[sdiy] Yamaha patents

[riccardo]

Hi All,
I have read with interest about Korg releasing  the schematics of its
patented filter, and  also I saw  the Moog's  patents collection of  Don
Tillman.
I have this old Yamaha GX1 which  I would like one day to completely restore.
Joachim Verghese has given loads of support but the distance and my lack of
knowledge about fine electronics things made the project to  slow down.

Some time ago I was told by Mr. Kitazume of Yamaha (who also was so kind to
send me all the remeining spares for free) that they do not have anymore
the schematics of the epoxy encapsulated modules (which later become the IG
chips on the CS80).

Now I have this idea buzzing in my head: they  must had a patent on them
and it is laying somewhere, probably in the US too.
I do not have a clue on how to make a search in the US patent database to
see if  I 
am right, and I wich somebody can help or pass some infos.

On the other side I am writing again to Yamaha, hoping to be as lucky as
Martin was with Korg.

ciao
riccardo