[3dem] F20 microswitch

James Riches james.riches at embl.de
Tue Jan 19 06:34:34 PST 2010

Dear Takashi,
	We have had this problem a few times on CM series microscopes, and it 
seemed to be due to user error. The engineers should just replace the 
part and you should tell the users to be more careful and to avoid 
hitting the microswitch with the pin on the sample holder. Apart from 
that there isn't much you can do to prevent it, as far as I know. If you 
can't get an engineer there quickly, you can usually use a pair of 
tweezers to pull the switch out and/or push it back in to activate your 
roughing pump. In this way you can still insert sample holders and keep 
working until you get someone there to fix the problem. Alternatively, 
you can use a couple of pairs of tweezers to bend the switch back to its 
original shape and you may get it working again. It is difficult to 
access in there though, and you'll probably end up activating the pump 
during this repair. Let me know if you need more information.


Ishikawa Takashi wrote:
> Dear all,
> We have a problem on the microswitch (mechanical sensor) inside the 
> compustage of Tecnai F20 (FEI). This is located at the left side of the 
> pathway of the holder (~2cm from the entrance) and recognizes the 
> insertion and the removal of the holder. This switch is covered by a 
> thin cupper block and, when this block is pushed by the holder, it 
> recognizes the insertion.
> Recently in our F20 (ten users share this microscope), this microswitch 
> is occasionally bent, maybe either during insertion or removal of the 
> holder. Onc we have this problem, the switch does not recognize the 
> removal any more (always in the state “holder in”) and therefore cannot 
> be ready to insert another specimen. We think it is due to improper 
> usage of the holder and instructed our users not to rotate the holder 
> inside of the compustage (as you know, the holder is tilted ~120degrees 
> in the pre-evacuation chamber), i.e. the user must rotate first and then 
> insert the holder into the stage (same when it is taken out; first take 
> it out and then rotate back to the normal angle). But, it did not really 
> help and we still have this problem.
> Did any of you have the same problem before? I would appreciate it if 
> you give us any suggestion to avoid this problem.
> Best regards,
> Takashi
> Takashi Ishikawa
> Research Scientist / Group Leader
> Department of Biology
> Swiss Federal Institute of Technology (ETH Zürich)
> ETH Hönggerberg, HPK F18
> CH-8093 Zürich, Switzerland
> phone: +41 44-633-2462
> Fax:  : +41 44-633-1073
> e-mail: takashi.ishikawa at mol.biol.ethz.ch 
> <mailto:takashi.ishikawa at mol.biol.ethz.ch>
> Web:  http://www.mol.biol.ethz.ch/groups/ishikawa_group
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Jamie Riches
Briggs Group
European Molecular Biology Laboratory
Heidelberg, 69115

Ph: +49 6221 387195
Fax: +49 6221 387519
Email: riches at embl.de


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