Hi,

I found a MIDI retrofit which suits to many synths with a matrix based
keyboard. It is produced by Mungo Enterprises vulgo John Pillans in
Australia. http://home.netspeed.com.au/aistorm/midiretrofits.html

The retrofit has a sysex programmable offset, so the keyboard can start
at any key number you like.The retrofit is available either as a
shortform kit for $50(~30 Euros) an contains PCB + microcontroller. Or
as a fully assembled and tested unit for $225 (~135 Euros). The
shortform kit requires about $20-30(~15 Euros) worth of parts to be
purchased for it and takes about 2 hours to build (according to John).
John Pillans would offer a reduction on bulk buys of the kit. For the
assembled version he cannot offer any reduction.

I will order at least two - one for my Monopoly and one for my SH-101.
We could share the shipping costs and the hassle with the customs would
only happen one time.
So if you want to buy such an interface and if you live in the European
Union contact me by mail until 15th of December.

best regards, Florian