[3dem] Column vacuum problem with a Tecnai F20

[Bruno Klaholz]

Dear John,

the values for our F20 here are usually around:
IGP1 (column)  6
IGP4          9
IGP2/3 (gun)    1
camera with films in 31 if stably pumped

Vacuum deterioration upon cooling sounds like a leak close to a 
sealing or O ring in vicinity to the cooled metal part,
maybe at the rod level connected with the cold trap (between cryo-box 
and the outside blades)?
Do you get contamination on your cryo samples?

Best,

Bruno






>Dear Colleagues,
>
>We have been having a strange vacuum problem with our FEI Tecnai F20 
>G2 .  Our engineer says that he has not come across reports of this 
>problem through FEI, but I was wondering whether anyone in the 3DEM 
>community has seen the problem before and knows what the cause is.
>
>Our column vacuum deteriorates when liquid nitrogen is added to the 
>cold trap.  At room temperature the column vacuum (IGP1) sits at around 13.
>Upon addition of liquid nitrogen, IGP1 deteriorates to ~20.  We have 
>aready had some work done on the microscope and learned some 
>interesting things.  We had the component that couples the external 
>copper braid to the cryobox replaced but that did not solve the 
>problem.  Subsequently, as a test, our engineer  removed the cryobox 
>from the column and blanked off the cryobox bellows.  Without these 
>components,  IGP1 improved to ~5-6.  However, replacing the cryobox 
>bellows with a new one did not solve the problem.
>As you will know, vacuum leaks can take a long time to sort out, so 
>any advice that helps us solve this one faster would be greatly 
>appreciated.  Also, could people who use a F20 (with or without 
>film) please send me some typical values for their column IGPs (IGP1 
>and IGP4 in our instrument).
>
>Best wishes and many thanks,
>John
>
>--
>John Rubinstein
>Molecular Structure and Function Program
>The Hospital for Sick Children
>555 University Avenue, Rm. 3330
>Toronto, ON
>Canada
>M5G 1X8
>Tel: (+001) 416-813-7255
>Fax: (+001) 416-813-5022
>www.sickkids.ca/rubinstein
>
>
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############################################################################

Dr. Bruno P. Klaholz
Department of Structural Biology and Genomics
Institute of Genetics and of Molecular and Cellular Biology
IGBMC - UMR 7104
1, rue Laurent Fries
BP 10142
67404 ILLKIRCH CEDEX
FRANCE


Tel. from abroad: 0033.388.65.57.55
Tel. inside France: 03.88.65.57.55

Fax from abroad: 0033.388.65.32.76
Fax inside France: 03.88.65.32.76
e-mail: klaholz at igbmc.u-strasbg.fr
websites:
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