Vintage Synth Repair

I've got a micromoog with a problem; a note is always triggered when
the micro is on.

If I were to turn on my micro right now, it would sound a note, even
though no keys are pressed down. If I were to press a key while the
micro is on, the note sounded will change pitch to that key, but will
still sustian indefinatley after the key is released.

I've looked at the service manual, and so far the only thing I have
done is clean the buss bar and j-wires with rubbing alcohol and
q-tips. That did not do anything.

This is really getting frustrating, because this is my second
micromoog that has had this problem. My first one I sold (to someone
who knew the moog had issues) had the exact same problem.

I'd really like to fix this thing, and will even do it myself (if I
can manage it), but I don't know where to begin. I'm at my wit's end.
it's really frustrating.

Thanks for your help

>I've got a micromoog with a problem; a note is always triggered when
>the micro is on.

It's not necessarily that a note is triggered, just that the VCA is for some 
reason stuck on.  Check the gate signal from the keyboard and the control 
voltage going into the VCA, it should narrow the search down a lot.  If you 
don't have a service manual it will be a bit more difficult...

_________________________________________________________________
Get free, personalized commercial-free online radio with MSN Radio powered 
by Pandora http://radio.msn.com/?icid=T002MSN03A07001

--- In vintagesynthrepair@yahoogroups.com, "Scott Nordlund"
<gsn10@...> wrote:
>
> >I've got a micromoog with a problem; a note is always triggered when
> >the micro is on.
> 
> It's not necessarily that a note is triggered, just that the VCA is
for some 
> reason stuck on.  Check the gate signal from the keyboard and the
control 
> voltage going into the VCA, it should narrow the search down a lot.
 If you 
> don't have a service manual it will be a bit more difficult...

Well, I cracked open the moog, got the 'board open... and realized
that I'm in way over my head with this one. Way, way over my head.

So now this is an appeal for either really, really good instructions
on how to check on the electrons goin' round in the moog - like how to
check the gate signal of the keyboard and the VCA, or an appeal for
someone who is knowledgable in micromoogs to offer to repair it.

I'd really feel much better sending this thing off to a synth tech,
but if someone could walk me through checking voltages and stuff, that
would be great.

Failing that, does anybody know of a synth tech that isn't swamped
with work this time of year that I could send this to?

>So now this is an appeal for either really, really good instructions
>on how to check on the electrons goin' round in the moog - like how to
>check the gate signal of the keyboard and the VCA, or an appeal for
>someone who is knowledgable in micromoogs to offer to repair it.

I'm not familiar with the Micromoog in specific so I can't really offer any 
finer details, but the basic idea is this: the gate signal from the keyboard 
(i.e whether a key is pressed or not) triggers the envelope (attack when the 
key is pressed down or release when it's let up), and the control voltage 
from the amplitude envelope goes to the VCA to determine the output 
amplitude.  Obviously somewhere in there something is messed up, the first 
thing you need to do is determine where the problem is, whether it's a stuck 
gate signal, bad envelope generator, or VCA.  As to where you might find the 
specific signals and what they should be, I have no idea.  A service manual 
would likely tell you a lot of what you want to know.

_________________________________________________________________
Get FREE company branded e-mail accounts and business Web site from 
Microsoft Office Live 
http://clk.atdmt.com/MRT/go/mcrssaub0050001411mrt/direct/01/

Go here for Micromoog schematics and user manual, in pdf format:

http://www.fantasyjackpalance.com/fjp/sound/synth/synthdata/07-moog-micromoog.html

and here for the service manual in jpg format:

http://www.univox.org/moog/