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Re: A-155 New/Old differences???

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  • phaeton777
    Does anybody the difference in circuit design that would cause this effect? Can I easily modify my newer A-155 to behave the same way? R. ... and it does the
    Message 1 of 7 , Dec 31, 2003
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      Does anybody the difference in circuit design that would cause this
      effect? Can I easily modify my newer A-155 to behave the same way?

      R.

      --- In Doepfer_a100@yahoogroups.com, "ps_minor" <pscottm@h...> wrote:
      > hi richard, no this is not a defect. my a155 is an older one too
      and it does the
      > same thing when clocked w a sawtooth wave. i use it this way
      often!
      > -psm
      >
      >
      >
      > --- In Doepfer_a100@yahoogroups.com, "phaeton777" <phaeton777@y...>
      > wrote:
      > > I have 2 A-155s. One is an older model and one is is brand new. I
      > > lent the older one to a friend who is learning about modulars and
      he
      > > discovered a strange anomaly:
      > >
      > > When an A-145 sawtooth wave is used as the clock, the A-155 will
      step
      > > randomnly through its 8 steps. I stood watching it for 20 minutes
      and
      > > sure enough-its randomn!
      > >
      > > This only happens with the older A-155. The newer one just steps
      in
      > > sequence.
      > >
      > > Do I have a pleasantly defective A-155?
      > >
      > > Richard.
    • Tim Stinchcombe
      Hi Richard, ... Newer 155 s have a small mod on them, which I believe is to stop it stepping more than one step when manually clocking it (and it s also the
      Message 2 of 7 , Jan 1, 2004
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        Hi Richard,

        > Does anybody the difference in circuit design that would cause this
        > effect? Can I easily modify my newer A-155 to behave the same way?

        Newer 155's have a small mod on them, which I believe is to stop it
        stepping more than one step when manually clocking it (and it's also
        the thing that stops you clocking it very fast!). Underneath 'Board 4
        (Controller Board)' (one of the small ones), on your newer 155 you
        should see a capacitor and resistor soldered together and bridging a
        couple of pins on an IC. I suspect this mod may be what stops newer
        ones behaving this way. I know Bakis (for one) has removed this mod
        on his 155's, so perhaps if he is listening he can quickly try
        clocking it with a sawtooth to see if it does clock 'randomly'?
        (It'll save me getting my soldering iron out, but I will carry on
        looking at it to see if I can figure the exact mechanism out...)

        Tim
      • Tim Stinchcombe
        ... this ... also ... 4 ... a ... I can indeed confirm that removing this mod causes the behaviour you have observed with the sawtooth clock input,
        Message 3 of 7 , Jan 1, 2004
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          > > Does anybody the difference in circuit design that would cause
          this
          > > effect? Can I easily modify my newer A-155 to behave the same way?
          >
          > Newer 155's have a small mod on them, which I believe is to stop it
          > stepping more than one step when manually clocking it (and it's
          also
          > the thing that stops you clocking it very fast!). Underneath 'Board
          4
          > (Controller Board)' (one of the small ones), on your newer 155 you
          > should see a capacitor and resistor soldered together and bridging
          a
          > couple of pins on an IC. I suspect this mod may be what stops newer
          > ones behaving this way. I know Bakis (for one) has removed this mod
          > on his 155's, so perhaps if he is listening he can quickly try
          > clocking it with a sawtooth to see if it does clock 'randomly'?
          > (It'll save me getting my soldering iron out, but I will carry on
          > looking at it to see if I can figure the exact mechanism out...)

          I can indeed confirm that removing this mod causes the behaviour you
          have observed with the sawtooth clock input, particularly noticeable
          with a falling sawtooth. I simply de-soldered the junction between
          the extra resistor and capacitor. The (comparatively) slow fall of
          the sawtooth causes havoc with the logic - it cannot decide if it
          should be 'high' or 'low', quickly flipping between both states until
          the ramp has come down enough for it to be sure. This 'noise' on the
          logic clocks the sequencer very fast, thus giving the appearance of
          randomly jumping backward and forward through all the steps. The mod
          prevents this from happening. (Without it, as previously mentioned,
          it is now possible to clock the sequencer at frequencies well into
          the audio range - nearly 6kHz from my A-145 at full bore!)

