Discussion about the Korg PolySix synthesizer

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@yahoo.com>
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