Vintage Synth Repair

BCC'd to vintagesynthrepair@... (I'll bring anything relevant back to
oldsynth)

From: "Carl Oehling" <oehlinc@...>

> Hello, Problem is in the tuning. IC304 will not heat up to spec. All IC's
in
> the circuit have been changed and all other components tested. I'm out of
> ideas. Can anyone offer suggestions before I sell it?

Yeah, I have a similar problem with my micromoog I bought a little while
ago. I've spent a few hours now, poking around it with a CRO and still not
100% sure what is up with it. I think the exponential convertsion or the
voltage to current conversion isn't working properly on mine. basically the
unit isn't 1V/octave, and there's not enough range in the trimpots to bring
it into line. actually - it seems to be a very common problem with the
multi/micro moog design, as you get a few people saying they can't tune
it... :-(

does anyone have any experience repairing micro/multi moogs??

hmm... maybe I do need to join synth-DIY again, but I'd rather not. Its got
too much traffic.

PS, thanks for all the suggestions about the system 100m pannels I got!!! I
think the easiest thing to do is just to build the naked modules into a box
of some sort (maybe make the box the same size as a 191-J box, so that I can
stack them up. ) I looked into getting copies of originals made. We have a
mechanical engineer at my work.... he expected at least $150 per panel for
computer routed metalwork, and went and got me a quote on plastic moulded
copies... they were still going to be $325 for the mould, then $20 each
after that....


julian

......................
. http://bleepin.com .
......................



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I had the same problem on my Micomoog and found that somebody had 
already put a resistor in front of the trimpot. Still the range 
wasn´t big enough. I put a bigger resistor in front of the trimpot 
(some trial and error to find the right one) and: it´s working!!!

(I´m not an expert in this so I can´t promise that it works)

Uwe








--- In vintagesynthrepair@y..., "julian" <jujulilianan@y...> wrote:
> BCC'd to vintagesynthrepair@y... (I'll bring anything relevant back 
to
> oldsynth)
> 
> From: "Carl Oehling" <oehlinc@n...>
> 
> > Hello, Problem is in the tuning. IC304 will not heat up to spec. 
All IC's
> in
> > the circuit have been changed and all other components tested. 
I'm out of
> > ideas. Can anyone offer suggestions before I sell it?
> 
> Yeah, I have a similar problem with my micromoog I bought a little 
while
> ago. I've spent a few hours now, poking around it with a CRO and 
still not
> 100% sure what is up with it. I think the exponential convertsion 
or the
> voltage to current conversion isn't working properly on mine. 
basically the
> unit isn't 1V/octave, and there's not enough range in the trimpots 
to bring
> it into line. actually - it seems to be a very common problem with 
the
> multi/micro moog design, as you get a few people saying they can't 
tune
> it... :-(
> 
> does anyone have any experience repairing micro/multi moogs??
> 
> hmm... maybe I do need to join synth-DIY again, but I'd rather not. 
Its got
> too much traffic.
> 
> PS, thanks for all the suggestions about the system 100m pannels I 
got!!! I
> think the easiest thing to do is just to build the naked modules 
into a box
> of some sort (maybe make the box the same size as a 191-J box, so 
that I can
> stack them up. ) I looked into getting copies of originals made. We 
have a
> mechanical engineer at my work.... he expected at least $150 per 
panel for
> computer routed metalwork, and went and got me a quote on plastic 
moulded
> copies... they were still going to be $325 for the mould, then $20 
each

> after that....
> 
> 
> julian
> 
> ......................
> . http://bleepin.com .
> ......................
> 
> 
> 
> _________________________________________________________
> Do You Yahoo!?
> Get your free @... address at http://mail.yahoo.com