This document is a service manual for the JVC JR-S81M/S81W/S81H Stereo Receiver, published in December 1977. It provides detailed information for servicing and maintaining the device, including specifications, removal procedures, part locations, exploded views, part numbers, and alignment procedures.
Function Description:
The JVC JR-S81M/S81W/S81H is a stereo receiver, combining an amplifier and a tuner (FM/AM) into a single unit. It is designed to receive radio broadcasts and amplify audio signals from various sources, delivering sound to speakers. The receiver features controls for volume, bass, treble, balance, and speaker selection, as well as input selectors for phono, AUX, and tape monitor. It also includes a tuning knob for radio station selection and meters for signal strength and tuning.
Important Technical Specifications:
- Dimensions (H x W x D):
- JR-S81M: 15.1 cm (6") x 47.4 cm (18-11/16") x 35.0 cm (13-13/16")
- JR-S81W: 15.1 cm (6") x 49.8 cm (19-5/8") x 35.0 cm (13-13/16")
- JR-S81H: 15.1 cm (6") x 53.4 cm (21-1/16") x 37.0 cm (14-5/8")
- Weight (Net):
- JR-S81M: 9.4 kg (20.8 lbs.)
- JR-S81W: 10.4 kg (23.0 lbs.)
- JR-S81H: 9.6 kg (21.2 lbs.)
- Amplifier Section:
- RMS Power (both channels driven, 20 Hz - 20 kHz, 8 ohms, 0.5% THD): 35 watts per channel
- RMS Power (both channels driven, 1 kHz, 8 ohms): 38 W per channel
- RMS Power (both channels driven, 1 kHz, 4 ohms): 43 W per channel
- Total Harmonic Distortion (at rated output power): 0.5%
- Damping Factor (at 8 ohms): 40
- Input Sensitivity, Impedance:
- Phono: 2.5 mV/50 kΩ
- AUX: 200 mV/50 kΩ
- Tape Mon: 200 mV/50 kΩ
- Recording Output Level: 150 mV (Pin), 30 mV/80 kΩ (DIN)
- Frequency Response: 20 Hz - 20 kHz +0 dB, -0.8 dB
- Bass Control: ±10 dB at 50 Hz
- Treble Control: ±10 dB at 10 kHz
- FM Tuner Section:
- Usable Sensitivity (IHF): Mono 12.1 dBf
- Usable Sensitivity (DIN): Mono 1.2 µV/75 Ω (S/N 26 dB, 1.8 µV/300 Ω)
- Total Harmonic Distortion (at 1 kHz, 100% Modulation):
- Mono: 0.2% (100 Hz or 1 kHz), 0.6% (6 kHz)
- Stereo: 0.4% (100 Hz or 1 kHz), 0.8% (6 kHz)
- Signal to Noise Ratio: 78 dB (Mono), 70 dB (Stereo)
- Selectivity: 70 dB IHF Alternated
- Capture Ratio: 1.5 dB
- Image Rejection: 60 dB
- IF Rejection: 80 dB
- Stereo Separation: 40 dB at 1 kHz, 30 dB at 50 Hz to 10 kHz
- AM Tuner Section:
- Usable Sensitivity: MW 30 µV, 300 µV/m at 1000 kHz
- Image Rejection: MW 45 dB
- Selectivity: MW 30 dB
- IF Rejection: MW 50 dB
- Signal to Noise Ratio: MW 55 dB
- Power Supply Section (Line Voltage & Frequency / Power Consumption):
- U.S.A. / Canada: AC 120 V, 60 Hz / 175 W (UL/CSA Standard)
- UK & Australia: AC 240 V~, 50 Hz / 290 W (BS and SAA Standard)
- European Continent: AC 220 V~, 50 Hz / 280 W (IEC Standard)
- Other Areas: AC 100/120/220/240 V~ Selectable, 50/60 Hz / 280 W (IEC Standard)
Usage Features:
The receiver is designed for ease of use with clearly labeled controls on the front panel. It offers multiple audio inputs, including Phono for turntables, AUX for general audio devices, and Tape Mon for tape decks, allowing users to connect various components. The tuning knob and meters facilitate precise radio station selection. The different models (JR-S81M/S81W/S81H) likely indicate variations in external design, such as cabinet finish or specific regional configurations, as suggested by the differing dimensions and power supply specifications. The "Other Areas" power supply is selectable, offering flexibility for international use.
Maintenance Features:
The service manual provides comprehensive instructions for maintenance and repair:
- Removal Procedures: Detailed steps are given for removing the top cover, bottom plate, and front panel, including specific screw locations and part numbers. This is crucial for accessing internal components.
- Main Part Locations and Part Numbers: Exploded views and lists of part numbers are provided for the front panel, printed circuit boards (P.C. Board Ass'y), and other key components. This aids in identifying and ordering replacement parts.
- Printed Circuit Board Ass'y and Parts List: Detailed diagrams and lists are included for the TFC-20C FM/AM Tuner & Equalizer Amp P.C. Board, TPS-93G AC Fuse P.C. Board, TSC-107 Speaker Switch P.C. Board, TPS-124A Lamp P.C. Board, and TAP-256C Audio Amp P.C. Board. These sections list transistors, integrated circuits, diodes, coils, transformers, capacitors, and resistors with their ratings and descriptions.
- FM/AM Tuner Alignment Procedures: Step-by-step instructions are provided for aligning the FM and AM tuner sections, including discriminator, center meter, distortion, signal gain, tracking, sensitivity, multiplex, and stereo separation adjustments. This ensures optimal performance of the radio tuner.
- Packing Materials and Part Numbers: Information on packing materials is included, which can be useful for safe transport or storage.
- Accessories List: A list of accessories and their part numbers is provided, such as the instruction book, warranty card, FM antenna, fuses, and plug covers, which are often region-specific.
- Transistor, I.C., and Diode Lead Identification: Diagrams illustrate the lead configurations for various semiconductor components, which is essential for correct installation and troubleshooting.
- Schematic Diagram: A full schematic diagram (JR-S81 Schematic Diagram) is included, offering a detailed electrical representation of the receiver's circuitry. This is invaluable for advanced troubleshooting and repair.
- Voltage Selector Plug: The manual highlights the importance of the voltage selector plug for different regions, ensuring the device is configured for the correct local power supply.
- Safety Parts: Specific parts are designated as "SAFETY PARTS," indicating their critical role in ensuring the safe operation of the device.
The manual emphasizes that design and specifications are subject to change without notice and includes precautions for adjustments, noting that tracking and sensitivity are factory-adjusted and should only be altered if absolutely necessary. It also provides specific part numbers for different designated areas (U.S.A., Canada, Australia, U.K., European countries, PACEX, and other countries) for components like power transformers, power switches, power cords, AC outlets, AC fuse P.C. boards, contact clips, composition resistors, instruction books, warranty cards, and fuses.
Need help?
General
To Next Page
