How to troubleshoot a PCB?

[fogus]

So I have this circuit from my speakers which has an amplifier and adjusts bass, treble and volume. The problem is, for one of the speakers the output has decreased to almost zero volts, and only faint sound can be heard if volume is at maximum.

I tried the ohmmeter test on the caps and they all seem fine, and there don't seem to be any problems with connections, so it might be a problem with the amp itself.

Does anyone know how to determine a problem with these things?



Thanks

 

[RODALCO]

Swap the speakers over to the other channel and see if the problem reoccurs with the same speaker on the other channel.
Check the balance setting, the pot may be dirty and need a bit of alcohol on the contacts to clean them up a bit.
Look for the obvious, burnt out components, cracks in the circuitboard,
Check an other input from the amp e.g. aux 2 or tape , could be the selector switch is dirty too.

 

[mister_e]

also some may have a relay between power amp and speaker terminal. If the contact in is poor this will give you some problem.

 

[fogus]

I tried all these but to no avail. The circuit is not very complicated, it's composed of a main switch, pots, diodes, resistors and caps, and the amp (ka2206b).

I checked the voltages, and the channel that's not working seems to have higher input and output voltages in the amp.