iPhone 6 Power Troubleshooting Help

You first need to rule out parts so a known good charge port and battery are essential. Just because you have got 5V going into the charge port doesn’t mean it should appear on the battery terminal. I would grab the schematics for the 6 to see where the power goes before it reaches the battery terminal.

The most commonly shorted lines on the 6 are:

·         PP_VCC_MAIN

·         PP_BATT_VCC

·         PP3V0_NAND

·         Backlight circuit

You can check all these with a multimeter in diode mode while you are waiting for parts. I think the battery needs to have at least 3.7V to boot the phone but I might be mistaken on the 6.

EDIT:

The schematic from union repair would be the same one I have got. They can be extremely difficult to understand for the beginner but they are searchable and if you learn the functions of the components like filters, diodes, coils, inductors, capacitors, transistors, resistors, mosfets and buck converters the schematics can be easily understood.

 For instance if you needed to find the values and source of the battery power line you would search for voltage properties or power aliases depending on the schematic, and it would bring you to the page that has all the power rails. From there you can copy and paste say PP_VCC_MAIN and follow it, you would see it comes to a buck converter “Tigris” (U1401) which converts the 5V into 4.3V the “VCC_MAIN” which than goes to the mosfet  ”Q1403” which you could than copy the mosfet number into google which would bring up the data sheet and you would see it is used for high side switching. You would than go back to the schematics with that information and find that the mosfet “Q1403” delivers the voltage to the battery, and the VCC_MAIN voltage to the rest of the phone.

If you looked further into the buck converter “Tigris” (U1401) you would see it has a BATTERY_SWI line which if you searched on google it would tell you it is a battery information line which goes to the battery terminal. So let’s say the battery was disconnected, than the buck converter “Tigris” would have no information on the battery thus Telling the CHG_ACT_DIO gate in Q1403 to stay open so there would be no voltage going to the battery terminal.

There is a lot that can be learned from the schematics it might take some time but they are an essential tool in electronics repair.

If you are just learning I would purchase the IC’s from someone like microsoldering supply.com as they use the chips they sell every day so you know they are not faulty especially chips like Tristar and Tigris.