Need help diagnosing iPhone earpiece issue

[Mpulsive81]

So I'm struggling to isolate the issue. Replaced the back case and evidently I blew my proximity sensor because the sensor and the earpiece wouldn't work. I purchased a new one and replaced it, which resolved the proximity sensor issue...but the earpiece still isn't working.

Here's my results of my attempts to troubleshoot:

1. Swapped screen into a known working phone.
Results: Doesn't work in the working phone either. Proximity sensor still works. (this led me to believe the issue was with the earpiece itself...but I can't wrap my head around how I could've messed up the earpiece as well).

2. Put a screen with a known working earpiece into the this phone.
Results: Known-working earpiece doesn't work in this phone either, which led me to believe there's something wrong with the logic board perhaps.

Misc notes:
- I've confirmed that I can utilize the speakerphone and a pair of iphone headphones without issue.
- All other aspects of the phone work.
- When I call someone with the "bad" phone, they can hear me just fine.

I'm mechanically and technically inclined and I rarely find myself needing help isolating an issue. But anything that anyone can do to help would be tremendously appreciated.

 

[Mpulsive81]

Took it to the Genius Bar last night and they said they couldn't touch it because they could tell it has been opened, so getting Apple's assistance is out.

Most importantly, I need to understand what I did incorrectly to insure that I don't make the same mistake going forward.

Recap:
Issue: Proximity sensor works, earpiece doesn't.

- Yes, I ensured that I had the phone off before opening it.
- When I plug a known working digitizer in, the earpiece still doesn't work. But if I plug that digitizer back into my other 3gs it still works fine. (which still leads me believe it's something to do w/ the logic board).
- This digitizer's earpiece doesn't work in either of my other 3gs iPhones, but the proximity sensor consistantly works (so perhaps I have a bad FPC *and* a earpiece??)
- Noticed that the FPC ribbon connector doesn't seem to actually lock the #3 ribbon in, so I have to be careful that it doesn't come out when reconnecting #1 & #2. But not sure if that has anything to do with it because I have another iPhone that does the same thing.

I'm not one to just fiddle around and break stuff so I'd really like to know what I can do to troubleshoot, isolate, and fix this.

 

[chargit]

good idea pm'ing me so I would see your thread. now, you could have 2 issues off the top of my head after reading everything you have done. well actually 3....

it could be it is not making a good connection when you plug in #3 but then it should work on the other working phone.

it could be your headphone jack cable but then again it would work on your working phone.

most likely your ear speaker is bad. I very rarely ever see an ear speaker go bad it is usually the proximity sensor causing the issue. but it could come down to you damaged the mother board in some way but then your assembly that you fixed should work in another phone if thats the case. try the ear speaker and the headphone jack cable. also make sure #5 is securely plugged in cause that is what controls the headphone jack cable.

 

[Gadgetgeezer]

If you gave this phone to me as a repairer, it would be under the microscope to check connector 3 and ensure that all the pins make good contact with the board. I would say that is the fault - you may not be able to see it with the naked eye, but I would go for that as an educated guess. There are also a couple (4 from memory) of resistors to the right of the proximity which then connect to the sound integrated circuit. These too need checking with a microscope and a meter.

 

[chargit]

If you gave this phone to me as a repairer, it would be under the microscope to check connector 3 and ensure that all the pins make good contact with the board. I would say that is the fault - you may not be able to see it with the naked eye, but I would go for that as an educated guess. There are also a couple (4 from memory) of resistors to the right of the proximity which then connect to the sound integrated circuit. These too need checking with a microscope and a meter.

Spencer you and your microscope.........lol with my eye sight I need to get one!

 

[Gadgetgeezer]

Get yourself a scope. You will be able to do previously impossible repairs - trust me!