I'm not familiar with the resistor value notation used here.
What are 4k7 and 1k2? 4.7k? 47k?
--- In
PolySix@yahoogroups.com, "Peter Andersson"
<peter.peppe.andersson@...> wrote:
>
>
> Hi,
>
> I wanted to let you know that I've finally managed to repair my
> Precious (Polysix). It was indeed the opto resistor, the PC-1, that
> was faulty. It was suggested to me that I replace the old
mysterious
> PC-1 component with a VTL5C3 and change R93 from 4k7 to 1k2 (to get
> the VTL5C3 working properly). I did and then the synth was as good
> as new!
>
> Appearently, the PC-1 is what stabilizes the expo-converter
circuit.
> If it's broken, the circuit can't manage to keep the synth in tune
> as the voltages vary (which is especially noticeable during the
time
> the machine is warming up).
>
> Thanks for the help!
>
> Peter
>
> --- In PolySix@yahoogroups.com, Johannes Hausensteiner
> <jo.synth@c...> wrote:
> > I would not start to replace all components; I would rather try
> > to find out the faulty one. Heat up the whole area of the PCB
> > using a hot fan. Then you can selectively cool down single
> > components with cooling spray. If you start the Arpeggiator
> > before you can let play the Polysix for its own and hear changes
> > immediately.
> >
> > Johannes
> >
> >
> > Peter Andersson wrote:
> > > 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:
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> > >>>>>>>>>
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> > >>>>>>>>>
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> > >>>>>>>>>
> > >>>>>>>>>
> > >>>>>>>>>
> > >>>>>>>>>
> > >>>>>>>
> > >>>>>>>
> > >>>>>>>
> > >>>>>>>PolySix "Digiest" Page: http://www.acc.umu.se/~amber/Poly6
> > >>>>>>>
> > >>>>>>>Yahoo! Groups Links
> > >>>>>>>
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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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> > >>>>>
> > >>>
> > >>>
> > >>>
> > >>>PolySix "Digiest" Page: http://www.acc.umu.se/~amber/Poly6
> > >>>
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> > >>>
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> > >
> > >
> > >
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> > >
> > > Yahoo! Groups Links
> > >
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