Sharp MD-MT20 Service Manual
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Sharp MD-MT20 Service Manual

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Illustration: MD-MT20/20C
Illustration: MD-MT20W
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
CONTENTS
SHARP CORPORATION
- 1 -
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.
This document has been published to be used
for after sales service only.
The contents are subject to change without notice.
MD-MT20/20C/20W
No. S6943MDMT20//
Page

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Summary of Contents for Sharp MD-MT20

  • Page 1: Table Of Contents

    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 ..........................

  • Page 2: Safety Precaution For Service Manual (Md-Mt20W Only)

    MD-MT20/20C/20W SAFETY PRECAUTION FOR SERVICE MANUAL (MD-MT20W ONLY) Precaution to be taken when replacing and servicing the Laser Pickup. The AEL (Accessible Emission Level) of Laser Power Output for this model is specified to be lower than Class I Requirements.

  • Page 3: Specifications

    MD-MT20/20C/20W FOR A COMPLETE DESCRIPTION OF THE OPERATION OF THIS UNIT, PLEASE REFER TO THE OPERATION MANUAL. SPECIFICATIONS MD-MT20/20C MD-MT20W General General DC 2.4V: Rechargeable Nickel-Metal Hydride battery (AD- Power source: DC 2.4V: Rechargeable Nickel-Metal Hydride battery (AD- Power source:...

  • Page 4: Names Of Parts

    32. Microphone Input Socket 33. Hold Switch 34. 5V DC Input Socket 35. Battery Cover Remote control unit 1. Headphones Jack (MD-MT20/20C) 1. Earphones Socket (MD-MT20W) 2. Fast Reverse/Recording Level Down/ Name Select Button 3. Hold Switch 4. Play/Pause Button 5.

  • Page 5: Power Source

    MD-MT20/20C/20W OPERATION MANUAL – 5 –...
  • Page 6 MD-MT20/20C/20W – 6 –...
  • Page 7 MD-MT20/20C/20W – 7 –...

  • Page 8: Quick Guide (Md-Mt20 Only)

    MD-MT20/20C/20W OUICK GUIDE (MD-MT20 ONLY) – 8 –...
  • Page 9 MD-MT20/20C/20W – 9 –...

  • Page 10: Disassembly

    MD-MT20/20C/20W DISASSEMBLY (B1)x2 Cares before disassembling Key Switch ø1.4x2mm When assembling the machine after disassembling or Top Cabinet repair, observe the following requirements so as to ensure (A1)x2 safety and performance. ø1.4x2mm 1. Remove the batteries from the machine, and take out the (A1)x1 ø1.4x2mm...

  • Page 11: Removing And Reinstalling The Main Parts

    MD-MT20/20C/20W REMOVING AND REINSTALLING THE MAIN PARTS Remove the mechanism according to the disassembling meth- (A2)x3 ods 1 to 4. (See Page 10.) ø1.4x2.8mm (A1)x1 Spindle Motor Mechanism Flexible How to remove the spindle motor (See Fig. 11-1.) PWB Solder joint 1.

  • Page 12: Adjustment

    MD-MT20/20C/20W ADJUSTMENT Test disc MD adjustment needs two types of disc, namely recording disc (low reflection disc) and playback-only disc (high reflection disc). Parts No. Type Test disc High reflection disc MMD-110 (TEAC Test MD) 88GMMD-110 Low reflection disc MMD-212 (TEAC Test MD) 74-minute disc...
  • Page 13 MD-MT20/20C/20W Operation in each TEST mode 1. AUTO1 Mode • When the STOP button is pressed while the AUTO1 menu appears or during automatic adjustment, the mode changes to the TEST mode stop state. At this time the adjustment value is not output.
  • Page 14 MD-MT20/20C/20W 5. NORMAL Mode • When the STOP button is pressed while the NORMAL menu appears, the mode changes to the TEST mode stop state. • Indication during operation Indication of memory capacity on main unit LCD [ ] + Level meter...
  • Page 15 MD-MT20/20C/20W EEPROM (IC402) writing procedure 1. Procedure to replace EEPROM and write initial value of microcomputer in EEPROM (1) Replace EEPROM. (2) Deprive EEPROM of protection (connect the pins 8 and 6 of IC402). (3) Refer to the latest EEPROM data list.
  • Page 16 MD-MT20/20C/20W EEPROM DATA LIST (EEPROM version f) TEMP setting Sled setting Item display Set values Item display Set values T M _ _ Calculate values S L G _ S L 2 _ S L M _ Fucus setting S L V _...
  • Page 17 MD-MT20/20C/20W – 17 –...
  • Page 18 MD-MT20/20C/20W – 18 –...
  • Page 19 MD-MT20/20C/20W – 19 –...
  • Page 20 MD-MT20/20C/20W – 20 –...
  • Page 21 MD-MT20/20C/20W – 21 –...
  • Page 22 MD-MT20/20C/20W – 22 –...
  • Page 23 MD-MT20/20C/20W – 23 –...
  • Page 24 MD-MT20/20C/20W – 24 –...

