AW: [Doepfer_a100] A-148 behaving erratically

From yahoo
Sent Mon, Mar 24th 2014, 10:56

Please refer to the A-148 info page:

"Since August 2005 an improved version of the module is manufactured: For
each sub-module the operation mode S&H (sample&hold) or T&H (track&hold) can
be selected by a jumper. In T&H mode the output signal follows the input
signal while the trigger input is "high". As soon as the trigger input turns
to "low" the last voltage is stored. The factory setting is S&H for the
upper device and T&H for the lower device. At the bottom of this page the
function of the jumpers is described. In addition the complete A-100 voltage
range -12...+12V can be processed (no longer limited to -8...+8V as for the
previous version).
The two versions can be identified by these details:
Version 1: four integrated circuits (2 x CD4053, 2 x TL064 oder TL084)
Version 2: three integrated circuits (1x DG442, 2 x TL084), see silk screen
at the bottom of this page."

Maybe you own the old version with max. about +8V/-8V signal level.

Best wishes
Dieter Doepfer


> -----Ursprüngliche Nachricht-----
> Von: xxxxxxx_xxxx@xxxxxxxxxxx.xxx
> [mailto:xxxxxxx_xxxx@xxxxxxxxxxx.xxx]Im Auftrag von Martin Fay
> Gesendet: Montag, 24. März 2014 10:30
> An: xxxxxxx_xxxx@xxxxxxxxxxx.xxx
> Betreff: Re: [Doepfer_a100] A-148 behaving erratically
>
>
>
>
>
> Further to the emails last week I've now received the problem
> A-148 back. Testing it myself I've noticed that bad behaviour is
> related to the amplitude of the Smp In signal. Low enough, all
> good, turn it up and I get what seems to be false triggers with a
> low value taken. With an A-110 as source the saw/square/sine
> waveforms are good, but Tri misbehaves. Using an attenuator I
> could get "arcade slide" effects.
>
>
> The question to the floor: is this normal for an early A-148 and
> what might fix it?
>
>
> Martin
>
> Sent from my iPhone
>
> On 17 Mar 2014, at 12:16, Martin Fay <xxxxxx@xxxxxxxxx.xxx> wrote:
>
>
>
> I'm the seller, and to give further background I also saw this
> behaviour some time ago, which stopped happening after
> rearranging modules.
>
>
>
> Martin
>
> Sent from my iPhone
>
> On 17 Mar 2014, at 11:15, <xxxxxxx@xxxxxxxxxxx.xxx> wrote:
>
>
>
> Hi
>
>
> I have picked up a second-hand A-148 Sample and Hold module and
> it's not working correctly. When fed with white noise and a
> steady clock it triggers more times than it should, semi-randomly
> (not in time with the clock). Also it doesn't hold the voltage
> once no more triggers are received, it quickly leaks down to 0
> volts. It's a very old unit made in 1995. It has no T&H/S&H
> option jumpers and also has flat-fronted LEDs.
>
>
> Anyone seen this problem before?
>
>
> Thanks
>
>
> Rich
>
>
>
> 



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