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Go Back   GSM-Forum > GSM & CDMA Phones / Tablets Software & Hardware Area > iPhone ,iPod & iPad (Apple Inc. Products) > iPhone, iPad, iPod Hardware Repair

iPhone, iPad, iPod Hardware Repair Hardware Repair discussions for iPhone, iPod , iPad & Apple Products, help, guides.

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Old 10-11-2018, 15:10   #1 (permalink)
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iPhone 7 Plus no baseband version after water damage


Hi, like commented was water damage, was sulfated just at bottom rear area, up to backlight capacitors anf filters. Changed a filter and capacitor and half backlight issue removed. But still stuck in searching and don't show baseband version, IMEI is OK. Also some times doesn't work the touch.
Rest of the board wasn't sulfated.
Any clue to start measuring/tests? Any trick to check if BBPMU_RF right or the issue withouth removing?
Thanks in advance for any help
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Old 10-18-2018, 02:19   #2 (permalink)
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1. you do not know how many layers of board shorted because of water damage.
2. layers you see on top is not only layers, thin layers are below ics they might get burn after water get in.
3. these water damage repairs are hard to fix completely because you fix 1 issue then 2ond isssue comes then you fix 2ond, third issue comes, then 4th and so on, and you keep working for same $$ all time
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Old 10-18-2018, 02:54   #3 (permalink)
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Rather than under layers I think when be with water or then sulfated some lines are jumped and managed over voltage than designed, due that or overheat side effect get damage any IC or other component. While BB CPU, RAM or CPU are OK I have hope in this case. Don't so bad, just bottom bad lucky like commented, if were sulfated allover I were leave it since beginning. Main issue for me it is the Intel model, ZXW and schematics around bet for Qualcomm one.

Enviado desde mi HTC 10 mediante Tapatalk
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Old 10-18-2018, 10:37   #4 (permalink)
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@christina is right.If you have zxw tool just check resistance values on all bottom connectors first,if anything abnormal look into that rail.As u have told that damage was only at bottom, in some cases backlight ic's and lcd ic''s are culprit.
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Old 10-19-2018, 23:50   #5 (permalink)
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Quote:
Originally Posted by mandango View Post
Hi, like commented was water damage, was sulfated just at bottom rear area, up to backlight capacitors anf filters. Changed a filter and capacitor and half backlight issue removed. But still stuck in searching and don't show baseband version, IMEI is OK. Also some times doesn't work the touch.
Rest of the board wasn't sulfated.
Any clue to start measuring/tests? Any trick to check if BBPMU_RF right or the issue withouth removing?
Thanks in advance for any help
1. Check 5 BBPMU_RF outputs
PP_VSW_S1 (0.9v)
PP_VSW_S2 (1.25v)
PP_VSW_S3 (1.16v)
PP_VSW_S4 (1.85v)
PP_VSW_S5 (1.01v)
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Old 10-21-2018, 12:28   #6 (permalink)
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Quote:
Originally Posted by ninos22 View Post
1. Check 5 BBPMU_RF outputs
PP_VSW_S1 (0.9v)
PP_VSW_S2 (1.25v)
PP_VSW_S3 (1.16v)
PP_VSW_S4 (1.85v)
PP_VSW_S5 (1.01v)
I think you are basing on QCOM model, this is Intel, no clue to follow that lines, BB_PMIC is different as well can't check it comparing the QCOM one

I put what I've measured in the coils next to BB CPU

This is QCOM one


My Intel with some measures


In the middle of boot time and eventually, with the power supply I appreciate the consume turns crazy for a moment, not sure if is short.
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Old 10-21-2018, 19:50   #7 (permalink)
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Quote:
Originally Posted by mandango View Post
I think you are basing on QCOM model, this is Intel, no clue to follow that lines, BB_PMIC is different as well can't check it comparing the QCOM one.
Yes was from Qualcomm version, so you have to check 4 coils right to BB_CPU, first diode mode, and then volts.
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Old 10-22-2018, 13:20   #8 (permalink)
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Quote:
Originally Posted by ninos22 View Post
Yes was from Qualcomm version, so you have to check 4 coils right to BB_CPU, first diode mode, and then volts.
If you mean the 4 one I mentioned the volts before I had compared with other working board and in diode mode the four was similar.
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Old 10-22-2018, 14:46   #9 (permalink)
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Quote:
Originally Posted by mandango View Post
If you mean the 4 one I mentioned the volts before I had compared with other working board and in diode mode the four was similar.
Do you try reballing BB_CPU?
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Old 10-22-2018, 15:34   #10 (permalink)
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Don't reball BB_CPU without being 100% sure it's the issue. You'll likely melt the CPU right next to it if you try, and then you'll have to reball CPU, and while reballing CPU you'll likely melt PMIC_RF right underneath it, you may also short the ram(extremely hard to replace without damaging CPU)... This is how you turn a fonctionning board into a useless board 99% of time.

First check your LDO lines powered from the Baseband PMIC, make sure they all have proper voltage, the intel version has a different baseband but you can rely on the Qualcomm version to test your Baseband PMIC voltage rails.

You may need to insert sim card in the iPhone while booted to trigger some of the LDO voltage rails and also check again all of the PP_VSW voltage rails. It's more then likely that the issue is baseband PMIC.

I suggest you should replace the baseband PMIC first, you lose nothing at trying it and it's less risky.
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