Chosen Solution

Hi all I have an iPhone 6 Plus that I’m battling with (and losing badly), that has a charging issue. The phone recognises the charger and shows the charging symbol, but the battery does not charge and battery % does not change. The amp meter shows quite an unstable amp reading constantly changing and ranging from 0.25amps to 0.6amps. When the screen goes to standby/inactive the reading drops to almost zero amps. I have all the correct diode readings on the dock connecter. I get 3v on PP3V0 Tristar. When I connect a charger with no battery connected I get between 3.8v to 4.2v on PP_BATT_VCC. I’ve tried the board with a known good charging port and battery, unfortunately I still have the same issue. I started with replacing Tristar/U1700 as I find this solves the issue in the vast majority of cases, however not this one sadly :(, I’ve also replaced Tigris/U1401 and Q1701, however I still have the same issue. Here’s the interesting part, I decided to replace the MOSFET Q1403, before doing so I bridged PP_BATT_VCC & PP_VCC_MAIN (with Q1403 removed). This solved the problem, the battery charges normally and the amp meter shows a more constant 0.8amps whether the screen is active or not. I thought I’d cracked it at this point and replaced Q1403 with a new one (well from a donor board). Unfortunately the same issue came back with the replacement of Q1403. I’m completely baffled now, any ideas anyone? I will be greatful of any thoughts as always :)

Whatever you do don’t touch the PMIC it cannot have anything to do with these symptoms. We use to encounter this quite often on the 6 series and the solution was to leave Q1403 off the board. If we thought we had caused the problem during a touch IC or baseband rework we would endeavour to find the solution so the phone would be returned as it came in. But in these cases I cannot remember if there was battery data or not. It is very rare you have to install a separate voltage divider like you have done with the two resistors. You could check that the gate on Q1403 is receiving the same or more voltage than the source, if it isn’t the gate will not open and since you have replaced Tigris it would point to a communication problem between the CPU and Tigris possibly giving you cause to install your voltage divider. I wouldn’t rule out the connectors as I have found that replacing them can solve the problem especially the battery connector even if the readings are okay as they can change when the connector is seated. It doesn’t take long to replace the charge port and battery connector on the 6 it would be something you need to rule out.