Marantz CDR631 Service Manual

The Marantz CDR631 is a professional CD recorder featuring digital and analog recording capabilities, digital signal processing, high-quality A/D and D/A converters, SCMS copy protection system, programmable recording functions, and comprehensive connectivity options. This service manual provides detailed technical information for qualified service personnel including schematics, alignment procedures, and troubleshooting guidelines.

1. Technical Specifications 2. Block Diagram Overview 3. Circuit Descriptions 4. Disassembly Procedures 5. Alignment and Adjustment 6. Test Points and Measurements 7. Troubleshooting Guide 8. Parts List and Exploded Views 9. PCB Layouts 10. Safety Precautions 11. Service Notes

Technical Specifications

Complete technical specifications for the Marantz CDR631 CD recorder system.

Parameter	Specification
Frequency Response	20Hz - 20kHz (±0.5dB)
Signal-to-Noise Ratio	>100dB
Dynamic Range	>95dB
Total Harmonic Distortion	<0.005%
Channel Separation	>90dB (1kHz)
Sampling Frequency	44.1kHz
Quantization	16-bit linear
Power Requirements	120V AC, 60Hz / 230V AC, 50Hz
Power Consumption	25W (operating)
Dimensions (W×H×D)	434 × 108 × 345 mm
Weight	5.2 kg

Block Diagram Overview

System architecture and signal flow description.

Digital Input Section: S/PDIF, optical inputs with digital receivers
Analog Input Section: Balanced and unbalanced inputs with A/D converters
Digital Signal Processing: Main processor and digital filter section
Recording System: Laser pickup mechanism and recording circuitry
Power Supply: Multi-voltage regulated power supply system
Control System: Microprocessor and user interface controls

WARNING! High voltages present in power supply section. Disconnect power before servicing.

Circuit Descriptions

Detailed analysis of major circuit blocks and their operation.

Digital Input Circuit: CS8412 digital receiver with PLL circuitry
Analog Input Circuit: PCM1800 A/D converter with anti-aliasing filters
Digital Filter: SM5843 oversampling digital filter
D/A Converter: PCM1702 20-bit D/A converters
Servo System: Focus, tracking, and sled servo circuits
System Control: HD6433254F10 main microprocessor
Display Driver: Front panel display and control interface
Power Supply: Switching regulator with multiple outputs

Disassembly Procedures

Step-by-step instructions for unit disassembly.

Remove top cover: Remove 6 screws from rear and sides
Remove front panel: Disconnect ribbon cables and remove 4 screws
Remove main board: Disconnect all connectors and remove mounting screws
Remove mechanism assembly: Release locking tabs and lift assembly
Access power supply: Remove shield and disconnect AC input

CAUTION! Handle laser assembly with care. Avoid static discharge on PCBs.

Alignment and Adjustment

Factory adjustment procedures and test requirements.

Required Test Equipment: Audio analyzer, oscilloscope, digital voltmeter, test CDs

Adjustment	Procedure	Specification
Laser Power	Adjust RV101 while monitoring test point TP101	450 ± 50mV
Focus Bias	Adjust RV102 using service remote	Center reading on scope
Tracking Balance	Adjust RV103 while playing test disc	Minimum jitter
Output Level	Adjust RV201 for 2.0V RMS at 1kHz 0dB	2.0V ± 0.1V

Test Points and Measurements

Critical test points and expected voltage measurements.

TP101: Laser power monitor - 450mV typical
TP102: +5V digital supply - 5.0V ± 0.2V
TP103: +12V analog supply - 12.0V ± 0.5V
TP104: -12V analog supply - -12.0V ± 0.5V
TP201: System clock - 16.9344MHz ± 10Hz
TP202: Focus error signal - 0V DC at rest
TP203: Tracking error signal - 0V DC at rest

Tip: Use high-impedance probes to avoid circuit loading.

Troubleshooting Guide

Common failure symptoms and diagnostic procedures.

Symptom	Possible Cause	Corrective Action
No power	Power supply failure	Check fuse F101, diodes D101-D104, regulator IC101
No disc recognition	Laser assembly fault	Check laser power, focus servo, replace pickup if necessary
No audio output	Audio circuit failure	Check IC201 (D/A converter), op-amps IC202-IC203
Display problems	Display driver issue	Check IC301, ribbon cables, +5V supply
Recording failures	Recording circuitry	Verify blank discs, check recording laser power, IC401

Parts List and Exploded Views

Complete parts listing with manufacturer part numbers.

Laser Pickup: KSS-213C or equivalent
Main Microprocessor: HD6433254F10
D/A Converter: PCM1702
A/D Converter: PCM1800
Digital Receiver: CS8412
Power Regulator: LM317T, LM337T
Fuse: T2A/250V (F101)
Transport Motor: SFW-1230-10T12

WARNING! Use only manufacturer-specified replacement parts.

PCB Layouts

Printed circuit board layouts and component locations.

Main Board (A-12345-1): Component side and solder side views
Power Supply Board (B-67890-1): Component placement diagram
Front Panel Board (C-24680-1): Switch and display layout
Mechanism Board (D-13579-1): Servo and motor driver components

Note: All boards are double-sided with plated-through holes.

Safety Precautions

Essential safety information for service personnel.

Always disconnect AC power before servicing. Use isolation transformer when testing live circuits. Beware of high voltages in power supply section. Follow ESD precautions when handling semiconductors. Use proper tools and test equipment.

CAUTION! Laser radiation - do not view directly with optical instruments.

Service Notes

Additional service information and updates.

Firmware version 1.2 or later required for CD-RW compatibility
Service mode access: Hold STOP and PLAY while powering on
Factory reset procedure: Service mode → System Reset
Common failure: Electrolytic capacitors C101-C104 in power supply
Recommended test discs: YEDS-18, SZP-1/6A

Service Support: Contact Marantz technical support for schematic updates and service bulletins.