I have an iPhone 4, 01.59.00, that has a mic issue. The caller doesn't hear me. The problem is intermittent, and when it happens I can generally tap (ie: HIT) the bottom, and it will come back to working... sometimes a tap works, other times I have to beat the hell out of it.... Anyway, I've tried to replace the dock connector, with the mic and speaker - but that didn't seem to fix it.

Because this is a 01.59.00, I don't want to exchange or anything... I would like to find a solution. Any guidance would be appreciated.

Based on the post, I'm assuming you've taken everything apart and made sure that all of the connections are firm and none of the parts are loose? I would look more for connectivity between the microphone/speaker/audio control board to the main logic board. As I recall, the iPhone 4 uses two gold tension pins that push against the main logic board and a flat ribbon cable to make the connection. I would check these to ensure there's no corrosion or water damage, no dust, etc., and make sure that the pads they're pressing against are also clean. Easy enough to do with a pencil eraser. If all the connections are clean, I'd check to ensure that the spring-pins that are making contact have enough tension to make a good connection. Usually they are fine since everything is being pressed into such a small location, but over time these can lose their springyness, and that can cause problems with intermittent connections.

I have gone as far as removing the main motherboard from this phone and replacing it in another known working iPhone 4, same issue... the problem is obviously part of the main motherboard

Shoot.. If it's on the main logic board that it's likely a failure of the audio processing chip -- that's surface mount on the board, so you'd need to get a replacement DSP as well as have available a solder sucker, heating element (to melt the existing solder) and perhaps a glass pen if any of the connections from the DSP to the main board are covered in epoxy. Also, since you can exacerbate this by tapping, it's very possible that the DSP has a flaky solder joint that you could see and repair fairly easily.

They have already identified the white-label audio processing and noise canceling chip on the device, it's an Audience white-label chip directly next to the A4 processor. See this pic for detail:

http://farm4.static.flickr.com/3246/...e40533a092.jpg

I don't know how easy it would be to source a replacement, but with the chip identified perhaps you can take a look and find out that one of the legs is loose or not making good contact, or that some of the solder eroded, etc. Good luck!

do still have the logic, could you sell it 2 me