Astute readers will recall I was attempting to get an old variac up to
modern safety standards. Well, it just spewed out a great deal of
acrid smoke and is now reposing in the dustbin. The only thing I can
think of that *might* have caused this was that I applied Servisol
contact cleaner/lube to the brush and the windings at the edge around
the circumference where they contact the brush. Could the Servisol
have dissolved the varnish on the windings and shorted them out?
I've checked everything else and it was wired correctly so I can't
think of what else could have caused it to spontaneously combust..
Any thoughts?

On Sunday, 23 August 2020 18:45:43 UTC+1, Cursitor Doom wrote:
Astute readers will recall I was attempting to get an old variac up to
modern safety standards. Well, it just spewed out a great deal of
acrid smoke and is now reposing in the dustbin. The only thing I can
think of that *might* have caused this was that I applied Servisol
contact cleaner/lube to the brush and the windings at the edge around
the circumference where they contact the brush. Could the Servisol
have dissolved the varnish on the windings and shorted them out?
I've checked everything else and it was wired correctly so I can't
think of what else could have caused it to spontaneously combust..
Any thoughts?

they're not too hard to rewind, I wouldn't bin it


NT

Yes how old was the Servisol? I trashed a headphone socket using the older
stuff, the glue holding the contacts melted.
Brian

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"Cursitor Doom" wrote in message
...
Astute readers will recall I was attempting to get an old variac up to
modern safety standards. Well, it just spewed out a great deal of
acrid smoke and is now reposing in the dustbin. The only thing I can
think of that *might* have caused this was that I applied Servisol
contact cleaner/lube to the brush and the windings at the edge around
the circumference where they contact the brush. Could the Servisol
have dissolved the varnish on the windings and shorted them out?
I've checked everything else and it was wired correctly so I can't
think of what else could have caused it to spontaneously combust..
Any thoughts?

Really? How do you get the contact area?
Brian

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The Sofa of Brian Gaff...

Blind user, so no pictures please
Note this Signature is meaningless.!
wrote in message
...
On Sunday, 23 August 2020 18:45:43 UTC+1, Cursitor Doom wrote:
Astute readers will recall I was attempting to get an old variac up to
modern safety standards. Well, it just spewed out a great deal of
acrid smoke and is now reposing in the dustbin. The only thing I can
think of that *might* have caused this was that I applied Servisol
contact cleaner/lube to the brush and the windings at the edge around
the circumference where they contact the brush. Could the Servisol
have dissolved the varnish on the windings and shorted them out?
I've checked everything else and it was wired correctly so I can't
think of what else could have caused it to spontaneously combust..
Any thoughts?

they're not too hard to rewind, I wouldn't bin it


NT

On 23/08/2020 18:45, Cursitor Doom wrote:
Astute readers will recall I was attempting to get an old variac up to
modern safety standards. Well, it just spewed out a great deal of
acrid smoke and is now reposing in the dustbin. The only thing I can
think of that *might* have caused this was that I applied Servisol
contact cleaner/lube to the brush and the windings at the edge around
the circumference where they contact the brush. Could the Servisol
have dissolved the varnish on the windings and shorted them out?
I've checked everything else and it was wired correctly so I can't
think of what else could have caused it to spontaneously combust..
Any thoughts?

Old windings are shellac insulated and that dissolves in ethyl alcohol.
And almost anything else. It is apparently used to coat pills so they
dissolve in the intestine and not the stomach.

So with shellac, the question is 'what will *not* dissolve it?'


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€œPeople believe certain stories because everyone important tells them,
and people tell those stories because everyone important believes them.
Indeed, when a conventional wisdom is at its fullest strength, ones
agreement with that conventional wisdom becomes almost a litmus test of
ones suitability to be taken seriously.€�

Paul Krugman

Brian Gaff wrote:

Really? How do you get the contact area?

mechanically remove the shellac where the wiper needs to touch it,
sander maybe?

On 24/08/2020 01:54, wrote:
On Sunday, 23 August 2020 18:45:43 UTC+1, Cursitor Doom wrote:
Astute readers will recall I was attempting to get an old variac up to
modern safety standards. Well, it just spewed out a great deal of
acrid smoke and is now reposing in the dustbin. The only thing I can
think of that *might* have caused this was that I applied Servisol
contact cleaner/lube to the brush and the windings at the edge around
the circumference where they contact the brush. Could the Servisol
have dissolved the varnish on the windings and shorted them out?
I've checked everything else and it was wired correctly so I can't
think of what else could have caused it to spontaneously combust..
Any thoughts?

they're not too hard to rewind, I wouldn't bin it


NT


Several different Servisols. The contact cleaner seems to be
hydrocarbons but they also do an IPA one (which will dissolve lacquer, I
think).

