Marantz SR-66 - Service Manual

The Marantz SR-66 is an A/V Surround Receiver, designed to deliver a high-quality audio-visual experience. This service manual provides comprehensive information for the maintenance, repair, and alignment of the device, ensuring its continued optimal performance.

Function Description

The SR-66 functions as a central hub for various audio and video sources, processing and amplifying signals to drive a multi-speaker surround sound system. At its core, the receiver integrates several key sections:

Front Amplifier Section: This section is responsible for amplifying the main stereo channels, providing robust power for the primary left and right speakers. It includes features like tone control (bass and treble) to allow users to adjust the audio characteristics to their preference. The front amplifier is designed for high fidelity, ensuring a clean and powerful sound output for music and movie soundtracks.
Center Amplifier Section: Dedicated to the center channel speaker, this amplifier is crucial for clear dialogue reproduction in surround sound setups. It operates in various modes, including PRO-LOGIC and 3-STEREO, to optimize the soundstage for different content. The center channel ensures that vocal elements are distinct and anchored to the screen.
Rear Amplifier Section: This section powers the surround speakers, creating an immersive audio environment by delivering ambient and directional effects. The rear channels contribute significantly to the spatial realism of movies and games, placing the listener in the heart of the action.
FM Section: The integrated FM tuner allows users to listen to radio broadcasts with clarity. It supports both 100 kHz and 50 kHz tuning steps, catering to different regional broadcasting standards. Features like usable sensitivity, image rejection, and IF rejection ratios ensure strong signal reception and minimal interference, providing a reliable radio listening experience.
AM Section: Complementing the FM tuner, the AM section provides access to amplitude modulated radio stations. It supports 10 kHz and 9 kHz tuning steps, again accommodating various regional requirements. The AM tuner is designed for good sensitivity and selectivity, allowing users to tune into a wide range of AM broadcasts.
MPX Section: This section handles the stereo decoding for FM broadcasts, separating the left and right channels to deliver a true stereo image. It includes features like automatic stereo threshold, which ensures that stereo reception is engaged only when the signal quality is sufficient, preventing noisy stereo reproduction.
Dolby Pro-Logic Adaptive Matrix (NJM2177A): A key component for surround sound processing, this matrix decodes Dolby Pro-Logic encoded audio, distributing sound elements to the appropriate front, center, and rear channels. This technology transforms stereo or matrix-encoded signals into a multi-channel experience, enhancing the realism and depth of movie soundtracks.
Digital Delay (NJU9701): Essential for creating convincing surround sound effects, the digital delay circuit introduces precise delays to the rear channels. This ensures that sound from the surround speakers reaches the listener at the correct time relative to the front channels, creating a cohesive and enveloping sound field.
Electric Volume Control (TDA7313, TC9176): The receiver incorporates electronic volume controls for precise and smooth adjustment of overall volume, as well as individual channel levels. This digital control offers greater accuracy and repeatability compared to traditional analog potentiometers.
Microprocessor (µPD78044GF): The brain of the SR-66, this 8-bit CMOS microprocessor manages all operational aspects of the receiver. It handles user inputs from the front panel and remote control, controls tuning, manages audio processing modes, and oversees power management. Its sophisticated control ensures seamless interaction and reliable performance across all functions.
Power Supply: A robust power supply unit ensures stable and clean power delivery to all sections of the receiver, which is critical for maintaining audio fidelity and overall performance. It includes various protection circuits to safeguard the device from power fluctuations and faults.

