Yamaha CS80

Heath Finnie wrote:
> If I plug in the main wire loom into the psu and turn it on, the middle fuse blows immediately 
> and I lose the +8.5 and -6.5. If I unplug the main socket into the PSU and turn it on (after 
> replacing the fuse it doesn't blow)
>   
Well, this isn't surprising.  Almost all the digital chips in the CS80 
want to run on 15 volts. However, since they want these chips to 
interface to analog voltages, mostly through the 4016/4051 analog muxes 
and switches, they changed +15v/gnd to +8.5v/-6.5v. Therefore, almost 
every part that uses one of these supplies also uses the other.

I guess you have to start disconnecting the +8.5/-6.5v wires from 
various boards to isolate which one has a short. You could disconnect 
from boards one at a time and check the resistance across the two to 
look for hard shorts.

Good luck,

 David