Marantz PM-66SE Service Manual

The Marantz PM-66SE is a high-quality stereo integrated amplifier featuring 2x50W RMS output power, MM/MC phono input, CD direct input, tone controls, loudness compensation, A/B speaker switching, and headphone output. This service manual provides comprehensive technical information for service technicians, including schematics, alignment procedures, parts list, and troubleshooting guidelines.

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

Technical Specifications

Detailed electrical and mechanical specifications for the PM-66SE integrated amplifier.

Parameter	Specification
Output Power	2 x 50W RMS (8Ω, 20Hz-20kHz, 0.02% THD)
Total Harmonic Distortion	<0.02% (20Hz-20kHz at rated output)
Frequency Response	5Hz-100kHz (+0/-3dB)
Input Sensitivity	CD: 150mV, Phono MM: 2.5mV, Phono MC: 200μV
Signal-to-Noise Ratio	CD: 100dB, Phono MM: 85dB, Phono MC: 74dB
Tone Control	Bass: ±10dB at 100Hz, Treble: ±10dB at 10kHz
Power Supply	220-240V AC, 50/60Hz (EU version)
Dimensions	440 x 115 x 355mm (W x H x D)
Weight	7.5kg

Block Diagram & Circuit Description

Complete system overview and detailed circuit analysis.

Power Supply Section: Toroidal transformer, bridge rectifier, filter capacitors
Preamplifier Stage: Phono equalization, line amplification, tone control
Power Amplifier Section: Complementary symmetry output stage, protection circuit
Control Circuitry: Input selection, volume/tone control, speaker switching

NOTE: All voltages measured with respect to chassis ground unless otherwise specified.

Disassembly Instructions

Step-by-step guide for accessing internal components.

Remove top cover: Unscrew 6 Phillips screws on top panel
Remove bottom cover: Unscrew 4 screws on bottom panel
Front panel removal: Remove knobs and unscrew front panel screws
PCB access: Remove relevant mounting screws and connectors

WARNING! Disconnect power cord before disassembly. High voltages present even when unplugged.

Alignment & Adjustment Procedures

Factory calibration and adjustment methods.

DC Offset Adjustment: Adjust VR101/VR102 for 0mV ±5mV at speaker terminals
Bias Current Adjustment: Set VR103/VR104 for 15mA across emitter resistors
Phono Equalization: Verify RIAA curve compliance using test equipment
Volume Balance: Check channel balance at various volume settings

Schematic Diagrams

Complete circuit schematics for all sections.

Main Amplifier Circuit
Power Supply Schematic
Preamplifier and Tone Control
Input Selector and Volume Control
Protection Circuit

Tip: Use original Marantz schematics for accurate component values and layout.

PCB Layouts

Printed circuit board diagrams and component placement.

PCB	Description	Reference
Main Board	Amplifier and power supply circuits	PCB-001
Control Board	Input selection and tone control	PCB-002
Front Panel	Switches and indicators	PCB-003

Parts List

Complete component listing with manufacturer part numbers.

Power Transistors: 2SC3281/2SA1302 (Output), 2SC2705/2SA1145 (Driver)
ICs: NJM4558 (Op-amps), TA7317P (Protection)
Capacitors: 10,000μF/63V (Main filter), 220μF/16V (Coupling)
Resistors: Metal film 1%, Carbon film 5%
Potentiometers: ALPS volume and tone controls

Troubleshooting Guide

Common issues and diagnostic procedures.

Symptom	Possible Cause	Corrective Action
No sound output	Protection circuit, blown fuses	Check speaker terminals for DC offset; replace fuses
Distorted sound	Bias current, output transistors	Adjust bias current; test output transistors
Hum/buzz	Ground loops, filter capacitors	Check ground connections; test power supply caps
One channel dead	Input selector, volume control	Clean controls; check signal path components
Overheating	Bias current, ventilation	Adjust bias; ensure proper ventilation

Safety Precautions

Essential safety guidelines for service personnel.

Always use isolation transformer when servicing live circuits. Discharge large capacitors before handling. Use appropriate personal protective equipment.

CAUTION! High voltages present in power supply section. Risk of electric shock.

Service Notes

Additional technical information and service tips.

Use genuine Marantz replacement parts for optimal performance
Document all modifications and component replacements
Test amplifier under load conditions after repair
Verify thermal performance during extended operation

Service Support: Contact authorized Marantz service centers for technical assistance.