Dolby Laboratories CP65 manual Repeat, Action

Page 44

5-10

B-Chain Alignment Procedures

a. Setting Room Equalization

Step			Action							Indication
No.
12		Cat. No.
12		242
	mono eq
	mono
	gain
	non-syncL
		R								75-80 dBC
		L								75-80 dBC
		L
	signal	C
	present R
		Ls
	gnd
		L
				FF
		C	O						0	30
	test			80		70	60	50	0
	test					70	60	50	4
	points R
		Ls
		L	Dolby
		L
	gain	C
	gain	R
		R
		Ls
13	REPEAT 11		→ 12
		Cat. No.
		242
	mono eq
	mono
	gain									75-80 dBC
	non-syncL
		R
		L
	signal	C
	present R
		Ls
	gnd		FF
	gnd		O	0		0			0	30
				8	7	0	60	50	4
					7		60	50
		L
	test	C
	test
	points	R
		Ls
			Dolby
		L
	gain	C
	gain	R
		R
		Ls
	Cat. No.
		242
	mono eq
	mono									75-80 dBC
	gain
	non-syncL
		R
		L
	signal	C
	present R
	Ls		OFF
	gnd		OFF							0
				80	70		0	50	0	3
				80			0		4
							6
		L
	test	C
	test
	points	R
	Ls		Dolby
	Ls
		L
	gain	C
	gain	R
		R
	Ls

5-11

B-Chain Alignment Procedures

a. Setting Room Equalization

Notes

With a sound pressure level meter located at the position in the theatre used for step 6, adjust the center channel gain on the Cat. No. 242 card until the channel produces a reading of 75-80 dBC. (After room equalization for all channels is set, the sound pressure level will be set to 85 dBC.) The pink noise should be at least 20 dB above the background noise level of the theatre. If a level of 75-80 dBC cannot be obtained, adjust the gain of the amplifiers and and try again. A row of four LEDS, signal present L, C, R and S, is on the front edge of the Cat. No. 242 card. Each LED indicates the presence of signal for the appropriate channel and lights intermittently when pink noise is sent through the system from the Cat. No. 85C or from a film.

Repeat steps 11 and 12 for the left and right channels. Switch on the appropriate pink noise switch on the Cat. No. 85C pink noise generator, one channel at a time.

Compare the response displayed on the real time analyzer (RTA) for each channel (L, C, R). All should show a similar shape. Any large differences indicate faulty or misaligned crossovers or defective speakers. Speaker phasing could also be at fault. See Appendix A.

Image 44

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 Slot Card Function Cat. No Two-channel NoiseReduction Module 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