Chosen Solution
Hi guys… I’, struggling trying to solve an issue with this iPad Air…this is the scenario: while off, when connectin lighting cable it switches on but it does not charge the battery… what\s weird is that there is no “not chargin” message near battery icon… simply nothing. Analyzin with multimeter there are no shorts at all in the board, but 3.3 volts rail is completely missing….. all the other voltages are present. I tested continuity between dock pins soldered to the board and checkpoint and everything is ok… I already replaced the charging IC (U6000) but no result…. each and every smd belonging to PP3V3_ACC line is good and functional… should I replace the power manager (U8100) or anyone of you can suggest me other solutions? thanks everyone in advance….
The PP3V3_ACC line is only present when the phone powers on. Otherwise, unless there is an accessory plugged into the Lightning port, you don’t need to worry about it. Did you check all the rails generated by the PMIC, there are a few dozen? Perhaps your Tristar replacement did not succeed and you should try it again. EDIT This is the Tristar circuit. Check the following voltage rails PP3V0_S2R_TRISTAR PP1V8_S2R_TRISTAR PPVBUS_PROT (but not PP3V3_ACC) You should be able to find the schematic on the web
