Dolby Laboratories CP65 manual Chain Alignment Procedures Optical Preamplifier Adjustments

Page 31

	4-8
	A-Chain Alignment Procedures
	b. Optical Preamplifier Adjustments

Step	Action	Indication
No.	Action	Indication
No.
4	Cat. No.
4	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

5

format

01Mono

format

01Mono

6

			RTA
Cat. No. 240A
			IN
Proj. 1	Status
RV101	Gain	L
RV102 hf		L
RV102 hf
RV201	Gain	R
RV202 hf		R
RV202 hf
TP501 L tp			X
	L	SIGNAL
		SIGNAL
		PRESENT	Y
	R		Y
	R
TP502 R tp
RV301 Gain		L
RV302 hf		R
RV401 Gain		R	SCOPE
RV402 hf			SCOPE
Proj. 2	Status		DUAL TRACE
TP503 GND			DUAL TRACE
TP503 GND			MODE
			MODE

NOTE: Be sure that the vertical range is set the same on both channels.

4-9

A-Chain Alignment Procedures

b. Optical Preamplifier Adjustments

Notes

On the Cat. No. 240A Optical Preamplifier Card

Turn all of the Proj 1 and Proj 2 hf potentiometers fully counterclockwise (CCW).

Verify that power to the power amplifiers is OFF.

Press the Mono 01 format switch on the front panel; the LED in the switch should light.

Connect the RTA and the oscilloscope to the Cat. No. 240A TP501 L (left) and TP502 R (right) test points as shown in the interconnection diagram. Switch the scope to dual trace mode.

Earth (ground) both instruments at TP503 GND on the card.

The input to the RTA will be switched to the left channel or right channel in the following steps.

Image 31

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 Channel Decoder Slot Card Function Cat. NoTwo-channel Noise Reduction ModuleContains 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