I wonder if someone installed wrong bulbs causing excessive current...hmmmmm
Renée
On 2/11/26 7:57 AM, Thomas Hoyer via R-390 wrote:
Thanks for the sanity check Bob.
I've re-run the wires using the correct color code wire and lacing cord. On the
first radio I figured eh, mistake on somebody's part. On the second radio I
said Hmmmm..... When I looked at my R391, that was bought as a project and has
been on the shelf for a couple years, and saw the same thing - WTH? Is this a
trend?
I personally have one R390 and had another at one point but those didn't have
this issue, nor have I seen it on any of my (multiple) R390A's or on any of the
ones that I've worked on for others.
Either way, the first two have been rewired as described and I'll rewire the
R391 when that gets bench time.
For those working one these radios its something to look out for.
TomW3TA
PS:a couple pics in my post on ARF
https://antiqueradios.com/forums/viewtopic.php?t=454874
On Wednesday, February 11, 2026 at 10:31:33 AM EST, Bob kb8tq
<[email protected]> wrote:
Hi
Is it common on an R390 or a R390A? It’s not anything I have seen on either
radio.
Best guess:
Filament windings put out a lot of current. The chassis wires are rarely rated
to handle
the max output of the transformer. How much current is that? The fuse will
eventually
blow at some power level. A military grade transformer probably can deliver all
that power
to the filament winding
Pilot light wiring runs around on the front panel. It’s the least protected
part of the radio.
Having this or that “wander in” and create a short is a very real possibility.
Does this ever happen in the real world? Yes indeed it does. Back in my early
years
fiddling around on various radios, I did it at least once.
Bob
On Feb 11, 2026, at 7:36 AM, Tom via R-390 <[email protected]> wrote:
Is it "common" for the wires to the dial lights to be fried on an R390? I've
had three in here the last few months and each one has had the wires fried.
Tom
W3TA
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