Released September 25, 2015. Model A1688/A1633. Repair of this device is similar to previous generations, requiring screwdrivers and prying tools. Available as GSM or CDMA / 16, 64, or 128 GB / Silver, Gold, Space Gray, or Rose Gold options.

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Water damaged 6s board 1.2v to battery connector and on Vcc main

Hi, just wondering if anyone can help, I have a water damaged 6s, that wouldn't switch on or get any power to, after checking caps etc on vcc main and removing the short (I think ) also removing Tigris and putting back on board I am now getting 1.2v to vcc main and also to the battery connector, I'm guessing that still isn't the right voltage, and iTunes is still not detecting it. Any help would be great fully appreciated..

Thanks

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Anybody give me any guidance?

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Do you have a short on VCC_MAIN or not? Are you testing just the logic board or is it fully assembled (display, cameras etc.)?

Water damaged phones can have multiple problems and many times they are unfixable. You have to start at the beginning and do a thorough visual inspection (preferably with magnification) to see what parts of the board are affected by corrosion. If it is localized, focus your energy there otherwise take note of all the problem areas.

Test the main voltage rails (VCC_MAIN, BATT_VCC, PP5V0_USB). If those lines are not shorted, then you move on to the voltage rails created by the PMU/PMIC (U2000).

Now, because you have 1.2V on VCC_MAIN, I suspect that one of the secondary (PMIC) voltage rails is shorted, which draws too much current from the the power source and forcing the voltage down. It would help your troubleshooting if you had an ammeter to see how much current is being drawn.

Update (05/08/2017)

Thank you for your reply, :-).. I did have a short on vcc main yes as it was completely dead.. after removing the common capacitors that short on vcc main I think i have sorted the short now.. I have ultra sonic the board and there doesn't seem any corrosion left unless under ic's.

Yes I am just testing the board at this point.. when I plug the cable into the lighting dock and test the voltage on a vcc main line it comes back at 1.2v.

So you would recommend turning my attention to pmic rails?

Can I just ask what should vcc main be at about 4v? I could post some pictures of what I have done so far?

Thank you again..

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You are still saying you think you have solved the short on VCC_MAIN. Is it shorted or not?

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Sorry excuse me I'm still learning.. I will follow your answer later and test what you have said. And post back if that's ok.. thank you for your help so far..

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Well I can't of solved the short completely as the voltage is only 1.2v on vcc_main, and it should be higher shouldn't it. But before I started it had no voltage, so ive made progress :-)..

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Absolutely, don't hesitate to test and then come back with your findings. I can spew fifty things but that takes time to type and time to read ;>). Go at it one step at a time.

For VCC_MAIN, you should see about 4.2V.

As I said, water damaged phones can have multiple issues. So progress is always relative. As I suggested initially, I suspect that one of the PMIC rails is causing this low voltage on VCC_MAIN.

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Am I going to be able to find the pmic rails easy? I have the iPhone schematics that I can refer to? Don't have zxw tool yet :-(..

by pmic you mean Tristar chip and Tigris chip etc? Check there rails? Thanks

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Sometimes just leaving the board out in the sun for a few hours or in a drawer for a month helps. I had a phone that wouldn't even work. I left it in a drawer for a month and it magicly started working. The connector may be damaged preventing charging so buy a new one or test the battery for a charge.

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Jack Rhodes will be eternally grateful.
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