May well have been toluene. It was often used as a cleaner in all sorts
of
areas, some as pedestrian as the T/R/S plugs on old lamp-signalling
telephone
switchboards. Unfortunately proved to be a carcinogen and was banned, but
it
WAS used to clean a myriad of hardware in a myriad of situations.

It might have been carbon tet (tetracloride or however it is spelled). I
think it was taken off the market because of either liver or kidney failure
if the user had been drinking .

Other than speed, is there any difference between a 465B and
a 475/475A that I should know about? I am looking for a
replacement but I want all or nearly all of the knobs to be
the same.

Ralph Mowery wrote:

May well have been toluene. It was often used as a cleaner in all sorts


of


areas, some as pedestrian as the T/R/S plugs on old lamp-signalling


telephone


switchboards. Unfortunately proved to be a carcinogen and was banned, but


it


WAS used to clean a myriad of hardware in a myriad of situations.



It might have been carbon tet (tetracloride or however it is spelled). I
think it was taken off the market because of either liver or kidney failure
if the user had been drinking .




When carbon tet was removed from telephone offices there was a story
about a technician spilling some
on a operator. The operator lost here hair and finger nails. Don't know
if that is true but we had to
remove all carbon tet from the cleaning supplies.

Bill K7NOM

John Miles wrote in
:

In article ,
. says...

Considering how longlasting and popular the 465 is,that's not a very
smart sentence.The same HF and LF cam switches were also used in the
high- performance 7000 series lab scopes.


True enough in the case of the 465. That model in particular seems to
have been very robust. You don't see many owners asking about how to
clean 465 switches.

485 switches, though, are another thing entirely. It's very rare to
see a 485 whose vertical attenuator switches aren't noisy. Perhaps
gold-pad abrasion has caught up to the instruments over time; however,
I'm personally aware of at least two anecdotal cases of noisy 485
switches being fixed (at least for the time being) with contact
cleaner.

It's possible there's more than one cause of switch degradation at
work in the 485 and other notorious "problem children." Either way,
though, the original designers were clearly not omniscient in all
cases, or the problems with certain models wouldn't be as widespread
as they are. I wish there were a sure-fire way to fix the 485's
front-end switches; it was my favorite Tek scope of the bunch
otherwise.

-- jm

Both 465 and 485 use the same HF cam switch contacts.

TEK used to have a repair kit that included both contacts,drill bits to
remove the securing rivets,and tiny nuts and bolts to secure the new
contacts.


They also had a repair kit for the LF contacts used in the timing
switch,with an alignment guide to get them straight.

Both are no longer available.
--
Jim Yanik
jyanik-at-kua.net

On Thu, 23 Dec 2004 16:44:05 +0000, Bill Janssen wrote:
Ralph Mowery wrote:

It might have been carbon tet (tetracloride or however it is spelled). I
think it was taken off the market because of either liver or kidney failure
if the user had been drinking .

When carbon tet was removed from telephone offices there was a story
about a technician spilling some
on a operator. The operator lost here hair and finger nails.

This is so stupid it's ludicrous.

Don't know
if that is true but we had to
remove all carbon tet from the cleaning supplies.

That's typical government wisdumb for you. Make laws based on hysteria.

Cheers!
Rich

On Thu, 23 Dec 2004 08:20:30 +0000, John Woodgate wrote:

I read in sci.electronics.design that budgie wrote (in
) about 'Tektronix 465
Scope', on Thu, 23 Dec 2004:

May well have been toluene. It was often used as a cleaner in all sorts
of areas, some as pedestrian as the T/R/S plugs on old lamp-signalling
telephone switchboards. Unfortunately proved to be a carcinogen and was
banned, but it WAS used to clean a myriad of hardware in a myriad of
situations.

Toluene is one of the aromatics that is NOT carcinogenic. From the ATSDR
web site:

QUOTE
Studies in workers and animals exposed to toluene generally indicate
that toluene does not cause cancer. The International Agency for
Research on Cancer (IARC) and the Department of Health and Human
Services (DHHS) have not classified toluene for carcinogenic effects.
The EPA has determined that toluene is not classifiable as to its human
carcinogenicity.
ENDQUOTE

Toluene is available in small quantities as a solvent for contact
adhesive. It DOES attack some plastics, and those it attacks slowly can
exhibit surface dulling and crazing.

They banned it because it was the "active ingredient" in airplane glue,
which kids sniffed and got high.

Cheers!
Rich

Rich Grise wrote:
. . .

That's typical government wisdumb for you. Make laws based on hysteria.

Cheers!
Rich

Yeah, that's the stoopid guv'mint for ya! If they was just as smart as
we was, they wouldn't ban all this neat stuff.

According to a hazmat data sheet I have, carbon tet (which can be
absorbed by breathing, skin contact, or ingestion) causes damage to the
liver, kidneys, heart, adrenal glands, and nervous system, and is
particularly dangerous to people who have recently consumed alcohol, are
exceedingly fleshy or are undernourished, or have other problems like
hypertension. You can smell it at a concentration of 70 ppm; toxicity is
known at concentrations of 5 ppm.

I used the stuff quite a bit when I was a kid, and I'm just fine (I
think) so that's obvious proof that it's all a bunch of hogwash and a
government conspiracy.

Personally, I favor allowing anyone to buy and sell any kind of
hazardous chemical or object. By banning them, we've interfered with
natural selection, which seems to be resulting in a less and less
intelligent population. A sort of "unintelligent design" as it were.

Roy Lewallen, W7EL

On Thu, 23 Dec 2004 05:09:21 GMT, Rick Frazier wrote:



budgie wrote:

(snip)

May well have been toluene. It was often used as a cleaner in all sorts of
areas, some as pedestrian as the T/R/S plugs on old lamp-signalling telephone
switchboards. Unfortunately proved to be a carcinogen and was banned, but it
WAS used to clean a myriad of hardware in a myriad of situations.

Banned? Perhaps from use as a general solvent in assembly areas, but if you walk
into most hardware stores (such as Ace), you can buy it in gallons in their paint
sections... Pretty cheap too!

Different countries, different strokes.

On Thu, 23 Dec 2004 08:20:30 +0000, John Woodgate
wrote:

I read in sci.electronics.design that budgie wrote (in
) about 'Tektronix 465
Scope', on Thu, 23 Dec 2004:

May well have been toluene. It was often used as a cleaner in all sorts
of areas, some as pedestrian as the T/R/S plugs on old lamp-signalling
telephone switchboards. Unfortunately proved to be a carcinogen and was
banned, but it WAS used to clean a myriad of hardware in a myriad of
situations.

Toluene is one of the aromatics that is NOT carcinogenic. From the ATSDR
web site:

(snip)

That was the reason used when it was banned here, merit notwithstanding.

In article , says...
I used the stuff quite a bit when I was a kid, and I'm just fine (I
think) so that's obvious proof that it's all a bunch of hogwash and a
government conspiracy.

__________________________________________________ _________

Carbon tet was used in the dry cleaning industry in the early 20th
century. People worked over open vats, breathing the fumes all day
long, and it took about 20 years of exposure for harm to be done. It is
an excellent solvent for general purpose cleaning. I'm sorry it was
banned.

I used in the TV service business back in the olden days and I'm
perfectly n..n..n..normal, just like Roy.

On the other hand, some people would say this explains a lot. :-)

--
Bill, W6WRT