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iPhone 5s shorted motherboard

Hello,

I have an Iphone 5s board which is shorted. Connecting to power supply and appling 2A nothing getting hot to determine where the short is coming.

How’s that possible 2 Amps and nothing getting hot ?

Thanks.

답변되었습니다! 답변 보기 저도 같은 문제를 겪고 있습니다

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Thanks Minho. But i think i did not express myself correctly before.

I managed to remove the short from the VCC_MAIN. And i did put back these 3 ICs what i removed before. Display IC, U2 and PMIC.

And now the readings show to me i have not done the job correctly about the PMIC i guess.

Power rails what i have measured:

PP_VCC_MAIN - 3,8 V

PP_BAT_VCC - 3,8 V

PP1v2_SDRAM - 0,01 V (Diode mode shows "353" = no short)

PP1V0_SOC - 1,0 V

PP_CPU - 1,0 V

PP_GPU - 0V (Diode mode shows "309")

PP_1v8 Always - 1,8V

PP1v2 - 0,01 V (Diode mode "383")

PP1v8_SDRAM - 0,07 V (Diode mode "624")

PP3v0_SDRAM - 0,20 V (Diode mode "629")

PP3v3_USB - 0V (Diode mode "520")

Update.

I did removed the display IC for the reset line - Phone started to boot nicely was like 0,1 - 0,5 Amps and then suddenly 0. And now it wont boot at all.

Suddenly the PP1v8 line is not present - Diode mode shows "1700" something.

These diode result's looks a bit not normal - right ? Should be like 300-400 ?

And also after the promt to boot all the power rail's are missing (but in diode mode does not show the short circuit - showing like "1230" and moving up.

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That’s because your power supply is probably going into current limiting mode. When that happens, the voltage drops so the net result is there is very little power delivered to the board, hence no heat.

Can you be a bit more specific about the board being shorted…which power rail are you referring to?

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I removed the display IC , USB charging IC and PMIC - The short was still on vcc-main for example (These caps near to the PMIC are vcc-main line right ?

Is it possible to add jumper to VCC main line and insert 4v to see whats heating up ?

@kapuzta Yes, you can do that to get a hint about the shorted component/s

Kaspar, it sounds like you are just guessing. Take a step back and think about this before removing any more IC's. Shorted lines are almost always capacitors, not IC's. Removing large IC's (PMIC) forces you you to put a lot of heat on the board which may cause further damage.

You should inject 4V into VCC_MAIN and use freeze spray to determine the location of the short. If the phone was water damaged, then focus on the areas that had corrosion.

The issue is usually downstream from the PMIC. You have to figure out where the short is coming from. If you remove the PMIC and you still have the short, you will have even more work ahead of you.

Look through the schematic and check all of the areas that connect to your shorted line. If nothing is visibly damaged, then you'll have to make a choice between removing the PMIC first or focussing on the downstream components and IC's,

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