<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">We ordered some L4C's awhile back and discovered the same thing.<div>The polarity was reversed. Well, at least it was different.</div><div>After discussing the issue with the manufacture (I don't remember if it was Mark Products or Sercel),</div><div>we were told that they make all USGS orders oneway, and everyone else's the other way.</div><div><br></div><div>As I recall the story, the USGS evaluated the original prototype and found the polarity reversed.</div><div>Mark Products, wanting to please their customer, manufactured all subsequent USGS L4C's to the USGS spec.</div><div>All others were made with the original polarity.</div><div><br></div><div>Regards,</div><div>Steve Estes</div><div><br></div><div><br></div><div><blockquote type="cite">Date: Fri, 02 Mar 2012 13:34:11 -0800<br>From: "David S. Croker" <<a href="mailto:croker@usgs.gov">croker@usgs.gov</a>><br>To: <a href="mailto:anss-netops@geohazards.usgs.gov">anss-netops@geohazards.usgs.gov</a><br>Subject: [ANSS-netops] L-4C users beware<br>Message-ID: <<a href="mailto:OFD86DC885.EBFA1C35-ON882579B5.00767C4A@usgs.gov">OFD86DC885.EBFA1C35-ON882579B5.00767C4A@usgs.gov</a>><br>Content-Type: text/plain; charset="us-ascii"; format=flowed<br><br>If you don't use Sercel L-4C sensors you can delete this.<br><br>We recently found out the hard way that a batch of "new" seismometer <br>caps were wired with reverse polarity from the factory. This is <br>something we have never really checked before. The red lead <br>(positive, high) should go to the bottom contacts (closest to the <br>tip). We haven't bought many replacements over the years but we did <br>buy a batch of a dozen last year. It appears they were all wired in <br>reverse. Fortunately we caught the problem before we had too many <br>deployed and they were all a day trip away.<br><br>If you have purchased new caps from Sercel in the past year I <br>recommend you check the polarity.<br><br>Dave<br></blockquote></div></body></html>