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,

Flavio.

response

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...)

Anyhow, I donʼt remember offhand ever having to free up radiobutton sets.  Individual switches, yes; and usually cleaning with contact cleaner and then relubricating (or use of a lubricating contact cleaner) has done the job.  (Contact cleaner alone is inclined to make these switches stick.)  So my first thought would be, oil/clean the mechanism; but thatʼs not based on hard facts.

So, if lubricating fails, on to facts...  The mechanism consists of two moving plates attached to the PCB mounting plate; one seems to slide to the right (from front of synth) and back to release and lock the buttons.  This is stuck in the ‘open’ position, then?

On my VCO2, the mounting plate was slightly bent near the bolt hole at the plate-spring (right) end of the mechanism; it looks possible that if the bend was severe enough, the moving plate could come too far out and jam on this; but Iʼm not going to re-bend mine to test that.

the sliding plate in action, and the spring clip

Another possibility is that the spring clip which returns this plate to the lock position may be bent, corroded or missing.  If missing it may be very hard to replace like-for-like, but it may be possible to provide the same function, even using the bolt to attach something, rather than the original tiny clips.  Or possibly something is stuck between the plates, perhaps in a switch, which is too big to wash out with lubricant.

tiny clips
(the two bits of copper sticking through slots)

I suppose the first question should be – can you move the plate back into the lock position manually?

The switches themselves seem to be fixed to the mounting strip by bent metal prongs, so even if desoldered youʼd need to do some unbending to get them open; this may be damaging, so the options for cleaning inside the switches are probably limited.  And without removing the right-end switch I donʼt see any safe way of removing, and perhaps not even replacing, the spring clip.

Keyboard contact wires can be cleaned in a variety of ways, but Iʼd use contact cleaner and pipe cleaners.  Again, use a lubricating contact cleaner, at least to finish off – helps reduce future corrosion.  If the wires do have corrosion – or greasy rather than dry dirt – Iʼm not sure an eraser would do the trick.  Depends how greasy, what kind of eraser.  Note that the busbar also needs cleaning under the wires; some people will tell you to scrape the tarnished surface with a blade, but thatʼs dubious even with solid busbars; with these plated bars, itʼs likely to permanently damage them.

Wrong notes could result from several causes.  If the five keys all play A, there could be some kind of constant contact occurring between the A♭ and A positions in the chain of pitch CV resistors; I would suspect a bent contact wire; or some other loose bit of metal.  (Possibly a broken spring clip from a radiobutton set.  Weirder things have happened to me, which I will write about soon.)  Other possibilities are highly unlikely.  If (also unlikely) they play some other note, that would probably be a component failure.

Hope that helps.