Doepfer

yes , actually 5 minutes after posting the previous post the a-126 was dead again, and today it works again, better than not working at all.


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> yes , actually 5 minutes after posting the previous post the
> a-126 was dead again, and today it works again, better than not
> working at all.

Totally strange. But I have one last idea. We discovered that the internal
quadrature VCO of some A-126 does not start now and then if the
corresponding control is in the fully CCM position during power on (i.e.
lowest shifting frequency ~ 50Hz). But it should start as soon as the
frequency control is turned clockwise. We believe that it has to do with the
power on details, i.e. how fast and in which sequence the +12V and -12V turn
on which in turn has to do which power supply is used and which modules are
installed. In any case the VCO does not start if the frequency is less than
~ 50Hz (e.g. if the frequency offset trimming potentiometer has been changed
by the customer to obtain a lower shifting frequency than 50 Hz).

Best wishes
Dieter Doepfer

i tried this but it doesnt help here, when the 126 is not working there
seems to be no way to change this for the day. on next power up or some days
later its sometimes back to normal for a while.




2008/6/27 <hardware@doepfer.de>:

>   > yes , actually 5 minutes after posting the previous post the
> > a-126 was dead again, and today it works again, better than not
> > working at all.
>
> Totally strange. But I have one last idea. We discovered that the internal
> quadrature VCO of some A-126 does not start now and then if the
> corresponding control is in the fully CCM position during power on (i.e.
> lowest shifting frequency ~ 50Hz). But it should start as soon as the
> frequency control is turned clockwise. We believe that it has to do with
> the
> power on details, i.e. how fast and in which sequence the +12V and -12V
> turn
> on which in turn has to do which power supply is used and which modules are
> installed. In any case the VCO does not start if the frequency is less than
> ~ 50Hz (e.g. if the frequency offset trimming potentiometer has been
> changed
> by the customer to obtain a lower shifting frequency than 50 Hz).
>
> Best wishes
> Dieter Doepfer
>
>  
>


[Non-text portions of this message have been removed]

> i tried this but it doesnt help here, when the 126 is not working there
> seems to be no way to change this for the day. on next power up
> or some days
> later its sometimes back to normal for a while.

Are you able to do some simple measurement? I'd like to know if the
quadrature VCO is the problem, i.e. you would have to check if the
sine/cosine waveforms are present while the A-126 does not work. They are
available at pin headers on the pc board of the module (no soldering
required, it would be sufficient to touch the corresponding pin of the pin
header with the tip of a patch cable with the other side connected to an
audio mixer).

Best wishes
Dieter Doepfer

ok i can try this as soon as i have a day with no function on the 126.
could you please post a picture with the points marked where i have to test
the vco ?

2008/6/27 <hardware@doepfer.de>:

>   > i tried this but it doesnt help here, when the 126 is not working
> there
> > seems to be no way to change this for the day. on next power up
> > or some days
> > later its sometimes back to normal for a while.
>
> Are you able to do some simple measurement? I'd like to know if the
> quadrature VCO is the problem, i.e. you would have to check if the
> sine/cosine waveforms are present while the A-126 does not work. They are
> available at pin headers on the pc board of the module (no soldering
> required, it would be sufficient to touch the corresponding pin of the pin
> header with the tip of a patch cable with the other side connected to an
> audio mixer).
>
> Best wishes
> Dieter Doepfer
>
>  
>


[Non-text portions of this message have been removed]

> ok i can try this as soon as i have a day with no function on the 126.
> could you please post a picture with the points marked where i
> have to test
> the vco ?

These are the only two pin headers that are equipped with jumpers: ST3 and
ST4. When the jumper is removed the left pin should output the
sine(ST3)/cosine(ST4). You find the position of the jumpers on our website
in the document that describes how to connect the external quadrature VCO
A-143-9: www.doepfer.com > PRODUCTS > A-100 > Module Overview > A-126 >
A126_A143_connection.pdf. The pin headers ST3 and ST4 are even used to
connect an external quadrature VCO.

Best wishes
Dieter Doepfer

--- In Doepfer_a100@yahoogroups.com, wille hermansson
<astroschnautzer@...> wrote:
>
> yes , actually 5 minutes after posting the previous post the a-126
was dead again, and today it works again, better than not working at all.
> 

i can remember that one or two times my a126 did not work too,
but when i simply switched the power off and on it worked again.
i never had these issues again, so i blamed it on the full moon
or something like that.

best wishes

ingo

actually I got it to work too but it has a quirk; it doesn`t work if  you power it up with the 
shift knob at zero, but if you power it with the knob anywhere else it works....


--- In Doepfer_a100@yahoogroups.com, "selfoscillate" <synaptic_music@...> wrote:

>
> --- In Doepfer_a100@yahoogroups.com, wille hermansson
> <astroschnautzer@> wrote:
> >
> > yes , actually 5 minutes after posting the previous post the a-126
> was dead again, and today it works again, better than not working at all.
> > 
> 
> i can remember that one or two times my a126 did not work too,
> but when i simply switched the power off and on it worked again.
> i never had these issues again, so i blamed it on the full moon
> or something like that.
> 
> best wishes
> 
> ingo
>

> actually I got it to work too but it has a quirk; it doesn`t work
> if  you power it up with the
> shift knob at zero, but if you power it with the knob anywhere
> else it works....

