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The Dust Problem

Discussion in 'Electronic Repair' started by Paul Burridge, Jul 19, 2004.

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  1. Hi guys,

    There have been many times IME that a piece of electronic equipmenet
    has failed to function altogether or more likely developed some
    annoying intermittent fault and the cure was simply to take the lid
    off and blast the circuit board(s) with an aerosol of compressed air.
    Dust must have been the problem. But why? It's hardly a great
    electrical conductor after all.

    p.
     
  2. Jerry G.

    Jerry G. Guest

    The dust allows for the heat to not dissipate. Some components can overheat
    when coated with dust. It makes a sort of insulated coating, something like
    wool on your body. Also, the dust can have some dielectric reaction and
    effect the performance of high frequency circuits.

    --

    Jerry G.
    ==========================


    Hi guys,

    There have been many times IME that a piece of electronic equipmenet
    has failed to function altogether or more likely developed some
    annoying intermittent fault and the cure was simply to take the lid
    off and blast the circuit board(s) with an aerosol of compressed air.
    Dust must have been the problem. But why? It's hardly a great
    electrical conductor after all.

    p.
     
  3. I read in sci.electronics.design that Jerry G. <>
    wrote (in <cdgfeq$q1v$>) about 'The Dust Problem',
    What really happens is that when you open their cage and clean it out,
    you frighten the electrons, so that they are on their best behaviour of
    a week or two.
     
  4. Phil Hobbs

    Phil Hobbs Guest

    Dust also absorbs water, leading to lots of nasty surface leakage,
    drift, and 1/f noise in damp weather. It will also have ionic
    components (e.g. from salt aerosols due to sea spray, salt from skin
    flakes, or sulphates from combustion) which make this effect worse.

    Cheers,

    Phil Hobbs
     
  5. I read in sci.electronics.design that Phil Hobbs <[email protected]
    I prefer my explanation - it's less dull. (;-)
     
  6. N Cook

    N Cook Guest

    Beaten by a whisker
    Older data centres and e-government sites should take heed of problems
    assailing the Colorado secretary of state's office. A series of computer
    outages has been traced to small metallic filaments, known as zinc whiskers.
    The fibres form a fuzzy surface on zinc-coated surfaces such as data centre
    flooring and ageing computer casings. As the minute filaments detach, they
    are sucked into computers by their cooling fans, and can cause power
    supplies to short or even cause data errors by shorting out the connectors
    on microchips. In Colorado, the resulting downtime prevented electronic
    filings of business and elections documents.
    http://nepp.nasa.gov [pdf]

    source
    http://www.guardian.co.uk/online/story/0,3605,1255870,00.html
    Thursday July 8, 2004

    Not experienced it myself repairing mainly domestic kit
    electronic hints and repair briefs
    http://homepages.tcp.co.uk/~diverse
     
  7. Joerg

    Joerg Guest

    Hi Paul,

    Most of the dust problems I found were related to contacts not properly
    closing anymore because the dust on them prevented it.

    Also, much depends on what is in that dust. Folks who clean their pellet
    stoves with a brush and not with an ash vacuum will have a lot of soot
    in their dust. When they hasten the task and do it while the convection
    fan is still going that aggravates the soot content.

    Regards, Joerg
     
  8. Ken Smith

    Ken Smith Guest

    Circuits work better after you blow them off because they are hoping you
    will do it again.
     
  9. E curious

    E curious Guest

    That reminds me that electronics run on smoke . It doesnt work anymore once
    you let the smoke out LOL
     
  10. Orange

    Orange Guest

    Interesting..
    What would you reccomend for cleaning dust? I've got some compressed
    air called "Blaster" but it contains some
    tetrafluoro-dont-know-exactly. Label says that it can cause plastic to
    "discolor", so I haven't used it at all.
    Computer power supplies are sooo dusty. I've heard there are some
    filters for dust. Can they be used on any PC or just some special
    cases?
     
  11. hemyd

    hemyd Guest

    I have found that in most cases dust causes problems only when it gets
    dislodged and jammed *into* things, such as sockets and connectors, or when
    it gets wet. I have on many occasions found that attempts by people to clean
    dust off electronic circuits often cause more problems than the dust itself.
    Removing dust should be done as a planned service operation rather than
    piecemeal. A socket or connector should definitely be dusted before
    inserting a plug or card.

    Henry
     
  12. hemyd

    hemyd Guest

    Contrary to my previous comment, I do believe that cooling fans and
    heatsinks should be dusted occsionally.

    Henry.
     
  13. Discolouration's one thing; static's another altogether. I'm just
    wondering if anyone's actually blown a chip (or chips) by dusting them
    off with an aerosol? I only ask because on occasions where I've used a
    C02 fire extinguisher, it's caused a large build-up of static on me
    that was discharged with a huge spark the next time I approached
    something earthed. If there are any additives in the compressed air
    sprays that could give rise to the same effect, then it'd be wise to
    avoid them around CMOS circuitry!
     
  14. Orange

    Orange Guest

    dirty mind :)))))
     
  15. Roy McCammon

    Roy McCammon Guest

    I took over an Antarctic satellite tracking station some
    years ago. The previous manager said that every so often
    things would quit working and he had to take out the circuit
    cards and dust them off. (McMurdo has plenty of ground
    volcanic dust). I said OK, thanks for the tip. Sure
    enough, about once every 6-12 weeks things would stop
    working. But instead of taking the cards out and dusting
    them off (very high static electricity area), I just cycled
    the power and it would work again for 6-12 weeks.

    By the way, one day I was foolish enough to separate
    two wool blankets and while holding one, I threw the
    other onto a metal bed frame. After about one second,
    a three foot long arc snapped out from the bed frame
    and hit me in the ankle. And it hurt!
     
  16. No. But I make sure to use a can of compressed air from a known brand with a
    guarantee that they won't harm anything.

    I would recommend Belkin and Fellowes aerosol dusters out of anything else
    except buying a high pressure electric air compressor. - Reinhart
     
  17. I read in sci.electronics.design that Roy McCammon <>
    We must immediately write a standard for ESD requirements for
    Antarctica. Air discharge testing at 500 kV sounds about right, based on
    your field report.

    You re-invented the electrophorus, of course.
     
  18. Roy McCammon

    Roy McCammon Guest

    Does it hurt?
     
  19. I read in sci.electronics.design that Roy McCammon
    You told us that it did!
     
  20. JW

    JW Guest

    And everyone knows that semiconductors smoke and blow out to protect the
    fuse!
     
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