You're right, searching for "2SC1583" does give me a bunch of
interesting matches. No seller in Sweden but there are shops in
Germany, for example, selling both that and the 2SA733. I'll ask a
friend to get them and post them to me. Like you say, the opto
resistor (PC-1) could be tough to get hold of, though. I'll start by
replacing the transistors anyway and see if that does anything. Oh,
and what about those amplifier ICs? Is that a long shot you think?
Peter
--- In
PolySix@yahoogroups.com, Johannes Hausensteiner
<jo.synth@c...> wrote:
> I read from the schematic:
> ∗ Q12 is a dual npn transistor, common emitter.
> The used type is 2SC1583.
> I found a company Dönberg Electronics, who does sell this
> component, by entering "2sc1583" into Google
>
> ∗ Q3 is a standard (Japanese) pnp small signal transistor,
> type 2SA733. Dönberg also do have this one or you can take
> a BC557 as a substitute. But be careful, the pinout is
> different:
> 2SA733 BC557
> B-C-E E-B-C
>
> ∗ PC-1 seems to be a Korg custom component. Doesnt it have a
> black rubber tube on it? It is drawn in the schematics as
> an LED optically coupled to an LDR. Hm.
> Maybe someone of the list has a spare?
>
> Johannes
>
>
>
> Peter Andersson wrote:
> > Wow, that's very useful info! Thanks Johannes!
> >
> > The control voltage must be crucial for the expo conversion to
work
> > properly then. If any of the amplifier circuits would be broken
> > (IC17, 18 or 19), could that cause this behaviour do you think,
or
> > would that just make everything fail "from start"?
> >
> > Well, speaking of which... The synth no longer tunes up
correctly
> > after 20 minutes. Now the tuning and the note intervals are
screwed
> > up period. So whatever needed "warming up" a few days ago seems
to
> > have failed permanently now.
> >
> > I just went over the soldering points around the components you
> > pointed out and resoldered most of them to be sure. I still get
the
> > same problem, though, so I guess it's time to start replacing
> > components. I'll definitely try testing with cooling spray. Good
> > suggestion!
> >
> > BTW, it seems I can replace all components in the expo
conversion
> > circuitry easily except Q12, Q3 and PC-1. Can't seem to find
info on
> > these anywhere. You wouldn't happen to know of components
compatible
> > to any of these three, would you?
> >
> > Peter
> >
> >
> > --- In PolySix@yahoogroups.com, Johannes Hausensteiner
> > <jo.synth@c...> wrote:
> >
> >>The hold capacitors are C56 in unit0..5. But I do not think that
it
> >>is the hold capacitors very likey. If it were, not all six voices
> >>would be affected equally. No, it must be something common. If it
> >>is not the wires to/from KLM-396, then the "expo converter" is my
> >>no.1 candidate. KLM-396 seems to be a part of it. The KBD works
> >>logarithmically; that is going up a certain number of keys (e.g.
> >>12 for one octave) multiplies the frequency of the generated note
> >>by a certain factor (times 2 in case of an octave). So the KBD CV
> >>logarithmic by its nature, whereas the oscillators work linear;
> >>that is, the generated frequency changes linearly with the
control
> >>voltage (e.g 1V gives 1000Hz, 2V give 2000Hz, 3V give 3000Hz,
> >
> > etc.).
> >
> >>These two schemes are not compatible to each other but it is
> >
> > possible
> >
> >>(and necessary) to convert from one to the other. When converting
> >>from logarithmic to linear you have to do the opposite of
logarithm
> >>which is exponential function. It happens that diodes and
> >
> > transistors
> >
> >>have exponential transfer curves, so they can be used for this
> >>purpose. But the exponential function is extrem sensitive to
small
> >>variations; a small variation of the input causes a big change at
> >>the output. Furthermore the human ear is very sensitive to
changes
> >>in pitch. This means that there must be taken special measures
that
> >>the whole thing does not run out of tune.
> >>The expo converter in the Polysix is made of IC17, 18, and 19,
Q12
> >>(the expo component), PC-1 (kind of an opto-coupling device), Q3,
> >>and surrounding components. In case of "old production" units
> >>KLM-396 belong to this circuitry, too. Polysix has 6 voices but
> >>the analog (de)multiplexers for the CV have 8 inputs/outputs. The
> >>additional 2 inputs/outputs are used for some kind of calibrating
> >>the exp. amplifier and thus stabilizing tuning of the instrument.
