Marantz PM44SE Service Manual

The Marantz PM44SE is a high-quality stereo integrated amplifier featuring advanced circuitry, multiple input options, and premium audio performance. This service manual provides comprehensive technical information for qualified service personnel, including schematics, alignment procedures, troubleshooting guides, and replacement parts lists for proper maintenance and repair.

1. Technical Specifications 2. Block Diagram Overview 3. Circuit Description 4. Disassembly Instructions 5. Alignment Procedures 6. Test Points & Measurements 7. Troubleshooting Guide 8. Replacement Parts List 9. PCB Layout Diagrams 10. Safety Precautions 11. Service Notes

Technical Specifications

Complete technical specifications and performance characteristics of the Marantz PM44SE integrated amplifier.

Parameter	Specification
Power Output	60W + 60W (8Ω, 20Hz-20kHz, 0.02% THD)
Frequency Response	5Hz-50kHz (+0/-3dB)
Total Harmonic Distortion	0.002% (1kHz, 1W)
Input Sensitivity	Phono: 2.5mV, Line: 150mV
Signal-to-Noise Ratio	Phono: 85dB, Line: 100dB
Input Impedance	Phono: 47kΩ, Line: 50kΩ
Tone Control Range	Bass: ±10dB, Treble: ±10dB
Power Supply	AC 120V/230V, 50/60Hz
Dimensions	440 x 125 x 355mm (W x H x D)
Weight	8.5kg

Block Diagram Overview

System block diagram showing signal flow and major functional blocks.

Input Selector: Multiple input routing (Phono, CD, Tuner, Aux, Tape)
Phono Equalizer: RIAA equalization circuit
Tone Control: Bass and treble adjustment circuits
Volume Control: Precision stepped attenuator
Power Amplifier: Dual-monaural power amplifier stages
Power Supply: Regulated dual power supply system
Protection Circuit: DC offset and thermal protection

WARNING! High voltages present - discharge power supply capacitors before servicing.

Circuit Description

Detailed circuit analysis of major amplifier sections.

Phono Stage: Discrete transistor design with RIAA equalization
Line Stage: High-quality op-amp based buffer amplifier
Tone Control: Active bass and treble circuits
Power Amplifier: Complementary symmetry output stage
Power Supply: Toroidal transformer with dual rectifiers
Protection: Speaker relay with DC detection

CAUTION! Use proper grounding techniques when testing live circuits.

Disassembly Instructions

Top Cover Removal: Remove 6 screws from rear panel and sides
Front Panel Removal: Remove knobs and 4 mounting screws
Main PCB Access: Remove 8 standoff screws after disconnecting wiring
Power Supply Removal: Disconnect all wiring and remove 4 mounting bolts
Heat Sink Removal: Remove output transistors and 6 mounting screws
Rear Panel Removal: Remove input/output jacks and 4 screws

Alignment Procedures

Step-by-step alignment and calibration procedures.

DC Offset Adjustment: Adjust VR401/VR402 for 0mV ±5mV at speaker terminals

Bias Current Adjustment: Adjust VR403/VR404 for 20mA across emitter resistors

Phono Equalization: Verify RIAA response using audio analyzer

Input Level Matching: Adjust input sensitivity for uniform gain across inputs

Test Points & Measurements

Critical test points and expected voltage measurements.

Test Point	Voltage	Description
TP1 (+B)	+45V DC	Positive rail voltage
TP2 (-B)	-45V DC	Negative rail voltage
TP3 (+15V)	+15V DC	Positive regulator output
TP4 (-15V)	-15V DC	Negative regulator output
TP5 (VAS)	+1.2V DC	Voltage amplifier stage
TP6 (Offset)	0V ±5mV	DC offset measurement

Troubleshooting Guide

Common problems and diagnostic procedures.

Symptom	Possible Cause	Corrective Action
No power	Fuse, power switch, transformer	Check F701/F702; verify AC input; test transformer primary
No sound	Protection circuit, power supply	Check relay K701; measure rail voltages; test output transistors
Distortion	Bias current, output stage	Adjust bias current; test output transistors; check driver stage
Hum/buzz	Grounding, power supply	Check ground connections; test filter capacitors; verify shielding
One channel dead	Input selector, amplifier stage	Test input switching; verify signal path; check channel components

Replacement Parts List

Critical replacement components and part numbers.

Output Transistors: 2SC3281/2SA1302 or equivalent
Driver Transistors: 2SC2705/2SA1145
Power Supply Diodes: 1N5404 (4A, 400V)
Main Filter Capacitors: 10,000μF/63V (C701/C702)
Regulator ICs: 7815/7915 (+15V/-15V regulators)
Speaker Relay: MY4-02-DC24 (24V DPDT)
Power Transformer: PM-44-501 (Primary: 0-100-120V)

PCB Layout Diagrams

Printed circuit board layouts and component locations.

Main Amplifier Board (PWB-100): Shows component placement for left/right channels

Power Supply Board (PWB-200): Power regulation and filtering components

Control Board (PWB-300): Input selection and tone control circuits

Note: Refer to silkscreen markings for component identification

Safety Precautions

Essential safety procedures for service technicians.

Always disconnect AC power before servicing. Discharge power supply capacitors. Use isolation transformer when testing live circuits. Verify proper grounding. Wear safety glasses when working with high voltages.

WARNING! Lethal voltages present - qualified personnel only.

Service Notes

Important service information and updates.

Use original Marantz parts for optimal performance
Apply thermal compound when replacing output transistors
Verify bias current after 30 minutes of operation
Check DC offset after any amplifier repair
Test with dummy load before connecting speakers

Service Support: Contact authorized Marantz service centers for technical assistance and genuine replacement parts.