Sony Ericsson DFP-D3000 - Manual (Page 86)

9-52 DFP-3000
9.10 Adjusting the Analog Track Pickup
Digital audio tracks set a very high standard of quality for theatrical sound playback. In order to minimize
the difference between sound from digital tracks and sound reproduced from a film’s optical tracks, the
proper skills as well as caution are required for ensuring the best performance of the optical reader. This
chapter mainly describes the forward scan reader. As reverse scan readers have related adjustments which
may be slightly different for each brand, contact the appropriate manufacturer for specific instructions.
When adjusting the optical reader, follow the adjustment method indicated in the manual of the reader
used.
When adjusting A-Chain inputs, it is not necessary to provide commands to the Automation system of the
projector if the exciter lamp of the analog surround track is lit. (Only when the exciter lamp is off must
the Automation system be operated to light the exciter lamp.) The exciter lamp voltage should normally
be set to 75-85 % of its rated voltage as recommended by the manufacturer. As the following adjustments
typically interact with each other, they must be rechecked after initial settings.
9.10.1 Preliminary Preparations Before Adjustments
First thoroughly clean the sound head optics. Replace the exciter lamp if it is discolored or if it is not
sufficiently bright across the width of the slit and when its light falls on a white card held about an inch in
front of the optics. Be sure that the solar cell is mounted 1 mm away from the film. The most common
causes of uneven illumination are misaligned optics, dirty or aged exciter lamp, dirty optics or slit, and
running of the exciter lamp at a voltage that is too low.
9.10. 2 Lateral Film Guide Adjustment
The next step in adjusting the projector’s optical reader is to ensure that the optical pickup is correctly
adjusted to the optical tracks on the film. This is done by playing a loop of the SMPTE Buzz Track test
film and adjusting the projector’s lateral film guide for equal and minimum high and low frequency sound
from the left and right outputs. If you are adjusting an overscanning reverse scan reader you can also
perform this adjustment using the X-Y oscilloscope by equalizing the perpendicular X and Y traces.
9.10.3 Lateral Exciter Lamp Adjustment
Next in setting up a forward scan reader, roll a Cat. 97 “left/right” or “crosstalk” loop and observe the
signal when the film is run using a dual trace oscilloscope. Adjust the lateral position of the exciter lamp
to equalize the left and right output signal levels. Generally this adjustment can be facilitated by setting so
that the two channels overlap on the oscilloscope.
9.10.4 Lateral Solar Cell Adjustment
While playing the left/right loop, adjust the lateral position of the solar cell so as to achieve minimal
crosstalk between left and right output outputs. Generally, this adjustment can be facilitated by setting so
that two input states can be observed separately on the oscilloscope.