Marantz PM 44SE Service Manual

The Marantz PM 44SE is a high-quality stereo integrated amplifier featuring advanced audio circuitry, multiple input/output options, and professional-grade components. This service manual provides comprehensive technical information for qualified service technicians, including schematics, alignment procedures, troubleshooting guides, and replacement part specifications. Below are key sections covering technical specifications, circuit descriptions, adjustment procedures, and maintenance guidelines.

1. Technical Specifications 2. Block Diagram Overview 3. Circuit Descriptions 4. Adjustment Procedures 5. Disassembly Instructions 6. Parts List & Replacement 7. Schematic Diagrams 8. PCB Layouts 9. Troubleshooting Guide 10. Service Notes 11. Safety Precautions

Technical Specifications

Complete technical specifications for the Marantz PM 44SE integrated amplifier.

Parameter	Specification
Power Output	60W + 60W (8Ω, 20Hz-20kHz, 0.02% THD)
Total Harmonic Distortion	0.005% (1kHz, 1W)
Frequency Response	5Hz - 100kHz (+0/-3dB)
Input Sensitivity	Phono: 2.5mV, Line: 150mV
Signal-to-Noise Ratio	Phono: 80dB, Line: 100dB
Input Impedance	Phono: 47kΩ, Line: 50kΩ
Damping Factor	100 (8Ω, 1kHz)
Tone Control	Bass: ±10dB at 100Hz, Treble: ±10dB at 10kHz
Power Consumption	220W maximum
Dimensions	440 x 130 x 360mm (W x H x D)
Weight	8.5kg

Block Diagram Overview

System architecture and signal flow description.

Input Selector: Multiple input source selection circuitry
Phono Equalizer: RIAA equalized phono preamplifier stage
Tone Control: Bass and treble adjustment networks
Volume Control: Precision stepped attenuator
Power Amplifier: Dual-monaural power amplifier sections
Protection Circuit: DC detection and speaker protection
Power Supply: Regulated dual-rail power supply system

WARNING! High voltages present in power supply section. Exercise extreme caution during service.

Circuit Descriptions

Detailed analysis of major circuit blocks and their operation.

Phono Stage: Discrete transistor design with RIAA equalization
Line Amplifier: High-quality op-amp based amplification
Tone Control: Active bass and treble control circuits
Power Amplifier: Complementary symmetry output stage
Protection Circuit: Relay-based speaker protection
Power Supply: Toroidal transformer with regulated outputs

CAUTION! Static-sensitive components present. Use proper ESD precautions.

Adjustment Procedures

DC Offset Adjustment: Adjust VR701/VR702 for 0mV ±5mV output
Bias Current Adjustment: Set VR703/VR704 for 20mA idle current
Phono Balance: Adjust for equal channel output at 1kHz
Protection Circuit Test: Verify relay operation and timing
Power Supply Voltages: Verify ±42V rail voltages within 5%

Disassembly Instructions

Step-by-step disassembly procedure for service access.

Front Panel: Remove knobs, unscrew front panel mounting screws

Top Cover: Remove rear panel screws, slide cover backward

Main Board: Desolder connections, remove mounting screws

Power Supply: Discharge capacitors, remove transformer mounting bolts

Disconnect AC power cord
Remove bottom panel screws
Lift top cover carefully
Document wire connections before disassembly
Use proper tools to avoid damage to components

Parts List & Replacement

Critical replacement parts and equivalents.

Part Number	Description	Replacement
2SC2240	Low noise transistor	KSC1845
2SA970	PNP transistor	KSA992
2SC2705	Driver transistor	KSC3503
2SA1145	Driver transistor	KSA1381
2SC2922	Output transistor	MJ21194
2SA1216	Output transistor	MJ21193
1000μF/63V	Main filter capacitor	Same value, 105°C
Relay MY4-02	Speaker protection relay	MY4-02-DC24

Schematic Diagrams

Complete schematic diagrams for all circuit sections.

Main Amplifier Circuit: Power amplifier and driver stages
Preamplifier Section: Phono and line amplifier circuits
Power Supply: Transformer, rectification, and regulation
Protection Circuit: DC detection and relay control
Control Circuits: Input selection and tone control

Tip: Refer to PCB layouts for component locations and orientations.

PCB Layouts

Printed circuit board layouts and component placement guides.

Main Board: Component side and solder side views
Power Supply Board: Component locations and traces
Front Panel Board: Switch and control circuits
Grounding Scheme: Star grounding implementation
Test Points: Voltage measurement locations

WARNING! High temperature components identified. Allow cool-down before handling.

Troubleshooting Guide

Systematic troubleshooting procedures for common issues.

Symptom	Possible Cause	Corrective Action
No power	Fuse, power switch, transformer	Check F701/F702 fuses; verify transformer primary
No sound	Protection circuit, power supply	Check relay operation; verify amplifier voltages
Distortion	Bias current, output transistors	Adjust bias; check output devices for damage
Hum/buzz	Grounding, filter capacitors	Check ground connections; test filter capacitors
One channel dead	Amplifier section, input selector	Trace signal path; check channel-specific components

Service Notes

Important service observations and modifications.

Thermal Management: Ensure proper heatsink contact for output transistors

Capacitor Replacement: Use high-temperature, low-ESR capacitors for power supply

Transistor Matching: Critical for output pairs (2SC2922/2SA1216)

CAUTION! Always verify replacement transistor pinouts before installation.

Safety Precautions

FCC Part 15: Class B digital device compliance. Copyright © Marantz. All safety standards compliance verified. High voltage sections clearly marked. Use isolation transformer during live measurements. For technical support, contact authorized Marantz service centers only.