> >>I am not 100% sure how this works as the CPU never measures any
> >>value and therefore cannot adjust to changing values. From what I
> >>can see from the code there is always the value 0 ouput
to "voices"
> >>6 and 7.
> >>
> >>According to what you tell, it may be a thermal problem. So I
would
> >>carefully check all solder points and try to heat up / cool down
> >>the PCB in the area where these components are located. With
> >
> > cooling
> >
> >>spray you may identify a faulty component.
> >>
> >>Johannes
> >>
> >>
> >>Peter Andersson wrote:
> >>
> >>>Yes, it's an old production unit alright. I've checked the
wires
> >>>between the 366 and the 396. It seems ok, the solder joints too.
> >>>
> >>>Can you tell me which major components are actually involved in
> >
> > the
> >
> >>>lin/log conversion/tuning? I've been told to "check" the key
> >
> > voltage
> >
> >>>selector chip, the DAC and the S/H capacitors as well as
> >
> > something
> >
> >>>called an expo converter. (I don't understand half of this
stuff
> >
> > to
> >
> >>>be honest - I know you're not surprised. I'm learning,
though...
> >>>quickly!). These are some of the key components of the 366 as
> >
> > far as
> >
> >>>I understand. Do they handle the conversion/tuning you're
> >
> > refering
> >
> >>>to? I thought I'd start out by replacing the S/H capacitors.
The
> >>>cheapest and easiest operation to start with, I thought.
> >
> > However, I
> >
> >>>haven't even been able to locate them. It's nearly impossibe to
> >
> > read
> >
> >>>the numbers on the 366 schematics I got off the Old Crow web
> >
> > site.
> >
> >>>(Man what a fantastic resource his site is, btw!).
> >>>
> >>>Again, thanks for helping!
> >>>
> >>>--- In PolySix@yahoogroups.com, Johannes Hausensteiner
> >>><jo.synth@c...> wrote:
> >>>
> >>>
> >>>>From what you tell I would say it is a problem on the KLM-366,
> >
> > in
> >
> >>>>the log/lin conversion/tuning section.
> >>>>Or maybe you have one of the rare "old production" units. Is
> >
> > there
> >
> >>>>a small add-on board "KLM-396" to the KLM-366?
> >>>>It could be a lose wire (if "old production") and/or a bad
solder
> >>>>joint.
> >>>>I can see that you are located in Sweden; maybe you ask Ricard
> >>>>( http://home.swipnet.se/ricard2/p6index.html ) for technical
> >
> > help.
> >
> >>>>
> >>>>Peter Andersson wrote:
> >>>>
> >>>>
> >>>>
> >>>>>Actually, tones are quite stable even during the first 20
> >>>
> >>>minutes, but
> >>>
> >>>
> >>>>>the synth is not in tune generally. Also, an octave is a
quite
> >>>
> >>>stable
> >>>
> >>>
> >>>>>major 7 interval for the first 20 minutes, until suddenly,
the
> >>>
> >>>synth
> >>>
> >>>
> >>>>>goes into tune and then the octave is correct as well. I'll
> >
> > check
> >
> >>>>>tonight if a single generated tone changes a lot during the
> >>>
> >>>first 10
> >>>
> >>>
> >>>>>sec.
> >>>>>
> >>>>>All six voices are affected. If I play a chord when it
suddenly
> >>>
> >>>slides
> >>>
> >>>
> >>>>>out of pitch, all notes follow. It actually sounds like I'm
> >>>
> >>>turning
> >>>
> >>>
> >>>>>the pitch wheel. (I disconnected the pitch wheel, btw, just
to
> >>>
> >>>be sure
> >>>
> >>>
> >>>>>it wasn't playing tricks on me).
> >>>>>
> >>>>>It is not related to the MG setting and I've played around
with
> >>>
> >>>all
> >>>
> >>>
> >>>>>three - VCA, VCF and VCO. I'm quite sure it's not affected by
> >
> > the
> >
> >>>>>waveform setting either (whether I use a saw or a pulse) but
> >
> > I'll
> >
> >>>>>double check that tonight. The PWM setting does not make any
> >>>>>difference.
> >>>>>
> >>>>>Does this give you any clues? Thanks for helping!
> >>>>>
> >>>>>
> >>>>>--- In PolySix@yahoogroups.com, Johannes Hausensteiner
> >>>
> >>><jo.synth@c...>
> >>>
> >>>>>wrote:
> >>>>>
> >>>>>
> >>>>>
> >>>>>>It is not normal that it takes 20 miuntes to tune up.
