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/
>>>>>
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>>>>>
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>>>>>
>>>>>
>>>>>
>>>>>
>>>
>>>
>>>
>>>PolySix "Digiest" Page: http://www.acc.umu.se/~amber/Poly6
>>>
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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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