[R-390] R-390 Woes

[Adam Morehouse]

I might have found the issue.

Can anyone tell me if the white coax in the follow pictures is supposed to
be there?

https://photos.app.goo.gl/M6Qcr9mXFrZ6sgiRA

It doesn't look original to me, nor does the the resistors and caps in
front of the BFO. They seem to be hooked to V508 and RT512.




On Tue, Oct 7, 2025, 16:55 Adam Morehouse <morehouse90 at gmail.com> wrote:

> Hey guys,
>
> I appreciate the pointers on my R-392, and now that it's buttoned up, it's
> time to work on my R-390. I only tested this briefly when I first got it,
> today I threw it up on the bench. Supposedly this was restored by Rick
> Mish, it is very clean (except the gear train, which has a lot of fresh
> grease...), and the front panel is pristine.
>
> It does pull stations, but the volume is extremely low in AGC mode, and
> gets slightly louder when placed into MGC.
>
> In MGC, with the BFO switched on, it plays at a normal (not super loud,
> but loud) volume.
> In AGC, with the BFO switched on, it hums, low volume audio.
>
> The limiter seems to have no effect, and varying the BFO doesn't do
> anything at all no matter AGC/MGC.
>
> I have Tom's solid state kit installed, and B+ at the AF deck test point
> is a steady 180.5vdc.
>
> I am going to dig out the TM's later on, I have them somewhere...but maybe
> somebody here can help point me in the right direction.
>
> Thanks!
>
> Adam K2AAM
>
>
>