Doepfer

Hello

I have an A-131 and it's not passing audio. I put a signal into input, output to amplifer and when I turn gain knob up, nothing happens. No idea how this happened. How/where can I get this fixed?

Thanks

-Matt

Hello


Which version of the A-131 is it? To identify the version see 
http://www.doepfer.de/a130.htm:
-------
Over the years three different versions of the module A-130 und A-131 
have been manufactured:
Version 1:
The first versions of A-130 and A-131 were equipped with the Curtis 
chips CEM3381/PA381 (A-130) and CEM3382 (A-131). These versions of 
A-130/131 were not able to process slowly varying control voltages as 
they had AC coupled signal in/outputs. They were manufactured until 
about 2001.
Version 2:
The second versions of A-130 and A-131 were equipped with the OTA 
circuit CA3080 and they were able to process even slowly varying control 
voltages as they had DC coupled signal in/outputs. They were 
manufactured from 2001 until March 2013.
Version 3:
Die latest versions of von A-130 and 131 are equipped with the high-end 
VCA circuits SSM2164/V2164 (A-130) and THAT2159/V2159/SA2159 (A-131). 
Even they are able to process slowly varying control voltages as they 
have DC coupled signal in/outputs. These are manufactured since March 2013.
-------

Florian

On 29.06.14 16:49 , matthewmelnick@gmail.com [Doepfer_a100] wrote:
>
>
> Hello
>
>
> I have an A-131 and it's not passing audio. I put a signal into input,
> output to amplifer and when I turn gain knob up, nothing happens. No
> idea how this happened. How/where can I get this fixed?
>
>
> Thanks
>
>
> -Matt

> I think it's version #2 I see a chip CA3080E and V2 on the board

First of all I'd replace the CA3080. If this does not help I'd continue with
the opamp (probably LM324 or TL084/074) and then the transistor (BC557).

Best wishes
Dieter Doepfer