Jupiter-4 CV/Gate Mod

// I’ve been hearing the tale, and occasionally seen a photo of a modified JP-4 with 8 jacks installed to control the voice cards via CV/Gate and to use the keyboard (and the arpeggiator) as a controller. Like having a Jupiter-4 and a Polyphonic 4CV Module 184 in one! Pretty exciting.
There’s always a link to a website from someone called “legoluft” and the link goes to a German 404 page. So I assumed it was gone. Lost to us.
Well tonight, after a number of hours inside of a Jupiter-4 today, I decided to check the web archive. And what do you know, I found it.

The official link if you’d like to read it’s here. Or keep a pdf of the page for yourself here

What I learned there is that essentially the JP-4 is already wired for CV/Gate input and output, it’s just not wired up. Legoluft created a little board, and switch box for making choices about how to combine these signals.
He also points out the basic pin out of the connectors with which to wire the jacks.

I’ve translated this into these simple diagrams:
Fig. 1 – The Wiring

Fig. 2 – The pin out of the board connectors to use.

This is incomplete. I don’t yet understand the switching box, or the little board which I assume goes between the connectors and the jacks, but in theory this means that the dream of polyphonic CV/Gate control (with an arpeggiator) for my other CV instruments, and 4 voice control of the JP-4 from analog sequencers.

I’m not sure if I’m seriously going to try this mod, my JP-4 is pretty close to perfect and I’m unlikely to drill a hole in it anywhere, but the idea is thrilling, and it’s so lovely to discover that it’s actually real and not just a lost myth.

I will update this page as I discover more.