The JVC KD-X2 is a stereo cassette deck, designed for high-quality audio recording and playback. This service manual provides comprehensive details for its maintenance, adjustment, and repair.
Function Description
The KD-X2 operates as a standard stereo cassette deck, supporting both recording and playback functions. It features a 4-track, 2-channel system and a tape speed of 1-7/8 inches per second (4.8 cm/sec). The deck is equipped with a METAPERM head for recording/playback and a 2-gap ferrite head for erasure, ensuring optimal performance across different tape types.
Key operational features include:
- Tape Type Selection: The deck supports Metal, Chrome, and Normal tapes, with specific frequency response characteristics for each.
- Dolby B NR: Integrated Dolby B Noise Reduction significantly improves the signal-to-noise ratio, especially at higher frequencies, enhancing audio clarity.
- Input/Output: It includes two mic jacks and two input jacks for recording, along with two output jacks for playback, allowing for versatile connectivity with other audio equipment.
- Fast Forward/Rewind: The deck offers efficient fast forward and rewind capabilities, completing a C-60 cassette in approximately 100 seconds.
- LED Meter: An LED meter provides visual indication of audio levels, aiding in accurate recording.
Important Technical Specifications
Audio Performance:
- Frequency Response (0 dB recording):
- Metal tape: 40-11,000 Hz (±3 dB)
- Chrome tape: 40-8,000 Hz (±3 dB)
- Normal tape: 40-8,000 Hz (±3 dB)
- Frequency Response (-20 dB recording):
- Metal tape: 40-15,000 Hz (±3 dB)
- Chrome tape: 40-15,000 Hz (±3 dB)
- Normal tape: 40-14,000 Hz (±3 dB)
- S/N Ratio: 58 dB (1 kHz, K3=3%, A-weighted, Metal tape). Dolby B NR improves S/N by approximately 15 dB at 500 Hz, up to 20 dB at 1 kHz-10 kHz, and MOL by 4 dB at 10 kHz.
- Wow and Flutter: 0.08% (WRMS), 0.20% (DIN 45 500).
- Crosstalk: 60 dB (1 kHz).
- Harmonic Distortion: K3; 0.5%, THD; 1.0% (Metal tape, 1 kHz, 0 dB).
Inputs/Outputs:
- Mic Jack x 2: Max. sensitivity; 0.4 mV (-68dBV), Matching impedance; 600 Ω-10 KΩ.
- Input Jack x 2: Min. input level; 80 mV, Input impedance; 100 KΩ.
- Output Jack x 2: Output level; 300 mV, Output impedance; 5 KΩ.
General:
- Power Requirement: AC 240 V, 50/60 Hz.
- Power Consumption: 10 W (power ON), 0.8 W (power switch OFF).
- Dimensions (WHD): 17-1/8" (435 mm) x 4-9/16" (115 mm) x 9-3/8" (237 mm).
- Weight: 7.7 lbs (3.5 kg).
- Accessories: Pin plug cord.
Usage Features
The KD-X2 is designed for straightforward operation. The front panel features clearly labeled controls for recording, playback, fast forward, rewind, stop/eject, and pause. Input level controls allow users to adjust recording levels, monitored by the LED meter for optimal signal input. The tape type selector ensures appropriate equalization and bias settings for different cassette formulations. The Dolby B NR switch can be engaged to reduce tape hiss during recording and playback.
Maintenance Features
The service manual outlines detailed procedures for maintaining and adjusting the KD-X2, ensuring its longevity and optimal performance.
Safety Precautions:
- Emphasizes the use of original design parts and qualified personnel for service.
- Warns against unauthorized alterations to design or circuitry.
- Highlights special safety-related characteristics of many electrical and mechanical parts, identified by (A) in schematics and parts lists.
- Provides instructions for leakage current checks after re-assembly to ensure electrical safety.
