iPad 2 charging issues - voltage on battery SWI? - GSM-Forum

cqljohn · 08-01-2015, 22:23

Got an iPad 2 "fake" charging. I have check the normal parts, and all seem to be good.

L5757 - good
Q8323 - 5v
C8124 - 5v
DZ8120 - beep one way

What I did notice is FL7500 (TP34) only has 1.7 volts. This should have 2.5 volts? What would cause me not to have 2.5 volts here?

cqljohn · 08-01-2015, 23:09

Also, I have a new battery in it and port. I am testing with another board as well that is working perfect with this battery. The battery shows 2.5 v on SWI output without board mounted. The SWI battery connector pin and FL7500 show 2 ohms. Yet as soon as board is mounted, the voltage drops to 1.7 on this component? why?

israelq · 08-02-2015, 05:59

Does it happen with both boards or only with the one you are trying to repair?

cqljohn · 08-02-2015, 16:14

Only on the board I'm trying to repair. The other board is fine. To explain again so I am clearer on my issue.

Shop board works fine, with the new battery, new charging port, same cable and AC adapter.

Defective board shows "fake charge", and the normal bad parts look good to me.
L5757 - good
Q8323 - 5v
C8124 - 5v
DZ8120 - beep one way
What I did notice is the SWI battery connector pin FL7500 (TP34) only has 1.7 volts. This should have 2.5 volts? What would cause me not to have 2.5 volts here? My test board SWI battery connector pin FL7500 (TP34) shows 2.5 volts with the same parts (in the same frame, same battery, same charging port, same cable, same AC adapter) being used with defective board. The battery shows 2.5 v on SWI output without board mounted. The SWI battery connector pin and FL7500 show 2 ohms on defective board. Yet as soon as defective board is mounted, the voltage drops to 1.7 on this component? why?

israelq · 08-03-2015, 14:50

It seems to me like the problem is coming from the line itself. You can do a few things to make sure this thought is correct

1. Measure FL7500 before and after its mounted on the board and compare with test board. This is the only component before BGA so it makes sense to completely be sure this is not the issue. I would even replace it I had one handy just for the heck of it, it is cheap anyways. Some filters need some specs when data is being handled in the line and it is the case in the SWI line IMO.

If FL7500 checks out

2. Diode mode - test before and after connector and before and after filter and as far as you can follow that line (do this without power to the board). Measure before and after you mount it (id recommend to make a spreadsheet). If any of these change post it here and Ill help troubleshoot further.

If my theory is correct and the connector is not the one causing it then you can build a jumper line and hopefully that will fix the issue.

08-01-2015, 22:23	#1 (permalink)
cqljohn Freak Poster Join Date: Aug 2012 Posts: 106 Member: 1796117 Status: Offline Thanks Meter: 16	iPad 2 charging issues - voltage on battery SWI? Got an iPad 2 "fake" charging. I have check the normal parts, and all seem to be good. L5757 - good Q8323 - 5v C8124 - 5v DZ8120 - beep one way What I did notice is FL7500 (TP34) only has 1.7 volts. This should have 2.5 volts? What would cause me not to have 2.5 volts here?

08-02-2015, 16:14	#4 (permalink)
cqljohn Freak Poster Join Date: Aug 2012 Posts: 106 Member: 1796117 Status: Offline Thanks Meter: 16	Only on the board I'm trying to repair. The other board is fine. To explain again so I am clearer on my issue. Shop board works fine, with the new battery, new charging port, same cable and AC adapter. Defective board shows "fake charge", and the normal bad parts look good to me. L5757 - good Q8323 - 5v C8124 - 5v DZ8120 - beep one way What I did notice is the SWI battery connector pin FL7500 (TP34) only has 1.7 volts. This should have 2.5 volts? What would cause me not to have 2.5 volts here? My test board SWI battery connector pin FL7500 (TP34) shows 2.5 volts with the same parts (in the same frame, same battery, same charging port, same cable, same AC adapter) being used with defective board. The battery shows 2.5 v on SWI output without board mounted. The SWI battery connector pin and FL7500 show 2 ohms on defective board. Yet as soon as defective board is mounted, the voltage drops to 1.7 on this component? why? Last edited by cqljohn; 08-02-2015 at 16:24.

08-01-2015, 23:09	#2 (permalink)
cqljohn Freak Poster Join Date: Aug 2012 Posts: 106 Member: 1796117 Status: Offline Thanks Meter: 16	Also, I have a new battery in it and port. I am testing with another board as well that is working perfect with this battery. The battery shows 2.5 v on SWI output without board mounted. The SWI battery connector pin and FL7500 show 2 ohms. Yet as soon as board is mounted, the voltage drops to 1.7 on this component? why?

08-02-2015, 05:59	#3 (permalink)
israelq Junior Member Join Date: Aug 2015 Location: Memphis, TN Posts: 16 Member: 2438201 Status: Offline Thanks Meter: 0	Does it happen with both boards or only with the one you are trying to repair?

08-03-2015, 14:50	#5 (permalink)
israelq Junior Member Join Date: Aug 2015 Location: Memphis, TN Posts: 16 Member: 2438201 Status: Offline Thanks Meter: 0	It seems to me like the problem is coming from the line itself. You can do a few things to make sure this thought is correct 1. Measure FL7500 before and after its mounted on the board and compare with test board. This is the only component before BGA so it makes sense to completely be sure this is not the issue. I would even replace it I had one handy just for the heck of it, it is cheap anyways. Some filters need some specs when data is being handled in the line and it is the case in the SWI line IMO. If FL7500 checks out 2. Diode mode - test before and after connector and before and after filter and as far as you can follow that line (do this without power to the board). Measure before and after you mount it (id recommend to make a spreadsheet). If any of these change post it here and Ill help troubleshoot further. If my theory is correct and the connector is not the one causing it then you can build a jumper line and hopefully that will fix the issue.