On Monday, 24 August 2020 11:47:03 UTC+1, Andy Burns wrote:
Brian Gaff wrote:

Really? How do you get the contact area?

mechanically remove the shellac where the wiper needs to touch it,
sander maybe?

sandpaper, scraper, solvent, whatever. Not a problem.

On Mon, 24 Aug 2020 09:43:58 +0100, The Natural Philosopher
wrote:

Old windings are shellac insulated and that dissolves in ethyl alcohol.
And almost anything else. It is apparently used to coat pills so they
dissolve in the intestine and not the stomach.

The one now awaiting recycling was manufactured in the 1940s and
insulated with whatever they used back then. As you say, shellac I
guess back in those days.


So with shellac, the question is 'what will *not* dissolve it?'

That could well explain it then!

On Tuesday, 25 August 2020 19:09:21 UTC+1, Cursitor Doom wrote:
On Mon, 24 Aug 2020 09:43:58 +0100, The Natural Philosopher
wrote:

Old windings are shellac insulated and that dissolves in ethyl alcohol.
And almost anything else. It is apparently used to coat pills so they
dissolve in the intestine and not the stomach.

The one now awaiting recycling was manufactured in the 1940s and
insulated with whatever they used back then. As you say, shellac I
guess back in those days.


So with shellac, the question is 'what will *not* dissolve it?'

That could well explain it then!

There are probably people that would buy it as is. Variacs are hard to get now.


NT

On Tue, 25 Aug 2020 12:19:52 -0700 (PDT), wrote:

On Tuesday, 25 August 2020 19:09:21 UTC+1, Cursitor Doom wrote:
On Mon, 24 Aug 2020 09:43:58 +0100, The Natural Philosopher
wrote:

Old windings are shellac insulated and that dissolves in ethyl alcohol.
And almost anything else. It is apparently used to coat pills so they
dissolve in the intestine and not the stomach.

The one now awaiting recycling was manufactured in the 1940s and
insulated with whatever they used back then. As you say, shellac I
guess back in those days.


So with shellac, the question is 'what will *not* dissolve it?'

That could well explain it then!

There are probably people that would buy it as is. Variacs are hard to get now.

It would only be worth a fiver in the state it's in now - if that. Not
worf the bovver.

On 26/08/2020 14:46, Cursitor Doom wrote:
On Tue, 25 Aug 2020 12:19:52 -0700 (PDT), wrote:

On Tuesday, 25 August 2020 19:09:21 UTC+1, Cursitor Doom wrote:
On Mon, 24 Aug 2020 09:43:58 +0100, The Natural Philosopher
wrote:

Old windings are shellac insulated and that dissolves in ethyl alcohol.
And almost anything else. It is apparently used to coat pills so they
dissolve in the intestine and not the stomach.

The one now awaiting recycling was manufactured in the 1940s and
insulated with whatever they used back then. As you say, shellac I
guess back in those days.


So with shellac, the question is 'what will *not* dissolve it?'

That could well explain it then!

There are probably people that would buy it as is. Variacs are hard to get now.

It would only be worth a fiver in the state it's in now - if that. Not
worf the bovver.

Can't comment on the current market, but back in the 70's I worked in a
large and well-equipped industrial research lab. We were always in
trouble at the end of the FY if we hadn't spent our generous budgets.
Rumour has it that some people would go to stores and sign out some
large variacs, which got charged to the budget. In the new FY, you could
take them back and the funds would magically be switched across the year
boundary. (I've heard of other labs where the same trick was done with
gold or platinum wire and mesh).

On Wednesday, 26 August 2020 14:46:05 UTC+1, Cursitor Doom wrote:
On Tue, 25 Aug 2020 12:19:52 -0700 (PDT), tabbypurr wrote:
On Tuesday, 25 August 2020 19:09:21 UTC+1, Cursitor Doom wrote:
On Mon, 24 Aug 2020 09:43:58 +0100, The Natural Philosopher
wrote:

Old windings are shellac insulated and that dissolves in ethyl alcohol.
And almost anything else. It is apparently used to coat pills so they
dissolve in the intestine and not the stomach.

The one now awaiting recycling was manufactured in the 1940s and
insulated with whatever they used back then. As you say, shellac I
guess back in those days.


So with shellac, the question is 'what will *not* dissolve it?'

That could well explain it then!

There are probably people that would buy it as is. Variacs are hard to get now.

It would only be worth a fiver in the state it's in now - if that. Not
worf the bovver.

The 3 faulty variacs for parts only on ebay now are priced at £60, £225 and £53.38, all plus postage.


NT