Hello Motivasian, the sound on a POG originates from the lower right hand side of the board ( if dip switches are oriented in the upper left hand corner ) If you look at the board there are a cluster of electrolytic caps and a audio amp IC, there is also a small blue pot next to it, that is a volume adjustment.
If there is no sound it could be from one of several reasons.
1. Bad speaker or wire that runs from the board to the speaker.
2. Bad audio AMP IC or open or shorted caps.
3. Little blue pot turned all the way down.
4. faulty edge connector.
5. Sound turned down in Main Menu. [size=78%] [/size]