Starlight Xpress SXVR-M25C - Manual (Page 27)

Handbook for the SXVR-M25C Issue 1 June 2009
27
have small bottles of pure acetone. A bright light and a strong watchmakers eyeglass
will also be found to be essential.
Procedure:
1) Disconnect the lead from the camera head and remove it from the telescope. Place
it on a table with the optical window facing downward.
2) Remove the two M3 screws and the M8 nut from the camera back plate and ease
the plate out of the camera body. Unplug the fan lead from the camera PCB.
3) Withdraw the body cylinder and unscrew the two top spacer pillars from the PCB.
Now gently lift the PCB off the 20 way connector NOTING THE ORIENTATION
OF THE BOARD for correct replacement later. Now remove the lower two spacers
from the heat sink plate assembly.
4) The camera heat sink assembly can now be lifted away from the camera front
barrel and the CCD will be exposed. Note that a layer of white heat-sink compound is
applied to the periphery of the heat sink disc and this should be left undisturbed by
subsequent operations.
5) You can now closely examine the CCD faceplate under the spotlight using the
watchmaker's glass when any dust motes will show clearly. If there is only an odd
particle or two and the CCD is otherwise clean, carefully brush away the dust with a
corner of your lens cloth. A smeared or very dusty CCD will need a few drops of
alcohol to clean thoroughly and you may have to make several attempts before the
surface is free of contamination. One gentle wipe from one end to the other, with no
return stroke, will be found to be the most effective action. DO NOT rub vigorously
and be very careful to avoid scratching the window.
6) Before re-assembly, make certain that the inside surface of the front window is also
clean, and then carefully replace the camera front barrel and screw it into place. (If the
heat sink seal is disturbed, renew it with fresh compound before reassembling).
7) Replace all the camera parts in reverse order and the job is done.
Dealing with condensation:
The SXVR-M25C is designed to avoid condensation by minimising the volume of air
trapped within the CCD cavity and by preventing moisture ingress. This normally
works very well, but storage of the camera in a humid location can lead to the trapped
air becoming moist by diffusion through the optical window mounting thread etc. and
can result in condensation on the CCD window. If this becomes a problem, try storing
the camera in a warm, dry place, or in a plastic lunch box containing a sachet of silica
gel desiccant. If this is not effective, try opening the main barrel and loosening the
stand-offs to allow a gap to form between the heat sink and the front barrel assembly.
Now put the camera into a desiccator box (as above) or leave it in a warm place for
several hours before re-sealing it.
N.B. DO NOT leave the camera switched on for long periods between uses. The
cold CCD will collect ice by slow diffusion through any small leaks and this will
become corrosive water on the cooler and CCD pins when the power is removed. If
substantial amounts of moisture are seen, dismantle the camera and dry it
thoroughly.