I grabbed a sound board out of one my project machines in the shed and installed the ROMs in it of my recently restored Fishtales (see the restorations page for details). Turned the machine on and the volume was extremely loud and unable to be turned down.
After stopping my ears bleeding, i started to look for the problem. The volume control is ‘electronic’ in that there is a non mechanical potentiometer at U5 (X9503) – it just is a small 8 legged IC. I removed the old one, and put a socket in and tried a new one…..No luck – still the same problem. Since i carefully desoldered the old one (with a vacuum desoldering station), i put it back in the socket and started to look elsewhere. There is a 47uF capacitor that connects to this potentiometer. Since i have a heap of spares, and they are cheap, i cut the old one out and put a replacement one in – and it all worked!
Not all repairs are this easy (or cheap), but hopefully this might help someone who may have a similar problem.