Chosen Solution
Hi All, I have an iPhone 7 here which came in dead, even when connected to DCPS. First I replaced Tristar, which at first appeared successful, charging current was 0.95 amps on 1 amp charger. It took some time for phone to power up due to battery being depleted. Once the phone turned on charging current dropped to 0.40 amps, the began to fluctuate and eventually it goes down to 0.01 amps. ( Replaced Tristar twice ) I then thought one of the MOFSETs beside Tristar may have moved causing a short so I proceeded to remove both and use jumpers for testing purposes. Again the results where the same. Next I removed and reballed Trinity, again the results where the same. Finally I replaced Tigris with a known good chip I borrowed from a donor board and again same senario. I am really stumped at what this could be. Any advice greatly appreciated. Thanks!
You’ve done a good job of replacing the main components responsible for charging, other than the PMIC (which is a tough one to do and normally not required). However, what you haven’t done, at least as far as I can tell from your description, is to probe the circuit looking for anomalies. Normally, you shouldn’t have to remove MOSFET’s when you can simply probe them to see if they are working properly. Ideally, check the Tigris/Tristar circuit by comparing it to a known-good board (pretty much all modern iPhones have the exact same circuitry). Pay particular attention to the BATTERY_SWI line, C2105 and the coil in Trinity. Also look closely at the center contact in the battery connector. If the center pin is loose, that means the SWI line isn’t always getting through. Also, the first thing you should try if you haven’t already is a known-good charge port and battery. Mise à jour (20/09/2018) Thanks Minho, turns out it was the middle pin on the battery connector not making contact, phone is now charging steadily around 0.90 amps on a 1 Amp charger. I guess this was causing an issue on the BATTERY_SWI line. Thanks again.
