Chosen Solution
Hello all. I have an iPhone 5s that died after using a Car charger to charge the phone. The phone now wont charge anymore as it only shows a battery and cable sign when i try to charge with a good charger. Also it is stuck on apple logo when i try to power it on with a charged battery. I tried replacing tristar about 6 times using 1610A3 and 1610A3B chips on different occasions and the problem seems to be the same. I probed around the caps surrounding the Tristar and realised that the PP5V0_USB_PROT is 0v. Then i replaced Q2 and now PP5V0_USB_PROT is 5v, but the problem still remains the same. Finally i found that PP3V0_TRISTAR & PP1V8_SDRAM are all absent and i get 0v on both lines. Please i need advise on how i can fix this. Thanks.
PP3V0_TRISTAR & PP1V8_SDRAM are generated by the PMIC, which is the other IC involved in charging. Are they shorted? If they are, then I would remove Tristar once again and then probe those rails to see if they remain shorted shorted. If they are, then check for any are that may have been bridged or if any components got dislodged and possibly causing the issue. If the short persists, check the caps on the line and ultimately, you may have to remove the PMIC to see if that removes the short or not.
I was able to fix this by ordering specifically 1610A1 tristar chips. I have always believed 1610A3 and 1610A3b chips were backward compatible all the way to the 5s. In may case these chips did not work. Only the 1610a1 tristar chip worked for me. Thanks.
