KELMAR ATD-1200 User manual

Systems Inc., 284 Broadway, Huntington Station, NY 11746 • 631.421.1230 • FAX [phone]
ATD-1200 Dolby Digital/Analog Basement Reader
Test Setup with Oscilloscope
The following test setup will enable adjustment of focus and confirmation and adjustment of LED level and optical alignment.
1. Make sure power to ATD-1200 power supply is provided, Power to the Digital Processor should also be turned on.
2. Open the Digital Processor to gain access to the test points.
3. Connect a probe from Channel 1 of a 20MHz or greater bandwidth oscilloscope to the VIDEO test point of the Video
Acquisition Card, with the ground lead to the VGND.
4. Connect a second probe from the scope’s Channel 2 to the CLAMP signal test point to trigger the scope. Connect the
second probes ground to DGND.
5. Set the trigger source on the scope to Ch.2.
6. Adjust the Ch.2 vertical trace position to move the trace off the screen. It is not necessary to view this signal once
triggering has been established. Adjust the scope for 1 horizontal trace across the screen and adequate vertical gain
(approx. 2 usec
I div. horizontal, 1 V /div. vertical). With SRD film threaded and running in the projector, observe the
video waveform. (see figure 1 in next section)
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Focus Adjustment
The ATD-1200 Readers are factory adjusted and should not require adjustment during installation. If the unit has become
misadjusted focusing may be performed. Using the setup as above, adjust the lens/ CCD assembly in the reader by
loosening the clamp screw located on the upper lens holder assembly, and move the lens assembly back and forth. The best
focus is achieved when the scope pattern has minimum brightness in the center of the trace. There will always be some light
here; one is looking for the most “focused looking”display, with minimum brightness inside the envelope. This should
correlate with a minimum error rate. Re-tighten the lens clamping screw.
figure 1
Adjust for minimum brightness in center of image.

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LED Level Confirmation and Adjustment
The output voltage of the LED supply is factory set to be between 3.5 and 4 volts. LED intensity has a direct relationship to
the video signal voltage. The acceptable range for the peak video signal voltage (of unobstructed light through the perf
hole) is between 2.7 and 5 volts (see figure 1). Under normal circumstances, the LED power supply voltage will never need
adjustment to achieve the acceptable video voltage range. However, some combinations of individual LED intensity and
projector speed may result in a video signal out side the 2.7 and 5 volt range. in that case, it may be necessary to adjust
the LED power supply.
If the top of the video waveform is not reasonably flat (+1-1 division), check for dirt, dust, or other obstruction to the light
path, and clean as necessary.
Optical Alignment
The Reader is optically aligned at manufacture and should not require adjustment unless the CCD board has been removed
or replaced (the CCD sensor is located on the CCD circuit board, Optical alignment of the sensor depends on the positron of
the circuit board). The procedure for confirming or adjusting the position of the CCD board follows.
Lateral
Lateral position can be confirmed if the video signal (of unobstructed light through the perf hole) on the oscilloscope falls in
the center of the total CCD video signal to center the video signal on the scope do the following.
1. Use the scope setup described
in the first section of these in-
structions, observebothchannel
1 and 2.
2. Run SRD film through projector.
3. The scope image should be ad-
justed to look like the diagram
at right.
4. If theCCDcircuitboard isaligned,
the video signal of light through
the pert hole will be centered
between the falling edge of clamp (trigger trace and the rising edge of the clamp trace. As in the diagram, distance
“X’will be equal on each side of the video signal.
5. To re-align the CCD board, first loosen the lateral lock screw, and then adjust the lateral position using the lateral
adjust screw. When the video trace is centered with respect to the clamp trace, tighten the lock screw.

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Azimuth
The azimuth adjustment controls the angular position of the CCD board with respect to the film. To adjust the azimuth of the
CCD do the following.
1. Loosen the azimuth lock screw.
2. Turn the azimuth adjust screw clockwise then counterclockwise and observe the LEDs on the Cat.671 boards of the
processor.
3. Center the rotation of the CCD circuit board assembly between the angles at which synchronization pattern finding
begins to fail. See discussion below.
4. Tighten the azimuth lock screw, and then refocus the Soundhead.
Verification of synchronization pattern finding
The Cat.671 cards are responsible for resampling and locating sync patterns in the digital data. These cards display sync
found on their LEDs. The 8 LEDs from top to bottom display sync found as follows:
* Upper Left found first pass
* Upper Right found first pass
* Lower Left found first pass
* Lower Right found first pass
* Upper Left found at all
* Upper Right found at all
* Lower Left found at all
* Lower Right found at all
If any of these LEDs are constantly unlit, this may indicate improper positioning of the film or CCD circuit board.
Proper adjustment of position, intensity and focus will be verified by observing no error light flashing and minimum error rate
displayed on the Cat.673 FIFO/Resources/Error Correction/Delay board.