Re: Weak NST

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Jason by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jasonp-at-btinternet-dot-com>

Antonio,

With a non-tar filled coil, problems such as these are tricky to repair. If
you have the equipment however, it is possible that immersing it in
synthetic oil and then drawing a vaccum over the oil to bring out air
bubbles may work.

Best Regards,
Jason

----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Monday, November 04, 2002 1:03 AM
Subject: Weak NST


 > Original poster: "Antonio Carlos M. de Queiroz by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <acmq-at-compuland-dot-com.br>
 >
 > Hi:
 >
 > I found an abandoned high voltage supply where I work, that was
 > just a small NST, without any special (tar or similar) insulation
 > inside a box with two high voltage terminals at the top. Made by
 > the instrument builder Cenco. The NST has a 120 V primary winding
 > and a single 5000 V, 20 mA winding, each mounted at one side of a
 > core with two openings, with a shunt at the center. After cleaning
 > and disassembling the thing, I found that the NST works, but weakly.
 > The short-circuit current is really 20 mA, the DC resistance of
 > the secondary winding looks ok (~18 kOhms), but it produces at
 > most 1 mm weak sparks (5000 V should produce at least 2.5 mm sparks).
 > It can power my transformerless coils, but the output is insignificant
 > (I use normally a 5000V 30 mA NST with it, that produces far more
 > energetic sparks).
 > I imagine that this can be caused by internal sparking in the
 > secondary windings, a problem that appears only when the output
 > voltage is high. A carbon track crossing the paper insulation of
 > the windings is also a possibility. But the transformer doesn't heat
 > appreciably when left open, there is nothing wrong visibly,
 > and no funny smell.
 > Some idea about how to verify what is happening, or how to repair it?
 >
 > Antonio Carlos M. de Queiroz
 >
 >
 >