Marantz 19 Service Manual

The Marantz 19 is a classic stereo receiver from the 1970s featuring advanced tuning capabilities, high-fidelity audio performance, and the distinctive Marantz blue dial display. This service manual covers technical specifications, circuit diagrams, alignment procedures, troubleshooting guides, and maintenance instructions for qualified service technicians.

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

Technical Specifications

Detailed electrical and mechanical specifications for the Marantz 19 stereo receiver.

Parameter	Specification
Power Output	19 watts per channel (RMS, 8 ohms)
Frequency Response	20Hz - 20kHz ±1dB
Total Harmonic Distortion	0.3% at rated output
Input Sensitivity	Phono: 2.5mV, Aux: 250mV
Signal-to-Noise Ratio	Phono: 70dB, Aux: 80dB
Tuning Range	FM: 88-108MHz, AM: 530-1600kHz
Capture Ratio	2.0dB
Selectivity	70dB
Dimensions	17" W × 5" H × 14" D
Weight	22 lbs

Circuit Description

Detailed explanation of the Marantz 19 circuit topology and signal flow.

Preamplifier Stage: High-gain phono and line-level amplification
Tuner Section: FM/AM reception with multiplex decoding
Power Amplifier: Complementary symmetry output stage
Power Supply: Regulated DC voltages for all stages
Protection Circuitry: Overload and thermal protection

WARNING! High voltages present - discharge capacitors before servicing.

Alignment Procedures

Step-by-step alignment instructions for optimal performance.

FM IF Alignment: Adjust IF transformers for maximum signal
FM Detector Alignment: Center discriminator for zero DC offset
AM Alignment: Adjust oscillator and antenna trimmers
Stereo Decoder Alignment: Set separation and pilot cancellation
Bias Adjustment: Set idle current for output transistors

CAUTION! Use proper alignment tools and follow sequence exactly.

Block Diagrams

Overall System Block Diagram: Complete signal flow from input to output
FM Tuner Block Diagram: RF amplification through stereo decoding
Audio Section Block Diagram: Preamplifier to power amplifier stages
Power Supply Block Diagram: AC input to DC regulated outputs
Control Section Block Diagram: Selector switches and tone controls

Schematic Diagrams

Complete schematic diagrams for all circuit boards and sections.

Main Schematics: Power supply, main amplifier, control section

Tuner Schematics: FM front end, IF stages, multiplex decoder

Individual Board Schematics: Preamplifier, protection circuit, tone control

All schematics include component values, test points, and voltage readings.

Parts List

Complete component listing with manufacturer part numbers.

Component	Part Number	Description
Output Transistors	2SC1116	NPN power transistor
Driver Transistors	2SA726	PNP driver transistor
Filter Capacitors	6800μF/50V	Main power supply filter
Tuning Capacitor	FM-4GANG	4-gang variable capacitor
IC Multiplex	HA1156W	Stereo decoder IC

PCB Layouts

Printed circuit board layouts for all major assemblies.

Main Amplifier Board: Component placement and trace routing
Tuner Assembly: RF and IF circuit board layout
Power Supply Board: Rectifier and regulator component placement
Control Board: Selector switch and tone control layout

Tip: Refer to layouts when replacing components or tracing circuits.

Troubleshooting Guide

Systematic approach to diagnosing and repairing common issues.

Symptom	Possible Cause	Corrective Action
No power	Blown fuse, power switch	Check fuse F801; test power switch S801
Distorted audio	Bias current, output transistors	Adjust bias current; test output transistors
No FM reception	RF stage, local oscillator	Check transistor Q101; verify oscillator operation
Intermittent operation	Cold solder joints	Reflow solder on main amplifier board
Hum in audio	Filter capacitors, grounding	Replace C801, C802; check ground connections

Test Equipment Requirements

Essential test equipment for proper servicing.

Oscilloscope: Dual trace, 20MHz minimum
Audio Generator: 20Hz-20kHz sine wave
FM Signal Generator: Stereo modulation capability
Digital Multimeter: High impedance input
Dummy Load: 8 ohm non-inductive resistors
Distortion Analyzer: For THD measurements

Safety Precautions

Critical safety information for service personnel.

WARNING! Lethal voltages present - always disconnect power before working on unit. Use isolation transformer when testing live circuits. Discharge large capacitors before handling.

Service Notes

Additional information and common modifications.

Common upgrades: Replacement of electrolytic capacitors, transistor updates for improved reliability, LED dial lamp conversion. Factory service bulletins and known issues documented. For technical support, contact authorized Marantz service centers.