tecnai version 2.1.5

Angel M Paredes Angel.Paredes at uth.tmc.edu
Tue Jun 28 11:39:44 PDT 2005

Hi all,

Sunday we experienced a rather bad malfunction that people should be aware
of that destroyed our FEG tip.  On our Polara, the user working with the
scope decided to remove the MSC to exchange the specimen.  To do this you
have to vent the airlock.  He pushed the "vent airlock" button.  Since he
had not closed the column valves, the software I believe was supposed to
have detected this and closed the column valves for him to protect the
FEG.  The software unfortunately did not.  What the user did not know was
that there was an electrical short in valve B that told the software that
valve B was closed when it was in fact opened.  Instead of telling him to
close valve B as it should have done, the software detected that valve B
was already closed and told the user instead to close valve A... which he
did.  The software then vented the airlock but with valve B opened instead
of closed, the column was vented and since the software had not closed the
column valves when the user pushed "vent airlock", the FEG was vented too.  
FEG tip gone.

We are currently using version 2.1.5 of the user interface.  Has anyone
out there been experiencing any other bugs with 2.1.5?  Thorsten had
problems with his system rebooting when a log file was full and I went
through the same thing during a bugcheck the system decided to perform.
Another bug we've seen is in low dose.  We use diffraction while in
search.  Every now and again the search mode goes from looking normal to
looking really strange and becoming very difficult to align.  When I go
from diffraction back to regular image mode in search, I find that the
microscope has gone from a magnification of 52,000x to 52x while in
diffraction and this is the reason why the search mode goes from looking
okay to looking strange.  FEI's response is that we are not supposed to be
using diffraction and experiments in the factory have shown that if one
switches in and out of diffraction too quickly, it causes the mag to
change.  All I know is that version 2.1.3 did not have this problem.  Are 
there any other problems I should be made aware of?


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