Released September 16, 2016. Model 1660, 1778 Available as GSM or CDMA / 32, 128 or 256 GB / Rose gold, gold, silver, black, and jet black.

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How to find small shorts on iPhone circuit

hi

i have an iphone 7 that wont turn on i believe there is a short somewhere on the board

but i can't find it as the short is small and i believe it's somewhere on data line

or maybe an IC is defected so when i connect phone to power supply the current is zero which means no short on pp_vdd_main but when i try to turn it on it stuck on 0.07 amp and stays there i did change the Tristar and Tigris but no luck so i come to conclusion that there maybe a small short i tried really hard to to find it but no luck would be great if you guys can help to locate this short that stop the phone from booting

just to let you know i dropped the voltage to run more current into board but only goes up to 0.10 amp which still doesn't help to locate the short

thanks.

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Deck the Halls
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1 Answer

Chosen Solution

Start by checking PP_BATT_VCC and the PP_VCC_MAIN for shorts. If those lines look good, then start checking the voltage rails generated by the PMIC (such as PP_CPU, PP_GPU etc.). If you identify a short, try to determine what is causing it and work your way through the process. You should also double check the IC's you have replaced. Inspect closely to see if they appear to properly soldered onto the board.

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Comments:

All the voltage rails generated from pmu IC have normal voltages,is that means they are not shorted right? And if not i still checked them all i can't locate the short is this mostly a short or defected IC ?

I really love your work minho thank you for your help.

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pp_vcc_main resistance is 2.67 is that right?

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2.67 what? What is the unit of measurement?

You should also check the outputs of the BB PMU. If something is wrong there, it would also not allow the phone to boot.

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it's diode mode, should i check for voltages or short in there?

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Use continuity mode to check for shorts and voltage mode to check for voltages. Diode mode is for comparative analysis.

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