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Dolby Laboratories CP65 manual Section A-Chainalignment

Models: CP65

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4-1

SECTION 4

A-CHAIN ALIGNMENT

The A-chain is the part of the sound system that covers the film path, solar cell, optical preamplifier, slit loss equalizer and Dolby noise reduction circuit.

The CP65 does not contain a magnetic A-chain but has facilities for switching external magnetic preamplifiers into the B-chain. An overview of external magnetic A-chain adjustments is given at the end of this section.

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Dolby Laboratories CP65 manual Section A-Chainalignment

Contents

Model CP65 Cinema Processor Installation and Alignment Instructions100 Potrero Avenue San Francisco, CA Telephone Dolby Laboratories Inc U.S. HeadquartersU.K. European Office Dolby Laboratories IncEQUIPMENT REQUIRED Table of ContentsINITIAL SET-UPAND INSTALLATION INTRODUCTIONAPPENDIX D APPENDIX AAPPENDIX B APPENDIX C60 Non-sync INTRODUCTIONCP65 04 Dolby Stereo A-type 05 Dolby Stereo SRPage SECTION EQUIPMENT REQUIRED 1 Dolby Tone and Pink Noise - Cat. No2 1kHz, 100% Modulation, Left/Right - Cat. No JIFFY TEST FILM3SMPTE Buzz Track 4Stereo Optical Surround Level - Cat. NoSECTION INITIAL SET-UPAND INSTALLATION Voltage Range SettingVoltage AcceptableCat. No Cat. No. 249, Power Supply Module Cat. No. 242, B-ChainCardJ5 J6 J7 J8 J3 IN Cat. No. 443, Control Logic CardStandard CP65 or CP65A CP65 BackplaneCP65-300 In a CP65-300when Cat. No. 300 modules are fitted in place of the normal Cat. No. 350 modules J16 and J18 should be rotated so that the words “Format 42” appears the right way up. With J24 in the “NR” position input signals will be A-typedecoded when the Mag/Aux format is selected. With J24 in the “NO NR” position signals pass through the noise reduction modules but the processing will be turned off. If both of these processing options are required frequently an external switch may be connected to J24J1 Optical Bass Extension output level sets the output level range for the subwoofer channel. In the HIGH position J1 is set at the factory for a power amplifier input sensitivity of between 90 mV and 1.23 V. If the power amplifiers used in the installation are very sensitive 10 mV to 100 mV input sensitivity, it may be necessary to set J1 to the LOW position. If you are unsure of the sensitivity of your power amplifiers set J1 to the LOW position initially. If the high output position is required this will be determined during OBE alignment Card selected projector. Electronic switches selectCard Descriptions Slot7,8,9 Two-channelNoiseReduction Module 2 4 Channel DecoderCat. No SlotCard FunctionType Voltage SettingInternational FuseIMPORTANT - NOTE DE SECURITE IEC NOTICESGB F D I E S NL IMPORTANT SAFETY NOTICEHUM PROBLEMS 3.Room lighting dimmer controls SCR-TYPEModel CP65 With CP65 FADER turned up and format 04 selected SECTION AN OVERVIEW OF THE ALIGNMENT PROCEDURE 1. Aligning the A-Chain2. Aligning the B-Chain and with a broad range of speakers. Accurate equalization requires the use of standardized acoustic measurement procedures Many loudspeakers used in theatres are far from ideal and require boosting of the low- and high-frequencyextremes in order to produce an approximation of the standard reference response curve. Bass and treble controls-centeredon the turnover points of typical loudspeakers-liftthe ends of the spectrum without the need for large amounts of narrow- band boost from the third-octavecontrols in the Cat. No. 64 cards. The third-octavecontrols are used for minor adjustments that are required to smooth the frequency response curve SECTION A-CHAINALIGNMENT Indication