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 hacve 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
> blowingon 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
>
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> PolySix "Digiest" Page: http://www.acc.umu.se/~amber/Poly6
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