[NJARC] Hallicrafters SX-16 PS

[John Ruccolo]

Scott,

I figured you replaced the caps -- but I had to do a
sanity check, just in case. ;-)

Hey, what about this "adapter" you put on the BFO
socket? Could that have shorted to something?

I don't think the tube failed on its own (although
*anything* is possible). I think something external
caused it to fail. By your description, it sounds like
the B+ got shorted to ground.

JR

--- Scott Roberts <ng19delta at yahoo.com> wrote:

> Visit our web site - See http://www.njarc.org
> _______________________________________________
> ALL CAPS REPLACED!!!!
> 
> The only change I made from last night was I rotated
> the chassis
> on the bench 180 degrees so I could access the BFO,
> and put in
> the adapter between the BFO 6J7 tube and socket, so
> I could test
> the voltages...
> 
> I will make the checks you just mentioned tonight,
> and post my
> findings. (I'm hoping my findings include another
> 5Z3 tube in my
> spares pile...)
> 
> When I was working on testing last night, I had the
> chassis
> upside down while I found the problem: then I put it
> right side
> up and ran it- I wonder if something in the tube was
> damaged, and
> came loose after it cooled, and shorted it
> internally? 
> 
> Scott
> 
> 
> --- John Ruccolo <jr6v6gt at yahoo.com> wrote:
> 
> > Visit our web site - See http://www.njarc.org
> > _______________________________________________
> > Ouch! Somehow, it appears that the B+ shorted to
> > ground. Or the rectifier tube failed.
> > 
> > The 690V sounds reasonable to me, Scott. Don't
> forget,
> > it's a *full* wave rectifer (half the HV winding
> > working at a time) so it's really only 345 vols.
> And,
> > that's without a load, so it's probably closer to
> 300.
> > 
> > But what the heck happened? If the *transformer*
> > failed that would *not* cause the recitifer tube
> to
> > melt down. Somehow, you shorted the B+, I think.
> > 
> > With the power OFF, try measuring resistance from
> the
> > main B+ bus from the rectifier socket to ground.
> If
> > you get a really low reading (near zero or just a
> few
> > ohms) something is very wrong. A stray clip lead?
> A
> > solder blob, or bit of wire?
> > 
> > Measure the resistance from each side of the
> xformer
> > plate winding (power OFF, please!) to the center
> tap.
> > If they're close, you porbably didn't damage the
> > transformer.
> > 
> > Check resistance across the filter caps. HEY, YOU
> > DIDN'T LEAVE THE OLD FILTER CAPS IN THE CIRCUIT,
> DID
> > YOU?
> > 
> > Regards,
> > 
> > John
> > 
> > --- Scott Roberts <ng19delta at yahoo.com> wrote:
> > 
> > > Visit our web site - See http://www.njarc.org
> > > _______________________________________________
> > > Just took a look at tthe tube: it is partially
> > > shrapnelized
> > > inside- large round bits of melted metal, and
> one of
> > > the
> > > conductors blown out. I Think It's Dead Jim.
> > > 
> > > And so I checked the transformer output: close
> to
> > > 690VAC at the
> > > tube. I think that is a BIT high... And there is
> > > transformer wax
> > > melted out of it underneath.
> > > 
> > > Thoughts?
> > > 
> > > Scott
> > > 
> > > 
> > > --- Scott Roberts <ng19delta at yahoo.com> wrote:
> > > 
> > > > Visit our web site - See http://www.njarc.org
> > > >
> _______________________________________________
> > > > ARRRGGGHHHHH!!!
> > > > 
> > > > I just went to warm up the set to do some
> > > troubleshooting of
> > > > the
> > > > BFO, and got something completely unexpected:
> a
> > > veritable
> > > > lightning storm in the rectifier tube! It was
> > > glowing purple
> > > > and
> > > > yellow, with  electrical charges jumping all
> over
> > > the place
> > > > inside- looked like one of those Tesla balls,
> and
> > > heated up
> > > > very
> > > > fast. I switched it off after a couple
> seconds.
> > > Hope the tube
> > > > is
> > > > ok- I will check it after it cools off...
> > > > 
> > > > I am suspecting a transformer issue... Any
> > > thoughts? I have it
> > > > switched off, and unplugged, although I tried
> to
> > > get a reading
> > > > from the empty rectifier socket, all I got was
> > > real high: I
> > > > need
> > > > to figure out the transformer ower
> connections,
> > > and what should
> > > > be where...
> > > > 
> > > > Frustrating- get one thing straight, another
> > > decides to go to
> > > > ...
> > > > 
> > > > Scott
> > > > 
> > > > 
> > > > --- John Ruccolo <jr6v6gt at yahoo.com> wrote:
> > > > 
> > > > > Visit our web site - See
> http://www.njarc.org
> > > > >
> _______________________________________________
> > > > > Hi Scott,
> > > > > 
> > > > > Good work! You're learning the
> troubleshooting
> > > > > process.
> > > > > And, yes, sometimes luck plays a role in
> > > > > troubleshooting -- thought we don't always
> like
> > > to
> > > > > admit it. ;-)
> > > > > 
> > > > > Pretty soon, you will graduate from student
> to
> > > > > instructor at our clinics. We can always use
> > > more
> > > > > "experts" at the clinics.
> > > > > 
> > > > > 
> > > > > Regards,
> > > > > 
> > > > > John
> > > > > 
> > > > > 
> > > > > --- Scott Roberts <ng19delta at yahoo.com>
> wrote:
> > > > > 
> > > > > > Visit our web site - See
> http://www.njarc.org
> > > > > >
> > > _______________________________________________
> > > > > > Just thought I'd update those paying
> attention
> > > to my
> > > > > > latest
> > > > > > efforts...
> > > > > > 
> > > > > 
> > > > > > 
> > > > > > Anyway, I thought it wasn't too bad for a
> > > first try
> > > > > > after major
> > > > > > work! Should be on top of my game for the
> next
> > > DX
> > > > > > contest... ;)
> > > > > > 
> > > > > > Scott
> 
=== message truncated ===



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