[sdiy] EKO Stradivarius

[Rutger Vlek]

Brief update: service manual is now also posted on GearSlutz (I mean...
GearSpace):
https://gearspace.com/board/electronic-music-instruments-and-electronic-music-production/1224572-eko-stradivarius.html

Op zo 27 mrt. 2022 om 23:28 schreef Paul Perry <pfperry at melbpc.org.au>:

> A radial electrolytic can be converted to axial by bending back one lead
> along the body of the cap (lengthening it if necessary) and then possibly
> covering the whole thing with clear heatshrink. Modern electros are usually
> much smaller than the old ones, so there will be plenty of room. Great to
> know something wonderful and strange is getting some TLC!
>
> pau perry melbourne australia
>
> On Mon, Mar 28, 2022 at 5:28 AM Rutger Vlek via Synth-diy <
> synth-diy at synth-diy.org> wrote:
>
>> Thanks, great suggestion!
>>
>> Op zo 27 mrt. 2022 20:05 schreef Jean-Pierre Desrochers <
>> jpdesroc at oricom.ca>:
>>
>>> Hi Rutger,
>>>
>>> For the first ‘connected’ tests you could run your power cord in series
>>> with a 25 watts or lower wattage bulb.
>>> If there is a short (which I believe there is) the bulb will lit
>>> brightly to show excessive current draw but preventing any damage
>>> to the shorted circuit. Then you can go further to spot the offending
>>> short..
>>>
>>>
>>>
>>> *De :* Synth-diy <synth-diy-bounces at synth-diy.org> *De la part de*
>>> Rutger Vlek via Synth-diy
>>> *Envoyé :* 27 mars 2022 13:12
>>> *À :* SDIY List <Synth-diy at synth-diy.org>
>>> *Objet :* [sdiy] EKO Stradivarius
>>>
>>>
>>>
>>> Dear list,
>>>
>>>
>>>
>>> for reasons of knowledge (and instrument) preservation, and out of
>>> enthusiasm I wanted to share some info on my current restoration project. A
>>> few months ago I saw an ad listed on internet for an Eko Stradivarius,
>>> which I didn't know, and by the looks of it assumed it to be a cheap/cheesy
>>> kind of organ. I remember skipping over it, thinking "that's one heck of a
>>> pretentious name for an instrument". Shortly after that I was watching this
>>> documentary on Italian synth industry:
>>> https://www.youtube.com/watch?v=FZ-sVujDlS8 and was amazed at the
>>> sounds of some of the more obscure Italian machines (I owned a few less
>>> obscure Italian instruments but was never impressed with them). It brought
>>> me back to the Stradivarius, and after seeing a short video of it, I
>>> realised it was an amazing sounding string ensemble, easily on par with
>>> (and technically very similar to) the first version of the Solina. Luckily,
>>> the instrument was not yet sold, and I managed to buy it at a very decent
>>> price. Optically, it is in a very good condition, even the original lid was
>>> still there (despite the tolex no longer sticking to some of its corners),
>>> and it was fully functioning!
>>>
>>>
>>>
>>> Arriving back home, I opened it up, wondering what to find inside. The
>>> first, and best surprise was: a service manual with full schematics
>>> stitched to the inside of the case! Since this instrument is so rare and I
>>> could not find any technical info online, I decided to scan and share it
>>> with you (assuming that any legal restrictions are long overdue). EDIT:
>>> attatchment turned out too big for this list, so available on request and
>>> submitted to synfo.nl.
>>>
>>>
>>>
>>> Internally, the instrument seems to be in fully original state,
>>> including a gigantic amount (126!) of electrolytics that are probably
>>> several decades beyond their expected life, but show very little sign of
>>> leakage or bulging. I wondered, since there are so many, if I could leave
>>> them in place, but decided to replace them as I want to give this
>>> instrument a much longer life. Many of them are axial capacitors, by the
>>> way, which are much harder to come by these days (especially when you want
>>> a decent brand). I was wondering how others go about this? Replacing them
>>> with radial versions could mean more physical stress to the legs of the
>>> radial ones. Would that be a problem?
>>>
>>>
>>>
>>> After finishing my shopping list for capacitor values I took a brief
>>> glance at the power inlet, wiring and fuse holder, which generally looked
>>> tidy except for mains insulation that was stripped back a little too far to
>>> my taste, leaving bare copper to be fairly close to the metal casing. I
>>> almost decided to go for lunch, but then thought a quick check of the fuse
>>> couldn't harm, even though the instrument was working fine, so I expected
>>> no problems... well aaaarggh! Glad I checked, because I found an example of
>>> the worst kind of electronics practice: aluminium foil wrapped around a
>>> burned-out fuse, creating a bypass for it without any current limitation
>>> whatsoever. After seeing that I was glad I had decided against using the
>>> instrument much, until at least all PSU electrolytics were replaced. Also,
>>> I'm curious what will happen to a newly inserted fuse at the proper rating,
>>> if there's a hidden malfunction that will trigger it.
>>>
>>>
>>>
>>> Rutger
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
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