Hello Ben,

that's strange. The level of the up/down sounds should not depends upon the
shift frequency. This points to a problem with the quadrature oscillator
(i.e. that the sine and cosine are not stable/present at each frequency). I
don't think that it's a problem of the adder/subtractor for the up/down
generation. I'd recommend to measure the sine and cosine of the oscillator
while the frequency is changed.

I also don't think that capacitors are responsible. That's very uncommon
(but who knows ...). In the first place I'd replace the integrated circuits
and then the (trimming and normal) potentiometers.

And also the correct adjustment is very important. I remember that it took
up to one hour to do carry out all the adjustments of the A-126.

Best wishes
Dieter Doepfer

> -----Ursprüngliche Nachricht-----
> Von: Doepfer_a100@yahoogroups.com [mailto: Doepfer_a100@yahoogroups.com ]
> Gesendet: Mittwoch, 20. Februar 2019 23:35
> An: Doepfer_a100@yahoogroups.com
> Betreff: Re: AW: 1 A-126 Malfunction
>
>
> Thank you for your reply, Dieter.
> Today I replaced the TL084 and indeed I could now hear
> down-sounds, but not at every Shift value/level. It's irregular.
> And the down and up outputs are still equal (same sound).
>
> Next I will look for a new trimming potentiometer for the down
> adjustment. I think it's the P18 / 5K.
> If that does not help I will replace the other IC's except the
> CEM. After that I will replace the caps, if that does not help.
>
> I'm not in a hurry, and I have lots of other modules to play
> with, although the A126 is one of the sweetest to play with.
>
> All the best
> Ben
>
>
>
>
> ---In Doepfer_a100@yahoogroups.com , <yahoo@...> wrote :
>
>
> As already mentioned in the other email the A-126 is a very
> complex circuit.
> But if the up shift is working there is some chance that only the
> adder for
> the down shifting is faulty. It's built around the TL084 between the two
> ring modulators MC1496. If replacing the TL084 does not help one has to
> track the circuit with an oscilloscope to find out what's wrong. Maybe the
> trimming potentiometer for the down adjustment is broken.
>
> Best wishes
> Dieter Doepfer
>
>
> > -----Ursprüngliche Nachricht-----
> > Von: Doepfer_a100@yahoogroups.com [mailto: Doepfer_a100@yahoogroups.com ]
> > Gesendet: Mittwoch, 20. Februar 2019 01:29
> > An: Doepfer_a100@yahoogroups.com
> > Betreff: 1 A-126 Malfunction
> >
> >
> > Hello to you all,
> >
> > [What a coincidence with Rigo's broken A-126!].
> >
> > Today I started to try to fix my old A-126 by just replace some
> > suspected components.
> > Because the Shift and Mix and Up-Down outputs do not work
> > properly at all; for you just hear some changes in sound, when
> > turning the knobs. I mean you do not hear up and down sounds at
> > the same time. And it also does not go/sound from down to up and
> > vice versa.
> > And you do not hear any mix sounds at the Mix output.
> > And the Up and Down outputs sound the same.
> >
> > I started to replace IC 5 (TL064).
> > And now you can hear the sound goes from down to up (up-shifting
> > part), but no down-shifting sound to hear.
> > And the Up and Down outputs still sound the same.
> >
> > And now I do not know which components I should replace next.
> > Is there somebody who please can give me a hint, for I do can
> > solder very well, so I won't dissapoint you.
> >
> > Benny
>
>
>
>