STATUS: Done! (Nov 14, 2015).
I bought the MTG Turbo CPU replacement, the extra MIDI board, and the CV option (to control filter and stuff via midi).
Check out Music Technologies Group Turbo CPU here!
The Turbo CPU board replaces the original Pro-One CPU and fits right in the old CPU socket. The main reason for me to get it was that there was a MIDI option for it as well. There are other benefits such as faster performance (although this may border on unnoticable) and also completely new features such as an extra LFO (which I probably won’t use).
The new CPU board
The Turbo CPU attaches to the separate MIDI board with 6 wires. 4 for MIDI, 2 for the extra CV stuff that will control pitch bend, cutoff etc over MIDI.
Step 1 – soldering the 6 wires to the CPU board
Step 3 – drilling holes in PCB for cable ties
Step 4 – mounting new CPU board and cable ties
I added molex connectors to the board and the 6 wires so that the Pro-One lid (which has the PCB with the CPU) can be detached from the bottom (which has the MIDI board and connectors)
Step 1 – Molex Connectors on MIDI board
Step 2 – Molex connectors on wires from main PCB
Step 3 – MIDI board wiring (MIDI connectors and LEDs)
Step 4 – Mounting MIDI connectors

Step 5 – Mounting MIDI board and connecting it all
Now I did a quick test of both MIDI In and Out – all working!
The CV connections
The remaining 5 pin connector is for the wires with CV signals going from the MIDI board and back to the main PCB (for pitch bend, filter control etc over MIDI).
Step 1 – soldering 2 wires to control Filter Cutoff and Resonance
Step 2 – soldering 2 wires to control Osc 1&2
Step 3 – soldering molex connector in the other end
Another test. Now I could control pitch bend over MIDI! The range defaults to 2 semitones, nicer than the Pro-One’s “about a fifth” and much more playable (Looking at you, non-spring loaded pitch bend wheel). I also had control over filter resonance and cutoff (connected to mod wheel and using the extra LFO of the new CPU.. not sure how I like this, but it’s all configurable).
Finally I pushed the MIDI LEDs into the holes drilled in the chassis.
They are ‘modern’ bright blue LEDs – not a big fan.. Maybe I’ll replace them with something more retro like green or red in the future.
Here is an overview pic of the internals (the bigger brownish board is from my keybed replacement mod):
There – all done!
Thanks for sharing. I’m about to perform the same installation!
LikeLiked by 1 person
Cool! Good luck! I got everything working tonight but haven’t updated the blog yet.
LikeLike
Blog updated 🙂
LikeLike
I just installed your TM2 keyboard replacement and it’s working great. I also installed the Turbo CPU and MIDI and the Midi In is working fine but can’t seem to get the Midi out to work. I’ve checked and resoldered but still no signal. Any ideas
LikeLike
Hmm not sure.. I assume it is the same with the old keyboard..? Maybe check with Grant at MTG?
LikeLike
Lars, may I ask a question…while reading the instructions for wire connections for OS1 & 2 I noticed that your wiring in Step 2 is different from the MTG installation instructions. Is there a reason your wiring differs?
LikeLike
Not that I know of.. Either I oopsed or the installations have changed?
LikeLike
looks the same to me? page 8 here: http://musictechnologiesgroup.com/files/ProOneTurboCPU_CVInstall_v141.pdf
LikeLike