Damp electronics

Discussion in 'General Electronics Chat' started by vernors, Aug 19, 2009.

  1. vernors

    Thread Starter New Member

    Aug 19, 2009
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    0
    Hello. I maintain a system that was built in the 1980s. I can't go into details but the equipment has video equpment with CRTs, racks of circuit cards, power supplies, etc. It is operated indoors in a climate controlled environment. The climate control equipment went bad and the equipment got very damp from the high humidity - like someone sprayed a fine mist of water over it. The humidity in the room got up to about 90%. The adverse environment conditions occurred when the system was powered off - I haven't turned it on yet. My basic question is: what should I do before I turn it back on? When the climate control equipment is fixed should I just wait a day or two for it to dry out? Or should I do something more proactive to help remove any moisture? Thanks.
     
  2. rjenkins

    AAC Fanatic!

    Nov 6, 2005
    1,015
    69
    I'd open any access panels to help air circulate and use a normal desk fan or two to encourage air flow.

    Once everything is visibly dry, some gentle heat (like a warm air heater) blowing towards equipment from a few feet will help drive out residual moisture.

    How long it needs very much depends on how items are constructed and how much airflow there is to assist drying.

    I was working on a factory machine a couple of years ago when a hose burst on a nearby machine and blasted the electrical panel with tens of gallons of water.

    Everything was dripping wet - transformers, contactors, electronics boards...
    They got several hot-air fan heaters and left them blowing into the panel for a couple of days, so everything in it was quite warm to touch. It all worked fine, not so much as a blown fuse.

    As long as everything is _completely_ dry, it should work OK.
     
  3. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    Agreed. I have seen electronics just dripping with condensed moisture after an a/c failure work fine after it was allowed to completely dry out.
     
  4. studiot

    AAC Fanatic!

    Nov 9, 2007
    5,005
    513
    Completely being the operative word. Water can hide in the smallest interstices and the boards appear completely dry.

    Fans, a hair dryer, etc are a good idea but forced drying is not reliable. You need a period where the surrounding air is dry so remaining water will evaporate.

    I usually allow 24 to 48 hours air drying time after scrubbing circuit boards and other kit in a bucket of warm soapy water. I learned the hard way the 4 to 6 hours and forced drying is not enough, particularly for keyboards and the like.
     
  5. ELECTRONERD

    Senior Member

    May 26, 2009
    1,146
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    So I can completely envelop circuit boards in water and turn them back on when they are dry? I guess that would be ok, the water will act like electroastatic foam and as long as you don't turn anything "on" you're ok.
     
  6. vernors

    Thread Starter New Member

    Aug 19, 2009
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    Thank you all for the advice.
     
  7. russ_hensel

    Well-Known Member

    Jan 11, 2009
    818
    47
    Water, if pure, is not a problem, but other substances tend to travel with it. Most are less of a problem when dry. I knew a tech. who used to wash circuit boards first with alcohol then distilled water. Then he dried them. He said that just that ( these were home built boards ) fixed about 1/3 of them and made errors easier to see on the rest.
     
  8. DC_Kid

    Distinguished Member

    Feb 25, 2008
    638
    9
    rubbing alcohol will disperse water, and then quickly evaporate. just need to make sure no parts will react with alcohol (which most will not). hot/dry airflow will be key. all the parts need to heat soak so you can be sure all the water and/or alcohol has evaporated. another problem with condensation is that it deposits contaminants when the water evaporates, or it corrodes junctions, which can still cause oxide shorts even after all the liquid is gone, etc.
     
  9. bigcape

    Member

    Sep 18, 2009
    158
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