Dolby Laboratories CP65 manual CAT. no Test Film

Page 33

4-12

A-Chain Alignment Procedures

b. Optical Preamplifier Adjustments

Step

 

 

Action

 

Indicationn

 

No.

 

 

 

 

 

 

 

 

 

 

9

 

 

 

 

 

 

 

 

 

CAT. NO. 97 TEST FILM

 

 

 

 

 

 

 

 

OSCILLOSCOPE TRACE

 

10

 

 

 

CAT NO.

 

 

 

 

 

222

Cat. No.

 

 

 

 

 

 

240A

 

 

 

 

 

 

Proj. 1

 

 

 

 

 

 

GAIN

 

 

 

 

 

 

Lt

 

 

 

 

 

 

hf

Lt

 

 

 

 

 

GAIN

 

 

 

 

Lt

 

 

 

 

 

Rt

 

 

 

 

 

hf

 

 

 

 

 

Lt tp

 

 

 

 

 

 

 

 

 

 

 

 

Lt

Rt

 

 

 

 

 

signal

 

 

 

 

 

 

 

 

 

 

 

present

 

 

 

 

 

 

Rt

 

 

 

 

 

Rt

Rt tp

 

 

 

 

 

GAIN

 

 

 

 

 

 

 

 

 

 

 

 

Lt

 

 

 

 

 

 

hf

 

 

 

 

 

 

GAIN

 

 

 

 

 

 

Rt

 

 

 

 

 

 

hf

 

 

 

 

 

 

Proj. 2

 

 

 

 

 

 

gnd

 

 

L R

 

 

 

 

 

11

REPEAT

8

AND 9

 

 

 

4-13

A-Chain Alignment Procedures

b. Optical Preamplifier Adjustments

Notes

Remove the SMPTE Buzz Track Film and thread and play the Cat. No. 97 Stereo Cell Alignment Film. While the film is playing, look at the oscilloscope. If a large amount of crosstalk is present, loosen the stereo solar cell head and move the head from side to side until the crosstalk both left-to-right and right-to-left are both at a minimum and are equal.

(The right channel is the track toward the outside of the projector.) You should be able to adjust the position of the cell to obtain better than 20 dB of crosstalk rejection (10:1 voltage ratio) both left-to-right and right-to-left. Setting the gain of both channels of the preamplifier to a known setting such as minimum or maximum gain will assist in judging when the crosstalk is equal right-to-left and left-to-right NOTE: On some projectors, it may be necessary to stop the film to adjust the position of the cell.

Lock the cell bracket into position after completing this adjustment. Check that the crosstalk has not changed as the bracket was tightened.

Verify that the outputs of the right and left solar cells are properly connected per the diagram in Step 2. Then place a white card over the right solar cell (nearer the outside of the projector) and verify that the level of the right channel drops — as indicated by the R LED on the Cat. No. 222 card, and the R LED on the Cat. No. 240A card.

Repeat the SMPTE Buzz Track alignment in Step 8. If the film or optics/exciter lamp position must be readjusted, repeat Step 9. The optimum setting is attained when no further adjustments are required in Steps 8 and 9.

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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 Two-channel Noise Slot Card Function Cat. NoReduction Module Channel DecoderContains 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 Adjustment of Surround Delay Thumbwheel SwitchMsec 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 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 Terminal Block TB3 Appendix D Backplane Connections ListConnector J18
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