Marantz PM4001 Service Manual

The Marantz PM4001 is a high-quality stereo integrated amplifier featuring 45 watts per channel, MM phono input, multiple audio inputs, tone controls, headphone output, and remote control capability. This service manual provides technical specifications, circuit diagrams, adjustment procedures, troubleshooting guides, and maintenance information for qualified service technicians.

1. Technical Specifications 2. Block Diagram 3. Circuit Description 4. Adjustment Procedures 5. Parts List 6. PCB Layouts 7. Schematic Diagrams 8. Troubleshooting Guide 9. Service Notes 10. Safety Precautions 11. Contact Information

Technical Specifications

Complete technical specifications and performance characteristics of the Marantz PM4001 integrated amplifier.

Parameter	Specification
Power Output	45W + 45W (8Ω, 20Hz-20kHz, 0.08% THD)
Total Harmonic Distortion	0.08% (20Hz-20kHz at rated output)
Frequency Response	10Hz-50kHz (+0/-3dB)
Input Sensitivity	Phono: 2.5mV, Line: 200mV
Signal-to-Noise Ratio	Phono: 80dB, Line: 100dB
Inputs	Phono, CD, Tuner, Tape, Aux
Outputs	Speaker A/B, Tape Out, Headphone
Tone Controls	Bass: ±10dB, Treble: ±10dB
Power Supply	AC 120V/230V, 50/60Hz
Dimensions	440 x 125 x 345mm (W x H x D)

Block Diagram

System block diagram showing signal flow and major functional blocks.

Input Selector: Phono, CD, Tuner, Tape, Aux selection
Phono Equalizer: RIAA equalization circuit
Tone Control: Bass and treble adjustment circuits
Volume Control: ALPS motorized potentiometer
Power Amplifier: Dual mono power amplifier sections
Power Supply: Toroidal transformer with regulated supplies
Protection Circuit: DC offset and thermal protection

WARNING! High voltages present - qualified technicians only.

Circuit Description

Detailed description of major circuit sections and their operation.

Power Supply: Toroidal transformer with dual secondary windings
Phono Stage: Discrete JFET input stage with RIAA equalization
Pre-amplifier: Low noise op-amp based design
Power Amplifier: Complementary symmetry output stage
Protection Circuit: Speaker relay with DC detection
Control Circuit: Microprocessor based input selection

CAUTION! Always discharge power supply capacitors before servicing.

Adjustment Procedures

DC Offset: Adjust VR101/VR102 for 0mV ±5mV at speaker terminals
Bias Current: Set to 15mA ±2mA across emitter resistors
Phono Gain: Verify 40dB gain at 1kHz
RIAA Equalization: Check frequency response per RIAA curve
Input Sensitivity: Confirm proper input level matching
Protection Circuit: Test DC offset and thermal protection
Power Supply: Verify ±35V DC rails under load

Parts List

Complete component listing with manufacturer part numbers and specifications.

Main Board: Resistors, capacitors, transistors, ICs

Power Supply: Toroidal transformer, rectifiers, filter capacitors

Front Panel: Switches, potentiometers, indicators

Rear Panel: Input/output connectors, speaker terminals

Power Transistors: 2SC5200/2SA1943 complementary pairs

Op-amps: NJM4580 dual low-noise operational amplifiers

Filter Capacitors: 10,000μF 50V main supply capacitors

PCB Layouts

Printed circuit board layouts for all major assemblies.

Main Amplifier Board: Component placement and routing
Power Supply Board: High current traces and component layout
Control Board: Microprocessor and switching circuits
Front Panel Board: User interface components

Tip: Use original Marantz replacement parts for optimal performance.

Schematic Diagrams

Complete schematic diagrams for all circuit sections.

Power Amplifier Section: Output stage and driver circuits
Pre-amplifier Section: Input switching and tone control
Phono Equalizer: RIAA compliant equalization network
Power Supply: Rectification and filtering circuits
Protection Circuit: Speaker relay control
Control Circuit: Input selection and remote control

WARNING! Schematics contain lethal voltages - extreme caution required.

Troubleshooting Guide

Systematic troubleshooting procedures for common issues.

Symptom	Possible Cause	Corrective Action
No power	Fuse, power switch, transformer	Check main fuse F001; verify transformer primary
No sound	Protection circuit, power supply	Check speaker relay; measure power supply rails
Distorted output	Bias current, output transistors	Adjust bias current; check output transistors
Hum/buzz	Grounding, filter capacitors	Check ground connections; test filter capacitors
Intermittent operation	Cold solder joints, connectors	Inspect solder joints; check cable connections

Service Notes

Important service information and common repair procedures.

Use insulated tools when working on live circuits. Always replace output transistors in matched pairs. Thermal compound must be reapplied when replacing power transistors. Speaker protection relay contacts may require cleaning after extended use.

CAUTION! Always use isolation transformer when servicing primary side circuits.

Safety Precautions

Essential safety procedures for service technicians.

Disconnect from AC power before servicing. Discharge all large capacitors. Use proper grounding techniques. Wear safety glasses. Keep work area clean and organized. Follow electrostatic discharge precautions.

Contact Information

Marantz America, Inc. Service Department: 1-800-270-8877. Marantz Europe B.V.: +31-20-654-3201. Official website: www.marantz.com. Service parts ordering: [email protected]. Technical support available Monday-Friday 9:00-17:00 EST.