Dolby Laboratories DA20 User Manual - Page 17

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1. About the Dolby Da20 and the Dolby Stereo Digital Format

If One Channel Fails or is Distorted

This is unlikely to be a fault of the DA20. Check for analog audio path continuity. If the

problem is isolated to the DA20, contact your authorized Service Engineer.

If Switching to Analog Does Not Restore Sound

If switching to analog occurs when in Format 10 (indicated by the yellow Analog LED on

the DA20 front panel), but no analog sound is heard, FIRST select Format 05 (SR) by

means of the Cinema Processor format selector switches. If this doesn't work, remove

power to the DA20 and reselect Format 05.

If Difficulty with Changeover is Experienced

Correct changeover operation relies on installation of two relays which close sets of

contacts when each projector motor is running. The normally open (closed when

projector is running) contacts on these relays must be attached to connector J9 on the rear

panel of the DA20. (Refer to Installation manual for further information.) In addition, a

changeover signal from the Cinema Processor must be present and connected to the

DA20. Correct operation of these signals may be observed by monitoring the Proj1,

Motor1, Proj2, and Motor2 LEDs on the front panel of the DA20.

If Synchronization is Lost

Synchronization of the digital soundtrack with the picture requires that the film path

from the Soundhead to the picture gate be the same every time the projector is threaded.

If two projectors are used, the path lengths must be identical. Digital Soundhead delay is

set by switches on the Cinema Processor Interface Card (Cat. No.611A). If

synchronization becomes incorrect during a show, press Format 10. This re-sends a delay

turn-on command to the Cat No. 611A. If this does not solve the problem, then play the

rest of the show in Analog, Format 05, and when time permits, run a loop of Cat. No.1010

Digital Soundhead Test Film and adjust the delay as described in Section 3.

If none of the above techniques solves your problem, make sure the Cinema Processor is

not in format 10, and try cycling the power to the DA20. This will reset the DA20 and

may cure a transitory problem.

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