Removal of Main Parts:
- Step-by-step guides for removing the top cover, bottom cover, rear panel, front panel, mechanism assembly, tape counter, damper, power switch, and LED indicator board. These instructions are crucial for accessing internal components for repair or replacement.
Mechanism Section:
- Detailed procedures for disassembling and reassembling mechanical parts such as the Rec./PB head, erase head, pinch roller arm assembly, supply and take-up reel discs, and motor.
- Specific instructions for adjusting the motor pulley position (10.5mm) to prevent staining of the main and RF belts.
- Guidance on assembling the FM bracket and belts, including the full auto belt and RF belt.
Main Adjustment:
- Equipment Required: Lists necessary tools like electronic voltmeters, audio frequency oscillators, attenuators, standard tapes (Maxell UD, TDK SA, JVC ME), JVC Test Tapes (VTT703L for azimuth, VTT712 for motor speed/wow flutter, VTT739 for frequency response, VTT724 for playback level), and a torque testing cassette gauge (CTG-N).
- Electrical Adjustment:
- Record/Playback Head Position: Adjust screw (A) using VTT703L test tape until maximum output is achieved on an electronic voltmeter.
- Erase Head Height: Adjust screw (C) using a C-120 cassette to ensure the tape runs in the center of the erase head tape guide.
- Motor Speed: Connect a speed meter to LINE OUT terminals, play VTT712, and adjust the semi-fixed resistor in the motor until the speed meter reads 3000 Hz.
- Wow and Flutter: Check using a wow and flutter meter with VTT712; reading should be within 0.08% (WRMS).
- Playback Torque: Use a torque testing cassette tape; if standard torque is not met, replace the take-up disc assembly.
- Fast Forward/Rewind Torque: Measure torque; if not standard, clean or replace capstan belt, idler, motor pulley, flywheel, and reel disc circumferences.
- Electrical Circuit Adjustment:
- Main Amp P.W. Board: Provides a diagram showing adjustment points for bias frequency, recording frequency response, recording level, record/playback distortion, signal-to-noise ratio, and erasing coefficient.
- Playback Gain: Adjust R117 & R118 (L-ch) and R217 & R218 (R-ch) using VTT644/VTT724 to achieve -8 dBs ±2 dB at LINE OUT.
- Playback Frequency Response: Adjust VR102 (L-ch) and VR202 (R-ch) using VTT739 to achieve 0 ±2 dB at 1 kHz and 10 kHz.
- Bias Frequency: Adjust L951 to 95 kHz ±1 kHz.
- Recording Frequency Response: Adjust VR152 (LCH) and VR252 (RCH) for 0 ±3 dB deviation at 50 Hz and 12.5 kHz relative to 1 kHz output.
- Recording Level: Adjust R165 & R166 (L-ch) and R265 & R266 (R-ch) to achieve 0 ±2.0 dB at LINE OUT for a 1 kHz -23 ±3 dBV input signal.
- Record/Playback Distortion: Check THD for NORM tape (<2.0%), CrO2 tape (<3%), Metal tape (<2%).
- Signal to Noise Ratio: Check for NORM, CrO2, and Metal tapes (>42 dB).
- Erasing Coefficient: Check for >65 dB.
Parts Lists and Diagrams:
- P.C. Board Parts and Parts List: Includes detailed diagrams of the Power Switch P.C. Board, Main P.C. Board Ass'y, MS SW P.C. Board, LED P.C. Board, LED Meter P.C. Board Ass'y, and Voltage Selector P.C. Board, along with a comprehensive list of components.
- Wiring Connections: Provides a clear diagram of all internal wiring, color-coded for easy identification.
- Exploded Views: Offers detailed exploded diagrams for both the enclosure assembly and the mechanism assembly, with corresponding parts lists, facilitating identification and reassembly of all components.
This comprehensive documentation ensures that technicians can effectively troubleshoot, repair, and maintain the JVC KD-X2 stereo cassette deck to factory specifications.
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