Stereo Scan 440 - DCU

1. Admit air to the gun. Open the gun.
2. Lift out die anode.
3. Fit the anode spacer on the top of the gun align coils. Take care, this is a
high precision fit.
4 Fit the anode back. on top of the spacer. This is also a good fit.
~
This
S. Select Low kV anode in the Gun Setup panel.
automatically restricts the acceleration vollage to 3kV.
6 Close the gun. pump down. select the desired low voltage and obtain an
image.
The Slereoscan 440 should not be used at an acceleration voltage higher than
3k V with the anooe spacer fitted. It is important to ensure that the state of the
anode spacer p~ter reflects the state of the machine.
2.2.6. Getting a Vacuum
If the vacuum ready state is not achieved after several minutes of pumping, the
following guidelines provide an ordered approach to diagnosing the problem.
Investigating a vacuum leak. few simple rules:-
Before looking for a vacuum leak give the vacuum system time to pump. If
you have just changed a speci~n in a very humid atmosphere the pump
down may take longer. If the specimen is wet it may take several minutes
(up to I hour with a very large. very wet specimen has been known.) If the
stage has been left open for long periods it will take longer to pump. If the
column or chamber have been washed with solvents then it may take several
hours to achieve a good vacuum.
2. Vacuum leaks rarely happen by themselves; they are often caused. If you
have just done anything to the column or chamber then that is the most likely
cause of the leak. If the s~ has just been changed. check the stage
door '0' ring. Similarly if the filament has been changed check the gun '0'
ring.
Stereoscan 440 Operator Manual