Usage Features

The Marantz SR-66 is designed for intuitive operation, offering a range of features that enhance the user experience:

Multi-Source Connectivity: The receiver provides multiple input options, including CD/VCD, TV/AUX, TAPE, DCC, and VCR inputs, allowing users to connect a variety of audio and video components. This versatility makes it a central hub for a home entertainment system.
Front Panel Controls: The front panel features a comprehensive set of buttons and knobs for direct control over essential functions such as power, input selection, tuning, volume, bass, treble, balance, and surround modes (PRO-LOGIC, 3-STEREO, HALL). A clear FL display provides visual feedback on the current settings and status.
Remote Control Capability: The SR-66 is compatible with a remote commander, offering convenient control from a distance. This allows users to adjust settings without needing to be near the unit, enhancing comfort and ease of use.
Speaker Selection: The device includes speaker selector options (A and B) for connecting and switching between different sets of front speakers, providing flexibility for multi-room audio or different listening preferences.
Headphone Output: A dedicated headphone jack allows for private listening, providing a high-quality audio output for headphones.
Video Switching: The receiver supports video input switching for VCR1 and VCR2, allowing users to route video signals through the unit to a monitor, simplifying cable management and source selection.
Tuner Functionality: The FM and AM tuners offer precise tuning and station memory, enabling users to quickly access their favorite radio stations. The display provides information on tuning frequency, stereo reception, and signal strength.

Maintenance Features

The service manual emphasizes the importance of proper maintenance and provides detailed procedures to ensure the longevity and optimal performance of the SR-66:

Technical Specifications: A comprehensive list of technical specifications serves as a benchmark for performance, allowing service technicians to verify that the unit operates within its design parameters.
Block Diagram: The block diagram provides an overview of the receiver's internal architecture, illustrating the signal flow and interconnections between different functional blocks. This is invaluable for troubleshooting and understanding the system's operation.
Wiring Diagram: Detailed wiring diagrams show the physical connections between various boards and components, aiding in reassembly and identifying wiring faults.
Schematic Diagram and Parts Location: Schematic diagrams, coupled with parts location layouts (pattern side), are crucial for component-level repair. They show the circuit design and the physical placement of each component on the printed circuit boards, facilitating accurate diagnosis and replacement.
Service Test Program of the Microprocessor: The inclusion of a service test program for the microprocessor (IC200) allows technicians to diagnose and test the functionality of the central control unit. This program can help identify issues related to input processing, display control, and mode switching. Pin configuration details for the microprocessor are provided to assist in debugging.
Alignment Procedures: Specific alignment procedures are outlined for the AM IF, RF, Tuning Voltage, FM IF, and MPX sections. These procedures require specialized equipment such as signal generators, oscilloscopes, voltmeters, and frequency counters. Proper alignment ensures that the tuners receive and process signals accurately, and that the stereo decoder functions correctly, leading to optimal audio quality.
Exploded View and Parts List: An exploded view diagram illustrates the mechanical assembly of the receiver, showing how all physical parts fit together. This is accompanied by a detailed parts list, including part numbers and descriptions, which is essential for ordering replacement components and for correct reassembly.
Electrical Parts List: A comprehensive list of all electrical components, including resistors, capacitors, diodes, transistors, and integrated circuits, is provided with their respective part numbers and values. This list is critical for identifying and sourcing replacement parts during repair.
Safety Precautions: The manual includes important safety precautions, particularly regarding critical parts for safety (marked with a specific symbol). It stresses the use of original Marantz parts and advises technicians to perform leakage current or resistance measurements after servicing to ensure proper insulation from the supply circuit, adhering to UL Standard NO.1492. This ensures the safety of both the technician and the end-user.
Ordering Parts Information: Clear instructions are provided for ordering parts, including the necessary information to avoid delays. This ensures that technicians can efficiently obtain the correct components for repairs.

By providing these detailed descriptions and procedures, the service manual empowers technicians to effectively maintain and repair the Marantz SR-66, ensuring its continued performance as a high-quality A/V surround receiver.

Marantz SR-66 Specifications

General

Tuning range	FM, MW
Power output	80 watts per channel into 8Ω (stereo)
Input sensitivity	2.5mV (MM), 200mV (line)
Dimensions	439 x 141 x 365mm
Weight	9.3kg
Frequency response	20Hz to 20kHz