Now I see what happened... I guess that was a big mistake using the freeze spray on such a sensitive circuit. The problem is that I already even readjusted VR3, VR4 and VR5... So even if and when the bad componet gets to its natural state the synth will be out of tune ! shouldn't have touched it from the start ... Johannes, 1. can the dual transistor get back to its initial, natural state ? Maybe if I let the machine work a few days (so the components can "recover" from the freeze harm - maybe by warming up ?) 2. Do VR4 (Antilog Freq.), VR3 (Antilog Width) and VR5 (Antilog Offset) act like the VR6 (Hi Tune), VR7 (Mid Tune) and VR5 (Low Tune) - on the Polysix new-version ? So basically if and when the components are ok, I should be able to tune it the same way you tune a Polysix ? 3. Last question - should the TH1 heat sensor be located just over the multitransistor in general ? it was leaning over the circuit board when I check it out, just realized it is a sesnor... Thanks very much, I SHOULD fix that one it's one of a monster beautifully sounding instrument ! --- In PolySix@yahoogroups.com, Johannes Hausensteiner <johau@g...> wrote: > > The "multileg component" probably is the dual transistor for the > antilog amplifier. This is one of the most critical stages in terms > of note frequency. It has an exponential transfer characteristic, > which means that a tiny variation at the input may cause a huge at > the output. Applying a freeze spray definitely will have a large > effect on the tune of the instrument, but all voices are affected > equally, because the antilog conversion is applied to the multi- > plexed CV. > > gil_we wrote: > > ooops... the multileg component is IC6, not R40 > > > > > > --- In PolySix@yahoogroups.com, "gil_we" <gil_we@y...> wrote: > > > >>Thanks guys ! > >> > >>There was something strange going on.... After writing my previous > >>mail I ran over a few components with a "freeze" spray, among them > >>the transistors and caps area of both VCOs on the problematic > >>oscillator and the R40 component (what looks like a mutli-leg > >>transistor but I guess is a multi-resistor ?) > >> > >>Suddenly, two things happen (which still happen if I turn the > > > > machine > > > >>off for a few hours and back on... regardless internal temperature): > >> > >>1. The bad oscillator is no more out of tune ! > >> > >>2. The entire scale has changed - i.e the gap between each note to > >>the one that follows it is larger (there is more than one octave > > > > gap > > > >>between C4 and C5 for example) > >> > >>But that made me recall that when I got hte unit there was not > > > > tuning > > > >>issue at all, and the bad tuning problem on the second oscillator > >>only started once I started servicing the machine) > >> > >>Strange huh ? > >> > >>Could it be R40 that is defective ? does that make sense ? > >> > >>Thanks again ! > >> > >> > >> > >> > >> > >>--- In PolySix@yahoogroups.com, "Chromatest J. Pantsmaker" > >><chromatest@g...> wrote: > >> > >>> > >>> > >>>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@y...> > >>>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 > >>> > >> > > > > > > > > > > > > > > > > PolySix "Digiest" Page: http://www.acc.umu.se/~amber/Poly6 > > Yahoo! Groups Links > > > > > > > > > > > > > > > > >
Message
Re: Trident MKII - one oscillator is out of tune
2005-12-09 by gil_we