The Sony ST-5066 is an FM Stereo/FM-AM Tuner designed for use in the USA, Canada, AEP (presumably Asia/Europe/Pacific), and UK markets. It features a solid-state design and incorporates a switching MPX (multiplex) system for FM stereo reception.
Function Description
The ST-5066 serves as a radio tuner, capable of receiving both FM stereo and AM broadcasts. It is designed to integrate into an audio system, providing the signal output for amplification and playback. The front panel includes a tuning dial, a tuning meter, and controls for various functions such as HI-BLEND, MONO/STEREO mode, and input selection (FM/AM). The HI-BLEND switch is likely used to reduce noise in weak FM stereo signals by blending the stereo channels at higher frequencies. The MONO/STEREO switch allows the user to force mono reception for noisy stereo signals or to enjoy full stereo when available.
Important Technical Specifications
FM Tuner Section:
- Tuning Range: 87.5 MHz to 108 MHz
- Antenna Inputs: 300 ohms balanced, 75 ohms unbalanced
- Intermediate Frequency (IF): 10.7 MHz
- Usable Sensitivity: 2.2 µV (IHF), 1.7 µV (S/N = 30 dB)
- Signal-to-Noise Ratio (S/N): 68 dB
- Frequency Response: 30 Hz to 15 kHz ±3 dB
- Harmonic Distortion (100% Modulation):
- Mono: 0.5% at 400 Hz, 75 kHz deviation
- Stereo: 0.8% at 400 Hz, 75 kHz deviation
- Capture Ratio: 1.5 dB
- Selectivity: 55 dB
- Image Rejection: 45 dB
- IF Rejection: 95 dB
- Spurious Rejection: 75 dB
- AM Suppression: 45 dB
- FM Stereo Separation: Greater than 35 dB at 400 Hz
- 19 kHz, 38 kHz Suppression: 40 dB
AM Tuner Section:
- Tuning Range: 530 kHz to 1,605 kHz
- Antenna: Built-in ferrite bar antenna with external antenna provision
- Intermediate Frequency (IF): 455 kHz (USA, Canada, AEP Model), 468 kHz (UK Model)
- Sensitivity: 48 dB/m (built-in antenna), 100 µV (external antenna)
- Signal-to-Noise Ratio (S/N): 50 dB at 50 mV/m
- Harmonic Distortion: 0.6%
- Image Rejection: 45 dB at 1,000 kHz
- IF Rejection: 40 dB at 1,000 kHz
General:
- Circuit System: FM stereo, FM/AM superheterodyne, switching MPX
- Semiconductors: 2 FETs, 20 transistors, and 14 diodes
- Power Requirements:
- 120 volts, 60 Hz AC (USA and Canada Model)
- 110, 127, 220, 240 volts, 50/60 Hz AC (AEP and UK Model)
- Power Consumption: 23 watts
- Dimensions: 410 (w) x 120 (h) x 284 (d) mm (16 1/8 (w) x 4 11/16 (h) x 11 3/16 (d) inches)
- Net Weight: 4.8 kg (10 lb 9 oz)
- Shipping Weight: 6.8 kg (15 lb)
- Signal Outputs and Impedance:
- NORMAL: 0.75 V, 4.5 kΩ at 400 Hz, 100% Mod.
- HIGH: 1.5 V, 3.3 kΩ at 400 Hz, 100% Mod.
Usage Features
The ST-5066 offers several user-friendly features. The large tuning dial and tuning meter facilitate precise station selection. The front panel includes indicator lamps for AM, FM, and STEREO, providing visual feedback on the current operating mode and signal type. Pushbutton switches are used for function selection (FM/AM), mode (MONO/STEREO), and a HI-BLEND feature, which can be engaged to improve reception quality for weak FM stereo signals by reducing high-frequency noise. The unit provides both normal and high-level audio outputs, offering flexibility for connection to various audio amplifiers. It also includes provisions for both internal and external antennas for both FM and AM bands, allowing users to optimize reception based on their location and signal conditions.
Maintenance Features
The service manual provides detailed instructions for disassembly, replacement of components, and alignment procedures, indicating that the ST-5066 is designed to be serviceable.
- Disassembly: Step-by-step guides are provided for removing the front panel, dial lamps, and the front subchassis, as well as for stringing the dial cord. This allows access to internal components for repair or replacement.
- Component Replacement: Instructions cover the replacement of printed circuit boards and pushbutton switches, including details on screw types and soldering techniques.
- Alignment and Adjustment: Comprehensive alignment procedures are outlined for both FM and AM sections. This includes:
- FM I-F and Discriminator Alignment: Critical for optimal FM signal processing and distortion minimization. The manual highlights the importance of ceramic filter color codes for correct replacement.
- FM Frequency Coverage and Tracking Alignment: Ensures accurate tuning across the entire FM band.
- FM Stereo Separation Adjustment: Allows for fine-tuning of the stereo decoder to achieve maximum channel separation.
- AM I-F Strip Alignment: Although noted that factory settings are usually sufficient, the procedure is available if needed.
- AM Frequency Coverage and Tracking Alignment: Ensures accurate tuning across the AM band.
- Parts List and Diagrams: The manual includes a complete electrical parts list, mounting diagrams, and a detailed schematic diagram, which are essential for troubleshooting and repair.
- Repacking Instructions: Detailed repacking instructions are provided to ensure the unit can be safely shipped for service or relocation, emphasizing the use of original packing materials.
Overall, the Sony ST-5066 is a well-documented tuner, offering robust specifications and a design that supports both user operation and professional maintenance.
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