musical equipment

Vermona Synth Fault Requests

Message Received

Flavio, 2016-06-06

Hi there!

Thanks for your articles on the Vermona Synthesizer - I read entirely through the first part, went a bit too techy in the second article but still very interesting.

I got my Vermona Synthesizer a couple of days ago and Iʼm now facing two issue, which I hope you can help/suggest how to solve them.

First of all: for VCO 2 the register buttons donʼt remain pressed (none of them). I opened up the synth and I found out that the mechanism is somehow “stuck” in the “open” position (the position in which nothing gets blocked).

It can be seen in the difference to the VCO 1 register selectors: there, the right end of this longitudinal metal plate is in its “rest” or “inner” position, whereas for VCO 2 it can be seen that it is “out” and didnʼt get back (I donʼt know how to correctly describe, maybe I can show you pictures?!).

So of course, my question is: how do I repair this mechanical issue? I know itʼs only mechanical, because if I keep a register button pressed, VCO 2 is playing.

Second issue is the keyboard: as some keys were having “double triggers” or didnʼt trigger immediately, I took an eraser and tried to clean up what was accessible without removing any keys at all. I also moved the plated bars slightly a bit more left and then back right... now I got the lower 4-5 keys which play the same note (???) and all the others play ok but some of them are still not “clean” enough. What is your suggestion for this issue?

Thanks in advance and kind regards,



Well, sometimes I am a bit too techy.  Until itʼs the too techy bit you want.  Ignore the rest and let the search engines read it. :-)

(Iʼm writing these articles because I find it useful to record all the information I discover – less or more techy; and the interesting or entertaining thoughts that happen while looking; Iʼm publishing them specifically because I usually canʼt find the exact techy bit I want online, or anywhere else...)

Vermona Synth Update 1: Boards

(This is an update to Notes from an Exploration of a Vermona Synthesizer.)

In spite of the apparent quietness of the last few months, Iʼve been working on synths in between other things; in particular on the Vermona.  After the initial post, in the absence of any written technical information, I was planning to draw my own circuit diagrams.  Actually I did some board drawings, because thatʼs easier when all you have are last yearʼs photos and enough space to sit. :-) [1]  A couple of weeks ago, this was complicated by my discovery of a new (I think) and rather great old manuals page at, which includes circuit schematics [2] for both versions of the Synth.  The full update I was slowly working on will be rewritten in the light of the new information ... but it will be better.  For now, here are my drawings – with the component numbering brought into line with the schematics, as far as possible.  (My earlier numbering was entirely arbitrary as there is no screening on the boards.)

Korg MS-10 Notes

(Synthland 6)

MS-10s need no introduction, so – hereʼs one.  Probably from about 1980 but I havenʼt got it far enough apart to look for component dates.

This arrived in a purportedly “Pro-Serviced” state.  In contrast to my many other gripes on the topic, I must note that it was well-packed, and arrived faster than the estimated earliest date.  Also in near-perfect physical condition, which for me is a first, for a synth without a case.  So would buy again?  Maybe.  It doesnʼt even smell bad.  No rotting food or wildlife, no decaying components, no decades of garage-storage and no undead tobacco[1]

But Iʼd like to kow what “Pro-Serviced” means.  Perhaps that this time Iʼm paying someone to do the things I would normally do myself?  This clearly doesnʼt include cleaning, past a cursory wipe; thereʼs a lot of dust ingrained on the modwheel and at the back of the keys.

Notes from an Exploration of a Vermona Synthesizer

vermona synthesizer drawing
(Anorak Adventures in Synthland 4)

Back in the DDR days, before Vermona were reinvented as a purveyor of cool synthesiser and effects gear, they (or at least the brand) had already been a purveyor of moothies, organs, amps and effects to the people for decades, so far as the people were allowed such.  But in the early 1980s they came up with an all-in-one synth, simply named the Vermona Synthesizer.  (References to Vermonas below are to this model unless otherwise specified.)  They were manufactured from 1983 to possibly as late as 1990, though Iʼve not seen a definitive end date. [1]  This page begins with me getting one.  And recovering a few square feet of usable working space.  Up on the table with it:

Vermona Synthesiser front

Polivoks Update

(Anorak Adventures in Synthland 3)

This is an update to Polivoks Notes.

Getting Further In

As mentioned in the last edition, it turns out that the steel shims holding the Polivoksʼ rotary switch knobs on can fall out while the knob is being inserted. [1]  They could in principle fall through to the base so you might be able to pick them out and finish what youʼre doing.  Alternatively they could get trapped on top of the main circuit boards, where they could potentially cause shorts, and you have to get the whole thing open again and try to remove the boards to find them.  If they donʼt fall out visibly, you donʼt know where they are.  (I do understand why some resort to glue.)

So, refer to the previous getting-the-case-off process.  While shim-hunting, I also want to check the probably-failed reed switch, see whatʼs with the 2nd octave, and see whether thereʼs room for improvement on the key damping to reduce playing noise.  Iʼve commandeered a bit of table space ... and floorspace.  This isnʼt going to make me popular if Iʼm not done by nightfall, so letʼs go.

Поливокс / Polivoks Notes

(Anorak Adventures in Synthland 2)


Hey, got a Polivoks.

First, some points of nomenclature.  Iʼve had no occasion hitherto to consider it, but I now realise the correct English plural of Polivoks is Polivoksen.  With that established, on the Polivoks:

  • Generator (Генератор) = tone generator = (audio frequency) oscillator = VCO.
  • Modulator (Модулятор) is mainly an LFO.  (The control can select noise as well as periodic functions, so LFO would be incorrect ... a less cumbersome term than Korgʼs ‘modulation generator’.)
  • Glissando (Глиссандо) = portamento (a.k.a. ‘glide’).
  • Pedestal (Пьедестал) = sustain level.

Iʼll use the Polivoks terms here, mostly.

This Polivoks was made in 1987, and came with lid, pedal and cables (5-pin and 3-pin DIN; donʼt know what the 3-pin one was for...).  No power cable but has an IEC C-14 power socket mod. [1]

External Condition

Case: not great; sticky tape residues, heavily scraped and rather indented.  So much for all the “built like a tank” guff.  Built like a fake tank for to confuse the enemy, maybe.  Sheet aluminium bends (like plastic, unlike steel) but doesnʼt rebound.  It seems to have had carry handles at either end; not sure if they were original, but gone now.  The rubber feet on the underside are different sizes – presumably two were replaced at some point.

Anorak Adventures in Synthland 1

Rehab & Upgrade the Jen#2, stage 1.

(There will be a stage 2, as Iʼm not currently in a position to do the whole refurb.  No decent working space for soldering right now.)

Jen#2 cleaned, with knobs

Jen#2 (not a “Jenny”, thanks) is a newly-arrived Jen Synthetone SX1000, s/n3326, later-type keyboard, with veneer ends, in moderately poor condition.

After unpacking & supply lead check – 13A plug fuse replaced with 2A here '~' – external condition and basic audio function were checked.  Minor issues: some knobs are scratchy, some are loose.  This should be resolvable, but will require checks at stage 2.

External Condition & Issues

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