Pp1vo short on iPhone 5 - GSM-Forum

peppoR6 · 08-02-2015, 22:56

Hello I have repaired a water damaged phone. All was ok. I have then soldered back the emi shields I removed and phone stopped to work. I have the removed emi shields again and after a bit of research it seems that all caps connected to PP1V0 are on short.
How can I have created this problem soldering emi shields?? I have just soldered few points..
Any case any suggestion to what I can do?? I have fear that short is under the pmic U7...
Help!
Cheers

israelq · 08-03-2015, 15:55

Ok so these are your options! C349, C34, C23, C25, C8, C4, C5, C190.

I would try

1. Visual inspection to see if a capacitor looks bad and replace it or
2. Freeze spray and see which one gets hot first.

Please post what you find out!

peppoR6 · 08-03-2015, 16:01

israelq, what about if short has been generated directly by U7 (power manager)? and what do you think is the relationship with having soldered the emi shields?
C349 is not present in my card.. but both pins in that point are grounded...the others are not so bad looking at them

..i can try freezz spray..
my fear is that when i screwed back the motherboard as the emi shields where not well soldered i have made the motherboard to crack...do not know how to explain

israelq · 08-03-2015, 16:43

You can see if any of these capacitors are close to the emi shield and maybe you hit it while trying to resolder the shield.. either way I think you should troubleshoot further before giving up on it.

C349 is part of that line so both pins will be grounded at this point, it is to be expected.

If you dont find anything with freeze spray you can desolder one by one (there are only 8 capacitors) and test both pins after you remove each capacitor. If after removing all of them the board is still shorted then there are only two options (that I can think of right now)

1. bad chip
2. the line itself is grounded. This is commonly seen when people try to solder and scrape off the top mask around a pad and add solder to it resulting on soldering the pad with the ground layer.

peppoR6 · 08-03-2015, 17:45

Interesting exchange Israelq.
About point 2 I have just soldered back the emi shields, and moreover not resoldering all points. only 2 3 points to make the emi shield in place. I have soldered (have you in mind iphone 5 board?) just some points that are really soldered on the bord of the board, so I do not know but it is unlikely that I have grounded the line itself even it everything is possible...

I am almost for hypothesis 1...to be confirmed before trying with capacitors.. I will let you know!

thank you mate.

israelq · 08-03-2015, 18:10

Don't forget you have a water damage phone so that short could have only gotten worse unless you use a professional ultrasonic cleaner, some electronics cleaner and wait until it was COMPLETELY dry!

yeah man this definitely sounds like a fun project!

peppoR6 · 08-03-2015, 18:19

Israelq the phone was already repaired by myself, I have found and removed in this phone about 4 shorts and the phone was then working perfectly. Problem has arised when i wanted to give it back to the owner and i resoldered the emi shields. Btw yes i have cleaned it with ultrasonic cleaner and alcool... The problem is something that has cracked soldering the emi shields...****..this is not the first time i do this...i am not lucky

israelq · 08-03-2015, 18:47

haha it ***** when that happens! let me know what you find out

08-02-2015, 22:56	#1 (permalink)
peppoR6 Insane Poster Join Date: Jul 2007 Posts: 71 Member: 545078 Status: Offline Thanks Meter: 9	Pp1vo short on iPhone 5 Hello I have repaired a water damaged phone. All was ok. I have then soldered back the emi shields I removed and phone stopped to work. I have the removed emi shields again and after a bit of research it seems that all caps connected to PP1V0 are on short. How can I have created this problem soldering emi shields?? I have just soldered few points.. Any case any suggestion to what I can do?? I have fear that short is under the pmic U7... Help! Cheers

08-03-2015, 15:55	#2 (permalink)
israelq Junior Member Join Date: Aug 2015 Location: Memphis, TN Posts: 16 Member: 2438201 Status: Offline Thanks Meter: 0	Ok so these are your options! C349, C34, C23, C25, C8, C4, C5, C190. I would try 1. Visual inspection to see if a capacitor looks bad and replace it or 2. Freeze spray and see which one gets hot first. Please post what you find out!

08-03-2015, 16:01	#3 (permalink)
peppoR6 Insane Poster Join Date: Jul 2007 Posts: 71 Member: 545078 Status: Offline Thanks Meter: 9	israelq, what about if short has been generated directly by U7 (power manager)? and what do you think is the relationship with having soldered the emi shields? C349 is not present in my card.. but both pins in that point are grounded...the others are not so bad looking at them ..i can try freezz spray.. my fear is that when i screwed back the motherboard as the emi shields where not well soldered i have made the motherboard to crack...do not know how to explain

08-03-2015, 16:43	#4 (permalink)
israelq Junior Member Join Date: Aug 2015 Location: Memphis, TN Posts: 16 Member: 2438201 Status: Offline Thanks Meter: 0	You can see if any of these capacitors are close to the emi shield and maybe you hit it while trying to resolder the shield.. either way I think you should troubleshoot further before giving up on it. C349 is part of that line so both pins will be grounded at this point, it is to be expected. If you dont find anything with freeze spray you can desolder one by one (there are only 8 capacitors) and test both pins after you remove each capacitor. If after removing all of them the board is still shorted then there are only two options (that I can think of right now) 1. bad chip 2. the line itself is grounded. This is commonly seen when people try to solder and scrape off the top mask around a pad and add solder to it resulting on soldering the pad with the ground layer.

08-03-2015, 17:45	#5 (permalink)
peppoR6 Insane Poster Join Date: Jul 2007 Posts: 71 Member: 545078 Status: Offline Thanks Meter: 9	Interesting exchange Israelq. About point 2 I have just soldered back the emi shields, and moreover not resoldering all points. only 2 3 points to make the emi shield in place. I have soldered (have you in mind iphone 5 board?) just some points that are really soldered on the bord of the board, so I do not know but it is unlikely that I have grounded the line itself even it everything is possible... I am almost for hypothesis 1...to be confirmed before trying with capacitors.. I will let you know! thank you mate.

08-03-2015, 18:10	#6 (permalink)
israelq Junior Member Join Date: Aug 2015 Location: Memphis, TN Posts: 16 Member: 2438201 Status: Offline Thanks Meter: 0	Don't forget you have a water damage phone so that short could have only gotten worse unless you use a professional ultrasonic cleaner, some electronics cleaner and wait until it was COMPLETELY dry! yeah man this definitely sounds like a fun project!

08-03-2015, 18:19	#7 (permalink)
peppoR6 Insane Poster Join Date: Jul 2007 Posts: 71 Member: 545078 Status: Offline Thanks Meter: 9	Israelq the phone was already repaired by myself, I have found and removed in this phone about 4 shorts and the phone was then working perfectly. Problem has arised when i wanted to give it back to the owner and i resoldered the emi shields. Btw yes i have cleaned it with ultrasonic cleaner and alcool... The problem is something that has cracked soldering the emi shields...****..this is not the first time i do this...i am not lucky

08-03-2015, 18:47	#8 (permalink)
israelq Junior Member Join Date: Aug 2015 Location: Memphis, TN Posts: 16 Member: 2438201 Status: Offline Thanks Meter: 0	haha it ***** when that happens! let me know what you find out