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.