This document is a service manual for the FISHER MT-M23 Full-Automatic Linear Tracking Turntable, designed for the European market. It provides comprehensive information for servicing, including specifications, exploded views, parts lists, adjustment procedures, and circuit diagrams.
The FISHER MT-M23 is a full-automatic, linear tracking turntable, meaning it automates several playback functions and uses a linear tracking tonearm that moves parallel to the record's radius, theoretically reducing tracking error.
Function Description:
The turntable offers full-automatic operation, including:
- Automatic Start/Stop: The tonearm automatically moves to the record and returns at the end of playback.
- Reject Function: Allows the user to stop playback and return the tonearm to its rest position.
- Repeat Function: Enables continuous playback of a record.
- Automatic Tonearm Return at End of Record: Ensures the tonearm safely returns to its rest position after a record finishes.
- Manual Function: Provides manual control for starting and stopping playback.
- Record Speed Selector: Supports two standard playback speeds: 33-1/3 rpm and 45 rpm.
Important Technical Specifications:
- Motor: DC Servo motor, indicating precise speed control.
- Drive System: Belt-driven, which helps to isolate the platter from motor vibrations.
- Wow and Flutter (WRMS): 0.08%, a measure of speed stability, indicating minimal pitch variations.
- Rumble (DIN 45539B): -65 dB, representing a low level of unwanted low-frequency noise.
- Speed Variation: ±1.5%, indicating the allowable deviation from the set speed.
- Tracking Force: 2 g, the recommended downward force of the stylus on the record groove.
- Platter Diameter: 300 mm.
- Platter Weight: 0.4 kg.
- Tonearm Effective Length: 130 mm.
- Tonearm Shape: Straight.
- Tonearm Friction Sensitivity: Horizontal Pivot 0.15 g, Vertical Pivot 0.2 g, indicating low resistance to tonearm movement.
- Max. Tracking Error: ±0.2°, a very low figure due to the linear tracking design.
- Power Requirements: AC 220 V (50 Hz), specific to the European market.
- Power Consumption: 10 W.
- Dimensions (W x H x D): 335 x 92 x 345 mm.
- Weight (approx.): 3.6 kg.
Usage Features:
The turntable's full-automatic nature simplifies operation for the user. The linear tracking tonearm is designed to maintain a constant tangency to the record groove, theoretically minimizing distortion. The inclusion of both 33-1/3 rpm and 45 rpm speeds allows for playback of LPs and singles.
Maintenance Features (as detailed in the service manual):
The manual provides detailed instructions for various adjustments and component replacements, crucial for maintaining optimal performance:
- Arm Feed Cord Stringing: An illustrated guide for correctly routing the arm feed cord, essential for the linear tracking mechanism.
- Cabinet & Chassis Exploded View and Parts List: Detailed diagrams and lists of all cabinet and chassis components, including screws, springs, knobs, and various mounts, facilitating identification and replacement.
- Turntable Adjustments:
- Stylus Pressure Adjustment: Procedure to set the correct stylus tracking force (1.8~2.2 g) using a dedicated screw and meter.
- Stylus Height Adjustment: Steps to adjust the stylus height to 6mm±0.5mm above the turntable.
- Rotation Adjustment: Instructions for adjusting platter rotation speed (33-1/3 rpm and 45 rpm) using a stroboscope sheet and volume controls.
- Tonearm Position Adjustment: Guide to adjust the tonearm's resting position to be perpendicular to the cabinet's rear wall.
- Photointerrupter Position Adjustment for Arm Feed: Procedure to adjust the arm feed mechanism using a screwdriver.
- End Return Sensitivity Adjustment: Steps to adjust the tonearm's end-of-record return sensitivity.
- Lead-in Position Adjustment: Instructions for adjusting the tonearm's lead-in position to ensure correct record start.
- Arm Trace Adjustment: Procedure to ensure the tonearm correctly traces the silent groove on a record, involving a potential modification (cutting R29 on the Control P.C.Board).
- Printed Circuit Board (Bottom View) and Parts List: Detailed layouts and component lists for all PCBs (Control, PCR, PTR, LED, Terminal, Speed Switch, Switch, Fuse), aiding in troubleshooting and component replacement.
- IC Signal Flow & Equivalent Circuit: Diagrams illustrating the internal logic and pin configurations of key integrated circuits (LM 6416E, NJM 7812, NJM 7912).
- Semiconductor Lead Identification: Visual guides for identifying the leads of various semiconductors (ICs, transistors, diodes).
- Schematic Diagram and Point to Point Wiring Diagram: Comprehensive electrical diagrams for circuit analysis and wiring verification.
- Product Safety Notice: Emphasizes the importance of following safety precautions and using designated replacement parts, especially for components marked with the IEC symbol, to ensure product safety.
This manual is an indispensable resource for technicians performing repairs and maintenance on the FISHER MT-M23 turntable, ensuring its continued proper function and safety.
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