That's what I already mentioned in my message from June 26:

"We discovered that the internal quadrature VCO of some A-126 does not start
now and then if the corresponding control is in the fully CCM position
during power on (i.e. lowest shifting frequency ~ 50Hz). But it should start
as soon as the
frequency control is turned clockwise. We believe that it has to do with the
power on details, i.e. how fast and in which sequence the +12V and -12V turn
on which in turn has to do which power supply is used and which modules are
installed."

Best wishes
Dieter Doepfer

--- In Doepfer_a100@yahoogroups.com, <hardware@...> wrote:
>
> > actually I got it to work too but it has a quirk; it doesn`t work
> > if  you power it up with the
> > shift knob at zero, but if you power it with the knob anywhere
> > else it works....
> 
> That's what I already mentioned in my message from June 26:
> 
> "We discovered that the internal quadrature VCO of some A-126 does not start
> now and then if the corresponding control is in the fully CCM position
> during power on (i.e. lowest shifting frequency ~ 50Hz). But it should start
> as soon as the
> frequency control is turned clockwise. We believe that it has to do with the
> power on details, i.e. how fast and in which sequence the +12V and -12V turn
> on which in turn has to do which power supply is used and which modules are
> installed."
> 
> Best wishes
> Dieter Doepfer
>

Yes, on base of this comment I figured it out, I just did not first understand that you have 
to turn off the device to get this working. Thanks for the help!

> Yes, on base of this comment I figured it out, I just did not
> first understand that you have
> to turn off the device to get this working. Thanks for the help!

You'r welcome. I suppose the only solution would be to try another CEM3382
which is used in the internal quadrature VCO. But the CEM3382 is very hard
to find and even expensive (that's why we discontinued the A-126).

One last question: which power supply do you use (A-100PSU2 or another type)
?

Best wishes
Dieter Doepfer

I also had problems with my 126 dying on me, lots of times, but it doesn't seem to have 
happened for the past couple of years at least.  (My module dates from 1998 I think.)  At the 
time, it wasn't about it not powering on, but rather it would stop working in the middle of 
use.  Then if I powered off and back on (suitcase), usually it would start working again.  I had 
thought that it was maybe due to being overdriven at the input.  Is it possible to damage it or 
have adverse effects by overdriving the input (just with other A-100 signals)?

thanks,
Ernst

I use the doepfer DIY kit #1..

--- In Doepfer_a100@yahoogroups.com, <hardware@...> wrote:

>
> > Yes, on base of this comment I figured it out, I just did not
> > first understand that you have
> > to turn off the device to get this working. Thanks for the help!
> 
> You'r welcome. I suppose the only solution would be to try another CEM3382
> which is used in the internal quadrature VCO. But the CEM3382 is very hard
> to find and even expensive (that's why we discontinued the A-126).
> 
> One last question: which power supply do you use (A-100PSU2 or another type)
> ?
> 
> Best wishes
> Dieter Doepfer
>

> I also had problems with my 126 dying on me, lots of times, but it doesn't
seem to have
> happened for the past couple of years at least.  (My module dates from
1998 I think.)  At the
> time, it wasn't about it not powering on, but rather it would stop working
in the middle of
> use.  Then if I powered off and back on (suitcase), usually it would start
working again.  I had
> thought that it was maybe due to being overdriven at the input. Is it
possible to damage it or
> have adverse effects by overdriving the input (just with other A-100
signals)?
>
> thanks,
> Ernst

There is no chance to damage the A-126 by overdriving it with other A-100
signals. Btw this is valid for all A-100 modules. Only if external signals
beyond the A-100 voltages (i.e. more than +12V or less than -12V) are
connected an input of an A-100 modules damages may occur. But even with
voltages beyond these limits most of the modules will survive. It depends
upon the input circuit. If there is a virtual GND summing node (the standard
inverting amplifier/adder circuit) even higher voltages will not damage a
module.

Best wishes
Dieter Doepfer

The power supply of the DIY kit#1 uses nearly the same circuit as the PSU2,
only with external transformer. It should be not responsible for the
problems with the A-126.

Best wishes
Dieter Doepfer

> I use the doepfer DIY kit #1..
>
> --- In Doepfer_a100@yahoogroups.com, <hardware@...> wrote:
> >
> > > Yes, on base of this comment I figured it out, I just did not
> > > first understand that you have
> > > to turn off the device to get this working. Thanks for the help!
> >
> > You'r welcome. I suppose the only solution would be to try
> another CEM3382
> > which is used in the internal quadrature VCO. But the CEM3382
> is very hard
> > to find and even expensive (that's why we discontinued the A-126).
> >
> > One last question: which power supply do you use (A-100PSU2 or
> another type)
> > ?
> >
> > Best wishes
> > Dieter Doepfer
> >
>
>
>
>
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