Here's a simple solution that can be used to repair a damaged Nokia 1800 and Nokia 1616 Mouthpiece microphone problem, In this repair guide it shows the location of particular components that might possibly damaged when the problem occurs. Tis solution can be used after in-placing or installing a new microphone module on the device but the problem still exists and does not solve the problem.
Mouthpiece microphone components layout and tracing line paths for nokia 1800 and nokia 1616
1. Check or replace a new microphone replacement before proceeding..
2. make sure that microphone's contact pads is absolutely clean, a poor contact pads of the microphone's terminal also cause the problem.
3. check those two filter coil near the microphones contact pads, have a continuity check between the microphone's contact pad's core to each corresponding filter coil. The inner layer core is the positive and the outer layer core which is the negative.
4. Continue to check the line paths across to microphones circuit as shown on repair guide solution above. Trace and make sure that both positive and negative line is not cut or does not have an open circuit.
5. The B+ line indicated in the guide is the microphone's circuit power supply, If this said supply voltage is missing or cut also causes the microphone nonfunctional.
A poor quality audio sound signal also occurs if there is a damaged components on that part.
6. The IC component solder ball bumps that holds the microphones connection can be used to trace those lines if an internal cut or damaged occurred, when all of the above hints does not solve the problem.