Controlled opening not good idea. The Enclosure is 200 feet from house, 
in the middle a mowed grass area. The only time needing to open the 
aluminum box (which accessible once the enclosure is removed) is if 
there is a problem with the PIC's board itself including the temperature 
sensor. The pressure sensors, and wall wart can all be unplugged from 
aluminum box mounted sockets. This could happen at any time (granted 
probably rarely)  day or night, sun, rain, or snow. And then I probably 
want to get things back together quickly and get back inside.

Right now my game plan is to coat the boards, less the DIP socket tops 
with catalyzed clear urethane, make a little packet of silica gel, dry 
it, and put things back together.

apptech wrote:
> Conformal coating is seldom a bad idea.
>
> Dessicant may help.
>
> I won't even mention that a controlled opening environment is a nice idea if 
> you can manage it :-). Maybe a portable glove box with controlled humidity? 
> Could be very low tech and cheap to implement. "Plastic" bag and air 
> cartridge or even a hand pump to initially inflate via a dessicant 
> cartridge.
>
>
>    Russell
>
>
>   
>> I'm thinking it's condensation since the last time the aluminum box was
>> open, was much warmer temperatures and might have been light rain. What
>> would be appropriate actions- Coat most of the board with say a
>> catalyzed urethane clear paint (have stock of lots of it), let the
>> inside of the aluminum box open with cold low humidity ambient air (that
>> won't help if I open later in the summer though)? or??
>>     
>
>   
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