Marantz 4430 Service Manual

The Marantz 4430 is a high-performance stereo receiver featuring 30 watts per channel, advanced tuning capabilities, and professional-grade audio components. This service manual provides comprehensive technical documentation for qualified service technicians, including schematics, alignment procedures, troubleshooting guides, and replacement part information for proper maintenance and repair.

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

Technical Specifications

Complete electrical and mechanical specifications for the Marantz 4430 stereo receiver.

Parameter	Specification
Power Output	30 watts per channel (8Ω, 20Hz-20kHz)
Total Harmonic Distortion	0.08% at rated output
Frequency Response	10Hz-50kHz (+1/-3dB)
Input Sensitivity	Phono: 2.5mV; Aux: 150mV
Signal-to-Noise Ratio	Phono: 75dB; Aux: 90dB
Tuning Range	FM: 87.5-108MHz; AM: 530-1620kHz
Speaker Impedance	4-16Ω
Power Requirements	120V AC, 60Hz, 180W
Dimensions	17.3" W × 5.6" H × 13.8" D
Weight	22.5 lbs (10.2 kg)

Block Diagram Overview

Functional block diagram showing signal flow and major circuit sections.

Tuner Section: FM/AM RF amplification, mixing, and IF stages
Preamplifier: Phono equalization, tone controls, and input selection
Power Amplifier: Driver stages and complementary output transistors
Power Supply: Transformer, rectification, and voltage regulation
Protection Circuit: DC detection and relay control

WARNING! High voltages present in power supply section. Exercise extreme caution when servicing.

Circuit Descriptions

Detailed analysis of major circuit sections and their operation.

FM Tuner: RF amplifier (Q101), mixer (Q102), 10.7MHz IF strip
AM Tuner: RF amplifier, converter, 455kHz IF amplifier
Phono Preamp: RIAA equalization with low-noise transistors
Tone Control: Bass and treble controls with center detents
Power Amp: Complementary symmetry output stage with thermal protection
Power Supply: Center-tapped transformer with full-wave rectification

CAUTION! Always discharge power supply capacitors before servicing.

Alignment Procedures

FM IF Alignment: Adjust L102, L103, L104 for maximum output at 10.7MHz
FM Oscillator: Set L105 for proper frequency coverage
AM Alignment: Adjust T101, T102 for peak performance
Stereo Decoder: Adjust L201 for minimum pilot leakage
Bias Adjustment: Set VR701 for 20mA idle current
DC Offset: Adjust VR702 for 0V DC at speaker terminals

Disassembly Instructions

Step-by-step disassembly procedure for accessing internal components.

Procedure: Remove top cover screws, lift cover, disconnect wiring harnesses, remove front panel, extract circuit boards.

Front Panel: Remove knobs, unscrew front panel assembly

Main Chassis: Remove bottom screws, separate chassis from cabinet

Circuit Boards: Desolder connections, note orientation for reassembly

Troubleshooting Guide

Systematic approach to diagnosing and repairing common issues.

Symptom	Possible Cause	Corrective Action
No power	Fuse, power switch, transformer	Check F701 (3A), test power switch, measure transformer primary
No audio output	Protection relay, output transistors	Check relay operation, test Q701-Q704, measure DC offset
Distorted sound	Bias current, leaky capacitors	Adjust VR701, replace C701-C704, check driver transistors
No FM reception	Tuner section, MPX decoder	Check Q101-Q104, test IC201, verify antenna connection
Hum in output	Grounding, filter capacitors	Check ground connections, replace C801-C804

Replacement Parts List

Authorized replacement components with manufacturer part numbers.

Component	Part Number	Description
Output Transistors	2SC2581/2SA1106	Complementary pair, 120V, 10A
Power Transformer	TP-841	Primary: 120V, Secondary: 35V-0-35V
Main Filter Caps	CE-6800μF/50V	Electrolytic, 35mm diameter
Driver Transistors	2SC2344/2SA1011	120V, 1A, TO-126 package
IC Stereo Decoder	HA1156W	FM Multiplex Demodulator

Schematic Diagrams

Complete schematic diagrams for all circuit sections.

Main Amplifier Section: Power supply through output stage
Tuner Section: FM/AM RF through detector circuits
Preamplifier: Input switching through tone controls
Protection Circuit: DC detection and relay driver
Power Supply: Transformer through regulation

Tip: Use high-quality prints for accurate component identification.

PCB Layouts

Printed circuit board layouts with component placement and trace routing.

Supports main board, tuner board, and front panel assemblies.

Main Board: Power amplifier and preamplifier sections
Tuner Board: FM/AM tuner and stereo decoder
Power Supply Board: Rectification and filtering
Front Panel: Switches, indicators, and controls

WARNING! Observe electrostatic discharge precautions when handling PCBs.

Service Precautions

Essential safety procedures for service technicians.

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

CAUTION! Lethal voltages present. Only qualified technicians should perform service.

Test Equipment Requirements

Recommended test equipment for proper alignment and troubleshooting.

Equipment	Specification	Purpose
Audio Generator	20Hz-20kHz, low distortion	Frequency response testing
Oscilloscope	Dual trace, 20MHz minimum	Waveform analysis
Distortion Analyzer	0.01% resolution	THD measurements
RF Signal Generator	FM/AM modulation	Tuner alignment
Digital Multimeter	High impedance input	Voltage and resistance measurements

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