Dolby Laboratories CP65 manual HUM Problems, Room lighting dimmer controls SCR-TYPE

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STEP 11 Turn the front pannel FADER fully down, then connect the CP65 to mains power.

Model CP65

STEP 12 With the NORMAL/BYPASS switch (accessible with the front door open) in the NORMAL position, verify that all three LEDs on the Cat. No. 249 Power Supply Module are lit. Close the front door and verify that format 04 Dolby stereo optical with surround, local active, and proj 1 or proj 2 LEDs are on (unless a different wake-up format was selected on the Cat. No. 443).

STEP 13 Select each format in turn, using the buttons on the front panel and check that the associated LED lights.

STEP 14 Press the MUTE pushbutton switch; the LED on the switch should blink. Press the MUTE pushbutton switch again; the LED on the switch should be off.

STEP 15 Set the NORMAL/BYPASS switch to the BYPASS position. The bypass LED on the front panel should blink and all other LEDs should be off.

STEP 16 Return the NORMAL/BYPASS switch back to the NORMAL position and apply power to the other projection room equipment.

HUM PROBLEMS

If you hear undesirable hum from the speakers when you apply power to the CP65 and other projection room equipment, check the following list for possible causes:

1.Ground loops caused by audio signal wiring, especially to power amplifiers. Only one end of an audio shield wire should be connected. See Pages 2- 3 and 2-4. Be sure to check the booth monitor installation.

The CP65 backplane contains a link which connects frame ground to signal/power ground (TB2 terminals 8 and 9). If you have checked items 1 through 7 and hum is still present, removing this link may fix the problem.

2.Projector power wiring. All mains wiring should be properly grounded.

3.Room lighting dimmer controls (SCR-TYPE).

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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 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 Thumbwheel Switch Adjustment of Surround DelayMsec 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 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 Appendix D Backplane Connections List Terminal Block TB3Connector J18