[R-390] RF Deck B+ short (390A)

[David Wise]

At that order of magnitude of resistance, I'd suspect an internal short in a coil.

Dave Wise

________________________________________
From: R-390 [r-390-bounces at mailman.qth.net] On Behalf Of Dennis Wade [sacramento.cyclist at gmail.com]
Sent: Tuesday, November 18, 2014 9:14 PM
To: R-390 HF Receiver List
Subject: [R-390] RF Deck B+ short (390A)

Good evening,

      I've finally pulled the RF deck out of my Motorola 390a in an attempt
to track down a short on the B+ line.  My initial resistance measurement
suggested a dead short which lead me to C 308.  Unfortunately, removing
C308 left the short happily intact.

      Paying a little closer attention this time, the actual resistance to
ground from Pin A, J208 is 60 ohms, not a dead short.  This confuses
me...I'd think I'd be seeing R212 at 2.2K if C280 was shorted...but the 60
ohms is throwing me.  But, its not immediately obvious what else it could
be.  Could R212 have changed to 60 ohms?  (it doesn't look abused).

        Thoughts?

           Thanks,

              Dennis

--
"If they trust you, it is an extraordinary privilege, and you simply can't
abuse it."
      - A. Alan Post  1914-2011.  California Legislative Analyst 1949-1977.

-------------------------
Dennis L. Wade
KG6ZI
Carmichael, CA