Complete Fix Solution

Heres a solution for nokia N78 ringer and hands free speaker not working or no sounds can be heard on it. This solution shows the left and right speaker circuit components connections.
There is an audio amplifier IC that drives and boosts the audio signals before it goes trough to the left and right speakers. The audio data  signal is filtered by filter coils and an input capacitors.Repair hints:
1. Check and ensure that the speaker is working okay, a saturated sound output is caused by a damaged speaker, replace it with a new one.
2. Clean the speaker terminal contact pads, make sure it is free from dust, corrosion and oxidation.
3. Check or replace the filter capacitors and filter coils.
4. For the right channel speaker not working, see to it that UI flex cable is not damaged, replace it as well if damaged. If the UI flex cable is okay, check both filter coils and capacitors.
5. If the both speakers,filter coils and capacitors is okay, try to rework the audio amplifier IC or replace if the problem still exists. Dont forget to rest assured that the line connection paths is well okay and not open or cut, check and trace it as well also. Good luck!