Sharp MD-MT20 User Manual

MD-MT20/20C/20W
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CONTENTS
Page
SAFETY PRECAUTION FOR SERVICE MANUAL (MD-MT20W ONLY).............................................................................. 2
SPECIFICATIONS ................................................................................................................................................................. 3
NAMES OF PARTS ............................................................................................................................................................... 4
OPERATION MANUAL .......................................................................................................................................................... 5
QUICK GUIDE (MD-MT20 ONLY) ......................................................................................................................................... 8
DISASSEMBLY.................................................................................................................................................................... 10
REMOVING AND REINSTALLING THE MAIN PARTS....................................................................................................... 11
ADJUSTMENT ...................................................................................................................................................................... 12
NOTES ON SCHEMATIC DIAGRAM .................................................................................................................................. 25
TYPES OF TRANSISTOR AND DIODE .............................................................................................................................. 25
VOLTAGE ............................................................................................................................................................................ 26
BLOCK DIAGRAM ............................................................................................................................................................... 27
SCHEMATIC DIAGRAM ...................................................................................................................................................... 28
WIRING SIDE OF P.W.BOARD........................................................................................................................................... 31
WAVEFORMS OF MD CIRCUIT ......................................................................................................................................... 36
TROUBLE SHOOTING ........................................................................................................................................................ 37
FUNCTION TABLE OF IC.................................................................................................................................................... 40
CIRCUIT DESCRIPTION ..................................................................................................................................................... 42
PARTS GUIDE/EXPLODED VIEW
PACKING OF THE SET (MD-MT20 ONLY)
SERVICE MANUAL
SHARP CORPORATION
No. S6943MDMT20//
This document has been published to be used
for after sales service only.
The contents are subject to change without notice.
MD-MT20(S)
MD-MT20C(S)
MD-MT20W(BL)
MD-MT20W(GL)
MD-MT20W(S)
• In the interests of user-safety the set should be restored to its
original condition and only parts identical to those specified be
used.
Illustration: MD-MT20/20C
Illustration: MD-MT20W

Sharp MD-MT20 Specifications

General

Type	Portable Minidisc Recorder/Player
Release Year	1999
Sampling Rate Converter	Yes
Recording Format	ATRAC
Playback Format	ATRAC
Frequency Response	20 - 20000 Hz
Digital Input	Optical
Digital Output	Optical
Optical Input	Yes
Power Source	AC adapter
Included Accessories	Headphones
Display	LCD
Wow and Flutter	Below measurable level
Headphone Output	3.5mm stereo mini jack
Line Output	3.5mm stereo mini jack
Line Input	3.5mm stereo mini jack
Microphone Input	3.5mm stereo mini jack

Summary

Safety Precautions for Service

Laser Pickup Safety Precautions

Precautions for eye safety when servicing the Laser Pickup.

Specifications

Names of Parts

Operation Manual

Power Source Options

Details the available power sources: rechargeable battery, AC adaptor, and car adaptor.

Digital Recording via Optical Cable

Explains digital recording methods from external sources via optical cable.

Convenient Operation

Battery Level Indicator

Explains how to read the battery indicator and its limitations.

Hold Function for Preventing Accidental Operation

Details the use of the hold function to prevent unintended button presses.

MiniDisc System Limitations

Error Messages and Remedies

Lists error messages, their meanings, and corresponding remedies.

Quick Guide (MD-MT20 Only)

Recording and Playback Operations

Synchro Recording from CDs or MDs

Instructions for synchro recording from external audio sources like CDs or MDs.

Synchro Recording Using Microphone

Instructions for synchro recording using a connected microphone.

Playing a MiniDisc

Details how to play back a MiniDisc, including sound and bass control.

Disassembly Instructions

Precautions Before Disassembly

Important safety and performance considerations before starting disassembly.

Removing and Reinstalling Main Parts

Component Removal Procedures

Detailed instructions for removing the spindle motor, head motors, sled motor, and magnetic head.

Adjustment Procedures

Test Discs and Test Mode Entry

Identifies required test discs and describes methods to enter and exit the service test mode.

Shipping Setting Method

Procedure for setting the unit to shipping configuration.

EEPROM and Temperature Settings

EEPROM Writing Procedure

Step-by-step guide for writing initial values to the EEPROM.

Temperature Reference Setting Method

Method for measuring, calculating, and setting the temperature reference.

EEPROM Data List

Test Mode Overview and Chart

Specific Adjustment Parameter Settings

Focus, Tracking, and Spin Settings

Details for setting Focus, TEMP, Tracking, Spin, Sled, Bass, and Adjustment parameters.

Notes on Schematic Diagram

Transistor and Diode Types

Illustrates common transistor and diode symbols used in the diagrams.

Voltage Chart

Block Diagram

Schematic Diagram (1/3)

Schematic Diagram (2/3)

Schematic Diagram (3/3)

P.W. Board Wiring (1/5)

P.W. Board Wiring (2/5)

P.W. Board Wiring (3/5)

P.W. Board Wiring (4/5)

P.W. Board Wiring (5/5)

Waveforms of MD Circuit

Troubleshooting Flowcharts

Troubleshooting: When Device Does Not Function

Flowchart for diagnosing and resolving issues when the device fails to operate.

Troubleshooting: Specific Malfunction Diagnoses

Flowcharts for diagnosing specific issues like abnormal display or playback state errors.

Troubleshooting Specific Issues

Troubleshooting: Audio Playback Circuit Issues

Flowchart for diagnosing problems within the audio playback circuit.

Troubleshooting Motor and Recording Issues

Troubleshooting: Spindle Motor and Head Movement Issues

Flowcharts for diagnosing spindle motor failure and head movement problems.

Troubleshooting: Recording/Playback Operation Issues

Flowcharts for diagnosing issues with recording and playback operations.

IC401 Function Table (Part 1)

IC401 Function Table (Part 2)

Circuit Description: Charging Control

Battery Voltage Measurement

Parts Guide

How to Order Replacement Parts

Information on how to order replacement parts, including required details.

Capacitor and Resistor Part Codes

Explains the coding system used for capacitors and resistors.

Parts List: Integrated Circuits and Resistors

Parts List: Capacitors and Resistors (Continued)

Parts List: Transistors, Diodes, Coils, etc.

Parts List: Accessories and P.W.B. Assembly

MD Mechanism Exploded View

Cabinet Exploded View

Packing of the Set (MD-MT20 Only)