• Greasing up switches and connectors?

    From N_Cook@21:1/5 to DaveC on Sun Mar 6 08:13:36 2016
    XPost: sci.electronics.basics, sci.electronics.design, sci.electronics.repair XPost: alt.engineering.electrical

    On 05/03/2016 17:14, DaveC wrote:
    Cleaning up an old rotary mode switch used for 5v logic levels. It has some kind of grease in it.


    …which has always confused me: grease is an insulator (well, the grease in this switch is—just tested and it’s infinite ohms).

    I read that dielectric grease is good to keep contacts sealed against the elements that have high physical pressure (which overcomes any separation provided by the grease) but that signal and other low voltages grease is contra-indicated.

    What say y’all?

    Thanks.


    Over the years all those problematic radio multiway wavechange and tape recorder play/record slide switches. I never saw grease inside them and
    the failure was due to black corrossion product copper suplphide? which
    is an insulator that a phosphor bronze contact could not wipe/break
    through to make contact. The worst black was at the more open ends to
    the air, rather than the core of the switch body.

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  • From Kevin McMurtrie@21:1/5 to DaveC on Sun Mar 6 09:00:35 2016
    XPost: sci.electronics.basics, sci.electronics.repair, alt.engineering.electrical

    In article
    <0001HW.1C8B4B670002EE5111CD2E3CF@news.eternal-september.org>,
    DaveC <not@home.cow> wrote:

    Cleaning up an old rotary mode switch used for 5v logic levels. It has some kind of grease in it.


    …which has always confused me: grease is an insulator (well, the grease in this switch is—just tested and it’s infinite ohms).

    I read that dielectric grease is good to keep contacts sealed against the elements that have high physical pressure (which overcomes any separation provided by the grease) but that signal and other low voltages grease is contra-indicated.

    What say y’all?

    Thanks.

    Grease is more easily pinched through than corrosion. It extends the
    life of sliding switches by reducing friction.

    It's only used for low level signal switching. Grease and oil slow down switching time so they'll cause power switches to arc and catch fire.

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    because they host Usenet flooders.

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  • From N_Cook@21:1/5 to DaveC on Mon Mar 7 07:51:55 2016
    XPost: sci.electronics.basics, sci.electronics.design, sci.electronics.repair XPost: alt.engineering.electrical

    On 05/03/2016 17:14, DaveC wrote:
    Cleaning up an old rotary mode switch used for 5v logic levels. It has some kind of grease in it.


    …which has always confused me: grease is an insulator (well, the grease in this switch is—just tested and it’s infinite ohms).

    I read that dielectric grease is good to keep contacts sealed against the elements that have high physical pressure (which overcomes any separation provided by the grease) but that signal and other low voltages grease is contra-indicated.

    What say y’all?

    Thanks.


    Can we summarise this thread by saying -
    Any grease is better than no grease, in low voltage, wiped contact
    situations, as long as the grease doesn't go hard with age or otherwise
    degrade or corrode the contacts itself

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  • From Ian Field@21:1/5 to All on Sun Mar 6 21:34:34 2016
    XPost: sci.electronics.basics, sci.electronics.design, sci.electronics.repair XPost: alt.engineering.electrical

    "DaveC" <not@home.cow> wrote in message news:0001HW.1C8B4B670002EE5111CD2E3CF@news.eternal-september.org...
    Cleaning up an old rotary mode switch used for 5v logic levels. It has
    some
    kind of grease in it.


    …which has always confused me: grease is an insulator (well, the grease in this switch is—just tested and it’s infinite ohms).

    When I worked for a calibration firm, they had special contacts grease for
    the old decade boxes. AFAICR: it was called Elvolube - but I haven't been
    able to find it online.

    Often I use GT85 - its like WD40 but PTFE enhanced, it doesn't interfere
    with contacts but the solvent destroys any ABS plastics in anything you
    spray it on.

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  • From Ian Field@21:1/5 to diverse@tcp.co.uk on Mon Mar 7 18:15:00 2016
    XPost: sci.electronics.basics, sci.electronics.design, sci.electronics.repair XPost: alt.engineering.electrical

    "N_Cook" <diverse@tcp.co.uk> wrote in message news:nbjbp3$uo0$1@dont-email.me...
    On 05/03/2016 17:14, DaveC wrote:
    Cleaning up an old rotary mode switch used for 5v logic levels. It has
    some
    kind of grease in it.


    …which has always confused me: grease is an insulator (well, the grease
    in
    this switch is—just tested and it’s infinite ohms).

    I read that dielectric grease is good to keep contacts sealed against the
    elements that have high physical pressure (which overcomes any separation
    provided by the grease) but that signal and other low voltages grease is
    contra-indicated.

    What say y’all?

    Thanks.


    Can we summarise this thread by saying -
    Any grease is better than no grease,

    Some mechanical engineering greases contain a significant proportion of
    water.

    Not certain - but that may open the possibility of corrosive decomposition products.

    Many greases are lithium based, its probably bound up in stable compounds,
    but very reactive if it gets loose.

    Molybdenum grease is probably OK except in high voltage or high impedance
    work - graphite grease is probably not OK for anything electrical. Graphite
    is the lubricant of choice for brass, such as locks etc.

    PTFE penetrating oil works well on contacts, as for grease the one I know of
    is Finish-line PTFE fortified bicycle grease. It works OK on heavy contacts, but may isolate the wiper on light duty switchgear.

    Silicone grease is exactly opposite to hygroscopic - it repels water.

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  • From DaveC@21:1/5 to All on Mon Mar 7 18:31:53 2016
    XPost: sci.electronics.basics, sci.electronics.repair, alt.engineering.electrical

    Grease is more easily pinched through than corrosion. It extends the
    life of sliding switches by reducing friction.
    Kevin Mc

    And by extension, oil is better at preventing corrosion while not sticking up things.

    This research found that simple mineral oil reduced contact resistance dramatically:

    http://www.te.com/documentation/whitepapers/pdf/p154-74.pdf

    I (op) decided I’m going to cleans out this mode switch and try Caig
    DeOxit.

    Thanks for all the great discussion.

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  • From DaveC@21:1/5 to All on Sat Mar 5 09:14:15 2016
    XPost: sci.electronics.basics, sci.electronics.design, sci.electronics.repair XPost: alt.engineering.electrical

    Cleaning up an old rotary mode switch used for 5v logic levels. It has some kind of grease in it.


    …which has always confused me: grease is an insulator (well, the grease in this switch is—just tested and it’s infinite ohms).

    I read that dielectric grease is good to keep contacts sealed against the elements that have high physical pressure (which overcomes any separation provided by the grease) but that signal and other low voltages grease is contra-indicated.

    What say y’all?

    Thanks.

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