Marantz CDR420 Service Manual

The Marantz CDR420 is a professional-grade CD recorder featuring high-quality audio recording capabilities, digital and analog inputs, editing functions, and professional connectivity options. This service manual provides comprehensive technical information for service technicians, including schematics, alignment procedures, troubleshooting guides, and replacement parts information for proper maintenance and repair.

1. Technical Specifications 2. Block Diagrams 3. Circuit Descriptions 4. Disassembly Procedures 5. Alignment & Adjustment 6. Test Points & Measurements 7. Troubleshooting Flowcharts 8. Replacement Parts List 9. PCB Layouts 10. Wiring Diagrams 11. Service Notes

Technical Specifications

Detailed technical specifications and performance characteristics of the Marantz CDR420 CD recorder.

Parameter	Specification
Recording Format	CD-R/RW (74/80 minute discs)
Sampling Frequency	44.1 kHz
Quantization	16-bit linear
Frequency Response	20Hz - 20kHz (±0.5dB)
Signal-to-Noise Ratio	>95dB
Dynamic Range	>95dB
Total Harmonic Distortion	<0.005%
Inputs	Analog RCA, Digital coaxial, Digital optical
Outputs	Analog RCA, Digital coaxial, Digital optical
Power Requirements	120V AC, 60Hz / 230V AC, 50Hz
Power Consumption	25W (operating), 5W (standby)
Dimensions (W×H×D)	430 × 105 × 345 mm
Weight	5.5 kg

Block Diagrams

System block diagrams showing signal flow and functional relationships between major components.

Main System Block Diagram: Overall system architecture including digital and analog sections.
Digital Signal Processing Block: DSP chip and associated circuitry.
Laser Pickup System: Optical pickup assembly and servo control circuits.
Power Supply Block: Power distribution and regulation circuits.
Control System: Microprocessor and user interface circuits.

NOTE: Refer to detailed schematics for component-level analysis.

Circuit Descriptions

Detailed descriptions of major circuit sections and their operational principles.

Laser Pickup Circuit: KSS-213C laser pickup with focus and tracking servo systems.
RF Amplifier: CXA2549M RF signal processing IC.
Servo Control: CXD3068Q servo processor with digital PLL.
Digital Signal Processor: CXD3068Q handling EFM demodulation and error correction.
D/A Converter: PCM1716 24-bit/96kHz digital-to-analog converter.
A/D Converter: AK5355 24-bit/96kHz analog-to-digital converter.
Digital Interface: CS8415A digital audio receiver.
Power Supply: Switching regulator with multiple voltage outputs.
Control Microprocessor: HD6437043F28V 32-bit RISC processor.
Display Driver: Vacuum fluorescent display control circuit.

Disassembly Procedures

Step-by-step instructions for safe disassembly and reassembly of the CDR420.

Preparation: Disconnect power and all cables. Use anti-static precautions.
Top Cover Removal: Remove 6 screws from rear and sides, lift cover straight up.
Front Panel Removal: Remove 4 screws securing front panel assembly.
Main PCB Access: Remove 8 screws securing main circuit board.
Laser Pickup Replacement: Remove transport mechanism, disconnect flex cable, replace pickup.
Power Supply Board: Remove 4 screws and disconnect all connectors.
Reassembly: Reverse disassembly procedure, ensuring all connectors are secure.

WARNING! Laser safety - never look directly into laser beam. Use ESD protection.

Alignment & Adjustment

Factory adjustment procedures and service alignment specifications.

Adjustment	Test Point	Specification	Procedure
Laser Power	VR101	45-55mV	Measure RF amplitude at TP-RF
Focus Gain	VR102	2.5V ±0.2V	Oscilloscope at TP-FE
Tracking Gain	VR103	2.5V ±0.2V	Oscilloscope at TP-TE
RF Level	TP-RF	1.2Vpp ±0.2V	Play test disc, measure RF envelope
PLL Frequency	TP-PLL	4.3218MHz ±10kHz	Frequency counter at crystal X101
Output Level	Audio Out	2.0Vrms ±0.1V	1kHz 0dB test signal

NOTE: Use factory test discs and calibrated test equipment for all adjustments.

Test Points & Measurements

Critical test points and measurement procedures for performance verification.

Power Supply Voltages: +12V, +5V, +3.3V, -12V at designated test points.
RF Signal: TP-RF - should show clear eye pattern with 1.2Vpp amplitude.
Focus Error: TP-FE - S-curve with 3Vpp during focus search.
Tracking Error: TP-TE - sine wave during track crossing.

Spindle Motor: 500-900 rpm during play, controlled by FG signal.

