Polaroid SprintScan SS35, Repair Manual

Page: 142 / 187

Slide Scanner Repair Manual Diagnostics and Troubleshooting
142
Part 3
This portion of the test provides a 5-point measurement which is taken at equally spaced
points, left to right across the CCD. The results of this test lists a 5-point profile of the
uncorrected uniformity data for each channel of the CCD. The 5 points are taken from a
curve fit of the scanner’s uniformity calibration coefficients representing the basic illumination
profile of the lamp and optics. Peak uniformity is normalized to 100% for the profiles. The
test fails if the edge illumination is at 64% or less than the center uniformity.
Part 4
The Mean Uncorrected Dark Level is the mean response of the CCD in the dark. The
response is measured in digital numbers in terms of the lsb’s of the A/D converter. The
result is on a 10-bit scale for the SS35 ES and a 12-bit scale for the SS35 Plus. In all
cases, it is checked to be no more than a specified amount above the uncorrected
calibration target. For the SS35 ES, that target is 16 digital numbers (16 dn). For the
SS35 Plus, it is 68 digital numbers (68 dn). The Uncorrected Dark Standard Deviation
checks the standard deviation of the uncorrected dark response of a scan of the black
calibration target.
Table 5-12. Interpreting Measurements of the Uniformity Tests
Test Name Specification Specification Suggested Repair
SS35ES SS 35 Plus
Dust Count <1 <1 High dust counts suggest removal
and cleaning of CCD is required.
See CCD Cleaning procedure.
Also, look for obstructions in optic
path.
Note: A dust count of 1 indicates a
single spec of dust on the
outside of the lamp. Also look
for a black spec inside the
lamp. If found, replace lamp.
Illumination Min = 90% Min = 90% • Replace lamp.
Max = 110% Max = 110% • Obstruction in optic path such as
dust, dirt or hair in the light
tunnel.
• Re-align CCD.
Red Light Min = 64% Min = 64% • Replace lamp.
Uniformity • Obstruction in optic path such
as dust, dirt or hair in the light
tunnel.