[R-390] R-390 (non-A) Sudden and New Issue

[Thomas Hoyer]

 Alex, 
I'm working on a 390 now that had a popping sound. I traced it to the 6082 regulator tubes. I replaced them and all is well again.
If you can, check the B+ voltage should be steady and around 180v. There is a red test point on the side of the AF module that is accessible through the side of the radio. When the "pop" would happen, the B+ would shoot up to over 220v.
TomW3TA
    On Thursday, February 26, 2026 at 01:47:00 PM EST, Alex Hopper <ahopper0216 at gmail.com> wrote:   

 Hi Folks,

I have an R-390/URR (non-A model) that was restored by someone last year -
the individual who restored this set is quite competent and did good work.

Over the last few days I have noticed 'popping' and 'cracking' coming from
the set.  Sounds like what you would hear if there was a lightning strike
nearby, or if there was an internal component that aws arcing.

As a result the radio does not receive on any bands at the moment.  I took
it out of its cabinet and checked/replugged all the connectors between
modules.  I fired it up and it worked perfectly normal.  I turned it off,
put it back in the cabinet and...same issue!  I removed it again and the
issue persists.

I don't even know where to start with this, and I am upset that my beloved
R-390 seems to be dead in the water.

any suggestions or thoughts?

Thanks,
-Alex
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