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Dolby Laboratories CP65 manual c. Magnetic Preamplifier Adjustments, Magnetic Alignment

Models: CP65

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c. Magnetic Preamplifier Adjustments

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A-Chain Alignment Procedures

c. Magnetic Preamplifier Adjustments

Magnetic Alignment

The CP65 in its normal configuration does not provide noise reduction for signals entering through the Magnetic/Aux input. However an optional configuration using Cat. No. 300 SR/A modules in place of the normal Cat. No. 350 SR modules can be used for playing 70 mm Dolby Stereo prints. To use this option, headers J16, J17 and link J24 on the CP65 backplane must be in the correct position. See page 2-8 for information on the correct positions for J16, J17 and J24.

1.Inspect the magnetic head for evidence of wear. Wear can degrade the frequency response. De-magnetize the head and all elements in the film path, both metal and plastic (some plastic parts may have steel centers). If you have an Annis gauss meter or its equivalent, verify that no elements in the film path are magnetized. Repeat the degaussing, as required.

2.Inspect the penthouse and perform any mechanical adjustments in accordance with the manufacturer’s instructions. Verify that all bearings, gears, and guide rollers are in good working order.

3.Install the magnetic preamplifier according to the manufacturer’s information.

4.Connect the magnetic heads to the MPU input barrier strip with high-quality shielded cable, Belden 8451 or equivalent. Connect the shield at the MPU end only.

5.For a standard CP65 (fitted with Cat. No. 350 SR modules), no A-type noise reduction is provided for magnetic inputs.

•Connect the outputs of the magnetic preamplifier to the

“from mpu - no nr” inputs on the TB3 and TB4 barrier strips. See the wiring diagram on page 2-3.

For a CP65-300(fitted with Cat. No. 300 SR/A modules), A-type noise reduction is provided for L, C,R,S magnetic inputs.

•Connect the outputs of the magnetic preamplifier to the

“from mpu - (format 42)” inputs on TB6 (L,C,R,S) and "fmt 42" input on TB4 (Le, Re). See the wiring diagram on page 2-4.

6.Place the NORMAL/BYPASS switch in the BYPASS position.

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Dolby Laboratories CP65 manual c. Magnetic Preamplifier Adjustments, Magnetic Alignment

