オリジナル投稿者： Brad ,
The microphone is part of the Dock Assembly. Make sure Flex Connector #4 is perfectly connected to the Logic Board. If you decide to replace the microphone it is best to buy a new dock assembly for iPhone 3GS with everything included, including antenna. Keep the old part as some new docks have antenna issues and using of the old antenna fixes it. Before opening and during all repairs of iPhone 3GS make sure the iPhone is OFF.