Since the board is dedicated to amiga games, there is not really a place for this.
Anyway, you got two solutions.
- If the game uses a format for which a dedicated sound player has been written, then use that player. Most of them have a dedicated 'record as wav' function or something similar.
Here is a list of various dedicated players
- Otherwise, use the MAME wavwrite function, as detailed here.
If the game has a sound test function in the service mode, then go there and select the track you want to record. This way, you will avoid any additional sound effect.