Dolby Laboratories CP65 manual Chain Alignment Procedures Adjustment of Bypass Gain, Xx dBC

Page 61

	5-44
					B-Chain Alignment Procedures
g. Adjustment of Bypass Gain

Step	Action									Indication
No.
1	NORMAL BYPASS
	NORMAL BYPASS

2

3	local active
	4	5	6
	4		6
	3		7
	2		8
	1		9
	0		10
	select		mute
	local/remote
4			xx dBC
			Cat. No.
			240A
	04		Dolby Stereo
	04		A-type
			A-type
			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

5-45

B-Chain Alignment Procedures

g. Adjustment of Bypass Gain

Notes

This section of the alignment procedure covers the adjustment of the gain that is in effect when the CP65 is switched from NORMAL to BYPASS.

Verify that the NORMAL/BYPASS switch is in the NORMAL position.

Thread and play the Cat. No. 69 Pink Noise film loop on the projector.

Check that the local FADER is selected — the local active LED on the CP65 is lit. If necessary, select the local FADER by pressing the select local/remote switch.

Set the FADER to the 7 setting.

Press the format 04 Dolby Stereo A-typeswitch. Measure and note the SPL (sound pressure level) in the theatre.

Image 61

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 Thumbwheel Switch Adjustment of Surround DelayMsec 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 15V +12B Cat. No +24V +15V+15M Appendix a Checking Phasing of Speakers Appendix B Effect of Changes in Slit Height on Slit Losses Operation Appendix C CP65M Mono InstructionsCat. No a Circuit Description Schematic Cat. No a Terminal Block TB3 Appendix D Backplane Connections ListConnector J18