Polivoks power connector mod

Mmyeah, got a Formanta Polivoks on loan! A crude looking synth all-around to say the least, definitely something you’d expect to see on a device originating from the Soviet Union. As Wikipedia politely puts it, Polivox “is arguably the most popular and well known Soviet synthesizer in the west, likely due to both the uniqueness of its appearance and sound” :)

A Formanta Polivoks

Too bad that on this Polivoks, the original power connector was broken and had been replaced with a hazardous looking ‘on the road’ kind of hack. Seemingly the prongs on the connector had come off altogether, so the power cables inside had been pushed through the holes and wired to some speaker cable and a Schuko connector with a bit of electrical tape. So, prior to putting the Polivoks to any use I figured that, being the nice guy I am, I’ll replace the power connector with something less hazardous.. Without asking the owner for a permission :).

The power connector situation to boot with..

The Polivoks power input section.

I have no idea of what type the original connector is, but its dimensions reminded me a lot about a IEC C8 type. Checking for exact measures, the opening on the original connector turned out to be a few millimeters smaller on both parallel edges and also the prongs were spaced apart slightly wider. Not a direct replacement, then.. Not that I was in the mood for figuring out the correct type, let alone trying to source a suitable replacement.

This led me to think about a “fitting” approach, where the two connectors are milled to join in some way. After evaluating the options available, I decided to test enlarging the hole on the original connector and cutting down a C8 (pulled from some old VCR) to match. Should this approach fail, I can definitely make things work by soldering a power cable directly inside the Polivoks and fitting the opening left by the old power connector with some appropriate power cable stress relief grommet. Fair enough backup plan.

The IEC C8 and Polivoks connectors

So, I clamped down both connectors to a vice and started trimming away excess plastic with a manually operated vertical milling machine. My overall plan was to shrink the C8 connector down to something as small as possible, then measure the resulting dimensions and mill the Polivoks connector to match. With a large enough bit equipped on the machine, the C8 was easy to cut down with a single pass by sweeping over the sides one by one.

First milling pass on the C8 connector.

The Polivoks connector however proved a bit trickier since a smaller bit had to be used. Having very little experience with this kind of milling machine, I found myself operating the controls to wrong directions a couple of times. So in the end, the opening on the connector turned out off-center and slightly larger than intended. Oops!

Milled connectors..

..and they're somewhat a snug fit, even despite my small milling mishap.

I fastened the connectors together with a bit of contact glue, but presumably epoxy would’ve worked just as fine. After the glue had settled I filled the remaining openings with some hot glue, sanded the surface to level and spray painted the connector. Not the smoothest end result ever, but the gaps on the surface evened out enough to hide the construction of the mod, at least if viewed from a distance.

The new connector installed.

Now then, it only remains to be tested how this new connector will hold together in the long run. Though taking a second look at the picture above made me realized that maybe I should’ve replaced the fuse socket too while at it..

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