Usually
> >
> > it
> >
> >>>>>>takes about 10sec to tune and then it is quite stable.
> >>>>>>Check the following: hold a key down when switching power
on.
> >
> > The
> >
> >>>>>>generated note should change quite a lot until it stabilizes
> >>>
> >>>after
> >>>
> >>>
> >>>>>>a few secs.
> >>>>>>Are all six voice affected? Is the effect related to the MG
> >>>
> >>>setting
> >>>
> >>>
> >>>>>>(VCA/VCF/VCO)? Is it related to PWM setting?
> >>>>>>
> >>>>>>
> >>>>>>Peter Andersson wrote:
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>>>Hi all,
> >>>>>>>
> >>>>>>>I'm the proud new owner of a Polysix. I love it! Can't take
my
> >>>>>
> >>>>>hands
> >>>>>
> >>>>>
> >>>>>
> >>>>>>>off those knobs - the filters are just great! But I'm
having
> >
> > a
> >
> >>>>>>>problem with it and I'm hoping someone can tell me what it's
> >>>>>
> >>>>>about
> >>>>>
> >>>>>
> >>>>>
> >>>>>>>and maybe even what can be done...
> >>>>>>>
> >>>>>>>After I've played the synth for a while, notes start to go
> >
> > out
> >
> >>>of
> >>>
> >>>
> >>>>>>>pitch every now and then. It happens randomly every 10-30
sec
> >
> > or
> >
> >>>>>so.
> >>>>>
> >>>>>
> >>>>>
> >>>>>>>The notes go off pitch with a note or so and always jump or
> >>>
> >>>slide
> >>>
> >>>
> >>>>>>>back to the original pitch again within half a second.
> >>>>>>>
> >>>>>>>At first I thought it was some filter setting of mine that
> >>>
> >>>caused
> >>>
> >>>
> >>>>>>>it, but as it turns out I get this no matter how the Poly6
is
> >>>>>>>programmed (or if I use a preset or a fresh "manual"
sound).
> >
> > (By
> >
> >>>>>the
> >>>>>
> >>>>>
> >>>>>
> >>>>>>>way, it takes about 20 minutes for the unit to get in
perfect
> >>>>>
> >>>>>tune
> >>>>>
> >>>>>
> >>>>>
> >>>>>>>after a cold start. Don't know if that's normal or if it's
> >>>>>
> >>>>>related
> >>>>>
> >>>>>
> >>>>>
> >>>>>>>to this problem in any way).
> >>>>>>>
> >>>>>>>I'd be truly grateful for any help!
> >>>>>>>
> >>>>>>>Peter
> >>>>>>>
> >>>>>>>
> >>>>>>>
> >>>>>>>
> >>>>>>>PolySix "Digiest" Page: http://www.acc.umu.se/~amber/Poly6
> >>>>>>>
> >>>>>>>
> >>>>>>>Yahoo! Groups Links
> >>>>>>>
> >>>>>>>To visit your group on the web, go to:
> >>>>>>>http://groups.yahoo.com/group/PolySix/
> >>>>>>>
> >>>>>>>To unsubscribe from this group, send an email to:
> >>>>>>>PolySix-unsubscribe@yahoogroups.com
> >>>>>>>
> >>>>>>>Your use of Yahoo! Groups is subject to:
> >>>>>>>http://docs.yahoo.com/info/terms/
> >>>>>>>
> >>>>>>>
> >>>>>>>
> >>>>>>>
> >>>>>
> >>>>>
> >>>>>
> >>>>>PolySix "Digiest" Page: http://www.acc.umu.se/~amber/Poly6
> >>>>>
> >>>>>Yahoo! Groups Links
> >>>>>
> >>>>>To visit your group on the web, go to:
> >>>>>http://groups.yahoo.com/group/PolySix/
> >>>>>
> >>>>>To unsubscribe from this group, send an email to:
> >>>>>PolySix-unsubscribe@yahoogroups.com
> >>>>>
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> >>>>>
> >>>>>
> >>>>>
> >>>>>
> >>>
> >>>
> >>>
> >>>PolySix "Digiest" Page: http://www.acc.umu.se/~amber/Poly6
> >>>
> >>>Yahoo! Groups Links
> >>>
> >>>To visit your group on the web, go to:
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> >>>
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> >>>
> >>>
> >>>
> >
> >
> >
> > PolySix "Digiest" Page: http://www.acc.umu.se/~amber/Poly6
> >
> >
> > Yahoo! Groups Links
> >
> > To visit your group on the web, go to:
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