a. Preliminary Proceduresa. Preliminary Procedures Notes ActionAction A-ChainAlignment Proceduresa. Preliminary Procedures a. Preliminary Procedures NotesIndication b. Optical Preamplifier Adjustmentsb. Optical Preamplifier Adjustments Notes ActionAction A-ChainAlignment Proceduresb. Optical Preamplifier Adjustments b. Optical Preamplifier Adjustments Notesb. Optical Preamplifier Adjustments Notes L L R R L L R RCAT NO b. Optical Preamplifier AdjustmentsREPEAT ActionIndicationn CAT. NO. 97 TEST FILMb. Optical Preamplifier Adjustments OSCILLOSCOPE TRACESRTA DISPLAY A-ChainAlignment Proceduresb. Optical Preamplifier Adjustments 12 ANDREPEAT A-ChainAlignment Proceduresb. Optical Preamplifier Adjustments Notes CAT NOFOR PROJECTOR NO. REPEAT 1 → b. Optical Preamplifier AdjustmentsMagnetic Alignment c. Magnetic Preamplifier AdjustmentsA-ChainAlignment Procedures c. Magnetic Preamplifier AdjustmentsMagnetic Alignment SECTION B-CHAINALIGNMENT Action a. Setting Room Equalizationa. Setting Room Equalization Notes bypassAction Loudspeakers and Crossoversa. Setting Room Equalization a. Setting Room Equalization Notesa. Setting Room Equalization bypassAmplifiers GeneralIndication B-ChainAlignment Proceduresa. Setting Room Equalization Notes ActionAction REPEATa. Setting Room Equalization a. Setting Room Equalization NotesAction B-ChainAlignment Proceduresa. Setting Room Equalization a. Setting Room Equalization NotesAction Do not adjusta. Setting Room Equalization a. Setting Room Equalization NotesIndication a. Setting Room Equalizationa. Setting Room Equalization Notes Action22REPEAT b. Adjusting L,C,R Gainb.Adjusting L,C,R Gain L 14 → 21 R 14 →Action c. Setting Mono Gainc. Setting Mono Gain Notes 79 dBCAction d. Subwoofer Alignment Cat. Nod. Subwoofer Alignment Cat. No. Notes B-ChainAlignment ProceduresAction 90 dBCB-ChainAlignment Procedures d. Subwoofer Alignment Cat. NoAction FROMd. Subwoofer Alignment Cat. No d. Subwoofer Alignment Cat. NoREPEAT Select format 04 Dolby Stereo A-Typed. Subwoofer Alignment Cat. No ActionAction SAME ASd. Subwoofer Alignment Cat. No d. Subwoofer Alignment Cat. NoAction Re Se. Surround Equalization Alignment Cat. No e. Surround Equalization Alignment Cat. NoAction e. Surround Equalization Alignment Cat. Noe. Surround Equalization Alignment Cat. No ActionREPEAT 88 dBC e. Surround Equalization Alignment Cat. NoAction Indication B-ChainAlignment Procedurese. Surround Equalization Alignment Cat. No ActionSetting f. Adjustment of Surround DelayThumbwheel Switch msecB-ChainAlignment Procedures g. Adjustment of Bypass Gaing. Adjustment of Bypass Gain Notes xx dBCg. Adjustment of Bypass Gain Notes FROM xx dBC -3dB yy dBCB-ChainAlignment Procedures g. Adjustment of Bypass GainAction h. Adjustment of Non-syncGainh. Adjustment of Non-syncGain Notes Press the format 60 non sync switchIndication h. Adjustment of Non-syncGainh. Adjustment of Non-syncGain Notes ActionB-ChainAlignment Procedures i. Adjustment of Mono Gain and Equalizationi.Adjustment of Mono Gain and Equalization Notes 5REPEAT PAGE 5-20STEPj. Final Checks Notes Press the format 04 Dolby Stereo A-type switchJIFFY TEST FILM j. Final ChecksSECTION REFERENCE DIAGRAMS Cat. No. 222 Dual Noise Reduction Module OUTPUTS INPUTSPage Cat. No. 242 B-ChainFacilities Card Cat. No. 249 Power Supply Card Cat. No. 259 Transformer Module OUTPUTS INPUTSCat. No. 443 Control Logic Card +15V CP65 POWER DISTRIBUTION TABLECat. No +24VAPPENDIX A CHECKING PHASING OF SPEAKERS 20,000 Frequency in Hz5,000 10,000APPENDIX C CP65M MONO INSTRUCTIONS 1.Operation2.Cat. No. 327A Circuit Description A3C2984 rev C.2 Schematic Cat. No. 327ATerminal Block TB2 APPENDIX D BACKPLANE CONNECTIONS LISTCP65 Backplane Connections Terminal Block TB1D connector J18