Slide Scanner Repair Manual Diagnostics and Troubleshooting
141
Uniformity II Test
This test provides statistical information about the uncorrected dark and light non-conformity of
the slide scanner. Table 5-11 interprets the measurements of the Uniformity II Tests.
Note: A stand-alone version of this test can be run to provide graphical feedback of actual
profiles of the lamp output and the location of the defects and additional information.
Part 1
Checks for dust or dirt spots on the CCD. Dust is identified as deviations from a
polynomial curve fit to the illumination profile that exceed the threshold set in the constants
file, initially 9%.
Note:Before removing a CCD, check for spots on the lamp or obstructions (example: hair)
in the calibration window or entrance of the light tunnel.
Part 2
The illumination portion of this test fails if the scanner is 10% over-saturated or, if the
slide scanner is operating 10% below the nominal operating range and speed. New slide
scanners are typically at 100% illumination which covers an unsaturated signal of - 0.36V to
2V off each channel of the CCD. Table 5-12 shows some examples of illumination problems.
Table 5-11. Examples of Illumination Problems
Problem Cause Corrective Action
Illumination test result Slide scanner believes Replace lamp.
is <90% lamp is dim.
Illumination test result Slide scanner is saturated •Replace the original lamp
is >110% or has too much light.
Sample a few new lamps
and find the dimmest one.
Note:New lamps loose a bit
of strength after 100
hours of use.
•Burn-in a new lamp for 24 to
48 hours and then replace the
original lamp with the one that
was burned in.
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