iphone 6 not charging.

[Stayboe]

Hi all. I need some help with this iPhone 6. It will not charge or get detected by iTunes but will prompt to boot with the doc. It has not been water damaged and no evidence of physical damage. I have only removed the one shield. The phone boots normally with a good battery. Dc power supply shows no current draw before prompt to boot. I have changed the fpc and tested the pins, tried different doc connectors and cables, changed Tristar twice and Tigras twice. I have checked the voltage around Tigras, c1408 is getting its 5 volts. I do notice that U_PMRCIF gets really hot and there was some tiny solder balls around it but they could have come from my mat. I don't think anyone has tried to repair this problem as Tristar was original.

[crea2k]

There is a capacitor next to Tigris that is the bootstrapper. Without it you can't charge etc, have you knocked it off at all, is it intact, it's to the right of Tigris. If you look on the schemetic it's marked as 'critical' .

[Stayboe]

Every component around Tigras and Tristar have not been disturbed and tested against a known good board. I think I will bridge the gate next and see if that solves it. If not I will replace Tristar and Tigras again. It seems to me Tristar is no getting the permission it needs from the cpu to start charging.

[Sly]

Hi Stayboe,
You've mentioned that the phone was booting with a known good battery when you started, and DCPS current consumption was normal before, and after prompt to boot.
Have you verified if this is still the case?

[Stayboe]

Yes phone works as it should with a charged battery. Amp draw on dc power supply seems normal.

[Jessa_the_Professa]

ok let's focus this a bit. I want you to look at the schematic at Tristar and Tigris and try to differentiate their functions. You have changed both tristar and tigris twice. From what the device is doing now--does the problem seems more likely "I know I'm supposed to charge, but I can't do it" or "I can't give permission for charging to start" Does the fact that this device is not charging AND is not detected by iTunes give us any clues? Which chip actually does the charging vs give permission vs mediate communications with iTunes. You mentioned "getting hot" and heat = short. After you figure out which chip to focus on, then look at all of the lines coming into or out of that chip and diode mode to normal to look for a potential short that is making the chip unable to do its job despite replacing it.

Also--just to be clear when we say "it's not charging" that means "it is consuming 0.00A on usb ammeter" right?

[Stayboe]

Will take a better look at the schematics. Yes it is consuming 0.00A on usb ammeter.

[Stayboe]

Took a look at the schematics and to be honest I don't know how to read them properly LOL. I will put zxw aside for a while and start diagnosing from the fpc doc "only using the schematics". Thanks Jessa.

[Jessa_the_Professa]

No one knows how to read the schematics, you just guess! Take a look at both Tigris and Tristar and all the lines coming in and out and ask yourself "which chip seems to be primarily a data handling chip? Which seems to be a power handling chip?"