Damaged pin in Catalyst tip-holder seat

Alessandro Podestà posted on Fri, Feb 22 2013 9:15 AM

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Recently we went into a problem with our Catalyst head: some water contacted the retractable metallic pins located in the tip-holder seat on the microscope head. One of the pins (the one in the right lower-bottom position) got oxidized to the point that it detached, freeing a small spring below it.

http://idefix.mi.infn.it/~podesta/temp/Pins_tip_holder_Catalyst_after_oxydation.JPG

We noticed that there is no electrical connection in correspondance of this pin neither on the fluid nor in the air tip-holder side.

To our surprise however, and this is why the pin got damaged upon contact with water, this pin carries a voltage of -3.55 V with respect to ground.

Can someone tell us what is the real function of this pin, and why it is electrified despite it is not (apparently) used ?

Our microscope seems to be fully working despite this accident, and we are taking care not to expose any longer that part of the head to water and to avoid condensation of moisture on it.

Thanks for info and best regards,

Alessandro Podestà

Alessandro Podestà, PhD
Dept. of Physics and CIMAINA,
Università degli Studi di Milano
via Celoria 16 - 20133 MILANO, Italy
E-mail: alessandro.podesta@mi.infn.it
Web: http://www.mi.infn.it/~podesta/
Res.ID: http://www.researcherid.com/rid/E-6568-2010
ORCID: https://orcid.org/0000-0002-4169-6679