Water damaged iPhone 4S no response, no signs of life - GSM-Forum

xnecrosisx · 08-14-2014, 21:04

Hello everyone, long time iphone repairer but I have an issue with an iPhone 4s that has got me stumped.

I have purchased dozens of water damaged iphones and usually its just a matter of cleaning the board with iso and replacing the battery, dock connector, power button etc.

Got a friends iPhone 4s and she wanted to see if I could get it back on. I took the board out and cleaned it, although there was almost NO signs of corrosion or water damage other than slight discoloration on the bottom side of the logic board on the EMI shields. Took the shields off and no obvious corrosion anywhere on the ICs/components or A5 processor.

I swapped the board into a working iPhone 4s housing, so I knew that all buttons, connectors, and battery were working perfectly, but the phone shows absolutely no signs of life.

I have tried using just the dock plugged into the usb to power and battery only (its charged) and both together but no response.

The battery connector is good, measuring 3.915 volts and the battery is charging with the USB plugged in (now its up to 3.94v)

No ics are getting hot and again nothing happens when trying to power the device, it makes no sounds, does not vibrate, and the screen is completely black.

I have checked the test points by the battery and by the dock connector to logic board and all are correct voltages and has continuity. Ground from the connector also has continuity throughout the phone and on all shields etc.

I am not sure what else to test here and am looking for some experts to help me out. I was thinking maybe backlight coil at first, but since there are no signs of it turning on even without the screen I feel there is a different issue. Also with it charging still it makes me wonder what could be wrong.

The previous owner stupidly tried to turn it on after it got wet and I am wondering what could have shorted to cause this issue.

Any help is greatly appreciated

xnecrosisx · 08-20-2014, 02:40

No one's seen anything like this before?

iCall · 08-20-2014, 03:49

A ton of thing to do more. Have you connected to PC? What mode is it? connected to voltage supplier, what amp multimeter comes when power it on? Have you checked voltages coming out from Q3 5v and from PMIC to A5 1v1, SDRam 1v8, NAND 3v, wifi module 4v, led driver 4v, PA 4v...? check if these working then post here to the next step

xnecrosisx · 08-20-2014, 19:57

Thanks for the help.

How do I test q3 i mean its a bga chip with no test points near it?

Also, I was removing the shields and noticed some corrosion around Q3 so I cleaned it and reflowed it, and then stupidly tried to turn the phone on and something went up in a little puff of smoke, so I definitely now burned an ic.

Any tips on how to test these voltages or the test points? I have the full schematic but can't seem to find a few

best4free · 08-21-2014, 12:41

Hello, i got an iphone 4s with the same symptoms.

No sign of life, not detected on usb connection and no boot up.

I tried to replace diode D604 and the coil under it. Still no detection. Next step would be to reball/replace the power ic. I checked all output voltages from the power ic and they are all fine. Why is the phone not detected, is it a power ic fault?

08-14-2014, 21:04	#1 (permalink)
xnecrosisx Junior Member Join Date: Jan 2007 Posts: 3 Member: 441983 Status: Offline Thanks Meter: 0	Water damaged iPhone 4S no response, no signs of life Hello everyone, long time iphone repairer but I have an issue with an iPhone 4s that has got me stumped. I have purchased dozens of water damaged iphones and usually its just a matter of cleaning the board with iso and replacing the battery, dock connector, power button etc. Got a friends iPhone 4s and she wanted to see if I could get it back on. I took the board out and cleaned it, although there was almost NO signs of corrosion or water damage other than slight discoloration on the bottom side of the logic board on the EMI shields. Took the shields off and no obvious corrosion anywhere on the ICs/components or A5 processor. I swapped the board into a working iPhone 4s housing, so I knew that all buttons, connectors, and battery were working perfectly, but the phone shows absolutely no signs of life. I have tried using just the dock plugged into the usb to power and battery only (its charged) and both together but no response. The battery connector is good, measuring 3.915 volts and the battery is charging with the USB plugged in (now its up to 3.94v) No ics are getting hot and again nothing happens when trying to power the device, it makes no sounds, does not vibrate, and the screen is completely black. I have checked the test points by the battery and by the dock connector to logic board and all are correct voltages and has continuity. Ground from the connector also has continuity throughout the phone and on all shields etc. I am not sure what else to test here and am looking for some experts to help me out. I was thinking maybe backlight coil at first, but since there are no signs of it turning on even without the screen I feel there is a different issue. Also with it charging still it makes me wonder what could be wrong. The previous owner stupidly tried to turn it on after it got wet and I am wondering what could have shorted to cause this issue. Any help is greatly appreciated

08-21-2014, 12:41	#5 (permalink)
best4free Junior Member Join Date: Mar 2008 Posts: 7 Member: 720679 Status: Offline Thanks Meter: 1	water damaged iphone 4s no life Hello, i got an iphone 4s with the same symptoms. No sign of life, not detected on usb connection and no boot up. I tried to replace diode D604 and the coil under it. Still no detection. Next step would be to reball/replace the power ic. I checked all output voltages from the power ic and they are all fine. Why is the phone not detected, is it a power ic fault?

08-20-2014, 02:40	#2 (permalink)
xnecrosisx Junior Member Join Date: Jan 2007 Posts: 3 Member: 441983 Status: Offline Thanks Meter: 0	No one's seen anything like this before?

08-20-2014, 03:49	#3 (permalink)
iCall Freak Poster Join Date: Dec 2010 Posts: 209 Member: 1477098 Status: Offline Thanks Meter: 16	A ton of thing to do more. Have you connected to PC? What mode is it? connected to voltage supplier, what amp multimeter comes when power it on? Have you checked voltages coming out from Q3 5v and from PMIC to A5 1v1, SDRam 1v8, NAND 3v, wifi module 4v, led driver 4v, PA 4v...? check if these working then post here to the next step

08-20-2014, 19:57	#4 (permalink)
xnecrosisx Junior Member Join Date: Jan 2007 Posts: 3 Member: 441983 Status: Offline Thanks Meter: 0	Thanks for the help. How do I test q3 i mean its a bga chip with no test points near it? Also, I was removing the shields and noticed some corrosion around Q3 so I cleaned it and reflowed it, and then stupidly tried to turn the phone on and something went up in a little puff of smoke, so I definitely now burned an ic. Any tips on how to test these voltages or the test points? I have the full schematic but can't seem to find a few