[RASMB] CPU Board Malfunction on XL-I

[Ute Curth]

Hi Ian,

we bought an XL-I equipped with an Aviv AU-FDS in 2008 and also suffer 
from severe problems. Either the centrifuge stops spinning or the 
computer stops scanning within a run. This happens after unpredictable 
times (20 min to 20 hours), at different rotor speeds (e.g. 22, 35 or 50 
krpm), independent whether we measure absorbance only or absorbance and 
interference but not in every run. Our machine is still under warranty 
and Beckman has been trying for more than one year to solve this 
problem. A lot of components of the machine (all boards, the display, 
the radial drive....) were exchanged, but this did not solve the 
problem. After having ruled out that there were problems with the power 
supply in our institute, they admitted that there is a timing problem in 
the communication between centrifuge and computer and that similar 
problems exist in about 10 machines worldwide. Therefore, they modified 
the firmware and installed a new firmware pre-release (now the machine 
stopped scanning regularly in runs which were performed at 50000 rpm) 
and afterwards a new version of the GUI, which should solve this 
problem. In first tests with the new firmware/GUI combination the 
machine seems to work more reliable (it did not stop in several test 
runs at several speeds), but it turned out that the new firmware is not 
able to hand over the correct value for w^2t to the computer (a plot of 
w^2t against the time is not linear as expected, but looks like a saw 
tooth wave). They are trying to solve this problem for several weeks now 
and I still hope that our centrifuge will work properly soon. Just as a 
comment: the Aviv fluorescence detection system works without any problems.

Best wishes

Ute

-- 
PD Dr. rer. nat. Ute Curth
>  Medizinische Hochschule Hannover
>  Strukturanalyse
>  OE 8830
>  Carl-Neuberg-Str. 1
>  30625 Hannover
>  Germany
>
>  Tel.: +49-511-5329372
>  Fax : +49-511-5322909

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