[sdiy] Steiner-Parker: eye-kurumba1

[Michael Ruberto]

Peter,

I too was horrified by the "workmanship" inside the Synthacon I repaired 2 
years ago. The main PCB was connected to the panel by several bent-to-fit 
pieces of threaded rod which, due to clearance problems, had been put 
through rough gouged out channels in the wooden casing. It was murder trying 
to get it back in. The PCB itself was just as you describe yours. Soldering 
iron burns in the insulation of the wiring everywhere too. I was shocked! It 
looked worse then my first electronics project when I was 10.

This Synthacon had a similar problem - no output. I don't know if the 
Systhasystem has the same VCA circuit as the Synthacon. The Synthacons VCA 
was basically a transistor or 2 and a whole bunch of diodes - more than in 
it's VCF even. I adjusted a trimmer in the VCA then carefully set the levels 
of both the VCA and the E.G.s. It worked great after the tweaks though.

I didn't have the time to reverse engineer the VCOs before returning the 
synth to my client. Please remember me if you happen to be curious enough :)

~M





>From: Peter Grenader <pgrenader at mksound.com>
>To: synth <synth-diy at dropmix.xs4all.nl>
>Subject: [sdiy] Steiner-Parker:  eye-kurumba1
>Date: Thu, 27 Feb 2003 21:46:58 -0800
>
>
>all,
>
>I had the fortune of inheriting a Steiner-Parker Systhasystem from a dear
>friend who recently passed away.  Great little modular, with pnme of the
>best filters out there and some of the cleanest analog sinewaves I've ever
>seen.
>
>Most of it works, some didn't at first and I've since gotten them on-line,
>some are still scrwd up --> the three input VCA/Mixer and the third osc.
>
>Both work, sort of.  The VCO acts like it's being controlled by a sloped
>random voltage and the Mixer is giving me about an 1/8 of the output levels
>of the rest of the box.
>
>But this isn't why I'm posting.
>
>I removed the VCA/Mixer from the box last night and found what I would
>consider the worst workmanship I've seen in many many years.  90% of the
>joints were cold, globbed on like the head of a Fosters Freeze cone. Flux
>was caked on so thick in some places you could not see the solder
>underneath. Bits of solder all over the wire housing. It was just a fright.
>
>
>Cleaning it up didn't do didley for my problem, so me thinks one or both of
>the two output trannies (MPS 5172) have taken a powder.  I've got
>replacements on order.
>
>I was also surprised to see that none of the boards in this machine were
>either soldermasked OR solder plated!  They were soldering directly to
>copper traces.  That and the fact that many of the holes were not in the
>center of the pad leads me to beleive that Nyle was making these boards in
>his kitchen.  It is also interesting that there are only three different
>board sizes in the machine.  Again, I think he made these on his own.
>
>Remarkable as the machine really sounds good.  The filter is breathtaking,
>outside of the one wack one, the oscillators are stable and pure -
>everything outside of the phasor (which is a litttle weak) is top notch
>sonically.
>
>Intersting however I heard the another Steiner osc, on one of Roger
>Cordell's Synthacons and it also had this wack unstable frequency  problem.
>If any of you have any experience with this sepcific anomoly with SP gear,
>please let me know.
>
>P
>
>


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