Discussion about the Korg PolySix synthesizer

And another thing:
The copy of the schematics in the files section is very difficult to
read to the point where I can not figure the component numbers, and I
don't want to put this component in backwards. Can anyone tell me which
pins of the PC-1 is LED plus and minus, and which are the resistor pins?
One pin of the LED must be connected to R93, but is that the plus or the
minus?

/Frank
> My technician only had a VTL5C1, which does not exactly match the
> characteristics as the VTL5C3 recommended. Can anyone suggest how a
> VTL5C1 would behave in the P6 in place of the failing PC-1, and what
> sort of resistor replacements may be needed. Someone suggested to use
> a
> trimpot in place of the R93, and adjust until it scales correctly. 
> 
> Thanks
> 
> /Frank
> 
> On Tue, 2013-08-13 at 17:00 -0400, backshall1 wrote:
> > 
> > Yes, that does sound like an opto-coupler issue. It's the P1501 chip
> > on the
> > oscillator board. It looks like a 6-pin DIP chip, but it only has 5
> > pins and
> > one of those isn't connected to anything, so it really has 4 pins
> that
> > are
> > used. Current replacements are Silonex NSL32SR3 and the Vactrol
> Vactec
> > VTL5C3, and a couple of others in the Silonex and Vactrol families.
> > You'll
> > have to search the message threads to see what other people have
> used,
> > or
> > check out the file "PC-1 opto replacement.txt" in the group files
> > section.
> > 
> > Too bad there are no DIP package replacements available. All of
> these
> > parts
> > are radial lead so you have to figure out which leads are the diode
> > side and
> > what the polarity is before installing. Also, R93 usually needs to
> be
> > changed, and it might take some experimenting to figure out what
> value
> > works
> > best.
> > 
> > Don Backshall
> > 
> > _____ 
> > 
> > From: PolySix@yahoogroups.com [mailto:PolySix@yahoogroups.com] On
> > Behalf Of
> > Frank Carvalho
> > Sent: Tuesday, August 13, 2013 4:43 PM
> > To: PolySix@yahoogroups.com
> > Subject: [PolySix] P6 scaling issue
> > 
> > Hello
> > 
> > I am sure this is a classic issue, but it just happened to me now,
> and
> > I
> > need some advice.
> > 
> > My P6 has not been used for a while, and since electronic equipment
> > should be turned on once in a while, I pulled it out to give it some
> > time turned on. But in the meantime it has developed an issue with
> the
> > scaling of the octaves. Every octave has become about a semitone too
> > wide. All the oscillators line up fine across the entire range, but
> > the
> > range is just scaled wrong.
> > 
> > I read suggestions that it may be an issue with an opto-coupler, and
> > if
> > that is the case, where is it located, and what modern day component
> > may
> > replace it?
> > 
> > If it is something else, please give me your suggestions.
> > 
> > And before you ask, the battery was replaced long ago, before it got
> > bad.
> > 
> > Thanks
> > 
> > Frank Carvalho
> > 
> > [Non-text portions of this message have been removed]
> > 
> > 
> > 
> > 
> > 
> 
> 
> 
> 
>