[R-390] R390a Audio Amplifier

[Norman Ryan]

Hi, Steve,

This is interesting.  I have an R-390A with the same issue which I assumed was due to a faulty volume control potentiometer.  Now I'm curious to see if swapping the audio deck with a working spare will eliminate the problem which would tend to confirm your diagnosis of a failed screen grid cap.

73 de Norman, KG4SWM


--- On Tue, 5/28/13, Steve Hobensack <stevehobensack at hotmail.com> wrote:

> From: Steve Hobensack <stevehobensack at hotmail.com>
> Subject: Re: [R-390] R390a Audio Amplifier
> To: "r390 reflector" <r-390 at mailman.qth.net>
> Date: Tuesday, May 28, 2013, 9:27 AM
> The audio from the Local gain
> circuitry can couple itself over to the Line gain circuitry
> via the 6ak6 screens (and vice versa) should the screen
> bypass cap fail. This happened to me. The local gain would
> not minimize unless I turned the line gain to minimum. As I
> remember,  one of the plug-in electrolytics was the
> culprit.
> 
> Steve N8YE
>     
>         
>           
>   
> ______________________________________________________________
> R-390 mailing list
> Home: http://mailman.qth.net/mailman/listinfo/r-390
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:R-390 at mailman.qth.net
> 
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>