Marantz SR-19EX Service Manual

The Marantz SR-19EX is a high-end AV receiver featuring Dolby Digital and DTS decoding, 7-channel amplification, advanced video switching capabilities, comprehensive connectivity options, and sophisticated audio processing. This service manual provides detailed technical information for qualified service personnel including schematics, alignment procedures, troubleshooting guides, and replacement parts information.

1. Technical Specifications 2. Block Diagrams 3. Circuit Descriptions 4. Disassembly Instructions 5. Test and Adjustment Procedures 6. Troubleshooting Flowcharts 7. Parts List 8. PCB Layouts 9. Wiring Diagrams 10. Safety Precautions 11. Firmware Updates

Technical Specifications

Detailed technical specifications and performance characteristics of the Marantz SR-19EX AV receiver.

Parameter	Specification
Power Output	110W x 7 channels (8Ω, 20Hz-20kHz, 0.08% THD)
Frequency Response	10Hz - 100kHz (+1/-3dB)
Total Harmonic Distortion	0.08% (20Hz-20kHz at rated power)
Signal-to-Noise Ratio	100dB (IHF-A weighted)
Input Sensitivity	200mV (line level)
Digital Inputs	Coaxial x 3, Optical x 3
Analog Inputs	RCA x 8, Phono x 1
Video Inputs	Composite x 5, S-Video x 5, Component x 2
Power Consumption	650W maximum
Dimensions	440 x 470 x 185mm (W x D x H)

Block Diagrams

System block diagrams showing signal flow and functional relationships between circuits.

Main System Block Diagram
Audio Processing Block Diagram
Video Switching Block Diagram
Power Supply Block Diagram
Control System Block Diagram

WARNING! These diagrams are for qualified service personnel only. Unauthorized modifications may void warranty and create safety hazards.

Circuit Descriptions

Detailed descriptions of major circuit sections and their operation.

Power Supply Circuit: Switching power supply with multiple regulated outputs
Main Amplifier Circuit: 7-channel discrete power amplifier design
Digital Audio Processor: 24-bit/192kHz processing with Dolby Digital and DTS
Video Switching Circuit: High-bandwidth video switching matrix
Microprocessor Control: System control and user interface management

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

Disassembly Instructions

Step 1: Remove top cover by unscrewing 6 Phillips screws
Step 2: Remove front panel assembly (4 screws, 2 connectors)
Step 3: Remove main board mounting screws (8 locations)
Step 4: Disconnect all inter-board cables and connectors
Step 5: Remove heat sink assembly (4 screws, thermal compound)
Tools Required: Phillips screwdrivers, anti-static wrist strap, plastic tools
Safety: Always disconnect AC power before disassembly

Test and Adjustment Procedures

Factory alignment and test procedures for proper unit calibration.

Required Equipment: Audio analyzer, oscilloscope, distortion analyzer, test discs, dummy loads

Amplifier Bias Adjustment: Adjust VR801-VR807 for 10mV across emitter resistors. Power Supply Voltages: +12V, -12V, +5V, +3.3V within ±5%. Center Voltage: Adjust for 0V DC at speaker outputs. Digital Processor: Verify clock frequencies and digital signal integrity.

Troubleshooting Flowcharts

Systematic troubleshooting guides for common failure modes.

Symptom	Possible Cause	Corrective Action
No power	Fuse, power supply	Check F801 (8A), test standby voltage, verify AC input
No audio output	Protection circuit, amplifier	Check protection relay, test amplifier stages, verify input signals
Distorted audio	Bias, DC offset	Adjust bias voltages, check for DC offset, test output transistors
No video	Video processor, switching	Test video ICs, check switching matrix, verify input signals
Display issues	Front panel, microprocessor	Test display driver, check microprocessor, verify power to front panel

Parts List

Complete list of replacement parts with manufacturer part numbers.

Power Transistors: 2SC5200 / 2SA1943 (output stage)
Power Supply IC: STR-G6653 (main switcher)
Digital Processor: MN67763MH (audio/video processing)
Microprocessor: HD6437045F20 (system control)
Main Fuse: F801 8A/250V (slow blow)
Electrolytic Capacitors: Various values and voltages
Connectors: Specific part numbers for all internal connectors

Tip: Always use genuine Marantz replacement parts for optimal performance and reliability.

PCB Layouts

Printed circuit board layouts for all major assemblies.

Main Board: Double-sided PCB with ground plane. Power Supply Board: High-current design with proper spacing. Front Panel Board: Control and display circuitry. Amplifier Board: 7-channel layout with thermal management.

WARNING! Observe proper ESD precautions when handling PCBs. Use grounded workstations and tools.

Wiring Diagrams

Complete wiring diagrams showing all internal connections and cable routing.

Main inter-board cable connections
Front panel wiring harness
Power supply wiring
Speaker output connections
Input/output connector wiring

CAUTION! Verify all connections are secure and properly routed to prevent shorts and interference.

Safety Precautions

Essential safety information for service personnel.

High Voltage Areas: Power supply section contains lethal voltages. Thermal Hazards: Heat sinks can reach high temperatures during operation. ESD Protection: Use anti-static equipment when handling semiconductors. Isolation: Use isolation transformer when servicing live circuits. Ventilation: Ensure proper airflow and thermal compound application during reassembly.

Firmware Updates

Procedures for updating system firmware and software.

Version	Date	Changes	Update Method
V1.2	2002-05-15	Improved DSP algorithms	Service port programming
V1.3	2002-11-08	Bug fixes, new features	Service port programming
V1.4	2003-03-22	Compatibility updates	Service port programming

Reset: Service menu > System > Factory Reset if available.

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