I just acquired an old Yamaha SY35 Synthesizer! I had to replace the little internal battery (lithium ion) that kept the memory for custom programmed sounds.
I soldered in a battery holder ( Cr2032) so that it will be easier next time.
I Love this thing it sounds GREAT! I can hardly wait till I get to start composing some new music on it!
It has both FM and Vector synthesis and as a result has some awesome sounds, I also Love the natural piano sounds.
Now I need to make or buy a sustain pedal.