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Re: [korg_mono-poly] Vco offset voltage

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  • Florian Anwander
    ... Others may correct me, but I think you misunderstood the adjustment description: As far as I understand it right this is not a trimming to absolute 0.000V
    Message 1 of 4 , Oct 29, 2012
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      Am 29.10.2012 01:53, schrieb ohmstudiste:
      > Hi,
      >
      > I got a mp4 that I recently recalibrated and is working very nicely. Tuning/scaling is very good.
      > I checked all the voltage and got good and steady readings on the power supply and keyboard CV voltages.
      >
      > But when it comes to measure the VCO offset in the klm398 I don't get the 0.000v +/- 1mv. Instead I read voltages bretween 1v and 3v and they change if I play notes on the keyboard. The voltages are responsive to the different VR on the board but I can't make them 0.000v.
      >
      > So question are:
      > - Am I reading the good points ? i connected to J12 and to the respective 4 colour wires mentionned in the manual (and corrected here for new version)
      > - Is there a key to press while reading ?
      > - Is it dangerous for the OSC to have these readings ? As i mentionned my mp4 is really nice tuned and scaled, for every oscillators.

      Others may correct me, but I think you misunderstood the adjustment
      description: As far as I understand it right this is not a trimming to
      absolute 0.000V +/- 1mV, but the voltages should not vary more than 1mV
      in relation to each other.

      Florian
      --
      http://fa.utfs.org/
    • willacyman
      I went through this when I rebuilt my trainwreck Mono/Poly. The offset is obviously only a part of the overall procedure but it was a case of adjusting to get
      Message 2 of 4 , Oct 29, 2012
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        I went through this when I rebuilt my trainwreck Mono/Poly. The offset is obviously only a part of the overall procedure but it was a case of adjusting to get as close to zero as possible but measured at pins 1,3,5&7 on connector 39. The whole procedure I used is in the forum 'Files' section under 'Misc Files' - 'Poly.pdf'.
        Good luck
        Steve

        --- In korg_mono-poly@yahoogroups.com, "ohmstudiste" <ohmstudist@...> wrote:
        >
        > Hi,
        >
        > I got a mp4 that I recently recalibrated and is working very nicely. Tuning/scaling is very good.
        > I checked all the voltage and got good and steady readings on the power supply and keyboard CV voltages.
        >
        > But when it comes to measure the VCO offset in the klm398 I don't get the 0.000v +/- 1mv. Instead I read voltages bretween 1v and 3v and they change if I play notes on the keyboard. The voltages are responsive to the different VR on the board but I can't make them 0.000v.
        >
        > So question are:
        > - Am I reading the good points ? i connected to J12 and to the respective 4 colour wires mentionned in the manual (and corrected here for new version)
        > - Is there a key to press while reading ?
        > - Is it dangerous for the OSC to have these readings ? As i mentionned my mp4 is really nice tuned and scaled, for every oscillators.
        >
      • ohmstudiste
        Oh stupid of me ! Than it makes sense of course. And now I managed to adjust them correctly (there was a 0.05v drift).
        Message 3 of 4 , Oct 29, 2012
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          Oh stupid of me !
          Than it makes sense of course. And now I managed to adjust them correctly (there was a 0.05v drift).

          > Others may correct me, but I think you misunderstood the adjustment
          > description: As far as I understand it right this is not a trimming to
          > absolute 0.000V +/- 1mV, but the voltages should not vary more than 1mV
          > in relation to each other.
          >
          > Florian
          > --
          > http://fa.utfs.org/
          >
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