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: > > >>>>>>>>>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 > > >>>>>>> > > >>>>>>>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 > > >>>>> > > >>>>>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 > > >>> > > >>>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 > > > > > > Your use of Yahoo! Groups is subject to: > > > http://docs.yahoo.com/info/terms/ > > > > > > > > > > > > >
Message
Re: Notes go out of pitch
2006-08-08 by sdlarch1