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Re: [TCML] Fried NST



 Yep.
But, I remember the days when you could beg a sign company and get TONS (not quite) of NSTs for free.
Many could be simply heated to melting point of potting, then cooled. If that didn't work, many hours (days, months?) later it could be cleaned/washed, then removing the first few layers of windings could find an easily fixable break.
    On Friday, November 30, 2018, 10:13:05 PM EST, Gary Lau <glau1024@xxxxxxxxx> wrote:  
 
 I fried my precious 15/60 back in the 90's.  I melted the tar in a
charcoal-fired BBQ and poured off the melted tar, then soaked the hot
carcass in paint thinner.  A VERY, dirty, smelly, laborious operation I
would not wish on anyone I like.  It ultimately succeeded, and I re-potted
the repaired NST in melted Vaseline jelly, so if I had to do it again, it
would be easier.  Having expended such effort, I took a serious interest in
protection networks.  I now preach the gospel of "setting your safety gaps
correctly."

Regards, Gary Lau
MA, USA

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On Fri, Nov 30, 2018 at 9:16 PM Steve White <steve.white1@xxxxxxxxx> wrote:

> Hello Dan,
>
> It is most likely that the secondary is shorted. Since the shunts will
> limit the current, the NST will work at 120 volts with a normal current
> draw and hum but will not put out much on the secondary.
>
> Steve White
> Cedar Rapids, Iowa
>
> ----- Original Message -----
> From: "Daniel Kunkel" <dankunkel@xxxxxxxxx>
> To: "Tesla list" <tesla@xxxxxxxxxx>
> Sent: Friday, November 30, 2018 8:48:26 AM
> Subject: [TCML]  Fried NST
>
> Previously on the TCML, episode "Adventures in SRSG"...
> > I finally got my SRSG online tonight...
> > ...I think I fried an NST or two...
>
> I had a chance to diagnose last night and found that one of my 15/30
> Franceformers did indeed die in the sacred duty of the coil. It is odd
> though, I apply 120v and it hums like it is working, it won't draw and arc
> anywhere...so I ramped up the power with a variac and at 120v my DVM only
> showed 280v on the secondaries (I forgot to check each HV leg to ground
> though). I am guessing this indicates some turns on the primary melted and
> shorted together. Furthermore, I am assuming there are no quick
> fixes...great...now I have a reason to attempt my first depotting...is this
> still the most current/best method?
> https://www.pupman.com/listarchives/1999/April/msg00182.html
>
>
> So back to a vacuum quenched gap for now.
>
> Thanks,
> ~Dan (taken down a few notches on the KVA scale)
> Kansas City area
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