Roland JX-3P Organix Mod Optimized Installation Procedure
Organix mod has been the best MIDI expansion mod available for the Roland JX-3P for many years already. The problem until now has been the long waiting lists to actually get a kit, but since October 2017 this expansion is managed by River Creative taking over production and sales while the original creator Laurens takes care of developement and other projects. Builds are now pre-built SMD instead of offering a DIY kit with an increase in price but in exchange the long queue is now a thing of the past.
In all, basically the Organix mod provides a solution to the main JX-3P had since its birth in 1983: you can’t use MIDI and the PG-200 programmer at the same time, having to switch between both to make edit adjustments while working with a sequencer. Additionally you get MIDI CC (send and recieve) support for every function in the programmer, making the synth engine compatible with virtually any MIDI controller, besides making MIDI automation possible. A convenient selection between 3 MIDI recieve channels eliminates another of the historical perks of the Roland JX-3P. Velocity sensitivity via MIDI IN is also added for those who don’t have the latest released Roland ROM OS in the JX-3P.
All said and done, the install procedure is relatively easy and straightforward compared to many other MIDI kits for vintage synthetizers and can be performed under 2 hours by any beginner with basic soldering knowledge. There are however a few points I wasn’t too happy about that I always try to avoid when installing mods: 2 trace cuts and several point insertions in the original MIDI PCB, so looking at the excellent Organix documentation I found a simple way of avoiding those. There are many reasons to do it this way but the main for me would be to make it easily 100% reversible with no damages, as well as making it easier to install for beginners.
I assume you have read the JX-3P MIDI Expansion Installation Manual, if not you can do so here. I will make a few notes on my recommendations in just a few places, so the rest of the manual should be followed. Lets start with the CPU and ROM modification:
My only change here is adding a heatshrink cable isolator at each of the pin joints to make sure it doesn’t touch either the socket or the control board once assembled. I have shortened the jumper wire as suggested by the manual, about 1cm shorter but you should measure this beforehand. Also notice my CPU and ROM ICs are socketed as on latest JX-3P revisions, so it’s easier to just lift the pin and solder to it with no risk of bridging legs. If your ROM is not socketed you will have to patiently desolder it and install a socket for the new one. If your CPU is not socketed you can carefully solder the jumper wire to the top of leg 26 making sure you don’t apply too much solder to avoid bridging.
Next are the MIDI PCB board modifications, to which I’ve provided a few easier and potentially less risky solder points in some cases (letters and points in red):
After removing components 3 and 4 as stated by the manual, let’s focus now on trace cuts 1 and 2. Instead of this you can free up the brown (trace cut 1 equivalent) and yellow (trace cut 2 equivalent) cables from the CN3 connector like this:
Help yourself with a needle to push out the pins from the side openings in the connector. Brown cable will be permanently nulled, so you can heatshrink isolate it. We will use the yellow cable to make the D connection with the Organix orange cable, so we just solder both and heatshrink isolate them (remember to insert the isolator in the cable before soldering if you don’t want to leave it out, we all make that stupid mistake some time).
And that’s about it! Finish the install, wrap things up and test. No permanent damages and a happy JX-3P MIDI Expansion Kit install. Hope this information is useful to you!
