the board in Canada and it is a tough one to troubleshoot. Plus removing the Baseband CPU is not easy as it is quite large and underfilled. If you have access to a known-good device (even the IP7), then you could do a comparison probe.

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I know it’s basically brain surgery but at least the patient doesn’t complain to much if anything goes wrong. I see you have a lot of experience with this do you usually find that these kind of issues are caused from mechanical damage in solder joints and just reballing fixes the issue or is it a problem with in the bb cpu or pmu itself. I’m pretty sure if the bb cpu has a fault there is no fixing that even if you replace it with a different one since it doesn’t have the right serial numbers. I don’t know if the phone would at least try to but or would it immediately brick itself.

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There a several issues here. First, you don't know the history of the device. It may have been oven reflowed or something worse ;>). Second, you have applied quite a bit of heat yourself and these Audio IC repairs can turn into nightmares very quickly. Online videos don't do it justice. It is an easy, straightforward repair but the Audio IC's proximity with the baseband CPU and SoC/CPU can make a routine repair go badly very quickly.

You can't replace the BBCPU (you can for data recovery) so if you are confident the Audio IC is properly seated and that the BBPMU rails are good, the only other option is to try and reball the BBPCU. Not an easy task...be forewarned.

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After a couple of hours I’ve managed to fix it thanks.

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Can you please say what fixed this? Was it a reball of the BBCPU as Minho suggested? I have a phone sent to me where I can see Audio IC repair has taken place (green solder mask) and it just draws 50mA on prompt to boot like yours. Thx

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Jaka Lovse zal eeuwig dankbaar zijn.
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