Yamaha CS80

I would have simply put the TSB board bypass capacitors from Vdd to Vee, 
since Vee=Vss (pins 7 and 8 are tied together).  I use Mil-max sockets 
with integral capacitors, myself.  More expensive than tacking caps on the 
bottom, but after doing 30 of these machines I go for efficiency these 
days. ;)  And yes, the slightly off-spec (300mil) side-to-side hole 
spacing is a pain.  It is best to buy strips of machined pins and solder 
them in flea-clip style, but with intergral cap sockets I don't have this 
luxury.  Still, it is not that hard to deal with.

Crow
/**/

On Sat, 23 Oct 2004, David Rogoff wrote:

> Update:
> 
> I finished the first of two KBC boards.  A bunch of pictures are in
> Photos -> CS80 Renovation -> KBC.  The caps on the back of each IC go
> between VDD and VSS.  The strange thing is that usually VSS is
> 0v/ground and VDD is anywhere from +5v to +18 for CMOS.  However,
> since the CMOS digital chips are also being used to swtich analog
> control voltages, Yamaha uses +8.5v for VDD and -6.5v for VSS. 
> 
> Therefore, the little bypass caps bypass the two supplies to each
> other, not to ground.  On the TSB board I put seperate caps to ground
> from each, but there weren't easily accessible grounds on the KBCs.