Marantz 2330B Service Manual

The Marantz 2330B is a high-performance stereo receiver featuring 33 watts per channel RMS, advanced tuner section with FM/AM reception, comprehensive input/output connectivity, precision tone controls, loudness compensation, and professional-grade construction. Below are key sections for technical specifications, circuit descriptions, alignment procedures, troubleshooting, and maintenance guidelines.

1. Technical Specifications 2. Block Diagram Overview 3. Circuit Descriptions 4. Alignment Procedures 5. Voltage Measurements 6. Parts List 7. Schematic Diagrams 8. Mechanical Assembly 9. Troubleshooting Guide 10. Safety Precautions

Technical Specifications

Key performance parameters and electrical characteristics of the Marantz 2330B stereo receiver.

Parameter	Specification
Power Output	33 watts per channel RMS (8 ohms, 20Hz-20kHz)
Total Harmonic Distortion	0.3% at rated output
Frequency Response	10Hz - 50kHz (+1/-3 dB)
Input Sensitivity	Phono: 2.5mV; Aux: 250mV
Signal-to-Noise Ratio	Phono: 70dB; Aux: 90dB
Tuner Section	FM/AM with muting and signal strength meter
Tone Controls	Bass: ±10dB at 100Hz; Treble: ±10dB at 10kHz
Loudness Control	Switchable compensation circuit
Power Requirements	120V AC, 60Hz, 180 watts
Dimensions	17-1/2" W × 5-1/4" H × 14-1/2" D

Block Diagram Overview

System architecture and signal flow description.

Input Selector: Phono, Aux, Tuner, Tape inputs
Preamplifier Stage: Low-noise transistor amplification
Tone Control Circuit: Bass and treble adjustment networks
Power Amplifier: Complementary symmetry output stage
Power Supply: Regulated DC voltages for all sections
Protection Circuit: Overload and thermal protection

WARNING! High voltages present in power supply section. Disconnect power before servicing.

Circuit Descriptions

Detailed analysis of major circuit sections.

Preamplifier: Dual transistor differential input with feedback
Equalization: RIAA compensation for phono input
Tone Control: Baxandall-type bass and treble circuits
Power Amplifier: Direct-coupled complementary output
Power Supply: Full-wave rectification with capacitor filtering
Protection: DC detection and relay muting

CAUTION! Use proper grounding techniques when testing live circuits.

Alignment Procedures

FM Tuner Alignment: Requires RF generator, oscilloscope, and VTVM
IF Alignment: 10.7MHz center frequency adjustment
AM Tuner Alignment: 455kHz IF and antenna trimmer
Stereo Decoder: 19kHz pilot carrier adjustment
Power Amplifier Bias: 20mA quiescent current setting
DC Offset: Zero volt adjustment at output
Test Equipment Required: Audio generator, distortion analyzer, multimeter
Alignment Points: Marked on main PC board and tuner sub-assembly

Voltage Measurements

Reference voltage readings at key test points.

Power Supply: +42V, +35V, +24V, -24V rails

Amplifier Section: Output transistor bases, driver stages, input differential pairs. Preamplifier: Phono EQ op-amp supplies, tone control IC voltages. Tuner: FM/AM mixer, oscillator, IF strip voltages.

Parts List

Complete component inventory with manufacturer part numbers.

Semiconductors: Transistors, diodes, ICs with replacements
Capacitors: Electrolytic, ceramic, film types and values
Resistors: Carbon film and metal oxide values
Controls: Pots, switches, selector mechanisms
Hardware: Screws, nuts, brackets, faceplate

Tip: Cross-reference original parts with modern equivalents where available.

Schematic Diagrams

Full schematics for all circuit sections.

Main Amplifier: Power output and driver stages
Preamplifier: Phono, aux, and tone control circuits
Power Supply: Transformer, rectification, and regulation
FM Tuner: RF front end, IF strip, and multiplex
AM Tuner: Converter, IF, and detector
Control Circuits: Input switching, protection, meters
PCB Layouts: Component placement and trace routing
Wiring Diagrams: Interconnect between assemblies

WARNING! Schematics show lethal voltages. Exercise extreme caution.

Mechanical Assembly

Physical construction and disassembly instructions.

Troubleshooting Guide

Systematic approach to diagnosing common problems.

Symptom	Possible Cause	Corrective Action
No power	Fuse, power switch, transformer	Check main fuse; verify AC voltage to primary
No audio output	Protection relay, output transistors	Test relay operation; check output devices
Distorted sound	Bias current, leaky capacitors	Adjust bias; replace coupling capacitors
No FM reception	RF stage, local oscillator	Verify oscillator operation; check RF transistors
Hum or noise	Grounding, filter capacitors	Check ground connections; test power supply filters

Reset: None - unit has no microprocessor

Service Notes: Document all adjustments and replacements

Safety Precautions

Essential safety procedures for technicians.

Always disconnect AC power before working on unit. Use isolation transformer when testing live circuits. Discharge large capacitors before handling. Follow ESD precautions with semiconductors. Use proper tools and test equipment.

CAUTION! Lethal voltages present even when unit is switched off.