Roland JX3P

[>>>marjan<<<]

Hi,


> 
> Roland JX3P: sounds like one of the oscillators is dead, because it 'misses
> out some notes'. This synth uses DCO's. 

Not really DCO, rather digitaly clocked analog oscilator.
May be bad tranny in osc or cap (integrator) or bad vca before VCF
(level)
or after VCF (main VCA).

>In addition, the seller descibed
> some problems with entering certain parameters. I think the user interface
> is playing up on this one (it's hard to be specific as I haven't seen it).
> He said something about filter settings not working properly.
> 

My unit had similar problems (apart from missing data slider), I've
traced
it to my unit was so dirty inside that something was making intermittent 
contact inside or parasitic cap, so sometimes controls went nuts
or pg200 not responding, or some voices buzzing (dirt was so built up
inside from dust&nicotine that all ic legs were shorted somewhere.
Also check elcos in audio path. Also check for corroded connectors.
After all, you'll get bunch of JRC4558s if nothing else (say Tube
Screamer :)

Also, there are at least two eprom revs: newer ones respond to external
velocity (kbd is just note on).
There are also some tricks to acess one more set of patch memories,seq,
4th lfo waveform etc. Mail me if interested (or look for it online).

> Also, this synth does not come with that pretty essential external
> controller box. 

Too bad but you can do it all from the synth.
Irony: I bought cheap beaten up, dirty half working JX3P one day.
Tomorrow I saw PG200 in ads for some cheap too. It was brand new
still in a box :)

>If I got the synth cheap enough, I thought about trying to
> build a suitable control unit myself rather than trying to find an original
> one. Daft idea?

I don't know what format of controls JX3P uses for controller. No sysex
either (or something limited). Making PG200 replica would be hard,
as it uses some standard uP but you'll need code... Otherwise box
inside is just uP and pots.

> 
> The Korg Delta works fine, then starts making funny noises after a while.
> The 'filter starts to play up' apparently. When switched on from cold, it
> does work fine for a while. He seems to think it's a common fault with this
> synth.
> 

Bad solder connection?


marjan who spent last night scrubbing JX's keys from nicotine tar :(