Dolby Laboratories CP65 manual 100mV

Page 38

4-21

A-Chain Alignment Procedures

c. Magnetic Preamplifier Adjustments

Magnetic Alignment

7.Remove the Cat. No. 242 card and locate the reversible plug-in Magnetic Input Sensitivity header.

100mV

in

in 1V

The CP65 accepts a nominal operating input level of either 100 mV or 1V — chosen by the position of the reversible plug-in header. The input impedance of the CP65 is 100K at both input levels. In addition, some preamplifiers may require a termination resistor (usually 600 ohms). You can connect the termination resistors at the input barrier strip TB3 and TB4 "from mpu–no nr" terminals on the backplane. Note that changeover between projector 1 and projector 2 must be accomplished in the magnetic preamplifier.

If noise reduction is to be used for decoding 70 mm Dolby Stereo soundtracks, the header on the Cat. No. 242 B-chain card must be set to the 100 mV position.

If the existing non-Dolby magnetic preamplifiers are used, their compatibility with the CP65 must be ensured.

8. Re-install the Cat. No. 242 card and restore the NORMAL/BYPASS switch to the NORMAL position.

Image 38

Contents Model CP65 Cinema Processor Dolby Laboratories Inc Headquarters Table of Contents Section Reference Block Diagrams Introduction Page Section Equipment Required Smpte Buzz Track Stereo Optical Surround Level Cat. No Jiffy Test Film Cat. No 2 Listen . . . Film Cat. NoSection Initial SET-UP and Installation Voltage Acceptable Setting Voltage Range Fuse Type Next, check the jumpers in the following locations Cat. No , Power Supply Module Cat. No , B-Chain CardCat. No , Control Logic Card J2 NON-SYNCCP65 Backplane Standard CP65 or CP65ACP65-300 High Low Subwoofer subwoofer Output output These Modules are Necessary for Bypass Operation Reduction Module Slot Card Function Cat. NoTwo-channel Noise Channel DecoderContains a semi-regulated power supply with Voltage Setting Fuse Type InternationalIEC Notices HUM Problems Room lighting dimmer controls SCR-TYPEPage Section AN Overview of the Alignment Procedure Aligning the B-ChainPage Page Section Chain Alignment Preliminary Procedures Action IndicationLamp Voltage Optical Preamplifier Adjustments Chain Alignment Procedures Optical Preamplifier Adjustments 222 CAT. no Test Film Oscilloscope Traces Repeat CAT no Repeat 1 →Magnetic Preamplifier Adjustments Magnetic Alignment 100mV Section Chain Alignment Setting Room Equalization BypassLoudspeakers and Crossovers Amplifiers GeneralChain Alignment Procedures OffRepeat ActionChain Alignment Procedures Setting Room Equalization Do not adjust Paul Setting Room Equalization b. Adjusting L,C,R Gain 14 → 21 R 14 →Setting Mono Gain 79 dBCChain Alignment Procedures Subwoofer Alignment Cat. No 90 dBC 85 dBCFrom Step NoSelect format 04 Dolby Stereo A-Type Same AS 441Surround Equalization Alignment Cat. No Surround Equalization Alignment Cat. No Notes Cat. No 441Desired 88 dBC Bypass Msec Setting Adjustment of Surround DelayThumbwheel Switch Chain Alignment Procedures Adjustment of Bypass Gain Xx dBCFrom Xx dBC -3 dB Yy dBCAdjustment of Non-sync Gain Press the format 60 non sync switchAuto Freq Adjustment of Mono Gain and Equalization Notes Repeat page 5-20 StepChain Alignment Procedures Final Checks Press the format 04 Dolby Stereo A-type switchSection 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 +15M Cat. No +24V +15V15V +12B Appendix a Checking Phasing of Speakers Appendix B Effect of Changes in Slit Height on Slit Losses Cat. No a Circuit Description Appendix C CP65M Mono InstructionsOperation Schematic Cat. No a Appendix D Backplane Connections List Terminal Block TB3Connector J18