Crown Audio CH Series, CL Series Power Indicator LED is driven from the low-voltage supply

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CH and CL Series Power Amplifiers

5 Principles of Operation

switch is set to 4/8 Ohm, only the negative and 4/8 ohm connections on the barrier block have audio present. This provides power to low impedance speakers. When the Channel Opera- tion switch is set to 70V, only the negative and 70V connections on the barrier block have audio present. This provides power to distrib- uted speakers in a high-impedance “constant- voltage” application.

The output relay, in conjunction with input sig- nal mute circuit, assures a quiet turn-on and turn-off. In the event of an amplifier output fail- ure, a triac will activate to turn off the offending channel to protect the speakers.

The turn-on delay circuit functions to keep the output relay open until all the voltages are up and stable, both in the amplifier, and in all the components in the system ahead of the ampli- fier.

Heatsink temperature is monitored by a thermal probe attached to the heatsink. As the tempera-

ture rises, the probe sends a proportional cur- rent to the proportional speed fan circuit which starts the fan. Should the power transformer reach its maximum safe temperature, an inter- nal thermal switch opens and the fan circuit turns on full speed to quickly cool down the amplifier. It also disconnects the load via the output relay, removing any output current and further speeding a cool-down cycle. This point is set both to protect speakers and to guard against nuisance tripping.

Whenever the heatsinks or the transformer reach a maximum temperature, or during the normal turn on delay window, the front panel Fault Indicators will blink.

An RJ11 modular jack is mounted on the back panel. Pins 2 and 5 are connected to an opto- isolator which is always in a low-resistance state whenever the unit is on and operational. Should a fault be detected or should the ampli- fier lose AC power, the opto-isolator will

change to a high resistance, allowing the user to remotely detect the status of the amplifier.

The Signal Presence Indicators tap the signal chain just before the level controls and prior to the power amplifier chain. They are not ampli- fier output indicators and should only be used to indicate the presence of signal at the ampli- fier front end.

The Clip Indicator is driven from the output of the compressor circuitry and lights to indicate the onset of audible distortion.

The Power Indicator LED is driven from the low-voltage supply.

A positive and negative regulator form the ±15- volt power supplies. Add to that the main trans- former, a full-wave bridge rectifier, and high energy electrolytic to form the main power sup- ply. They are protected by the front-panel line circuit breaker and controlled by the front-panel power switch.

BALANCED

INPUT STAGE

Figure 5.2 Models CL1 & CL2 Circuit Block Diagram

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Operation Manual

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Contents CH and CL Series Some models may be exported under the name AmcronImportant Safety Instructions Use only with a cart, stand, tripod, bracket, orSafety Standard Crown International, IncEuropean Representatives Name and Address EMC StandardsTable of Contents Features How to Use This ManualWelcome Setup Unpack Your Amplifier Install Your AmplifierChoose Input Wire and Connectors Choose Output Wire and ConnectorsReinstall no-touch cover to maintain safety Switch Settings Model CH4 Models CH1 and CH2Wire Your System Models CH1 & CH2 Stereo Mode Refer to .5 for output connector pin assign- mentsModels CH1 & CH2 140V Bridge Mode Model CH4 Stereo Mode Model CH4 Bridge ModeInputs Connect input wiring to Channel Models CL1 & CL2 Bridge Mode Models CL1 & CL2 StereoModel CL4 Stereo Mode Model CL4 Bridge ModeInputs Connect input wiring to CH1 All Models How to Parallel the Inputs in Stereo Mode Startup ProcedureScrew terminal Connect to AC MainsPrecautions OperationCH and CL Series Front Panel Controls and Indicators Operation Speed Fan-On-Demand Indicators If the amplifier output stage stops operatingControls Advanced Features Options SST-4622 SST-3632SST-4632 Fault Monitoring Location of Fault JackPrecision Detented Level Controls Attenuation in dBPrinciples of Operation CH1, CH2, CL1 and CL2Power Indicator LED is driven from the low-voltage supply Models CL1 & CL2 Circuit Block DiagramCH4 and CL4 Audio Signal Path Model CH4 Circuit Block DiagramModel CL4 Circuit Block Diagram Power Supply Operation Troubleshooting Amplifier output wires have developed a short circuitFlashing Specifications 120V/60 Hz Units, Bridge mono modeKHz at rated THD Ohms 560W Ohms 450WOhms 275W 600WModel CL1 & CL2 CH and CL Series Power Amplifiers Models CH4 & CL4 Damping Factor Typical Output Impedance AC Power Draw Thermal Dissipation Following equation is used to calculate thermal dissipationAC Power Draw Thermal Dissipation AC Power Draw Thermal Dissipation CL2 Service Warranty 12/01Worldwide Except USA & Canada Fax Mo/day/yrThis page Intentionally Left Blank Model Individual or Business Name Phone # Fax #‰ Personal/Consumer ‰ Business/Corporate
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