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From: whit@milton.u.washington.edu (John Whitmore)
Newsgroups: sci.electronics
Subject: Re: ?dielectric grease? on connectors
Summary: Sometimes dielectric, sometimes semiconducting, contact improvers
Message-ID: <6434@milton.u.washington.edu>
Date: 17 Aug 90 02:05:49 GMT
References: <312@sphere.UUCP>
Organization: University of Washington, Seattle
Lines: 38

In article <312@sphere.UUCP> ruck@sphere.UUCP (John R Ruckstuhl Jr) writes:
>Someone suggested cleaning pins of a connector inside a personal 
>computer, and applying  ?dielectric grease?  to the pins before 
>reassembly to prevent the connections from degrading quickly.
>(There is a connector in the AT&T UNIX PC that has been observed to be
>susceptible to dirty, poor connections, responsible for a ?myriad? of
>problems).

	There are a number of contact improvers on the market; Cramolin,
Tweek, and Blue Stuff are three I have heard of.  I've used Blue Stuff;
it fixed the selector switches in an old Tek 453 'scope after the
local technician pronounced the problem hopeless-and dumped his 453
for a new machine.  I have heard that Tweek is a liquid semiconductor;
nonconducting as a film, but when a thin layer is stressed with a high
field (probably microvolts per meter) it turns conductive.
	The chemical treatments work.  Beware of switch CLEANERS, which
often cause trouble by washing grease from the shaft into the
contacts.  For connectors, a good cleaner (usually Freon TF) is
recommended.  Alternately, soapy water/distilled water rinse/compressed
air blow-dry will do an adequate cleaning job; some amateur radio
rigs have been restored by simply putting them in the XYL's 
dishwasher...

	Go to an electronics parts store (preferably an industrial
outfit, not Radio Shack) and ask at the chemical counter.

>What residues does this WD40 leave (and are they both conductive and
>protective)?

	WD-40 works OK on high-voltage circuits that have moisture
problems, because it is detergent enough to stick to most surfaces
and displaces the moisture.  WD-40 is mainly kerosene, leaves little
residue, and is ONLY good for a quick fix (getting a car started after
the distributor has gotten wet).  WD-40 is not conductive, but if the
voltage is high enough, a thin film doesn't stop the current.


			John Whitmore