Sean,

I'll send you the pcb silk screen to your email address.

Best wishes
Dieter Doepfer

> -----Ursprüngliche Nachricht-----
> Von: Doepfer_a100@yahoogroups.com
> [mailto: Doepfer_a100@yahoogroups.com ]Im Auftrag von stupidpaddy
> Gesendet: Montag, 21. August 2006 19:51
> An: Doepfer_a100@yahoogroups.com
> Betreff: 1 Re: A-131 Increased Gain modification
>
>
>
> --- In Doepfer_a100@yahoogroups.com , <hardware@...> wrote:
> >
> > Sorry, I overlooked that Sean was asking for the old version of
> the A-131:
> >
> > Increasing the input level: increase R10 (now 47k)
> > Increasing the output level: increase R12 (now 47k)
> >
> > Best wishes
> > Dieter Doepfer
> >
> >
> > > -----Ursprüngliche Nachricht-----
> > > Von: Doepfer_a100@yahoogroups.com
> > > [mailto: Doepfer_a100@yahoogroups.com ]Im Auftrag von Florian Anwander
> > > Gesendet: Montag, 21. August 2006 14:14
> > > An: Doepfer_a100@yahoogroups.com
> > > Betreff: Re: 1 A-131 Increased Gain modification
> > >
> > >
> > > hi Sean
> > >
> > > > I'm trying to modify my old style A-131 Exp. VCA module to get a
> > > > gain >1 as the output often seems weedy and I would like the option
> > > > of a little (or a lot of) overdrive.
> > > >
> > > > I'm guessing that I can do this in 2 ways:
> > > > 1. change the resistors connected to the audio In pots to a
> lower value.
> > > > 2. change the resistor connected to the output voltage of the
> > > CV circuit.
> > > I think the VCAs OTA is not the place where you should change
> the level.
> > > Usually a change of amplification should be done by decreasing the
> > > feedback resistor of an OpAmp. As far as I remember, the old A131 with
> > > the Curtis CEM3382 does not use an separate buffer stage at the output
> > > (thats where you might do this). So I suggest to modify a Mixer A-138,
> > > where you could change either the feedback of the summing amp (to
> > > amplify all four inputs), or change the input resistor of one channel.
> > >
> > > Florian
> > >
> > >
> > >
> > > Yahoo! Groups Links
> > >
>
>
> hi Dieter
>
> Is there a PDF available for the service manual for the A-131 to
> help me identify the
> correct resistors
>
> vielen dank
> sean
>
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> Yahoo! Groups Links
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