[R-390] More On Low Audio Problem

[Frederick Bray]

I should have noted that it also works if I jumper terminals 1 and 4 of 
the switch.  In the wide position terminal 7 connects to terminal 4.   
Jumpering from 1 to 4 works regardless of whether the switch is in the 
wide or sharp positions.

TNX




Frederick Bray wrote:

> First, let me thank everyone who has replied -- both on and off list.
>
> I think I have narrowed the problem down to the first AF amp/cathode 
> follower.  I would appreciate it if those who are more experienced 
> that I with the 390A can confirm that I am on the right track.
>
> I used an audio signal generator to ascertain that a signal injected 
> at the local and line level controls seems to produce a normal audio 
> output.
>
> Using a VTVM, I confirmed that on there is an AC voltage on terminal 1 
> of the wide/sharp switch and that I can trace this voltage through the 
> switch.  Jumpering this voltage to terminal 6 on the switch seems to 
> restore the audio level to approximately normal, or at least much 
> closer to normal.
>
> From looking at the schematic, I think that what I am doing is 
> bypassing the first AF/cathode follower and going directly to the 
> local and line AF amps.
>
> Does this make sense?
>
> Thanks,
>
> Fred Bray
> KE6CD
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