Dolby Laboratories manual Appendix C CP65M Mono Instructions, Operation

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C-1

APPENDIX C

CP65M (MONO) INSTRUCTIONS

1.Operation

The CP65 can be configured for mono-only operation. Systems so equipped are shipped with only the center channel Cat. No. 64 house equalization module and without the Cat. No. 150 surround decoder module and Cat. No. 241 or 441 surround equalizer and optical bass extension board. A Cat. No. 327A mono board replaces the Cat. No. 150 module. The Cat. No. 443 control board should have diode D56 in the INC (Inhibit Center) row removed.

When the system is so configured, optical and non-sync sources will be summed and sent to the center channel via the fader or faders and house equalization. When using non-sync inputs the left, right, and center LEDs on the Cat. No. 242 will light although signal will only be present at the center channel output. Magnetic and auxiliary center channel inputs can be selected by choosing the appropriate format using the front panel controls.

Mono films should be played using format 01 Mono. However, with the CP65M, Dolby Stereo films can be screened with the noise reduction and wider frequency response usually only available in Dolby Stereo theatres. Simply select format 04 Dolby Stereo A-type. This turns on the noise reduction circuitry and disables the mono filter. Although the sound will be monophonic, the quality of reproduction will be improved. If your CP65M is fitted with Cat. No. 300 or 350 modules, you can play Dolby Stereo SR prints best by selecting format 05 Dolby Stereo SR.

Follow the level adjustment procedures in the installation and alignment manual. Adjust only the center channel.

2.Cat. No. 327A Circuit Description

The Cat. No. 327A mono board accepts four inputs: optical Lt and Rt from the Cat. No. 222 or Cat. Nos. 350/300 at both 300 and 500 mV levels. All inputs are combined and fed to the output, which appears at the same pin as the center output of a Cat. No. 150.

The Cat. No. 327A may be replaced by a Cat. No. 327 but this will require re-adjustment of levels. Follow the level adjustment procedures in the installation and alignment manual. Adjust only the center channel.

A signal present LED is provided at the output of the Cat. No. 327A. It will come on at about 15 dB below Dolby level, which is the same threshold as the other signal present lights in the system.

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Contents Model CP65 Cinema Processor Dolby Laboratories Inc Headquarters Table of Contents Section Reference Block Diagrams Introduction Page Section Equipment Required Jiffy Test Film Cat. No 2 Listen . . . Film Cat. No Smpte Buzz Track Stereo Optical Surround Level Cat. NoSection Initial SET-UP and Installation Voltage Acceptable Setting Voltage Range Fuse Type Next, check the jumpers in the following locations Cat. No , B-Chain Card Cat. No , Power Supply ModuleJ2 NON-SYNC Cat. No , Control Logic CardStandard CP65 or CP65A CP65 BackplaneCP65-300 High Low Subwoofer subwoofer Output output These Modules are Necessary for Bypass Operation Channel Decoder Slot Card Function Cat. NoTwo-channel Noise Reduction ModuleContains a semi-regulated power supply with International Voltage Setting Fuse TypeIEC Notices Room lighting dimmer controls SCR-TYPE HUM ProblemsPage Aligning the B-Chain Section AN Overview of the Alignment ProcedurePage Page Section Chain Alignment Action Indication Preliminary ProceduresLamp Voltage Optical Preamplifier Adjustments Chain Alignment Procedures Optical Preamplifier Adjustments 222 CAT. no Test Film Oscilloscope Traces Repeat Repeat 1 → CAT noMagnetic Preamplifier Adjustments Magnetic Alignment 100mV Section Chain Alignment Bypass Setting Room EqualizationLoudspeakers and Crossovers General AmplifiersOff Chain Alignment ProceduresAction RepeatChain Alignment Procedures Setting Room Equalization Do not adjust Paul 14 → 21 R 14 → Setting Room Equalization b. Adjusting L,C,R Gain79 dBC Setting Mono GainChain Alignment Procedures Subwoofer Alignment Cat. No 85 dBC 90 dBCStep No FromSelect format 04 Dolby Stereo A-Type 441 Same ASSurround Equalization Alignment Cat. No Cat. No 441 Surround Equalization Alignment Cat. No NotesDesired 88 dBC Bypass Thumbwheel Switch Adjustment of Surround DelayMsec Setting Xx dBC Chain Alignment Procedures Adjustment of Bypass GainXx dBC -3 dB Yy dBC FromPress the format 60 non sync switch Adjustment of Non-sync GainAuto Freq Repeat page 5-20 Step Adjustment of Mono Gain and Equalization NotesPress the format 04 Dolby Stereo A-type switch Chain Alignment Procedures Final ChecksSection Reference Diagrams Cat. No Dual Noise Reduction Module Inputs Cat. No Optical Bass Extension and Surround Equalizer Card Cat. No B-Chain Facilities Card Cat. No Power Supply Card Cat. No Transformer Module Inputs Cat. No Control Logic Card 15V +12B Cat. No +24V +15V+15M Appendix a Checking Phasing of Speakers Appendix B Effect of Changes in Slit Height on Slit Losses Operation Appendix C CP65M Mono InstructionsCat. No a Circuit Description Schematic Cat. No a Terminal Block TB3 Appendix D Backplane Connections ListConnector J18