Specifications
7-6
Proper adjustment of position, intensity and focus will be verified by observing no
error light flashing and minimum error rate (1 to 8) displayed on the Cat. No. 673
board in the CP500.
7.7 How to Identify Types of Soundtracks
A Dolby Digital print, or stereo optical (A-type or SR),or mono optical print should
be identified as such both on the film can and the leader. However, with handling
the identification may be lost. If neither are available, close inspection of the film
will help distinguish the various types. Digital data blocks are printed between the
perforations on the side of the film next to the analog (Dolby SR) track.
Figure 7- 6.
Soundtracks
Dolby Digital Print Analog Dolby SR or A-type Print Mono Print
The digital data is clearly visible
between perforations next to the
analog track. The analog track is
Dolby SR.
Clear differences between the stereo
channels will be seen in some places
along the track.
Both tracks are the same.
7.8 Film Threading
The Cat. No. 700 Digital Soundhead is similar in many ways to a conventional
analog soundhead, having a lightweight flywheel, toothed sprocket, two pad rollers,
and two dashpot-damped tension arms. The pad rollers on the toothed sprocket are
coupled to allow easy film threading. A spring loaded roller arm damps variations in
input film tension. Bypass rollers are provided to bypass the soundhead with either
35 or 70 mm film. The figure below shows Digital Soundhead film path threading.
Care must be taken to thread the film the same way every time, so that the distance
from the optical pickup point to the film gate is constant from show to show.
Circuitry in the CP500 processor delays the signal read at the optical pickup by an
amount set during installation. The threading must match this delay, or improper
synchronization will result.
NOTE
: Film tension is important. A proper loop is set when the tension arms match the white half circles.
The arms must not touch, or be too far apart (approximately 5mm is correct).
A
C
B
A
C
C
B
B
A
Set film path so that top and bottom tension
arm rollers are approximately 5 MM (1/4 inch) apart.
Use the white painted semi-circles for angular alignment
of tension arms . Make sure that the rollers do not touch.
SR•D Print Threading Path
Bypass Threading Path
Figure 7- 7.
Digital Film Path Threading.