C64 sound problems

[David Betz]

> are you using the correct cable plugged into the correct place?
> this is usually the biggest cause.
> sound was mono, and you need the proper wiring, and your tv/etc may  
> only accept
> mono sound on a specific input

One thing I've been wondering about is if this could be caused by  
problems with the 12v supply feeding the SID. Is there anything else  
in the C64 that uses that voltage or is it just for the SID?