iPhone 5S apparently dead

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iPhone 5s

苹果 iPhone 5s 于2013年9月10日公布。该设备的维修与以前的型号相似，需要螺丝刀和撬棒。可使用GSM或CDMA / 16、32或64 GB。颜色有银色、金色和太空灰。

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John Dupont @johndupont

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发帖于: 2019年6月16日

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iPhone 5S apparently dead

my iPhone 5s’ screen was damaged.

I changed it, together with the backside plastic parts at the top and bottom.

Since then it won’t turn back on. It is even not detected by iTunes.

I have made the following measurements with battery connected and USB port connected to power outlet:

PP_BATT_VCC: 0V
- measured between TP2 and a screwhole
PP5V0_USB_CONN: 0V
- measured between TP1 and a screwhole

I haven’t found any test point for PP_VCC_MAIN.

Would anyone have a clue as to where the problem lies, and how to move forward?

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Minho @refectio

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First, not all screw holes are connected to ground. Use the SIM reader as that is easily accessible and connected to ground.

Second, seeing as how this follows a screen replacement, I would double check my work and insure there are no damaged flexes (screen) and that the connectors and surrounding area did not sustain any damage or debris. The iPhone 5S is prone to developing Long-Screw Damage (LSD). This occurs when the screws for the LCD retaining bracket are mixed up and a long screw goes where a short one should be. This damages the pcb and cuts traces that pass directly underneath the standoff.

I would also re-install the original screen to see if that makes a difference as low cost/quality screens can be problematic.

If the screen makes no difference, then you most likely damaged something on the logic board. Continue your probing and if the 0V persists on VCC_MAIN, then you have a short somewhere that needs to be found. Depending on your skill level, you could either hunt it down yourself using the schematic and boardview or have it looked at by a reputable shop that does micro-soldering work.

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Thanks for the swift and friendly reply!

I tested for continuity between the battery connector’s ground pin and the screw hole, and I had it, so I guess that screw hole is connected to ground.

Thanks for sharing about Long Screw Damage. How can I test for that?

I think I tried with the old screen, and got the same result, but I’ll check again.

Do you have any hint as to how I can find the short? Just check for continuity with ground at different places?

Thanks again for your help!

由 John Dupont 完成的 2019年6月18日

Here's an interesting link for LSD.

As for finding shorts, using freeze spray can be helpful. However not all shorts leave a heat signature, especially if you are using a current-limiting DCPS.

由 Minho 完成的 2019年6月18日

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Thanks for the swift and friendly reply!

I tested for continuity between the battery connector’s ground pin and the screw hole, and I had it, so I guess that screw hole is connected to ground.

Thanks for sharing about Long Screw Damage. How can I test for that?

I think I tried with the old screen, and got the same result, but I’ll check again.

Do you have any hint as to how I can find the short? Just check for continuity with ground at different places?

Thanks again for your help! — John Dupont
Here's an interesting link for LSD.

As for finding shorts, using freeze spray can be helpful. However not all shorts leave a heat signature, especially if you are using a current-limiting DCPS. — Minho

iPhone 5s

iPhone 5S apparently dead

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