Dolby Laboratories CP65 manual Optical Preamplifier Adjustments

Page 30

4-6

A-Chain Alignment Procedures

b. Optical Preamplifier Adjustments

Step

Action

Indication

No.

 

 

 

 

 

1

2

3Cat. No.

240A

Proj. 1

GAIN Lt

hf

GAIN

Rt

hf

Lt tp

Lt

signal

present

Rt

Rt tp

GAIN Lt

hf

GAIN Rt

hf

Proj. 2 gnd

4-7

A-Chain Alignment Procedures

b. Optical Preamplifier Adjustments

Notes

Loosely install the stereo solar cell bracket on the projector. Position the bracket carefully until the surface of the cell is 1 mm from the film plane surface. Note that if this distance is exceeded, there will be crosstalk between the two optical stereo tracks. Check the image of the slit on the cell. The image should be a thin sharp line. The slit image should be as long as the cell, and positioned three-quarters of the way up the cell. Try to get the best compromise among all of these conditions and then tighten the cell bracket mounting screws.

Connect the cells to the correct CP65 input terminals via the terminal block, using a single “twisted pairs” shielded (screened) 4-conductor cable or two shielded 2-conductor cables. Connect the inner conductors to the projector input + and – terminals exactly as shown. Connect the shields only at the CP65 end. Note that the cell associated with the right channel is closest to the edge of the film.

Separate cells are used for each channel in reverse scan projectors. Both use identical red (high) and black (low) wires. A check will be made in Step 9 to determine the correct left and right placement.

On the Cat. No. 240A Optical Preamplifier Card

Turn all of the Proj 1 and Proj 2 gain potentiometers fully clockwise (CW).

Image 30
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 Adjustment of Surround Delay Thumbwheel SwitchMsec Setting 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 Cat. No +24V +15V 15V +12B+15M Appendix a Checking Phasing of Speakers Appendix B Effect of Changes in Slit Height on Slit Losses Appendix C CP65M Mono Instructions OperationCat. No a Circuit Description Schematic Cat. No a Appendix D Backplane Connections List Terminal Block TB3Connector J18