The TEAC T-X150 is a digital synthesizer AM/FM stereo tuner, designed to provide high-quality radio reception with a focus on precision and clarity. This service manual outlines its specifications, alignment procedures, block diagrams, and parts lists, offering a comprehensive overview for technical understanding and maintenance.
Function Description
The T-X150 functions as a stereo tuner, capable of receiving both AM and FM radio broadcasts. Its digital synthesizer design ensures accurate and stable tuning across the frequency bands. The tuner processes incoming radio signals, demodulates them, and outputs an audio signal suitable for amplification and playback through a stereo system. Key components include an FM frontend, AM tuner unit, PLL synthesizer/control, FM IF detector amplifier, stereo MPX decoder, and signal processing circuitry for both AM and FM.
Important Technical Specifications
FM Tuner Section:
- Tuning Range: 87.5 MHz – 108 MHz
- Antenna Impedance: 300 ohms balanced / 75 ohms unbalanced
- Usable Sensitivity (Mono): 11.2 dBf
- 50 dB Quieting Sensitivity (Mono): 20.2 dBf
- 50 dB Quieting Sensitivity (Stereo): 40.2 dBf
- Image Response Ratio: 40 dB
- IF Response Ratio: 85 dB
- Spurious Response Ratio: 85 dB
- AM Suppression Ratio: 45 dB
- Capture Ratio: 1 dB
- Selectivity (±400 KHz): 65 dB
- Signal-to-Noise Ratio (Mono, IHF-A curve): 80 dB
- Signal-to-Noise Ratio (Stereo, IHF-A curve): 75 dB
- Harmonic Distortion (Mono): 0.1%
- Harmonic Distortion (Stereo): 0.3%
- Stereo Separation (1 kHz): 40 dB
- Frequency Response: 30 Hz – 15 kHz, +0 dB, -3 dB
- Subcarrier Product Ratio: 60 dB
- Output Level/Output Impedance: 775 mV/2.2 k ohms
AM Tuner Section:
- Tuning Range: 531 kHz – 1,602 kHz
- Usable Sensitivity (Loop antenna): 450 µV/m
- Selectivity (±9 kHz): 22 dB
- Image Response Ratio (1 kHz): 45 dB
- Harmonic Distortion: 0.5%
- Signal-to-Noise Ratio: 45 dB
- Output Level/Output Impedance: 230 mV/2.2 k ohms
General:
- Power Requirements (General Export Model): 100/120/220/240 V AC 50/60 Hz, 10 W
- Power Requirements (Europe): 220 V, AC 50 Hz, 14 W
- Power Requirements (U.K./Australia): 240 V, AC 50 Hz, 14 W
- Dimensions (W x H x D): 432 x 72 x 289 mm (17" x 2-13/16" x 11-3/8")
- Weight (Net): 3.2 kg (70.4 lbs)
- Standard Accessories: AM Loop Antenna, "T"-type FM antenna (300 Ω) except Europe, Input-output connection cords
Usage Features
The T-X150 features a user-friendly interface with a digital display for tuning information, including frequency and stereo indication. The front panel includes various operation buttons for memory presets (1-10/11-20), tuning (Up/Down), FM/AM band selection, and Mono/Stereo/Auto/Manual modes. The digital synthesizer ensures precise frequency selection and stability, enhancing the listening experience. The tuner's design allows for integration into existing stereo systems, providing a reliable source for radio content.
Maintenance Features
The service manual provides detailed information crucial for maintenance and repair:
- Voltage Conversion: For general export models, the unit supports 110V or 220V AC operation, with a switch to select the appropriate line voltage. This feature is important for ensuring compatibility with different regional power supplies and must be set correctly before connecting the power cord.
- Adjustment and Test Point Locations: The manual includes a diagram of the PC board with clearly marked adjustment and test points (e.g., TVR201 for AM signal indicator, IFT202 for AM IF transformer, TVR401 for VCO frequency). This facilitates accurate troubleshooting and calibration.
- Alignment Procedures: Comprehensive alignment charts are provided for both FM and AM sections, detailing the necessary test setup, initial tuner settings, adjustment points, measuring points, and desired adjustments. These procedures cover FM tracking, sensitivity, distortion, stereo separation, VCO frequency, and AM tracking, sensitivity, and output level. Specific instructions are given for using a stereo modulator, FM signal generator, AM signal generator, AC VTVM, oscilloscope, and distortion meter.
- Block Diagram: A detailed block diagram illustrates the signal flow and interconnections between major functional blocks, aiding in understanding the tuner's overall architecture and diagnosing issues.
- Exploded View and Parts List: An exploded view diagram with corresponding parts lists (including reference numbers, part numbers, and descriptions) is provided. This is invaluable for identifying and ordering replacement components, from the front panel and chassis to specific electronic parts like ICs, transistors, diodes, capacitors, resistors, and transformers.
- PC Board and Parts List: Specific PC board layouts with component designators and associated parts lists are included for the main tuner board (TU-A801) and switch boards (S-A817). This level of detail is essential for component-level repair.
- IC Block Diagram: Block diagrams for key integrated circuits (e.g., TC9172P, TC9303AN, LA1245, LB1403N, LA3390, UPC7806/7815A) are provided, showing their internal structure and pin assignments. This helps in understanding the function of each IC and troubleshooting IC-related faults.
- Safety Critical Components: The manual explicitly marks safety-critical components with a special sign, emphasizing that these parts must always be replaced with identical components from the appropriate parts list to ensure safety and proper operation.
- Schematic Diagram: A full schematic diagram offers a detailed circuit representation, allowing technicians to trace signals, measure voltages, and identify faulty components at a granular level.
The TEAC T-X150 is a robust and precisely engineered tuner, and its comprehensive service manual ensures that it can be effectively maintained and repaired to deliver consistent performance over its lifespan.
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