The Technics RS-D225W is a Dolby NR-equipped double cassette deck, designed for stereo audio recording and playback. It is part of the RS-D550W mechanism series, indicating a shared internal architecture with other models in that line.
Function Description:
The primary function of the RS-D225W is to record and play back audio on standard compact cassette tapes. Being a double cassette deck, it offers enhanced functionality compared to single decks, including:
- Continuous Playback (Series Playback): Tapes can be played continuously from deck 1 to deck 2, or vice versa, allowing for extended listening without interruption.
- Edit-Recording/Auto Space: This feature enables users to create non-recorded spaces (approximately four seconds long) between tunes during recording. It also allows for tape speed changes during editing, automatically shifting to record mute until the motor speed stabilizes.
- High-Speed Editing: The deck supports high-speed editing, allowing for faster copying or editing processes.
- Dolby Noise Reduction: The integrated Dolby NR system (B/C NR selector) is a crucial feature for improving audio quality. It reduces tape hiss, especially noticeable during quiet passages, by processing low-level signals during recording and playback. The system is manufactured under license from Dolby Laboratories Licensing Corporation.
- Automatic Tape Selector System: This system automatically detects the type of tape (Normal, CrO2, Metal) inserted into the cassette holder and adjusts the bias and equalization settings accordingly for optimal recording and playback performance.
- Input Level Control: Users can manually adjust the recording input level to prevent distortion and achieve optimal sound quality.
- Recording Level Indicators (Peak Level Meter): These indicators provide visual feedback on the recording level, helping users monitor and adjust input levels effectively. The segment (-∞) of the level meter remains lit when power is on.
Important Technical Specifications:
- Deck System: Stereo cassette deck.
- Track System: 4-track, 2-channel.
- Heads:
- TAPE 1 (Playback): Solid Permaloy head.
- TAPE 2 (Record/Playback): Solid Permaloy head.
- TAPE 2 (Erasing): Double-gap ferrite head.
- Motors:
- TAPE 1 (Capstan/Reel Table Drive): 2-speed electronically controlled DC motor.
- TAPE 2 (Capstan/Reel Table Drive): 2-speed electronically controlled DC motor.
- Recording System: AC bias.
- Bias Frequency: 80 kHz.
- Tape Speed: 4.8 cm/sec. (1-7/8 ips).
- Frequency Response (without Dolby N.R.):
- METAL: 20 Hz ~ 16 kHz (30 Hz ~ 15 kHz DIN).
- CrO2: 20 Hz ~ 15 kHz (30 Hz ~ 15 kHz DIN).
- NORMAL: 20 Hz ~ 15 kHz (30 Hz ~ 15 kHz DIN).
- Signal-to-Noise Ratio (S/N) (signal level max. recording level, CrO2 type tape):
- Dolby NR in: 66 dB (CCIR).
- NR out: 56 dB (A weighted peak).
- Wow and Flutter: 0.08% (WRMS), ±0.2% (DIN).
- Fast Forward and Rewind Time: Approximately 105 seconds with a C-60 cassette tape.
- Input Sensitivity and Impedance (LINE): 60 mV/47 kΩ.
- Output Voltage and Impedance (LINE): 400 mV/1.5 kΩ.
- Power Consumption: 18 W.
- Dimensions (W x H x D): 430 x 115 x 227 mm (16-15/16" x 4-1/2" x 9-1/32").
- Weight: 3.4 kg (7.5 lb.).
- Color: Black Type.
- Areas: The device is available in various regions, including Europe (excluding UK), UK, Holland, F.R. Germany, Belgium, Asia, Oceania, Latin America, Middle Near East and Africa, and Australia.
Usage Features:
- Double Cassette Holders: Two cassette holders allow for simultaneous playback, recording, or tape-to-tape dubbing.
- Tape Counter/Reset Button (Tape 2): Provides a numerical display for tracking tape position and a reset function.
- Tape Indicator (Auto Tape Select): Visually indicates the type of tape currently in use (Normal, CrO2, Metal).
- Recording Indicator (Rec Indicator): Lights up to show when the deck is in recording mode.
- Playback Controls: Dedicated buttons for play, fast forward, rewind, stop/eject, and pause for both Tape 1 and Tape 2.
- Remote Control Compatibility: The deck can be operated using a remote-control transmitter for playback functions.
- Power Switch: Standard power on/off control.
Maintenance Features:
The service manual provides detailed instructions for measurement and adjustment, crucial for maintaining optimal performance:
- Head Azimuth Adjustment: Ensures proper alignment of the playback and record/playback heads for accurate sound reproduction. This involves playing a test tape (QZZCFM) and adjusting screws to maximize output from both channels and eliminate phase deflection.
- Band Speed Adjustment: Calibrates the tape speed for both normal and high-speed modes using a test tape (QZZCWAT) and adjusting potentiometers (VR904, VR903, VR902, VR901) to achieve the standard frequency output (3000±20 Hz for normal, 6000±40 Hz for high).
- Playback Frequency Response Adjustment: Checks the deck's ability to accurately reproduce a range of frequencies (315 Hz, 12.5 kHz ~ 63 Hz, -20 dB) using a test tape (QZZCFM).
- Playback Gain Adjustment: Calibrates the output level during playback using a test tape (QZZCFM) and adjusting potentiometers (VR1, VR2, VR3, VR4) to a standard output of 0.4V ± 0.5dB.
- Overall Frequency Response Adjustment (Recording): This comprehensive adjustment involves recording test signals onto blank tapes (Normal, CrO2, Metal) and then playing them back to verify frequency response. Bias current (VR301, VR302) is adjusted to ensure the frequency level is within standard ranges.
- Overall Gain Adjustment (Recording): Calibrates the recording gain by recording a reference signal onto a blank tape and adjusting potentiometers (VR7, VR8) to achieve a standard output of 0.4V +0.1/-0.08V.
- Dolby NR Circuit Adjustment: Ensures the Dolby noise reduction system functions correctly by applying a 5 kHz signal and adjusting the output level between IC401 terminals and ground to 12.3mV, then verifying the level change when NR is activated.
- Disassembly Instructions: Detailed steps for removing the cabinet, mechanism unit, LED meter PCB, VR/SW PCB, and main PCB, facilitating repairs and component replacement.
- Wiring Connection Diagram and Schematic Diagram: Essential for troubleshooting and understanding the internal electrical connections.
- Printed Circuit Boards and Parts Lists: Provide component layouts and identification for all PCBs, aiding in repair and replacement.
The RS-D225W is a robust and feature-rich double cassette deck, designed for enthusiasts and general users alike, offering comprehensive recording and playback capabilities with a focus on audio fidelity through its Dolby NR system and precise calibration options.
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