Ha, so I got my parts unit, it's got some heavy repairs.
Interestingly, IC13 - which I've noticed is sometimes different from
unit to unit - is installed with a socket. I'm guessing that's not OEM

The cartridge interface is roland, but not original, it's got a new DC
input jack, too. There are some mods, too: Several caps and
resistors are soldered on the back of the board, one cap running from
a chip pin to ground, as well as a hard-wired jumper connecting two
other points, interestingly. I'll post a pic of the guts when I get
the chance, someone might find something interesting in there.

Bart, if you are interested in the LCD off of this thing, shoot me an
e-mail.