Oberheim Four Voice (FVS-1) Restoration – Part 6: Cosmetology

I’ve been making some progress on this restoration, and thought I’d lump together a bunch of the more superficial, cosmetic-oriented work in this post.

While I’ve had the synth chassis separated from its roadcase, I felt that it would be a good time to freshen things up a bit.  The I/O and power supply panels were somewhat gunked up, the mixer module could stand some care and cleanup, and the tolex roadcase had its share of rips and tears, fading, and the wood frame had pulled apart on the front left corner.  Black cloth tape was covering some of the really rough parts, and that was starting to peel away in areas.

I first disassembled the I/O and power supply panels, cleaning off label residue and other grime.  The jack nuts and metal hole-filler plugs were soaked in WD-40 and polished up with some #0000 steel wool prior to reassembly.





Part of me wants to replace that old power inlet with a modern IEC-320 type connector.  This one poses a bit of a safety risk in that the female mains connections (on the cable itself) sit flush with the connector’s surface.  As a result, it looks like it would be very easy to get zapped by the business-end of that cord if being handled while left plugged into the wall!  Then again, once I have this synth in place it won’t be getting moved around much.  Guess the jury is still out on this one… (well, at least until I accidentally electrocute myself =)

Moving on to the mixer module, I cleaned that up in a similar fashion.  It needed its tantalum power supply decoupling caps replaced with new electrolytics, the usual old flux cleanup, and its pots were kind of gummy-feeling.

The knobs on this unit are of the collet variety, and so removing them involves carefully popping the caps off and using a nut driver to loosen the collet bolts – after which the knobs can be pulled free.


After removing the PCB and replacing the caps, I addressed the gummy pots.

Now, there are some strong opinions about the right and wrong way to “clean” potentiometers.  Some techs will remove them completely, carefully pry the tabs open, pull the covers off, disassemble and wash the resistive element.  That approach is no doubt thorough and will likely yield the best results.  Its also time consuming, and introduces some risk (breaking tabs, PCB traces, etc…) if not executed carefully.

Being that the pots on this unit weren’t especially dirty, I didn’t opt to go that far.  I’ve been using Caig products for some time, and I feel that if used judiciously and sparingly good results can be achieved.


I used an air duster to gently blow any dust out of the pots, and followed that with light application of the FaderLube products – first the F-5 to flush out the pot, and again followed with the air duster to blast out any excess.  I then applied a light treatment of the F-100 concentrated FaderLube to lubricate the pots.  A few twists side-to-side, and these things feel fantastic now!

Note that I always err towards the FaderLube products when cleaning pots, as I’ve read that there is a chance that DeOxit may cause harm to the carbon resistive elements (see here for more info:  http://store.caig.com/s.nl/ctype.KB/it.I/id.2919/KB.215/.f).  I use DeOxit only for cleaning dirty jacks, switch contacts, and keyboard bus-bars.

With the pots taken care of, I gave the board a good scrubdown with isopropyl alcohol and reassembled the mixer.


Now on to the enclosure…

I wanted to keep this thing as original as possible, and as such I didn’t want to go as far as re-covering the roadcase.  The majority of the tolex was still in serviceable shape, and I felt confident that I could touch up the rough spots.

Using some Weldwood contact cement, I worked over the rips and tears and got them secured…


Lots of adhesive residue was present on some of the rough spots, where a black cloth tape was used to cover up damage…


After getting the tolex glued back down, mineral spirits and elbow grease got rid of any tape residue.

I hadn’t ever attempted this before, but being that the tolex had faded a bit I tried a Liquid Leather touch up kit to re-blacken the enclosure (I had this sitting around for household-related duties).  It only took a little bit of the black dye on a dampened sponge, and it made a huge difference!


After that dried, I applied some of the clear sealer over the top.  This was included in the leather touch-up kit – not sure what it is, but it resembled Thompson’s Water Seal.  That took quite a while to dry.  It remained tacky for a few days afterward, but feels and looks like new now.

One other little trick I tried here was using a spray-on rubberized undercoating (sold at auto parts stores) to fill the gaps in some of the damaged areas of the tolex.  I didn’t actually spray it on, but rather sprayed it onto a piece of cardboard and used a brush to apply it carefully in places where bare wood was exposed.

Here’s a before shot of the busted-up front left corner…


…and after gluing it back together and covering the exposed wood with the rubberized undercoat:


Granted, its not perfect… but it looks much better than it did!  That stuff dries hard and can be sanded to the appropriate contour, and if enough time was taken it could probably even be textured to match the tolex.  I was feeling only moderately obsessive-compulsive that day, and so I cut it short there.

Here’s the finished result:


That’s all for the beautification efforts.   At present, I’ve taken to sorting out the programmer module.  I’m going through now and recapping and proactively replacing a number of the old op-amps in it, and I will be troubleshooting the memory store/recall problems next.  More to come on that…

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