Now I got the feeling the the multitransistor has gone defected... I let the machine work all night long, and when I check it out the dualtransistor is not hot at all ! It used to get very hot when I let it work for a few hours... could it just has gone defected ? Any idea what voltages I should see on either of the legs ? Thanks --- In PolySix@yahoogroups.com, "gil_we" <gil_we@y...> wrote: > > 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