MODEL DA20 DIGITAL FILM SOUND PROCESSOR Users' Manual Issue 4 Part No.
USERS' MANUAL FOR MODEL DA20 DIGITAL FILM SOUND PROCESSOR Dolby Laboratories Incorporated U.S.A. 100 Potrero Avenue, San Francisco, CA 94103 Tel: 415-558-0200; Fax: 415-863-1373 U.K. Wootton Bassett, Wilshire SN4 8QJ, England Tel: +44 (0)1793 842100; Fax: +44 (0)1793 842101 www.dolby.com WARRANTY INFORMATION—U.S.A.
i TABLE OF CONTENTS INTRODUCTION About this manual ........................................................................................................................................ ii About the Dolby DA20 and the Dolby Stereo Digital Format ............................................................... ii SECTION 1 OPERATING INSTRUCTIONS 1.1 1.2 1.3 1.4 1.5 1.6 1.7 How to Identify Sound Tracks on Prints .................................................................................
ii INTRODUCTION Thank you for purchasing the Dolby Model DA20 Digital Film Sound Processor. It combines the high performance for which all processors manufactured by Dolby Laboratories are well known with the latest digital technology to decode the Dolby Digital print format. About this manual This User’s Manual has been prepared specifically to help theater personnel get the most from the Model DA20 and Cat. No.700 Digital Soundhead after proper installation.
iii • Adjustable time delay for mounting the Cat. No.700 Digital Soundhead up to 135 frames in advance of the analog soundhead. • Adjustable surround delay to match theater size. • Simple interface to the Dolby Cinema Processors. • Comprehensive Cinema Processor status display. • Automatic switching to analog soundtrack in the event of damaged or missing digital data. The DA20 includes interface cables to mate with the required Cinema Processor type.
a 1-1 SECTION 1 OPERATING INSTRUCTIONS 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.1 How to Identify Sound Tracks on Prints Film Threading Displays Format Control Single Projector Installations Two Projector Changeover Operation Operation With An Automation System How to Identify Sound Tracks on Prints A Dolby Digital film print or a stereo optical print (A-Type or SR), or a mono optical print should be identified as such on both the film can and leader. However, with handling the identification may be lost.
1-2 1.2 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. Figure 1.2 shows Digital Soundhead film path threading.
1-3 Error Rate Display 1 = CP55 Auto Digital 2 = CP45/65/500 Auto Digital 3 = CP200 Auto Digital 5 = CP55 Auto Digital Disabled 6 = CP45/65/500 Auto Digital Disabled 7 = CP200 Auto Digital Disabled Cinema Processor Type Switch Output Signal Present Indicators L C R LS RS SW Fixed Delay 100 perf 10 perf 1 perf S SR D digital analog +10 +1 -1 -40 +10 +1 -1 -40 L R +10 +1 -1 -40 +10 +1 -1 -40 +10 +1 LS -1 -40 +10 +1 RS -1 -40 Digital Status Indicators C.P.
1-4 Digital Status Indicators These LEDs indicate the format of the audio coming from the DA20. When the upper (green) LED is on, Format 10 has been selected, and the DA20 is producing decoded digital audio. When the lower (yellow) LED is on, Format 10 has been selected but the DA20 is unable to decode digital information from the film (either the film is not a Dolby Digital print, or the data is unreadable) and has switched to the analog track.
1-5 LED will also light if the cinema processor is in Format 10 and an analog only film is played. In order for the DA20 to switch the cinema processor back to Format 10 after a reversion, the digital track must become correctable after a damaged section of film has passed, or an un-damaged digital track must be played after an analog-only film. At this point, the DA20 will switch the cinema processor back to Format 10 and the green “Digital” LED will again light.
1-6 • The DA20 detects that the CP45/CP65/CP500 is in a film format (01, 04, or 05). • Dolby Digital Audio is available. • No format buttons are pressed. If all of the above conditions exist, then the DA20 will automatically switch the cinema processor to Format 10, eliminating the need to cue Dolby Digital films or trailers. Exception - CP45s built before mid-1997: The DA20 will not automatically switch the CP45 into Format 10 if Format 01 (mono) has been selected.
1-7 will remember which format selector is set to Format 10 and will select this format whenever the CP200 is in any film format and valid digital audio is. If Format 10 is not detected on one of the format selectors, the DA20 will operate in Auto Digital Disabled mode. Once this occurs, if the user wishes to enable the Auto Digital mode, one of the CP200 format selectors must be programmed to Format 10 and the CP Type switch on the DA20 must be rotated out of and then back into position 3.
1-8 1.5 Single Projector Installations In single projector installations, the Proj 1 motor start input is normally grounded with a jumper. Presence of this conection is shown by a continuously illuminated Proj 1 led on the Cat. No. 611. If this connection is not present, a fault in the digital data will not cause the system to switch to analog; it will just go silent. For this reason it is very important to jumper pin 1 to pin 5 on the motor start connector J9 in a single projector system. 1.
2-1 SECTION 2 MAINTENANCE AND ADJUSTMENTS 2.1 2.2 2.3 2.1 Digital Soundhead Maintenance Print Cleanliness Adjustments Digital Soundhead Maintenance The Cat. No.700 Digital Soundhead should be kept clean and free of dust and dirt for best performance, just like your analog soundhead. Wiping the external surfaces with a clean cloth on a regular basis will keep the head looking new.
2-2 2.2 Print Cleanliness As with any soundtrack, keeping the print clean will give best performance. The Dolby Digital print format has robust error correction information encoded along with the audio data, and the DA20 uses a powerful digital error correction technique, allowing the data to be read perfectly even if scratches and dirt are present. However, best performance will be obtained if the print is kept clean. Standard film cleaners will provide good results.
3-1 SECTION 3 UNIT SERVICING / IN CASE OF DIFFICULTY 3.1 Troubleshooting During the Show Your theater sound system consists of a number of critical audio components in addition to the Dolby DA20 system. Thus, the first step when something goes wrong with the sound is to find the source of the problem. The troubleshooting chart for your cinema processor can be very helpful. If indications are that the fault lies in the DA20, the procedures in the following paragraphs may be useful.
3-2 2. 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. 3. 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.
A-1 APPENDIX A DA20 CIRCUIT BOARD LOCATIONS 670 671 671 673 674 675 686 611A Caution: Remove power before removing or inserting circuit boards. (Left to right, facing front of DA20): Slot Number 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 Cat. No.
