iphone 6s Not charging

[vic]

Hi jessa. i have had an iphone 6s brought in yesterday. Customer says the phone will show charging but the battery % wont increase meaning fake charging. I tried replacing the charging port first still the same, replaced the battery still nothing. Replaced Tristar, Tigirs, put a jumper on Q4500 pin 2-3. There is no short on PP_VCC_Main, or PP_BATT_VCC. Very confused.

[Jessa_the_Professa]

Is it charging or not? What does the usb ammeter say? You first need to differentiate a charging problem from a charge reporting problem.

[vic]

its fake charging. 0.00 amps on ammeter. shows charging but does not draw any current in.

[Jessa_the_Professa]

Unless there is water damage or connector damage then this is a tristar or tristar and Tigris failure just because those are really common failure points and nothing else is ever the problem across a zillion phones.

Make sure your replaced dock and battery are known good—they work in another 6s, not just new.

if so, then make sure you have 5v getting to tristar and Tigris with a voltage test.

if so, then your replacement of tristar or Tigris didn’t work and try again with brand new chips and make sure they are in the correct orientation

[Jessa_the_Professa]

Also prove the caps around Tigris on pmid line to make sure nothing is short

[vic]

Found the problem! while replacing the TRISTAR I probed around the pins and found the TRISTAR_BYPASS shorted to the ground. There is only one cap on that line and that was the culprit.

[Jessa_the_Professa]

That surprises me. When that cap in short, in my experience, the phone can’t boot at all. Are we sure that this phone was booting with a short on tristar bypass cap?

if so, things may have changed so that the iOS now allows a 6s to boot without tristar functions or in the cases that I’ve seen a bad bypass cap that one had other damage to tristar itself. I’d like to know which case it is.