The Marantz SR770 is a high-performance AV receiver featuring Dolby Digital and DTS decoding, 5.1 channel amplification, multiple audio/video inputs, digital optical/coaxial inputs, AM/FM tuner, preamp outputs, and advanced DSP processing. This service manual provides comprehensive technical information for service technicians, including schematics, alignment procedures, troubleshooting guides, and replacement parts information.
Complete technical specifications and performance characteristics of the Marantz SR770 AV receiver.
| Parameter | Specification |
|---|---|
| Power Output | 80W x 5 (8 ohms, 20Hz-20kHz, 0.08% THD) |
| Frequency Response | 10Hz-100kHz (+1/-3dB) |
| Total Harmonic Distortion | 0.08% (20Hz-20kHz at rated power) |
| Signal-to-Noise Ratio | 96dB (line input) |
| Input Sensitivity | 200mV (line), 800mV (digital) |
| Digital Inputs | Optical x2, Coaxial x2 |
| Analog Inputs | RCA x6, Phono |
| Video Inputs | Composite x3, S-Video x3 |
| Outputs | 5.1 channel preamp, composite video, S-video |
| Dimensions | 440 x 161 x 418mm (WxHxD) |
| Weight | 12.5kg |
System block diagrams showing signal flow and interconnections between major components.
NOTE: Refer to schematic diagrams for detailed component-level information.
Detailed descriptions of major circuit sections and their operation.
Step-by-step instructions for safe disassembly and reassembly.
WARNING! Always disconnect AC power and discharge large capacitors before servicing.
Factory alignment procedures and adjustment points.
| Adjustment | Procedure | Test Equipment |
|---|---|---|
| DC Offset | Adjust VR501-VR505 for 0mV ±5mV | Digital Multimeter |
| Bias Current | Set to 10mA across emitter resistors | Millivolt Meter |
| FM Tuner Alignment | Adjust L101, L102 for maximum sensitivity | FM Signal Generator |
| AM Tuner Alignment | Adjust L201 for peak performance | AM Signal Generator |
| Display Brightness | Adjust RV701 for proper intensity | Visual Inspection |
Systematic troubleshooting guides for common problems.
| Symptom | Possible Cause | Test Procedure |
|---|---|---|
| No Power | Fuse, power supply, standby circuit | Check F801, measure standby +5V |
| No Audio Output | Protection circuit, amplifier failure | Check protection relay, measure output DC |
| Distorted Sound | Output transistors, bias circuit | Measure bias current, check output devices |
| No Display | Display driver, microprocessor | Check +12V supply to display, measure clock |
| Tuner Problems | RF section, PLL circuit | Check tuner supply voltages, measure PLL lock |
Key voltage measurement points and expected values.
CAUTION! Use proper grounding and observe polarity when measuring voltages.
Complete list of replacement parts with manufacturer part numbers.
| Part Number | Description | Location |
|---|---|---|
| 2SC5200 | Output Transistor NPN | Q501-Q505 |
| 2SA1943 | Output Transistor PNP | Q506-Q510 |
| LM317T | Voltage Regulator | IC801 |
| NJM4580 | Dual Op-Amp | IC201, IC202 |
| F801 | Main Fuse 5A | Power Supply |
| C801 | Main Filter Cap 10000μF | Power Supply |
Printed circuit board layouts and component placement diagrams.
Essential safety information for service personnel.
WARNING! High voltages present in power supply and amplifier sections. Always use isolation transformer. Discharge large capacitors before servicing. Use proper ESD protection when handling integrated circuits.
Additional service information and common repair tips.
Service Support: Contact authorized Marantz service centers for technical assistance and genuine replacement parts.