[ANSS-netops] L-4C users beware

[David S. Croker]

If you don't use Sercel L-4C sensors you can delete this.

We recently found out the hard way that a batch of "new" seismometer 
caps were wired with reverse polarity from the factory.  This is 
something we have never really checked before.  The red lead 
(positive, high) should go to the bottom contacts (closest to the 
tip).  We haven't bought many replacements over the years but we did 
buy a batch of a dozen last year.  It appears they were all wired in 
reverse.  Fortunately we caught the problem before we had too many 
deployed and they were all a day trip away.

If you have purchased new caps from Sercel in the past year I 
recommend you check the polarity.

Dave

__________________________________________________________
USGS - Earthquake Science Center - NCSN Field Operations Manager
David S. Croker                                         office (650) 329-4697
345 Middlefield Rd, MS 977                           fax (650) 329-4732
Menlo Park, CA 94025                                 cell (650) 465-4334
email: croker at usgs.gov
Quake info: http://earthquake.usgs.gov/
USGS URL: http://www.usgs.gov/