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
>
>
>
>
>
>
>
>