I sold my JX-3P a while ago, but I found out I missed its chorus.
So I decided to clone it, and since the Juno-60 one is often described as better, this is the one I chose as a basis.
All components are still available, except maybe the BBDs, but you can source them from chinese ebay sellers, and they seem to be genuine.
All I did was to change input & output stages, and use a LFO design inspired from the BOSS CE-2, the remaining parts stayed mostly the same.
Enough said, here's the finished PCB:
And here's how it sounds (base sound from my Prophet 600):
Some more files: sfx.gligli.free.fr/zik/juno-chorus-clone/juno-chorus-clone.7z (pics, schematics, FLAC demo)
And, since it's a free/open source project, the project page: http://github.com/gligli/juno-chorus-clone
The debug phase went mostly well, but I still have to update the PCB from the fixes I made on the schematics, so better wait a little if you want to build one!
PCB update done, should be ok to build!
I compared it with a Juno-60 recording and found out the chorus was a bit weak on mine. Turns out I copied a resistor value wrong in the BBDs output stages.
I fixed it and now it sounds really close to the original!
Some more changes to input and output levels.
Here's a second demo on polyphonic & arpeggio sounds: