3Gs earpiece does not work, proximity sensor works.
The proximity sensor works.
The speaker works.
The headphones work.
Everything else works fine.
I took it to a local repairman and he tried a replacement earpiece but could not get it to work and told me that he thinks the problem was the connection at the logic board or software.
I've researched since, an it seems to be pointing to the #3 connector ribbon but I am puzzled by the proximity sensor still functioning.
I'm a newb and need some input from someone with experience.
A damaged Flex Cable #3 or damaged Connector #3 on Logic board may still have partial function like you are experiencing. The individual traces or components that are damaged, are broken, the ones that are not damaged still can work.
First step is to Replace Flex Cable #3, when you are there you can check with a voltmeter for conductance across the earspeaker. Also look for damage to the #3 connector on the Logic Board.
If still problems could be a damaged #3 connector on Logic Board as the repairman told you.
Replacing the #3 cable is rather tricky and I didn't manage to find a good description. So having done it, here is what I did:
- Note the number 3 cable is held down by a piece of metal which is folded over to make 3 clips. Google "iPhone 3G Proximity Sensor Cable" to see pictures of the cable and the metal cover with 3 bent metal clips
- use a fine pointed bent metal probe tool to unhook the metal clips.
- ( I used http://www.mendapump.com/MendaCatalog/To... and http://www.mendapump.com/MendaCatalog/To...
This is tricky but doable and a lot easier than removing the glass to get to the clips as I saw on one YouTube video.