Marantz 2265 Service Manual

The Marantz 2265 is a classic stereo receiver from the 1970s featuring 65 watts per channel, high-quality audio components, and the distinctive Marantz blue dial. This service manual covers technical specifications, circuit diagrams, alignment procedures, troubleshooting, and maintenance guidelines for qualified service technicians. Below are key sections for specifications, block diagrams, alignment procedures, troubleshooting, and parts list.

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

Technical Specifications

Complete electrical and mechanical specifications for the Marantz 2265 stereo receiver.

Parameter	Specification
Power Output	65 watts per channel (8Ω, 20Hz-20kHz)
Total Harmonic Distortion	0.1% or less at rated output
Frequency Response	10Hz-50kHz (+0, -1dB)
Input Sensitivity	Phono: 2.0mV; Aux: 250mV
Signal-to-Noise Ratio	Phono: 75dB; Aux: 90dB
Damping Factor	55 (8Ω)
Tone Controls	Bass: ±10dB at 50Hz; Treble: ±10dB at 15kHz
Power Requirements	120V AC, 60Hz, 450W max
Dimensions	17-3/8" W × 5-7/8" H × 15-1/4" D
Weight	32 lbs (14.5 kg)

Block Diagrams

System block diagrams showing signal flow and power distribution.

Main System Block Diagram: Overview of all major sections
Preamplifier Section: Phono, aux, tape monitor circuits
Power Amplifier Section: Driver and output stages
Power Supply Section: Transformer, rectifiers, regulators
Tuner Section: FM/AM RF, IF, and detector circuits

NOTE! All voltages measured with no signal input unless otherwise specified.

Circuit Descriptions

Detailed descriptions of major circuit sections and their operation.

Phono Equalizer: RIAA equalization with low-noise transistors
Preamplifier: High-level input processing with tone controls
Power Amplifier: Complementary symmetry output stage
Power Supply: Dual power supply with regulated sections
Protection Circuit: Speaker protection and thermal shutdown
Tuner Circuits: FM front end, IF strips, multiplex decoder

Alignment Procedures

Step-by-step alignment instructions for tuner and amplifier sections.

FM Tuner Alignment: RF, IF, and detector adjustments
AM Tuner Alignment: Oscillator and antenna trimmers
Stereo Decoder Alignment: 19kHz pilot and 38kHz subcarrier
DC Offset Adjustment: Power amplifier balance
Bias Current Adjustment: Output stage quiescent current

WARNING! Use proper test equipment and follow procedures exactly.

Disassembly Instructions

Proper disassembly sequence for service access.

Remove top cover: Four screws on rear panel
Remove bottom cover: Six screws on bottom
Remove front panel: Four screws after removing knobs
Remove main chassis: Disconnect wiring harnesses
Access individual boards: Remove mounting screws

CAUTION! Disconnect power and discharge capacitors before disassembly.

Troubleshooting Guide

Systematic troubleshooting procedures for common problems.

Symptom	Possible Cause	Corrective Action
No power	Fuse, power switch, transformer	Check main fuse; test power switch; measure transformer output
One channel dead	Output transistors, driver stage	Check output transistors; test driver stage voltages
Distortion	Bias current, leaky capacitors	Adjust bias; replace electrolytic capacitors
No FM reception	RF stage, local oscillator	Check FM front end; verify oscillator operation
Hum in audio	Grounding, filter capacitors	Check ground connections; test main filter capacitors

Parts List

Complete component listing with manufacturer part numbers.

Transistors: 2SC458, 2SA726, 2SC1344, 2SC1383
Diodes: 1S2473, 1S1555, WZ-240
Integrated Circuits: HA1156, HA1196, uPC1237
Electrolytic Capacitors: Values and voltage ratings
Resistors: Carbon film and metal oxide types
Transformers: Power, output, and filter chokes

Schematic Diagrams

Complete schematic diagrams for all circuit boards.

Main Amplifier Schematic: P700 board
Power Supply Schematic: P800 board
Preamplifier Schematic: P900 board
FM Tuner Schematic: P300 board
AM Tuner Schematic: P400 board
Protection Circuit Schematic: P750 board

NOTE! Schematics show actual component values and test points.

PCB Layouts

Printed circuit board layouts and component placement diagrams.

Main Amplifier Board (P700): Component side and solder side
Power Supply Board (P800): Component locations and traces
Preamplifier Board (P900): Input/output connections
Tuner Boards (P300/P400): RF and IF sections
Control Board: Switches and potentiometers

Service Notes

Important service tips and common modifications.

Replace original 2SC458 transistors with low-noise equivalents
Upgrade main filter capacitors for improved performance
Check and replace dried-out electrolytic capacitors
Clean all switches and potentiometers with contact cleaner
Verify thermal compound on output transistors

WARNING! High voltages present - exercise extreme caution.

Safety Precautions

Essential safety procedures for service technicians.

Always use isolation transformer when servicing live chassis
Discharge large capacitors before testing or replacing
Use proper grounding techniques to avoid shock hazard
Verify correct fuse values before power application
Test unit with dim-bulb tester after major repairs

DANGER! Lethal voltages present - qualified personnel only.