Johannes,  There are two PDS-32 circuit boards that burn out like
you described.  One is the power relay board, inside the front end,
and the other one is the sustain pedal board, which is mounted in
the bottom of the piano.

There are no schematics that I'm aware off and PianoDisc does not
support that system anymore. If it is the pedal board you need I may
have one laying around my shop that I can give you.  Let me know.

Richard Bourgeois
Pittsburg, California
ricflyer@comcast.net.geentroep [delete ".geentroep to reply]