Vintage Synth Repair

i forgot to mention it's the MK 1. i already have the zeners for the
mk 2 mod but i don't think i can make that mod on the mk 1.

thanks anyway,
johnny

--- In vintagesynthrepair@yahoogroups.com, "balderson04"
<djacklin@...> wrote:
>
> This might help: http://www.arpodyssey.com/odynois.gif
> 
> This is basically the MkII+ noise circuit, or so I understand.
> 
> Not sure how easy zener diodes are to find, though.
> 
> 
> 
> --- In vintagesynthrepair@yahoogroups.com, "Johnny" <cockandswan@>
> wrote:
> >
> > neither are "noise". the "pink" noise is just a slightly different
> > tone of the weird waveform i mentioned before. i messed around a
> > little bit "circuit bending" it with another transistor pluggined in
> > at the same time and got something closer to white noise but still
> > with a strange pitch.
> > 
> > is there a way i can find an older transistor or a better match? i'm
> > using a transistor labeled "2n 5172" with an F icon on it, so i'm
> > guessing it's a fairchild brand? something like that. i know i am
> > replacing a "sel 2n 5172"... maybe these two are too different?
> > 
> > -johnny
> > 
> > --- In vintagesynthrepair@yahoogroups.com, "balderson04"
> > <djacklin@> wrote:
> > >
> > > Hi, Johnny:
> > > 
> > > The service manual's description of the noise circuit mentions
that Q9
> > > is specially chosen "for optimum avalanche characteristics", so
it may
> > > be that the transistor you've installed is not breaking up in
the same
> > > way.
> > > 
> > > Try listening to the noise output at pin 6 of A3 and comparing it to
> > > the output at pin 6 of A4.  The first should be white noise and the
> > > second pink noise.
> > >
> >
>