AW: [Doepfer_a100] Re: Two A-141-1 modules, not the same curves

From yahoo
Sent Mon, Jul 14th 2014, 17:08

> Hello everyone,
>
>
> I'm happy to tell that my two A-141-1 modules have got very
> similar curves now.
> Moving the trimming potentiometer seems to change the overall
> envelope time. It is very touchy, but with a little patience I've
> been able to make the curves of the two modules very close to each other.
>
>
> Thanks to Dieter and Florian for their help, that's great
> customer support !
>
>
> By the way, I wondered if my second A-141-1 module is a revised
> version, since it has another IC and two added resistors. I'd be
> glad to know a little more about it !
>
>
> Anyway have a nice day, and thanks again.
>
>
> Thomas
> (komyta)

I took a look at our records. Until about end of 2007 the pins 11 and 15 of
the CD4052 were connected to GND directly. From 2008 these pins have been
cutted off GND and each connected via 100k to GND. These are probably the
two additional resistors you mentioned. The reason for the modification was
a noticeable offset voltage (up to 200mV) depending upon the CA3080 OTA
(i.e. the offset does not appear in any case but in combination with certain
batches of CA3080). If your module without resistors has a clearly higher
offset voltage adding the resistors should solve the problem.

But I did not find any notes that integrated circuits have been changed.

Best wishes
Dieter Doepfer




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