Sansui AU-101 Stereo Amplifier Service Manual
Model: AU-101
Brand: Sansui Electric Co., Ltd.
Introduction
This service manual provides detailed information for the Sansui AU-101 stereo amplifier. It is intended for qualified service technicians. The AU-101 builds upon Sansui's reputation for quality audio reproduction, offering robust performance for its class. While this manual focuses on the AU-101, it may offer insights relevant to other Sansui models, such as the more powerful AU-555A, which also features an all-silicon solid-state design.
Users are advised to use all other controls and switches according to their personal taste and room acoustics to achieve optimal sound reproduction.
Specifications
The following specifications detail the performance capabilities of the Sansui AU-101:
| Parameter | Specification |
|---|---|
| Continuous Power Output (RMS) | 20W + 20W (at 8 ohms, 1kHz) |
| Music Power Output (RMS) | 24W + 24W (at 8 ohms, 1kHz) |
| Total Harmonic Distortion (THD) | Less than 0.8% (at rated output) |
| Frequency Response | 20Hz - 40kHz |
| Input Sensitivity | Phono: 2.5mV / 50kΩ Aux/Tuner/Tape: 150mV / 100kΩ |
| Signal to Noise Ratio (S/N) | Phono: Better than 65dB Aux/Tuner/Tape: Better than 80dB |
| Power Consumption | Approx. 80W |
| Dimensions (W x H x D) | 380 x 120 x 250 mm |
| Weight | Approx. 7.5 kg |
Circuit Description
The AU-101 employs a discrete transistor circuit design for its preamplifier and power amplifier stages. The preamplifier section is responsible for signal amplification and tone control, featuring a phono equalizer circuit designed for accurate RIAA curve reproduction. The power amplifier utilizes a complementary symmetry output stage to deliver clean power to the speakers. ? The full schematic diagram, typically found in a service manual, details the specific component layout and signal flow through these stages.
Troubleshooting
This section outlines common issues and their potential solutions. Always disconnect the power cord before performing any internal inspection or repair. ⚙️
- No Sound Output: Check speaker connections, ensure volume is up, verify input source selection. Internally, check power supply voltages and output transistor integrity.
- Distorted Sound: This can indicate failing output transistors, overloaded input signals, or issues within the preamplifier stage. Check for DC offset at the speaker terminals.
- Hum or Noise: Investigate grounding issues, faulty capacitors in the power supply, or interference from nearby electrical devices. Ensure proper shielding is in place.
- Phono Input Not Working: Verify the phono cartridge wiring and the phono preamplifier circuit. Check the input selector switch for proper contact.
Refer to the detailed schematics and parts list for specific component identification and testing procedures.
Maintenance
Regular maintenance ensures the longevity and optimal performance of the AU-101 amplifier.
- Cleaning: Periodically dust the exterior and ventilation grilles using a soft, dry cloth. Avoid using liquids or aerosol cleaners.
- Internal Cleaning: If necessary, clean internal components with a soft brush or compressed air, taking care not to damage delicate parts. Ensure the unit is unplugged and capacitors are discharged.
- Component Checks: For units in long-term service, periodic checks of electrolytic capacitors for signs of leakage or bulging are recommended.
Controls and Switches
The AU-101 features several controls for audio adjustment:
- Volume Control: Adjusts the overall listening level.
- Tone Controls: Bass and Treble controls for shaping the frequency response.
- Selector Switch: Chooses the input source (e.g., Phono, Tuner, Aux, Tape).
- Speaker Selector: Allows selection of speaker outputs (e.g., A, B, A+B).
- Power Switch: Turns the unit on or off.
Users are encouraged to experiment with these controls to tailor the sound to their preferences and listening environment.
