SprintScan 35LE Service Manual
Troubleshooting
32
Optical Problems
Optical problems usually affect only image quality and not scanner operation. Once the
scanner power-up, self-test and communications link-up are all successfully completed,
images can be scanned, displayed on a monitor and inspected with the zoom function.
Checking Focus and Alignment
Notes:
•
If resolution is degraded across the entire image, the lens may
be out of focus.
•
An imbalance in shading or resolution between the left and right
sides of the image may be caused by improper alignment of the
CCD module or the lens.
Problems of focus and alignment can be most accurately analyzed by measuring CCD
response at TP1 on the main PC board.
1. Attach the scope’s probe to TP1 and its ground line to TP4, Analog GND (AGND).
2. Disconnect the stepper motor power cable from connector J1, making sure that all
other cables are connected, and then power up the scanner.
3. Rest the test slide on the slide carriage.
4. Push the slide carriage down so that the CCD sees the black/white line pairs.
5. Set the oscilloscope’s vertical trace to 1 V/div.
Figure 3-7 shows optimum CCD response as displayed on an oscilloscope
and a logic analyzer.
Figure 3-8 shows CCD response when lens focus, lens or CCD alignment, and
both focus and alignment are incorrect.
