6-8
which closes when power is applied to the projector) is used to initiate the digital
changeover. Digital changeover occurs at eight seconds minus the amount of delay set at
installation. Eight seconds is the time between the motor start cue at the end of a reel and
the last picture frame on that reel. If the Digital Soundhead were located at the analog
soundhead position, no fixed delay would be required, and the digital changeover would
happen simultaneously with the picture changeover. Any amount of delay added to the
digital signal to compensate for “early reading” (ahead of the analog soundhead) must be
subtracted from the 8 seconds to get the time that the digital signal must be switched after
the motor start.
6.7
Operation With an Automation System
The DA20 may be used in conjunction with any standard automation system, but the
following guidelines must be followed:
When used with a CP45, CP55, CP65 or CP500, the automation system must use
momentary Cinema Processor format select lines. The DA20 senses and controls these
lines to switch between digital and analog as required. If format lines are held
continuously, incorrect operation will result, and this situation will need to be corrected.
When used with a CP200, the automation system controls the Cinema Processor, which
sends a signal to the DA20 indicating that digital sound is desired. The DA20 responds
with a signal indicating that digital audio has been decoded and is present on its output
lines, or that such decoding is not possible. No direct connection between the automation
system and the DA20 is used.
