[R-390] (I found the problem) NOT!!

Fri, 29 Mar 2002 12:51:13 -0500

Alas, life is not so simple.

After a smooth replacement of Pin 1 of the 6DC6, (work with the dimple), and
reconnection of the leads, the symptoms remain.

The symptoms are essentially the same as below, except the putt,
putt/screeching is more intermittent.  All bands except 3 and below are
affected.  The putt, putt/screeching is most pronounced with peaking of the
antenna trim control.

A new observation is that with careful peaking of the putt, putt, I can
almost stop the putt, putt on a PUTT.  At this point, I hear harmonics.
Tapping anywhere on the chassis will produce stronger harmonics.  Tapping on
the 6DC6 will produce very strong harmonics.

I replaced the 6DC6 with two other tested tubes, with no improvement.

I will relist the total list of symptoms in a couple of hours.

For now, I am going to test/shotgun all the components associated with the
6DC6.  Any other suggestions??

Hard at work,

Jim

----- Original Message -----
From: "Jim Temple" <[email protected]>
To: <[email protected]>
Sent: Friday, March 29, 2002 10:52 AM
Subject: Fw: [R-390] R-390A trouble (I FOUND THE PROBLEM)

> CORRECTION.  The pin number is pin 1 (one).  With all those leads, walls,
> shields, and components to hack through, I miscounted the pin number.
>
> It is PIN 1.
>
> Jim
>
> ----- Original Message -----
> From: "Jim Temple" <[email protected]>
> To: <[email protected]>
> Sent: Friday, March 29, 2002 10:44 AM
> Subject: Fw: [R-390] R-390A trouble (I FOUND THE PROBLEM)
>
>
> > After wiggling almost all the leads to confirm security, I discovered
the
> > following.....
> >
> > Pin 5 of V201/6DC6, from the underside, seemed to be in place and
secure.
> > Upon wiggling, it seemed loose, so I gently tugged on the pin lead and
it
> > came out of the socket from below the plastic.  It was broken between
the
> > socket pin and where it emerges from the socket mold on the bottom.
> >
> > Apparently, there was enough contact to do the initial alignment, and
> after
> > a couple of hours burn in, it insulated itself, creating the below
> symptoms.
> >
> > What was maddening was that the break was within the plastic mold of pin
> 5,
> > which took a tug to break it from the plastic.  Three components are
> > attached.  Later I will summarize what was affected and the fix.
> >
> > WOW......this is one for the books.
> >
> > I think I will go for replacement, but if there is an easy fix, I will
> > consider it.
> >
> > Well, thats it.  Thanks for the support and help with this problem.
After
> I
> > complete the repair, I will post a summary of the symptoms and fix.  So
> long
> > for now.
> >
> > Regards,
> >
> > Jim
> > 73, KF4ICZ
> >
> > ----- Original Message -----
> > From: "Jim Temple" <[email protected]>
> > To: <[email protected]>
> > Sent: Thursday, March 28, 2002 10:56 PM
> > Subject: Re: [R-390] R-390A trouble
> >
> >
> > > OK, I replaced C227 .047.  The old one measured .075 when out of
> circuit.
> > I
> > > have a picked-over RF parts deck that happend to have this cap.  It
> > measured
> > > .04745, so hopefully this is the problem.
> > >
> > > HOWEVER, I am going to clean, inspect, wiggle, tap, eyeball, and
> generally
> > > give it the twice over before reinstalling in the morning.  I'm
winding
> > down
> > > for the night.
> > >
> > > Will report back after reinstallation of the RF deck in the morning.
> > >
> > > Thanks for the great support and suggestions.  Good night.
> > >
> > > Regards,
> > >
> > > Jim
> > > 73, KF4ICZ
> > >
> > > ----- Original Message -----
> > > From: "Barry Hauser" <[email protected]>
> > > To: <[email protected]>; "Jim Temple" <[email protected]>;
> > > <[email protected]>
> > > Sent: Thursday, March 28, 2002 9:55 PM
> > > Subject: Re: [R-390] R-390A trouble
> > >
> > >
> > > > > Barry, I think you've got it.
> > > > >
> > > > > But I thought of another thing to try. Because the set is
> > > > > oscillating within itself, something common to the IF and
> > > > > RF decks is carrying energy between them.
> > > > <snipped>
> > > >
> > > > Got what?  I dunno, but, hey, Bill, I think YOU"RE onto something.
> Jim
> > > > should check out all those jumpers with the mini-BNC's -- maybe one
of
> > 'em
> > > > was swapped with that Skyhighgain cable Norman told us about.
> > > >
> > > > Seriously, tho' -- wasn't that another thing that could cause weird
> > > > problems -- bad mini-coax?
> > > >
> > > > When the rational, logical, informed, incisive, deductive approach
> fails
> > > ...
> > > > Well, let's consider ALL the clues ...
> > > >
> > > > Squeal -- loud disturbing noise, alarm, or (sl.) to give
information,
> to
> > > > "rat" on.
> > > > Happens over 3 MC's, that could be written as >3.  Looks like a
bird,
> > > don't
> > > > it?
> > > > Motorboating, boats, water, ocean -- could be a seagull, or maybe
> > > > "putt-putt" = golf
> > > > Then there's the thing about cats.  Wait a minute!  A bird that
looks
> > like
> > > a
> > > > rat is a bat -- but then what's golf got to do with it?  This is
going
> > > > nowhere -- might mean something to a witch.  Is Les around?
> > > >
> > > > Forget all that -- pull the RF deck and check it out.  Could be an
> > > > "underneath-ARGHHH-do-I-hafta?" problem.  Give it the close eyeball
> > > > inspection.  By all means CLEAN the bandswitch -- twice. (unless I
> > missed
> > > > something and you did that already)
> > > >
> > > > Nobody seems to be focused on the >3 thing.  Why would this problem
> kick
> > > in
> > > > there?  What is different circuitry-wise about 0-1-2-3 vs 4+?  I
guess
> > one
> > > > thing might be a rotor section or two on the bandswitch, no?  Maybe
> not.
> > > > Any particular reason a bad cap would cause the squeal and
> motorboating
> > to
> > > > start at 4 MC's?
> > > >
> > > > Great, now I'm gonna be up all night 'cause of somebody else's
radio.
> > > >
> > > > Barry
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > > _______________________________________________
> > > > R-390 mailing list
> > > > [email protected]
> > > > http://mailman.qth.net/mailman/listinfo/r-390
> > > >
> > >
> >
>
>
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