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Having hard time locating short on PP3V0_NAND

Hi guys,

I have an iPhone 6 was not turning on. After connecting to DCPS I noticed that PMIC heats up. I confirmed that PP3V0_NAND is shorted to ground and using alcohol method I confirmed that PMIC heats up first in that circuit. I removed PMIC expecting that I removed short to ground on PP3V0_NAND but it remained. When I inject voltage up to 3V none of the components heat up but my DCPS showscurrent consumptions. What is going on?

There are not many components on that line but visually they all seem to be OK and none of them produce heat.

My wild guess would be that via within PCB on that line got shorted and that’s why I could not locate it. What do you think?

Update (08/10/2018)

As I mentioned before initially PMIC was heating up as I thought it is shorted but after removing it I still have short on this line. I know what other components are on that line. My question is how do I determine which is faulty as none of them get hot when injecting voltage to that line.

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Jeez, you removed the PMIC? Ouch. Don’t do that again.

The PMIC will always heat up for ANY short that is on one of its outputs. Unless you have water damage (you don’t, this is a drop damage fault) then the PMIC is NEVER the cause of a short on one of its outputs in the iPhone 6.

Don’t follow guys that teach “see hot = remove hot” That is bad repair.

For short detection, you have four strategies.

1. Vote the ugliest guy off the island (can’t help you here, the bad guy will appear undamaged).

2.) Heat can be your guide. (We know that the PMIC will always heat, so ignore that and see if you can find the component on the line that is heating. A cheap FLIR cam will find this one, or you can find it with freeze spray. Put away the alcohol, that is only for macbook short detection, it is not effective on iPhones)

3.) Experience. (This is my favorite—always the best one!)

4.) Brute force. It’s a short. There are only so many possibilities.

So for this short, the best strategy would have been #3—”Hey, has anyone seen a 3v0_NAND short on an iPhone 6 with history of drop, no water damage?”

And you’d find lots of people who will tell you….

YES, about 1000 times. It is ALWAYS the 3v0NAND cap on the end of the row behind the NAND. Flick off with a razor to solve, do not replace. This is a 10 second easy job.

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PP3V0_NAND is generated by the PMIC so if this line is shorted, then it’s normal that the PMIC would heat up first. If you removed the PMIC and the short is still present, then the short is either with one of the many caps on that line or the NAND IC itself.

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The only way is to remove one part at a time until you find the faultu part. You can either start with the NAND or start with the caps. A thermal camera might help bu there is no silver bullet solution.


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Thank you Jessa for the answer.

I am still learning and I appreciate that you took time to cover all the possibilities to find a short. I thought that when you have a short to ground on a particular line the faulty component will always become hot. It seems I was wrong.

The logic board in question is for learning therefore it does not matter if I fail to fix it.

Does that cap you have in mind is the one I have circled in the attached picture?

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