There seem to be a few issues. One is that the CVP-20 doesn't emit note-on and note-off events, only note-on events which have a velocity of zero if they're meant to be note-off events. I guess this is workable but seems odd.
The next is that the channel number on each event switches randomly between channel 0 and whatever send channel I've selected on the CVP-20. So if I've selected channel 0, this isn't a problem, but selecting any other channel leads to lots of notes left with non-zero velocities because the 'note-on' event happened on one channel and the note-off event happened on another.
There are some other gremlins kicking around - even with channel 0 selected, playing the CVP-20 keyboard through a MIDI synth leads to some very loud notes I definitely didn't hit occasionally, but tis is a bit hard to diagnose with the above issues going on.
The problems only seem to be in the data send from the keyboard; playing MIDI files back through it works fine.
Does anyone know if these are known problems with this model? Or is this likely to be a hardware defect of some sort in such an old model?
I've tried this with two different USB MIDI interfaces to make sure it's a not a hardware problem at that end.
Thanks for any help,