Discussion about the Korg PolySix synthesizer

ooops... the multileg component is IC6, not R40


--- In PolySix@yahoogroups.com, "gil_we" <gil_we@y...> wrote:
>
> Thanks guys !
> 
> There was something strange going on.... After writing my previous 
> mail I ran over a few components with a "freeze" spray, among them 
> the transistors and caps area of both VCOs on the problematic 
> oscillator and the R40 component (what looks like a mutli-leg 
> transistor but I guess is a multi-resistor ?)
> 
> Suddenly, two things happen (which still happen if I turn the 
machine 
> off for a few hours and back on... regardless internal temperature):
> 
> 1. The bad oscillator is no more out of tune !
> 
> 2. The entire scale has changed - i.e the gap between each note to 
> the one that follows it is larger (there is more than one octave 
gap 
> between C4 and C5 for example)
> 
> But that made me recall that when I got hte unit there was not 
tuning 
> issue at all, and the bad tuning problem on the second oscillator 
> only started once I started servicing the machine)
> 
> Strange huh ?
> 
> Could it be R40 that is defective ? does that make sense ?
> 
> Thanks again !
> 
> 
> 
> 
> 
> --- In PolySix@yahoogroups.com, "Chromatest J. Pantsmaker" 
> <chromatest@g...> wrote:
> >
> > 
> > 
> > replace them again?  Sometimes (and it will always bite you) you 
> put in a bunk part as a replacement.. then you spend all week 
looking 
> for something else, saying "it can't be X!  I replaced X"..
> > 
> > 
> > ----- Original Message -----
> > From: gil_we <gil_we@y...>
> > To: PolySix@yahoogroups.com
> > Subject: [PolySix] Re: Trident MKII - one oscillator is out of 
tune
> > Date: Tue, 06 Dec 2005 21:51:15 -0000
> > 
> > > 
> > > You know what ?... now I relaize I replaced IC8 and ICx11 as 
> well !
> > > 
> > > Any other idea you can think of ?
> > > 
> > > 
> > > 
> > > 
> > > --- In PolySix@yahoogroups.com, Johannes Hausensteiner 
> <johau@g...>
> > > wrote:
> > > >
> > > > If you already replaced Rx39/Cx10 then the only thing in 
common
> > > > for both VCOs in one voice is ICx11 (TL072).  THe value of 
Rx39
> > > > is not very critical unless it is very different to the 
nominal
> > > > value of 1k
> > > >
> > > >  > By IC8 are you refering to ICx08 ? it's a 4558 opamp.
> > > > No, I mean IC8, which is a 4051.  It is common to all voices; 
it
> > > > demultiplexes the CV for the VCOs
> > > >
> > > > Johannes
> > > >
> > > >
> > > > gil_we wrote:
> > > > > Thanks !
> > > > > > The Cx10 and Rx39 have been already replaced to no avail.
> > > > > > By IC8 are you refering to ICx08 ? it's a 4558 opamp.
> > > > > > btw, I now see that I had to replace Rx36 with a slightly
> > > different
> > > > > value because even after the machine is warm enough, with 
the
> > > > > original value the related VCO still cannot get tuned with 
the
> > > other
> > > > > oscillators, not matter how you set the VCO tuning trimmers.
> > > > > > Thanks again.
> > > > > > --- 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
> > > > >>>>>
> > > > >>>>>
> > > > >>>>>
> > > > >>>>>
> > > > >>>>
> > > > >>>>
> > > > >>>>
> > > > >>>
> > > > >>>
> > > > > > > > > > > > > PolySix "Digiest" Page: 
> > > > http://www.acc.umu.se/~amber/Poly6 > Yahoo! Groups Links
> > > > > > > >  > > > >
> > > >
> > > 
> > > 
> > > 
> > > 
> > > 
> > > 
> > > 
> > > PolySix "Digiest" Page: http://www.acc.umu.se/~amber/Poly6
> > > Yahoo! Groups Links
> > > 
> > > 
> > > 
> > > 
> > 
> > 
> > 
> > .sig
> > -Chromatest J. Pantsmaker
> > http://www.chromatest.net
> >
>