[NJARC] Hallicrafters SX-16 PS

Tue Mar 18 20:12:48 EST 2008

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
> > > > > 
> > > > > 
> > > > >      
> > > > >
> > > >
> > >
> >
>
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