Cambridge Audio 740A User Manual

Gallery Court Hankey Place London SE1 4BB UK
Tel: +44 (0)20 7940 2200 Fax: +44 (0)20 7940 2233
740A
Issue Date: 8
th
August 2007
SERVICE MANUAL
SPECIFICATIONS:
Power Output 100W RMS into 8 Ohms
150W RMS into 4 Ohms
THD (unweighted) < 0.001% 1 kHz
At 80% of rated power
< 0.01% 20 Hz – 20 kHz
At 80% of rated power
Frequency Response 10 Hz – 50 kHz +/- 1 dB
S/N Ratio (ref 1W/8 Ohms) > 96 dB
Input Impedances Inputs 1-6 47 kOhm
Power Amp Damping Factor > 110 at 1 kHz
Max Power Consumption 750W
Minimum Power Consumption Active (no signal) 45W
Standby 6W
Bass & Treble Controls Shelving Type
Max bass boost/cut
+/-10 dB at 10 Hz
Max treble boost/cut
+/- 7.5 dB at 20 kHz
Dimensions 115 x 430 x 350mm
(4.5 x 16.9 x 13.8”)
Weight 10.7kg (23.5Lbs)
AP22267/1
1

Cambridge Audio 740A Specifications

General

Brand	Cambridge Audio
Model	740A
Category	Amplifier
Language	English

Summary

Cambridge Audio 740A Service Manual

Specifications

Technical details of the Cambridge Audio 740A amplifier.

Safety Precautions & Important Notes

Essential safety guidelines for handling and servicing the amplifier.

Exploded Diagram Parts List

A list of components shown in the exploded diagrams for service.

Front Panel Circuit Diagram (Tone Control)

Schematic for the tone control section of the front panel circuit.

Front Panel Circuit Diagram (Microcontroller & LCD)

Schematic for the microcontroller and LCD components of the front panel.

Front Panel Board Layout (Top Side)

Visual layout of components on the top side of the front panel PCB.

Front Panel Board Layout (Bottom Side)

Visual layout of components on the bottom side of the front panel PCB.

Front Panel PCB Assembly BOM

Bill of Materials for the Cambridge Azur 740A front panel PCB.

Preamp PCB Circuit Diagram (Tone Control)

Schematic for the tone control circuit on the preamp PCB.

Preamp PCB Circuit Diagram (Protection Circuitry)

Schematic detailing the protection circuitry on the preamp PCB.

Preamp PCB Circuit Diagram (Power Supply)

Schematic for the power supply section of the preamp PCB.

Preamp PCB Circuit Diagram (Headphone Driver)

Schematic for the headphone driver circuit on the preamp PCB.

Preamp PCB Circuit Diagram (Buffers & Switches)

Schematic for the buffer and switch circuits on the preamp PCB.

Preamp PCB Board Layout (Top Side)

Visual layout of components on the top side of the preamp PCB.

Preamp PCB Board Layout (Bottom Side)

Visual layout of components on the bottom side of the preamp PCB.

Preamp PCB Assembly BOM

Bill of Materials for the Cambridge Azur 740A preamp PCB.

Amplifier PCB Circuit Diagram (Speaker PCB)

Schematic for the speaker output circuit on the amplifier PCB.

Amplifier Circuit Diagram (Right Channel)

Schematic for the right channel amplifier section.

Amplifier Circuit Diagram (Left Channel)

Schematic for the left channel amplifier section.

Amplifier Circuit Diagram (Protection)

Schematic detailing the protection circuits for the amplifier.

Amplifier Circuit Diagram (Power Supply)

Schematic for the power supply section of the amplifier.

Amp PCB Board Layout (Top Side)

Visual layout of components on the top side of the amplifier PCB.

Amp PCB Assembly BOM

Bill of Materials for the Cambridge Azur 740A amplifier PCB.

Abus PCB Circuit Diagram

Schematic for the Cambridge Control Bus (Abus) interface circuit.

Abus PCB Board Layout (Top Side)

Visual layout of components on the top side of the Abus PCB.

ABUS Hub PCB Assembly BOM

Bill of Materials for the Cambridge Azur 740A ABUS Hub PCB.

Mains PCB Circuit Diagram (Mains)

Schematic for the mains power input and filtering circuit.

Mains PCB Board Layout (Top Side)

Visual layout of components on the top side of the mains PCB.

Mains PCB Assembly BOM

Bill of Materials for the Cambridge Azur 740A mains PCB.

IC Pin Layout Details

Pinout diagrams and identification for integrated circuits and transistors.

Service Mode Instructions

Guide to accessing and using the amplifier's service mode functions.

Software Update Instructions

Procedure for updating the front panel control software.

Kanda PIC Hand Held Programmer Modification Instructions

Detailed steps for using the Kanda programmer for firmware updates.