iPhone 7 deep sleep
 
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[Solved] iPhone 7 deep sleep  

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Fozzo
(@fozzo)
Active Member
Joined: 10 months ago
Posts: 10
07/11/2019 4:10 pm  

Hi Mike, this is a very tuff one. So I got an iPhone 7 with many problems. Customer wanted data back so my target was the get the phone on and recover everything. It has a previous repair attempt from another shop to audio ic. Phone came in a bad shape, both anode line and chestnut line were shorted, I changed a couple components, a filter was blown on anode line and a cap was shorted on chestnut line, problem solved. The iPhone display was back together with backlight. After booting  I was able  recover data and I had an happy customer. He left the phone to our shop because he already bought another. So I started playing with it to see if I would be able to solve all related problems. Once the phone boots I noticed there was no firmware modem (intel board) so I went to audio ic, I did normal job and audio got back. Compared to a known good board everything looked fine around baseband pmu then I reballed the baseband, with many luck my job was good and now I also have firmare modem and calls works perfectly but... when iPhone goes to sleep mode, after 1/2 minutes there is no way to wake it up. If I put autosleep to never I have no problem but I have a big normal drain of battery, if I connect phone to a pc and it goes to sleep I have no problem to wake it either by home button or power button. I know when it goes to “deep sleep” it is still on because on dc power supply absorption is not 0 but 1/2ma. Also to get it power on again I need either to reset by buttons or remove battery and plug again. I already checked AP_TO_LCM_RESET_L line but seems ok. I’m thinking something about cpu get slightly damaged while baseband job but there might something else. As side note sometimes home button stop work and restart randomly but all the times it does not work at very first when booted (I don’t know if there might be any correlation). Home button fpc diode reading is ok compared to a known good board execpt for a copule of pins being .7.. against .5.. from zwx but I think this doesn’t really bother much. Any clue would be aprecoated. Thanks.


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Mike
 Mike
(@admin)
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Joined: 5 years ago
Posts: 507
11/11/2019 5:54 pm  

Well, take a look at Maggie or the rectangular black chip next to the audio ic.   Maybe reball those just to rule them out.  The last thing that I would look to replace is tristar.  Someone in the facebook microsoldering group posted that replacing tristar fixed this problem.


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Fozzo
(@fozzo)
Active Member
Joined: 10 months ago
Posts: 10
12/11/2019 2:40 am  

Hi Mike. Thanks for your answer. Homer IC (the black one) might not get reflowed since the airflow went to the opposite side. I will gibe a look at maggie and i will give a shot to tristar. Lets see!


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Mike
 Mike
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Joined: 5 years ago
Posts: 507
12/11/2019 7:35 am  

I wouldn't rule homer out, but it alone shouldn't cause the screen to go black.


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Fozzo
(@fozzo)
Active Member
Joined: 10 months ago
Posts: 10
21/02/2020 5:48 pm  

This is just for the records or for someone else having a similar problem. I managed to solve the issue. Actually problem was about wifi ic. After removing iPhone was able to recover from sleep. Just to be sure I used a different one, but I wonder if original one just needed a reballing.


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Mike
 Mike
(@admin)
Owner Admin
Joined: 5 years ago
Posts: 507
23/02/2020 8:14 am  

I don't work on wifi problems, but I think you can use another wifi chip, but you need to unbind/rebind?  Or maybe just unbind with some sort of reader.


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Fozzo
(@fozzo)
Active Member
Joined: 10 months ago
Posts: 10
23/02/2020 8:59 am  

I think I wasn’t clear, I used a different chip from a donor board. I unbinded wifi first then reballed nand and solder back and after reballed the donor board wifi ic and solder back. All if working good now and problem solved!


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