The Marantz SR 870 is a high-performance AV receiver featuring Dolby Digital and DTS decoding, 7-channel amplification, multiple audio/video inputs, AM/FM tuner, and advanced connectivity options. This service manual provides comprehensive technical information for qualified service technicians, including schematics, alignment procedures, troubleshooting guides, and replacement parts information.
Complete technical specifications and performance characteristics of the Marantz SR 870 AV receiver.
| Parameter | Specification |
|---|---|
| Power Output | 100W x 7 channels (8Ω, 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 | 100dB (IHF-A weighted) |
| Input Sensitivity | 200mV (line inputs) |
| Digital Inputs | Coaxial x 2, Optical x 2 |
| Video Inputs | Composite x 4, S-Video x 3, Component x 2 |
| Audio Inputs | Analog x 6, Phono (MM) |
| Outputs | 7.1 pre-out, Zone 2, Headphone, Composite/S-Video monitor |
| Dimensions | 440 x 430 x 171mm (W x D x H) |
| Weight | 14.5kg |
System block diagrams showing signal flow and functional relationships between major components.
NOTE: Refer to schematic diagrams for detailed circuit information.
Detailed descriptions of major circuit sections and their operation.
Step-by-step instructions for safe disassembly and reassembly.
WARNING! Disconnect AC power and discharge large capacitors before servicing.
Factory alignment procedures and adjustment points.
| Adjustment | Procedure | Test Equipment |
|---|---|---|
| DC Offset | Adjust VRxxx for 0mV ±5mV at speaker terminals | Digital multimeter |
| Bias Current | Adjust VRxxx for 10mA across emitter resistors | Digital multimeter |
| FM Tuner Alignment | Adjust Lxxx for maximum signal strength | FM signal generator, oscilloscope |
| AM Tuner Alignment | Adjust Txxx for peak performance | AM signal generator |
| Dolby Level | Adjust VRxxx for 200mV at test point | Audio generator, oscilloscope |
Systematic troubleshooting procedures for common problems.
| Symptom | Possible Cause | Corrective Action |
|---|---|---|
| No power | Power supply failure, fuse blown | Check AC input, replace fuse, test power supply voltages |
| No audio output | Amplifier failure, protection circuit active | Check speaker connections, test amplifier outputs, reset protection |
| Distorted audio | DC offset incorrect, bias current wrong | Adjust DC offset and bias current per service manual |
| No video output | Video processor failure, bad connections | Check video inputs, test video processor IC |
| Tuner not working | Antenna connection, tuner alignment | Check antenna, realign tuner if necessary |
| Remote control issues | Batteries, IR sensor, microprocessor | Replace batteries, test IR sensor, check microprocessor |
Recommended replacement parts and components.
NOTE: Use genuine Marantz parts for optimal performance and reliability.
Printed circuit board layouts and component locations.
CAUTION! High-voltage areas clearly marked - exercise extreme caution.
Complete wiring diagrams and interconnection information.
Essential safety information for service technicians.
WARNING! Lethal voltages present - qualified technicians only.
Important service information and common issues.
| Issue | Description | Solution |
|---|---|---|
| Protection mode | Unit enters protection on power-up | Check output transistors for shorts, verify DC offset |
| Display issues | Front panel display dim or missing segments | Check display driver IC, verify power to display |
| HDMI problems | No signal through HDMI inputs | Update firmware, check HDMI board connections |
| Network issues | Ethernet connection problems | Check network settings, test network IC |
| Overheating | Unit shuts down due to overheating | Clean ventilation, check fan operation, verify bias current |
Service Support: Contact Marantz technical support for complex issues.