iPad Air boot loop - GSM-Forum

mcmihai003 · 06-21-2017, 21:12

Hi,

I have an Ipad Air with the following behavior:
-when connected to USB nothing happening...not detected by PC and no image...; PPVCC_MAIN is present and steady
-when connected to power supply, apple logo appears and stay for approx 2 seconds and then go off, and again on for another 2 seconds and off...and so on
-when connect board to bench PSU with USB connected it cycle between 0.01A and 0A every second and PPVCC_MAIN is oscillating between ~4V and ~3.4V

Board is not having any visible damage, and no component seems to get hot..

Thx,

mcmihai003 · 06-21-2017, 21:36

it was a bad battery....i was thinking that if connected to psu should boot..i was wrong

TBC01 · 06-23-2017, 22:26

A little late but bootloop is most often battery browning out at low levels, if you add psu power you must isolate the battery or brown out indicator will still cause problem!
This seems common on a1475 4g and less so on a1474 wifi.

For good measure make sure no backlight diodes are open - this causes pmic to cook and pull way to much from battery, also causes brown outs after a few minutes ....

06-21-2017, 21:12	#1 (permalink)
mcmihai003 Freak Poster Join Date: Oct 2011 Posts: 206 Member: 1675922 Status: Offline Thanks Meter: 61	iPad Air boot loop Hi, I have an Ipad Air with the following behavior: -when connected to USB nothing happening...not detected by PC and no image...; PPVCC_MAIN is present and steady -when connected to power supply, apple logo appears and stay for approx 2 seconds and then go off, and again on for another 2 seconds and off...and so on -when connect board to bench PSU with USB connected it cycle between 0.01A and 0A every second and PPVCC_MAIN is oscillating between ~4V and ~3.4V Board is not having any visible damage, and no component seems to get hot.. Thx,

06-21-2017, 21:36	#2 (permalink)
mcmihai003 Freak Poster Join Date: Oct 2011 Posts: 206 Member: 1675922 Status: Offline Thanks Meter: 61	it was a bad battery....i was thinking that if connected to psu should boot..i was wrong

06-23-2017, 22:26	#3 (permalink)
TBC01 Crazy Poster Join Date: Mar 2017 Posts: 57 Member: 2697189 Status: Offline Thanks Meter: 37	A little late but bootloop is most often battery browning out at low levels, if you add psu power you must isolate the battery or brown out indicator will still cause problem! This seems common on a1475 4g and less so on a1474 wifi. For good measure make sure no backlight diodes are open - this causes pmic to cook and pull way to much from battery, also causes brown outs after a few minutes ....