AKTA FPLC Mixer 925 Problem and Solution

Chalmers via methods%40net.bio.net (by chalmers from nottingham.ac.uk)
Tue Nov 17 07:00:21 EST 2009


This is not exactly a method but could save you money.

We have an AKTA FPLC with the Mixer 925 unit.  We don't have a service  
contract so when the mixer unit stopped working and the system  
provided a short-circuit warning message, we asked the price of a new  
one.  We were quoted £10,000, which is half the price of the whole  
system.  Presumably this is a joke, designed to force you to call in  
the engineer and then get a service contract, perhaps.

The mixer is basically a magnetic stirrer.  I opened the unit and  
found a little 12 V DC motor that turns the magnet.  I was confused at  
first because it worked when I attached a 9V battery.  The final  
explanation was that the motor had difficultly getting started,  
particularly at 4 C, but not so bad at room temperature.  It worked  
intermittently for a while then failed.  It had only 2 ohms resistance  
between the terminals (I suspect it should be 12 ohms).

The ID numbers on the motor specify a custom motor supplied to the  
AKTA manufacturers, so you can not buy one.  However, it looked  
suspiciously like a Premotec 990412018105.  You can buy one for £47  
from RS components (the name on the motor is different but the  
manufacturers product code is identical).

The Premotec motor is rated to run at 3600 rpm at 12 V.  However, it  
receives only 1.89 V from the Mixer 925 unit.  It therefore runs close  
to the specified 600 rpm when drawing power from the Mixer 925.

It takes about 5 minutes to change the motor using simple tools, and  
we saved a significant amount of money.
This message has been checked for viruses but the contents of an attachment
may still contain software viruses, which could damage your computer system:
you are advised to perform your own checks. Email communications with the
University of Nottingham may be monitored as permitted by UK legislation.

This message has been checked for viruses but the contents of an attachment
may still contain software viruses which could damage your computer system:
you are advised to perform your own checks. Email communications with the
University of Nottingham may be monitored as permitted by UK legislation.



More information about the Methods mailing list