[R-390] R392

Sun Jun 25 12:42:23 EDT 2017

Hi

The 392 runs hot even under the best of conditions. On a really warm day I shudder to think how hot it must get in there.

Hope you found the problem !!!

Bob

> On Jun 25, 2017, at 12:35 PM, Guido Santacana <gsantacanav at gmail.com> wrote:
> 
> Gang,
> 
>     I removed the lower subchassis, checked everything. No resistors out of tolerance and caps OK. For the first time I really went through the solid state audio mod finding out that it mostly follows Mike Dinolfo's design.  Nothing seemed wrong here either. All tubes were tested and reseated in their sockets with Deoxit on the pins. Same thing with all connections. The subchassis was reinstalled and the radio had a run of several hours without any problems. I will give it another run today before returning it to the case and if everything is OK then the conclusion is that the noise came from some bad connection. It could have been induced by heat. The day that the problem occurred was a specially hot one. From now on I will slide it out to allow better cooling. Thanks to all of you for your recommendations. They will go into my notebook where I keep repair notes of all my BAs. 
> 
> BTW, this is the only BA in the shack that my YL likes! 
> 
> 
> Best 73s
> 
> Guido
> 
> Guido Santacana KP4FAR
> 
> On Mon, Jun 19, 2017 at 10:44 PM, Barry <n4buq at knology.net <mailto:n4buq at knology.net>> wrote:
> I've never owned one, but by the pictures I see on the internet, the 392 doesn't have a diode load connection brought to the outside like it's bigger cousins.  If there's a similar pickoff point inside, you could feed that to an external audio amp and see if the problem persists there.  Alternatively, you could take the IF output and feed that to a general coverage receiver (assuming the IF on the R392 is 455 kHz or some other frequency readily receivable on a general coverage radio).
> 
> If the problem doesn't persist listening on those alternative paths, then the problem is downstream from that point so that might at least narrow it down a bit.
> 
> 72 and good luck with it,
> Barry - N4BUQ
> 
> ----- Original Message -----
> > From: "Guido Santacana" <gsantacanav at gmail.com <mailto:gsantacanav at gmail.com>>
> > To: "Bob kb8tq" <kb8tq at n1k.org <mailto:kb8tq at n1k.org>>
> > Cc: "r390A" <r-390 at mailman.qth.net <mailto:r-390 at mailman.qth.net>>
> > Sent: Monday, June 19, 2017 8:45:04 PM
> > Subject: Re: [R-390] R392
> >
> > The more I hear it, the more it smells to an audio circuit problem. It
> > takes about 5 minutes for the noise to appear after turning on the radio.
> > After reading both Charles and Bob's recommendations sounds like a cracked
> > resistor but could be any of the other alternatives. Tomorrow the radio
> > goes on the work bench ( in my case a small mechanics folding bench from
> > PepBoys). I will report my findings. It's been quite a while since my last
> > R392 repair.
> >
> > Thanks for the recommendations gentlemen. Highly appreciated.
> >
> > Best 73s
> >
> > Guido
> >
> > Guido Santacana KP4FAR
> > EAC-R390A, Steward Warner-R392
> >
> > On Mon, Jun 19, 2017 at 6:59 AM, Bob kb8tq <kb8tq at n1k.org <mailto:kb8tq at n1k.org>> wrote:
> >
> > > Hi
> > >
> > > I’d put “60 year old unsoldered connection” on the list along with
> > > “cracked resistor”.
> > > Both are a poke around a bit and listen to what happens sort of thing.
> > >
> > > Bob
> > >
> > >
> > > > On Jun 19, 2017, at 12:12 AM, Charles Steinmetz <csteinmetz at yandex.com <mailto:csteinmetz at yandex.com>>
> > > wrote:
> > > >
> > > > Guido wrote:
> > > >
> > > >> There is some popping before it come back
> > > >> so I suspect a bad cap in the audio section.
> > > >
> > > > If the volume control has no effect, the problem would appear to be in
> > > the audio section (V606, V607, V608 and associated circuitry).
> > > >
> > > > Bad cap is certainly one possibility, but don't forget the most common
> > > source of such problems, namely noisy contact between tube pins and their
> > > sockets.  To check, just put your finger on top of each tube (one at a
> > > time) and wiggle it a little.
> > > >
> > > > Best regards,
> > > >
> > > > Charles
> > > >
> > > >
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