[time-nuts] HP 5370A

Chuck Harris cfharris at erols.com
Mon Oct 16 08:56:14 EDT 2006

Hi Robert,

Interesting.  I have used a variety of compounds to do this job
for years now.  My favorite is the old Chemtronics tuner cleaners
of the sort that contained silicone, and HFC's.  It left a silicone
film that kept the air off of the contacts.  I have equipment where
I did this that has been running without problem for 30+ years.

The Chemtronics tuner cleaner was formulated for precisely this problem.

There are silicones, and there are silicones.  Adding a silicon atom
to a hydrocarbon can make compounds that vary in properties all the way
from the toughest abrasives, to oils and greases, even to rubbers.
I can certainly imagine how a floor polish, which is supposed to leave
a protective wear resistant film, might cause serious problems for an
electrical circuit.

I looked on the label of the Chemtronics Goldguard 2000 and it says
it is an n-propyl alcohol, and polyphenyl ether mixture.

I don't precisely know what polyphenyl ether is, but I do know that it
is very slippery.  It works very nicely on the gold fingers of 7000 series
plugins... which is precisely the sort of duty it was made for.

-Chuck Harris

Robert Atkinson wrote:
> Hi Chuck,
> I'd agree on the use of connector wipes, but doubt that they have
> silicone as a lubricant. Silicone oil or grease is not generally
> suitable as a lubricant on electrical contacts as it can form an
> insulating layer that is virtually impossible to remove. This is
> especially true of contacts that may arc, even slightly. Many years ago
> when the UK telephone system was still electromechanical they had a
> sudden spate of contact failures. These only occurred close to the floor
> and the cause was traced to a change in the floor polish to a silicone
> formulation.
> Robert G8RPI.
> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
> Behalf Of Chuck Harris
> Sent: 15 October 2006 16:15
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] HP 5370A
> Didier Juges wrote:
>> PS: The card edge connectors on this unit are extremely tight. I 
>> "easily" broke one of the extractor on the CPU card, and the ROM card 
> I am very careful to remove boards like this, I don't like to break the
> extractors.  Once I get them removed, I give the card edge a wipe with
> one of those "gold saver" wipes made by Chemtronics and others.  It adds
> a little touch of a silicone lubricant to the fingers and reduces the
> insertion force by about 5x.  Plus, it cleans the gorp off of the gold
> fingers.
> -Chuck
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