Digital Audio: SPDIF output should show proper data stream.

Clock Signals: 16.9344MHz (system), 33.8688MHz (DSP).

CAUTION! Use proper grounding and observe safety precautions during measurements.

Troubleshooting Flowcharts

Systematic troubleshooting guides for common failure modes.

Symptom Possible Cause Diagnostic Procedure

No power Power supply, fuse, switch Check F101 (2A), measure DC outputs, verify AC input

No disc recognition Laser pickup, servo circuit Check laser emission, RF signal, focus/tracking servos

Disc not spinning Spindle motor, driver IC Measure motor resistance, check BA6791FP outputs

No audio output DAC, analog stage, muting Check PCM1716, op-amps NJM4580, muting transistors

Digital lock failure CS8415A, clock circuit Verify input signal, check PLL lock, measure clocks

Display problems VFD driver, power supply Check filament voltage, segment/grid signals

Recording failures Laser power, encoder Verify recording power, check encoder operation

Replacement Parts List

Original part numbers and specifications for service replacement components.

Laser Pickup: KSS-213C / SF-P101N

Spindle Motor: MF-310FK-12350 (6-pin)

Loading Motor: JF-12P2CN2 (12V DC)

Main ICs: CXD3068Q (DSP/Servo), PCM1716 (DAC), AK5355 (ADC)

Power Transistors: 2SC3852 (Q101), 2SA1490 (Q102)

Fuse: F101 - 2A 250V (T2A)

Belts: Loading belt SBL2.0

Capacitors: Main filter C101 2200μF/25V

Crystals: X101 16.9344MHz, X102 33.8688MHz

Display: VFD FUTABA 8D-02DG

PCB Layouts

Printed circuit board layouts for main board, power supply, and front panel.

Main PCB Top Layer: Component placement and routing for digital section.

Main PCB Bottom Layer: Ground plane and signal routing.

Power Supply PCB: Switching regulator and power distribution.

Front Panel PCB: Display, buttons, and control interface.

Connector Locations: All external and internal connector positions.

Test Point Locations: Designated test points for service measurements.

Adjustment Points: Location of all potentiometers and trim components.

NOTE: All layouts shown at 1:1 scale for accurate component location.

Wiring Diagrams

Complete wiring diagrams for internal and external connections.

Main Harness: Interconnect wiring between all major assemblies.

Power Supply Wiring: AC input and DC output distribution.

Front Panel Wiring: Display, switches, and indicator connections.

Transport Mechanism: Pickup, motor, and sensor wiring.

Audio I/O Wiring: Analog and digital audio input/output connections.

Control Wiring: Remote control and system control interfaces.

CAUTION! Verify all wiring against diagrams before applying power.

Service Notes

Important service information, updates, and special procedures.

Service Bulletin Date Description

SN-420-001 2002-03-15 Laser pickup KSS-213C replacement procedure update

SN-420-002 2002-06-22 Improved grounding for reduced digital noise

SN-420-003 2002-11-08 Power supply capacitor C101 specification change

SN-420-004 2003-02-14 Firmware update procedure for track marking issues

SN-420-005 2003-07-30 Spindle motor replacement compatibility notice

SN-420-006 2004-01-12 Recording level calibration procedure revision

Service Contacts: Marantz Service Department - 1-800-654-6633

Technical Support: service.marantz.com

Marantz CDR420 Service Manual © - All Rights Reserved 2025

Symptom	Possible Cause	Diagnostic Procedure
No power	Power supply, fuse, switch	Check F101 (2A), measure DC outputs, verify AC input
No disc recognition	Laser pickup, servo circuit	Check laser emission, RF signal, focus/tracking servos
Disc not spinning	Spindle motor, driver IC	Measure motor resistance, check BA6791FP outputs
No audio output	DAC, analog stage, muting	Check PCM1716, op-amps NJM4580, muting transistors
Digital lock failure	CS8415A, clock circuit	Verify input signal, check PLL lock, measure clocks
Display problems	VFD driver, power supply	Check filament voltage, segment/grid signals
Recording failures	Laser power, encoder	Verify recording power, check encoder operation

Service Bulletin	Date	Description
SN-420-001	2002-03-15	Laser pickup KSS-213C replacement procedure update
SN-420-002	2002-06-22	Improved grounding for reduced digital noise
SN-420-003	2002-11-08	Power supply capacitor C101 specification change
SN-420-004	2003-02-14	Firmware update procedure for track marking issues
SN-420-005	2003-07-30	Spindle motor replacement compatibility notice
SN-420-006	2004-01-12	Recording level calibration procedure revision