Complete Fix Solution

Heres the solution that may possibly help fix and repair a microphone failure on Nokia N78 cell phone handset. In Nokia N78 the microphone line track is connected over the keypad flex cable wire connection. If something went wrong and the microphone failed to have an audio signal output during transmission, The problem may possibly lies on a faulty mouthpiece microphone, a damaged flex cable and a faulty microphone signal line paths. This solution below shows the microphones line tracks that needs to be trace after ensuring that the microphone is okay and the flex cable is also okay.


The microphones positive terminal line tracks is connected on pin 22 of the keypad pin connector, while the negative terminal is on the PCB grounds. There is also a bypass capacitor connected to it, if the capacitor is oxidated or shorted due to a wet damaged this also result to microphone failure problem.

Heres 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.

Repair tips:
1. Check or replace a new microphone replacement before proceeding..
2. make sure that microphones contact pads is absolutely clean, a poor contact pads of the microphones terminal also cause the problem.
3. check those two filter coil near the microphones contact pads, have a continuity check between the microphones contact pads 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 microphones 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.