PAiA Proteus I restoration

Hello All!

I’m new to the forums, but I think this will be of interest to all.

I am restoring a PAiA Proteus I. I built one in 1982 and gave it away in 1987. Wish I still had the one I built, but oh well. Anyway I found a rough one on eBay. Most people would stay clear. But as the Proteus was a DIY back in the day, I knew it would be easy to disassemble and work on. When I got it, the first think I noted was the all the key bushings were either bad or gone. The keys would rattle around in their sockets. Got on the web and found I could buy replacement bushings. So, I took the keyboard apart and cleaned all the keys. Now that I have all the parts cleaned up and ready to go, I’m looking at what I’ve got.

As you can see the key-bed is a mess. It’s rusty and the paint is flaking off. I don’t think I should disassemble the key-bed completely because the switches are 40 year old plastic, I’m afraid I may break something that cannot be replaced. My plan is to use some Naval jelly to clean off the rust, scrape of all the loose paint then repaint the key-bed. What do you think?

The circuit board isn’t in bad shape. There is one broken trace and several nicks. My plan is to clean the corrosion off with a wire brush then “tin” the traces to protect them from further corrosion then clear coat the trace side of the board with an acrylic spray. Again, what do you think?

I have copper tape that I’ll use to fix the bad trace. It looks like they used a 100w soldering gun on the board. The trace was obliterated. I’ve tested this board and it works 100%. Only four chips, but it was a good first test. The key-scan circuit works perfectly. I hope the key switches all work, but I’ll deal with that later.

I’ve also included a few other pictures of the internals. It doesn’t look too bad. The key-bed got the worst of it from spills and general exposure, but the voice card was tucked up under the control panel and didn’t get too much corrosion. The power supply / backplane needs a good clean up (like the keyboard scanning board) and the same with the controls board.

My biggest problem is just taking my time with it. I want it working now! But it’s going to be a long haul and I don’t want to break something by going too fast.

Good wishes to you all,

Hey! I stored mine in a closet since built, so it fared a lot better over the years.

I haven’t pulled the keys off of my keybed, but from the pictures I’d say that the naval jelly sounds like a good idea.

Acrylic spray on the circuit board makes me a bit nervous. We used a non-conductive clear coat for production equipment. I would just clear a bit of area on the existing trace and solder a small wire (like a resistor lead) across the gap. As long as the traces are conductive, the appearance will be fine.

The boards look great. I’d recommend following the manual’s steps for testing each them. Do you have a copy of them?

The biggest issue I’ve had so far was that I’d forgotten that the knobs/switches don’t affect the sound unless you are in program mode.


Thanks for the reply. I was gettin’ a bit lonely. Just tonight I finished the keyboard scanning board. I completed the “tinning” and cleaned it all up. I agree with you about the clear coat. Not necessary and may cause unintended issues. And it would be difficult to reverse. I am going to clean the frame as best I can, then try a rust reformer, then spray paint the frame. I’m going to mask the switches and the key “springs”. I’m hoping by this weekend to be able to test the keyboard.

I have a low res copy of the manual / test procedures. Adequate but not pretty. I fixed the broken trace more or less how you described. It looks fine and I’m sure it’s working perfectly.

The rest of the boards don’t look too bad. I’m going to clean all the old flux off, do a general clean, check the caps and power them up. If the keyboard works, then I’ll do the backplane, the “controller” then the Proteus I synth itself. It’s all a process and I’m struggling to be patient.

Anyway making slow but true progress.


PS you wouldn’t want to sell your Proteus I would you???

I have the original manuals, so just say the word if you have any trouble reading your copy.

I broke mine out to see if I could fix an issue that I had with an oscillator, but several problems have cropped up on the way. (Like a broken connector for the transformer!) I’m just slightly ahead of your restoration.

In case you’re interested, I found a free VST/Standalone emulator based on the Proteus:

I’ve been wondering how you’re getting along on restoring that keyboard.

The preset buttons on mine are just too flaky. Sometimes you can advance, and sometimes not. Sometimes it advances several presets at a time. I’m convinced that the buttons are just too cheap. Ordered a few replacements and hope to have them soon. I’m in a hold until then.

Thanks for checking in! I’m not going very fast right now. I have taken the entire device apart. The keyboard itself is completely torn apart. I need to do rust protection / paint on the bottom tray and the keyboard frame. Then I’ll be ready to reassemble the keyboard. If that works (there are plastic switches for they key contacts). Then I’m confident I can get the rest of it going.

The power supply will be next. I have the transformer out and disconnected from the power supply back plane. I want to test it first, then connect it back to the power supply and move on from there.

The boards have a lot of rosin flux on them. Over time they have become gummed up with dust, dirt, insects, etc. I’m going to clean the boards to get all that goop off of them.

Really not a lot going on. But it’s still on the bench, my plan is to finish it.

On the flaky patch select switches, I had the same problem with my original Proteus. After about two years, it was difficult to select the patch. I thought that maybe the problem was switch chatter but there was also a de-bounce filter and some circuitry for the patch advance when you hold the button down. The thing is all switches chatter. It may be better to adjust the timing of the de-bounce filter (R4 / C1 on figure 35 in the Assembly Instructions). Tuning that should prevent any chatter from getting through.