In article ,
nicolas wrote:
It seems that the
tactile switches drive a row of 8 transistors that probably do the
switching part...

IIRC, they're CMOS switches. And IIRC again were replaced with a better
type at some stage in the amp's production.

--
*When companies ship Styrofoam, what do they pack it in? *

Dave Plowman London SW 12
RIP Acorn