Contents

Model CP65 Cinema Processor Installation and Alignment InstructionsU.K. European Office Dolby Laboratories Inc U.S. HeadquartersDolby Laboratories Inc 100 Potrero Avenue San Francisco, CA TelephoneINITIAL SET-UPAND INSTALLATION Table of ContentsINTRODUCTION EQUIPMENT REQUIREDAPPENDIX B APPENDIX AAPPENDIX C APPENDIX DCP65 INTRODUCTION04 Dolby Stereo A-type 05 Dolby Stereo SR 60 Non-syncPage 1 Dolby Tone and Pink Noise - Cat. No SECTION EQUIPMENT REQUIRED2 1kHz, 100% Modulation, Left/Right - Cat. No 3SMPTE Buzz Track TEST FILM4Stereo Optical Surround Level - Cat. No JIFFYSECTION INITIAL SET-UPAND INSTALLATION Voltage SettingAcceptable Voltage RangeCat. No Cat. No. 242, B-ChainCard Cat. No. 249, Power Supply ModuleJ5 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 Descriptions selected projector. Electronic switches selectSlot CardReduction Module Two-channelNoise2 4 Channel Decoder 7,8,9Card SlotFunction Cat. NoInternational Voltage SettingFuse TypeGB F D I E S NL IEC NOTICESIMPORTANT SAFETY NOTICE IMPORTANT - NOTE DE SECURITE3.Room lighting dimmer controls SCR-TYPE HUM PROBLEMSModel CP65 With CP65 FADER turned up and format 04 selected 1. Aligning the A-Chain SECTION AN OVERVIEW OF THE ALIGNMENT PROCEDURE2. 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 a. Preliminary Procedures Notes a. Preliminary ProceduresAction Indicationa. Preliminary Procedures A-ChainAlignment Proceduresa. Preliminary Procedures Notes Actionb. Optical Preamplifier Adjustments Notes b. Optical Preamplifier AdjustmentsAction Indicationb. Optical Preamplifier Adjustments A-ChainAlignment Proceduresb. Optical Preamplifier Adjustments Notes ActionCAT NO L L R R L L R Rb. Optical Preamplifier Adjustments b. Optical Preamplifier Adjustments NotesIndicationn ActionCAT. NO. 97 TEST FILM REPEATRTA DISPLAY OSCILLOSCOPE TRACESA-ChainAlignment Procedures b. Optical Preamplifier AdjustmentsREPEAT 12 ANDA-ChainAlignment Procedures b. Optical Preamplifier AdjustmentsFOR PROJECTOR NO. REPEAT 1 → CAT NOb. Optical Preamplifier Adjustments b. Optical Preamplifier Adjustments NotesMagnetic Alignment c. Magnetic Preamplifier Adjustmentsc. Magnetic Preamplifier Adjustments A-ChainAlignment ProceduresMagnetic Alignment SECTION B-CHAINALIGNMENT a. Setting Room Equalization Notes a. Setting Room Equalizationbypass Actiona. Setting Room Equalization Loudspeakers and Crossoversa. Setting Room Equalization Notes ActionAmplifiers bypassGeneral a. Setting Room Equalizationa. Setting Room Equalization Notes B-ChainAlignment ProceduresAction Indicationa. Setting Room Equalization REPEATa. Setting Room Equalization Notes Actiona. Setting Room Equalization B-ChainAlignment Proceduresa. Setting Room Equalization Notes Actiona. Setting Room Equalization Do not adjusta. Setting Room Equalization Notes Actiona. Setting Room Equalization Notes a. Setting Room EqualizationAction Indicationb.Adjusting L,C,R Gain b. Adjusting L,C,R GainL 14 → 21 R 14 → 22REPEATc. Setting Mono Gain Notes c. Setting Mono Gain79 dBC Actiond. Subwoofer Alignment Cat. No. Notes d. Subwoofer Alignment Cat. NoB-ChainAlignment Procedures ActionB-ChainAlignment Procedures 90 dBCd. Subwoofer Alignment Cat. No Actiond. Subwoofer Alignment Cat. No FROMd. Subwoofer Alignment Cat. No Actiond. Subwoofer Alignment Cat. No Select format 04 Dolby Stereo A-TypeAction REPEATd. Subwoofer Alignment Cat. No SAME ASd. Subwoofer Alignment Cat. No Actione. Surround Equalization Alignment Cat. No Re Se. Surround Equalization Alignment Cat. No ActionAction e. Surround Equalization Alignment Cat. NoAction e. Surround Equalization Alignment Cat. NoREPEAT e. Surround Equalization Alignment Cat. No 88 dBCAction e. Surround Equalization Alignment Cat. No B-ChainAlignment ProceduresAction IndicationThumbwheel Switch f. Adjustment of Surround Delaymsec Settingg. Adjustment of Bypass Gain Notes g. Adjustment of Bypass Gainxx dBC B-ChainAlignment ProceduresB-ChainAlignment Procedures FROM xx dBC -3dB yy dBCg. Adjustment of Bypass Gain g. Adjustment of Bypass Gain Notesh. Adjustment of Non-syncGain Notes h. Adjustment of Non-syncGainPress the format 60 non sync switch Actionh. Adjustment of Non-syncGain Notes h. Adjustment of Non-syncGainAction Indicationi.Adjustment of Mono Gain and Equalization Notes i. Adjustment of Mono Gain and Equalization5REPEAT PAGE 5-20STEP B-ChainAlignment ProceduresJIFFY TEST FILM Press the format 04 Dolby Stereo A-type switchj. Final Checks j. Final Checks NotesSECTION 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 Cat. No CP65 POWER DISTRIBUTION TABLE+24V +15VAPPENDIX A CHECKING PHASING OF SPEAKERS 5,000 Frequency in Hz10,000 20,0001.Operation APPENDIX C CP65M MONO INSTRUCTIONS2.Cat. No. 327A Circuit Description A3C2984 rev C.2 Schematic Cat. No. 327ACP65 Backplane Connections APPENDIX D BACKPLANE CONNECTIONS LISTTerminal Block TB1 Terminal Block TB2D connector J18