To late for my JX. First, every 8th (or was it 12th?)
keys was
stopping
to produce sound (but they still sended MIDI signals), so I was able
to
use it as a MIDI controller (one of the best keyboards I ever used)
and
use another MIDI controller for triggering the jx-sounds. Then I
could
not do program changes, and then it stopped to make sounds - all this
within two weeks.
It doesn't sound like an empty battery, anyway, I would replace the
battery.
It also doesn't sound like broken oscillators or filters.
Dunno if some special Roland chip manages the routing and controls.
I got my first one back in 1987 and the last one 3
years ago.
You don't own another borked JX anymore? With two of the same or similar
boards you might be able to repair one of them yourself or let it repair
one, for less money.
- Ralf