          Tim
        • TonyBlack [JohnnyBusca]
          Hello! I also own an old one, and I like that feature, but I m wondering if another thing is also fixed in the new version. When you use the trigger on the
          Message 4 of 7 , Jan 2, 2004
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            Hello!

            I also own an old one, and I like that feature, but I'm wondering if
            another thing is also fixed in the new version.

            When you use the trigger on the first step, it keeps on triggering when
            you use the sequencer in combination with the A-199 midi interface. (midi
            clock --> sequencer clock, midi reset --> sequencer reset.)

            I often use the seqeuncer to trigger a bass kick on my SDS-800, and
            pressing STOP on my MPC2000xl results in a lot of kicks.

            Does this also happen in the new version?

            Best regards,
            JohnnyBusca
            > Date: Thu, 01 Jan 2004 11:46:19 -0000
            > From: "Tim Stinchcombe" <timothy@...>
            > Subject: Re: A-155 New/Old differences???
            >
            > Hi Richard,
            >
            >> Does anybody the difference in circuit design that would cause this
            >> effect? Can I easily modify my newer A-155 to behave the same way?
            >
            > Newer 155's have a small mod on them, which I believe is to stop it
            > stepping more than one step when manually clocking it (and it's also
            > the thing that stops you clocking it very fast!). Underneath 'Board 4
            > (Controller Board)' (one of the small ones), on your newer 155 you
            > should see a capacitor and resistor soldered together and bridging a
            > couple of pins on an IC. I suspect this mod may be what stops newer
            > ones behaving this way. I know Bakis (for one) has removed this mod
            > on his 155's, so perhaps if he is listening he can quickly try
            > clocking it with a sawtooth to see if it does clock 'randomly'?
            > (It'll save me getting my soldering iron out, but I will carry on
            > looking at it to see if I can figure the exact mechanism out...)
            >
            > Tim
            >
            >
          • Bakis Sirros
            hello tim, yes, i have removed this mod on one of my 3 newer a155 s and it behaves just like my older a155 s.i ll remove this mod soon,also, from my other two
            Message 5 of 7 , Jan 2, 2004
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              hello tim,
              yes, i have removed this mod on one of my 3 newer
              a155's and it behaves just like my older a155's.i'll
              remove this mod soon,also, from my other two new
              a155's in order to be able to clock them in audio
              frequencies in combination with my a196's.
              bakis.




              --- Tim Stinchcombe
              <timothy@...> wrote:
              > Hi Richard,
              >
              > > Does anybody the difference in circuit design that
              > would cause this
              > > effect? Can I easily modify my newer A-155 to
              > behave the same way?
              >
              > Newer 155's have a small mod on them, which I
              > believe is to stop it
              > stepping more than one step when manually clocking
              > it (and it's also
              > the thing that stops you clocking it very fast!).
              > Underneath 'Board 4
              > (Controller Board)' (one of the small ones), on your
              > newer 155 you
              > should see a capacitor and resistor soldered
              > together and bridging a
              > couple of pins on an IC. I suspect this mod may be
              > what stops newer
              > ones behaving this way. I know Bakis (for one) has
              > removed this mod
              > on his 155's, so perhaps if he is listening he can
              > quickly try
              > clocking it with a sawtooth to see if it does clock
              > 'randomly'?
              > (It'll save me getting my soldering iron out, but I
              > will carry on
              > looking at it to see if I can figure the exact
              > mechanism out...)
              >
              > Tim
              >
              >


              =====
              Bakis Siros
              Parallel Worlds / Polariton
              Athens-Greece
              [Doepfer_a100] group owner
              http://www.rubber.gr
              http://www.ward12.com

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