[r-390] Strange R-390 problem

Wed, 20 Aug 2003 01:43:20 +0000

     Kinda like the problem I just fixed in my R390A. Working great and all 
of a sudden the carrier meter pins max right. The terminal of the carrier 
adjust pot that goes to ground just took a notion to fall off after 50 
years. Go figure.Had a junk IF chassis and used the pot off it. Works fine 
again. Did take a little while to find the problem though. Sure do like 
those voltage and resistance charts. Made it a lot easier for me as I am 
still quite the novice on these receivers.
     Also had a low audio problem on my other one and as several people 
suggested. It was the 2kc filter. Thanks for the advice.     John

John Page K4KWM
Hollow State since 1953
(ex W8PKU,N8BLB,NA8O)

>From: "Barry Hauser" <[email protected]>
>To: "David Medley" <[email protected]>, <[email protected]>
>Subject: Re: [r-390] Strange R-390 problem
>Date: Tue, 19 Aug 2003 19:27:17 -0400
>
>Not so strange, I guess.  We often start speculating about leaky caps, 
>Ohm's
>Law, grid emissions and esoterica.  Then you go and wiggle something, which
>is a more primitive version of the pointed stick approach.
>
>When I "fix" these odd problems, I have mixed emotions.  I'm pleased to 
>have
>made the repair, but, on the other hand, the accomplishment didn't draw 
>much
>from my intelligence and education.  Feel like a rocket scientist 
>scratching
>his head and then some guy who looks like Ed Norton (Art Carney) with a
>rumpled pork pie hat and his hands in his pockets saying "Y'know whatcha 
>got
>dere?  Whatcha got dere is bad CONTINOOOOITEEE."  Then he gives the rig a
>tap with his Stilson wrench and the rig starts blasting.  "Yah see?".  Then
>the guy in the white coat says "Zo den vhy did I bodda goink to de
>University?"  Trouble is, both the Norton guy and the Von Braun guy coexist
>in one skull and it drives me crazy.  It's great for procrastinating 
>though.
>;-)
>
>Just keep in mind -- some think in terms of Ohm's Law, but it's really all 
>a
>matter of .....
>CONTINOOOOITEE!
>
>Barry
>
>
>----- Original Message -----
>From: "David Medley" <[email protected]>
>To: <[email protected]>
>Sent: Tuesday, August 19, 2003 6:10 PM
>Subject: [r-390] Strange R-390 problem
>
>
> > I have an R-391 here which arrived with a known intermittent low audio
>problem. I quickly checked it out by replacing the audio and IF decks with
>known good units. Same problem. The problem was thus in the mainframe.
>Checked the volume control. Not that.
> > While I was fiddling about on the rear apron I found that by wiggling 
>the
>jumper on the diode load the radio suddenly came good and then died
>completely as the jumper fell apart in my hand. In the R-390 these jumpers
>are made of wire soldered in to spade terminals as distict from the metal
>ones in the R-390A. Anyway in this case the joint with one of the spades 
>had
>fractured probably due to stress giving an intermittent connection.
>Replacing the jumper with a good one made the radio play just great.
> > Dave
> >
> >
> >
> > Sincerely
> > David Medley
> > [email protected]
> > If you have a minute please check out:
> > http://www.adminder.com/c.cgi?davidmed&123
> > You might even make some money!
> >
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>
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