Juhannes, back to the second VCO tuning problem,
are the caps you mentioned suppsed to be of special make or
temperature resistant, ot does just about any polyester caps will do ?
--- In
PolySix@yahoogroups.com, Johannes Hausensteiner <johau@g...>
wrote:
>
> Hi,
>
> The caps are Cx10 ... where x is the voice number. On the schematics
> only voice #7 is drawn in detail, so you can see C710. Maybe it is
not
> the cap but the accompanying resistor (R739), or the demux (IC8).
>
> This is a great machine. Two really independant VCOs!
>
> Johannes
>
>
> gil_we wrote:
> > Thanks very much !
> >
> > The tuning is bad on both VCO1 and VCO2 of that oscillator
(although
> > it seems more extreme on VCO2).
> >
> > I uploaded the schematics diagram for the VCO board to the files
> > section - what would be the caps to check on that one ?
> >
> > Thanks again.
> >
> >
> > --- In PolySix@yahoogroups.com, Johannes Hausensteiner
<johau@g...>
> > wrote:
> >
> >>Hi,
> >>
> >>I only have the schematics for the MK I; which I do not know
whether
> >>it is similar to the MK II. Which VCO has the problem? Is it VCO-
1 or
> >>VCO-2 or both? If it is both then have a look at the hold
capacitors
> >>after the VCO CV demux IC15 (a 4051) on KLM-301 board. These are
the
> >>caps C25 - C32.
> >>
> >>Good luck,
> >>
> >>Johannes
> >>
> >>
> >>gil_we wrote:
> >>
> >>>I've been recovering this one, found in the flea market. Overall
it
> >>>had about 8-9 different faults that I fixed, leaving two
problems.
> >>>
> >>>The first is a bad SSM2056 chip which I need to find. The second
i
> >>>probably inherent in the discrete ciruit of the second
oscillator.
> >>>
> >>>Upon powering it up, that particular oscillator will be out of
tune,
> >>>till it gets to its max. internal temperature where the tuning
of
> >>>that VCO is geting more or less - stable.
> >>>
> >>>All other oscillators are immediately in tune, no matter what is
the
> >>>temperatue inside the machine.
> >>>
> >>>I, of course, tried to figure out what the bad component is by
> >>>blowing with a straw on each and each of the suspected
compnents, but
> >>>blowing on every component on the circuit of that oscialltor
which
> >>>seems to be pitch related, seems to effect the pitch.
> >>>
> >>>I also tried to switch transistors between the bad oscillator
and
> >>>another (working one) but the problem persisted.
> >>>
> >>>Does anyone have any other idea / direction ?
> >>>
> >>>Thanks
> >>>
> >>>
> >>>
> >>>
> >>
> >>
> >>
> >
> >
> >
>