Marantz 2600 Service Manual

The Marantz 2600 is a high-performance stereo receiver featuring 300 watts per channel, advanced tuning capabilities, comprehensive input/output options, and professional-grade audio circuitry. This service manual provides detailed technical information for qualified service technicians, including schematics, alignment procedures, troubleshooting guides, and replacement parts specifications.

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

Technical Specifications

Complete electrical and mechanical specifications for the Marantz 2600 stereo receiver.

Parameter	Specification
Power Output	300W per channel (8Ω, 20Hz-20kHz)
Total Harmonic Distortion	<0.05% at rated power
Frequency Response	5Hz-50kHz (+0/-3dB)
Signal-to-Noise Ratio	>90dB (phono)
Input Sensitivity	Phono: 2.5mV, Aux: 150mV
Tuning Range	FM: 87.5-108MHz, AM: 530-1620kHz
Dimensions	21.25" W × 7.5" H × 18.5" D
Weight	65 lbs (29.5 kg)
Power Requirements	120V AC, 60Hz, 750W
Speaker Impedance	4-16Ω

Block Diagrams

System-level block diagrams showing signal flow and major functional blocks.

Main Amplifier Section: Power supply, preamplifier, power amplifier stages
Tuner Section: RF amplifier, mixer, IF stages, detector circuits
Control Section: Input selection, tone controls, volume/balance
Protection Circuitry: Overload protection, thermal shutdown

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

Circuit Descriptions

Detailed analysis of major circuit sections and their operation.

Power Amplifier: Complementary symmetry output stage with Darlington configuration
Preamplifier: Low-noise FET input stages with RIAA equalization
Tuner Circuits: Phase-locked loop stereo decoder, quartz-filtered IF
Power Supply: Dual-secondary transformer with regulated ± supplies
Protection Systems: DC offset detection, over-current protection

CAUTION! Always discharge power supply capacitors before servicing.

Alignment Procedures

FM Tuner Alignment: RF tracking, IF alignment, stereo decoder adjustment
AM Tuner Alignment: Oscillator tracking, antenna trim
Amplifier Bias: Idle current adjustment, DC offset calibration
Protection Circuits: Trip point calibration, response time verification
Meter Calibration: Power output meters, tuning meters
Required Equipment: Audio generator, oscilloscope, distortion analyzer
Test Points: TP1-TP12 locations and expected voltages
Alignment Tools: Special alignment tools required

Disassembly Instructions

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

Procedure: Remove top cover, front panel, circuit boards in sequence.

Power off and unplug unit from AC outlet
Remove 8 screws from top cover
Detach front panel knobs and remove 4 mounting screws
Disconnect wiring harnesses from main board
Remove main amplifier board (12 screws)
Access tuner section by removing shield covers

Tip: Document wire positions and take photos during disassembly.

Troubleshooting Guide

Systematic approach to diagnosing and repairing common issues.

Symptom	Possible Cause	Corrective Action
No power	Blown fuse, power supply failure	Check F101-F103; test power transformer; verify rectifier diodes
Distorted audio	Bias misadjustment, failed output transistors	Adjust VR701/VR702; test Q701-Q708; check driver transistors
No FM reception	RF stage failure, alignment needed	Test Q101-Q103; realign front end; check varactor diodes
Protection circuit trips	DC offset, shorted outputs	Measure DC offset at speaker terminals; test protection IC501
Meter inoperative	Meter movement, driver circuit	Test meter coil continuity; check driver transistors Q801-Q804

Parts List

Complete listing of components with manufacturer part numbers.

Output Transistors: 2SC2581/2SA1106 or approved equivalents
Power Supply: Transformer T001, bridge rectifier D101-D104
Filter Capacitors: C701-C704 10,000μF 80V
Small Signal Transistors: 2SC945, 2SA733 in various locations
ICs: HA12016 (FM MPX), μPC1237 (protection), TA7136P (phono)
Potentiometers: Volume, balance, tone controls
Switches: Function selector, tape monitor, loudness
Meters: Power output meters, signal strength/tuning meters

WARNING! Use only manufacturer-approved replacement parts.

Schematics

Complete circuit diagrams for all sections of the receiver.

Includes: Main amplifier, preamplifier, power supply, tuner sections, protection circuits, and control systems.

PCB Layouts

Printed circuit board layouts showing component placement and trace routing.

CAUTION! Observe proper grounding techniques when working on PCBs.

Safety Precautions

Essential safety information for service personnel.

Isolation transformer required for live measurements. High voltages present in power supply (up to 80V DC). Large filter capacitors retain dangerous charge after power off. Always use grounded test equipment.

Service Notes

Additional technical information and service tips.

Service Bulletin	Description	Date
SB-2600-01	Output transistor replacement procedure	03/1978
SB-2600-02	Improved thermal compound application	06/1978
SB-2600-03	Meter calibration adjustment	09/1978
SB-2600-04	Protection circuit modification	12/1978
SB-2600-05	Power supply capacitor lifetime	03/1979

Service Contacts: Authorized Marantz service centers only.

Document Version: 2.1 (Revised March 1979)