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[wxsig] hot glue follow-up

John Bennett jabennett at insightbb.com
Fri Jun 25 02:45:38 UTC 2010


About three years ago I installed a T-238 station with the X1W-1, X1W-2 
and X1W-4 kits. The rain gauge option had been installed on the X1W-2 
(outdoor temp/humidity). It has been intermittent for some time and 
finally stopped working.

I had wrongly assumed that the counter chip had been fried. After 
determining the DS2423 was OK, I checked the opto-isolator to find that 
Vcc was missing on pin one. It did not take long to find the problem. 
Part of a trace had corroded away. The part that had vanished was not 
covered with hot glue. The only protection was the solder mask on the PC 
board itself. Moral of the story here is that all traces pads, pins, 
etc. that are exposed must be somehow sealed. Just be certain to follow 
the guidelines I gave on applying the glue in the manual.

As a point of interest, only the bottom of the board had corrosion 
problems. The board was installed in a Davis radiation shield and 
therefore was facing down. Apparently moisture with some contaminants 
routinely collects on bottom of the board which is facing up. The top of 
the board which faces down showed virtually no signs of corrosion.

In the process of trouble-shooting, it was necessary to peel away some 
of the hot glue. This was not an easy task, but when I did get if off, 
ICs, board, traces - virtually all components looked as if they had just 
been installed. No mold, dirt, peeled off paint or solder mask. Hot glue 
works. It just doesn't look pretty.

73,
John Bennett, N4XI




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