[R-390] Trouble shooting the R390A

[pete wokoun, sr.]

If anyone needs a schematic showing the current levels throughout a R390A I 
have one on my website in a .pdf format that you can download.  Great for 
troubleshooting.
It's at:
http://www.qsl.net/kh6grt/page4/r390aschematics/r390aschematics.htm

pete KH6GRT



>From: "Barry" <n4buq at aol.com>
>Reply-To: Barry <n4buq at aol.com>
>To: <R-390 at mailman.qth.net>
>Subject: Re: [R-390] Trouble shooting the R390A
>Date: Tue, 23 Aug 2005 22:03:30 -0500
>
>I had a similar thing happen.  After the fuse blew, I hooked up an ampmeter
>across the fuse and monitored the current, making sure it didn't exceed
>125mA while bringing the radio up with a variac.  Oddly, the current never
>went much over 80 or 90mA.  I replaced the fuse and it has worked okay ever
>since.
>
>I suspected one or both of the filter caps may have been drawing excess
>current, but if I remember the circuit correctly, the 1/8A fuse comes
>"after" the caps so I don't know what was causing the current draw.  Maybe
>the fuse was old?  Don't know.
>
>Did the radio work before you worked on the front panel?
>
>Barry - N4BUQ
>
>----- Original Message -----
>From: "Jon" <jonklinkhamer at comcast.net>
>To: <R-390 at mailman.qth.net>
>Sent: Tuesday, August 23, 2005 8:05 PM
>Subject: [R-390] Trouble shooting the R390A
>
>
> > To the Group:
> >
> > I have been going thru the IF and audio stage with respect to recapping,
> > taking resistance measurements, checking tubes, cleaning, etc, being 
>very
> > careful and taking notes along the way. I recently just received the 
>front
> > panel back from painting it and I decided before I continue to go thru 
>the
> > RF, xtal and PTO stages, I wanted to put it all back together and make
>sure
> > I didn't break anything. (I really wanted to see how the panel looked.)
> > Well, as of tonight, I fired it up and noticed right away no audio.
> > Immediately, I played around going from 1 to 20Mhz and I also switched 
>in
> > the CAL but noticed again no audio. The lamps however lite up.  I turned
>the
> > receiver off and checked the fuses and notice the 1/8 fuse has blown. My
> > thinking is to first see if it blows again and if so then take out both
>the
> > Audio and IF stage and power cycle again. I'm hoping to isolate it to 
>one
>of
> > these stages with the assumption I mess something up. I'm just shooting
>this
> > out to see if the group has another preferred way of debugging or knows
>the
> > cause(s) when this particular fuse blows.
> > I would like to thank everyone in advance for their comments. I am as
>always
> > much indebted.
> >
> > 73's,
> > Jon, KB1DC
> >
> >
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