  • Page 25: Notes On Schematic Diagram

    MD-MT20/20C/20W NOTES ON SCHEMATIC DIAGRAM • Resistor: • The indicated voltage in each section is the one measured To differentiate the units of resistors, such symbol as K and by Digital Multimeter between such a section and the chas- M are used: the symbol K means 1000 ohm and the symbol sis with no signal given.

  • Page 26: Voltage

    MD-MT20/20C/20W VOLTAGE IC101 IC201 IC401 IC501 IC701 IC801 VOLTAGE PIN VOLTAGE PIN VOLTAGE VOLTAGE VOLTAGE VOLTAGE VOLTAGE VOLTAGE 0.88V 0.72V 2.5V 0.72V 0.2V 2.5V 2.5V 2.32V 2.5V 2.34V 0.72V 1.27V 0.72V 2.35V 0.73V 1.24V 1.25V 2.32V 1.24V 1.25V 0.18V 0.73V 0.71V...

  • Page 27: Block Diagram

    MD-MT20/20C/20W J702 MIC IN J801 (READY FOR J703 J703 Ni - MH Battery PLUG/IN DC IN JACK J701 J701 HEADPHONES REMOTE (4~5.5V) POWER) OPTICAL IN LINE IN LINE CONTROL Dry Battery (2 pieces) 1.7~3.4V IC901 SPINDLE MOTOR DRIVER BA6966FV 1, 3, 4, 5,...

  • Page 28: Schematic Diagram

    MD-MT20/20C/20W P29 P30 MAIN PWB-A1 C112 0.033 L203 100mA C209 C111 C110 22P(CH) TP139 C107 C109 IC101 0.0033 0.22 C211 0.012 5P(CH) C106 RF SIGNAL PLAYBACK SIGNAL 0.22 PROCESSOR 47 46 45 44 43 42 41 39 38 37 RECORD SIGNAL...
  • Page 29 MD-MT20/20C/20W DADATA TP451 EDIT ADDATA TP452 DISPLY L203 DFCK TP453 SKIP DOWN 100mA BCLK TP454 SKIP UP (CH) LRCK HREC TP455 C211 TP456 P-MODE 5P(CH) ADPON TP457 HSTOP STOP DAPON TP458 VOL DOWN OPTCNT TP459 HPLAY R455 R456 R457 PLAY 5.6K...
  • Page 30 MD-MT20/20C/20W • NOTES ON SCHEMATIC DIAGRAM can be found on page 25. • The numbers are waveform numbers shown in page 36. TP451 EDIT TP452 DISPLY LCD ASS'Y TP453 SKIP DOWN TP454 SKIP UP TP455 KEY SWITCH TP456 P-MODE FLEXIBLE...

  • Page 31: Wiring Side Of P.w.board

    MD-MT20/20C/20W MAGNETIC HEAD FLEXIBLE PWB(18) M901 SPINDLE MOTOR OPTICAL PICKUP UNIT(13) MAGNETIC HEAD(24) SW902 DISC MECHANISM PROTECT FLEXIBLE PWB PH901 CN601 PHOTO TO MAIN PWB INTERRUPTER P32 5-H M902 SLED MOTOR CN101 M903 HEAD TO MAIN PWB UP/DOWN MOTOR P32 4-H...
  • Page 32 MD-MT20/20C/20W MAIN PWB-A1 (BOTTOM VIEW) R804 R269 TO AUDIO PWB Terminal, Battery IC805 CN702 (235) P34 3-A C258 R255 FLAT CABLE (243) R254 R262 C253 R261 To Key Switch Flexible Ass'y To LCD Ass'y P31 2-E P31 5-E Terminal, Battery...
  • Page 33 MD-MT20/20C/20W MAIN PWB-A1 (TOP VIEW) R256 SW801 SW801 Ni-MH BATTERY DETECTION R250 IC806 R251 D812 IC803 F871 C805 R268 T0.5A L 63V C876 L821 L822 C600 R600 C874 L600 C821 C651 IC841 C609 L609 C605 C834 R833 C610 C875 C826...
  • Page 34 MD-MT20/20C/20W TO MAIN PWB AUDIO PWB-A2 (TOP VIEW) CN701 P32 2-B FLAT CABLE (243) CN702 L752 L751 L453 R764 R763 R765 R761 L454 C755 R769 R770 R753 R762 IC703 C491 C758 C756 R716 R754 C712 L703 R714 C757 C759 L704...
  • Page 35 MD-MT20/20C/20W AUDIO PWB-A2 (BOTTOM VIEW) TP066 TP077 TP068 TP062 TP076 TP728 TP064 TP061 TP069 TP086 TP065 TP080 L452 TP093 TP727 TP063 TP082 TP067 TP072 TP092 TP724 TP729 J703 TP070 TP089 REMOTE CONTOL/ TP722 HEADPHONES TP721 TP723 TP071 TP070B TP721B TP725...

  • Page 36: Waveforms Of Md Circuit

    MD-MT20/20C/20W WAVEFORMS OF MD CIRCUIT Stopped 1994 / 12 / 15 22:54:19 Stopped 1994 / 12 / 16 00:24:17 Stopped 1994 / 12 / 16 01:03:40 CH1=1mV CH2=500mV CH3=5V CH4=2V 50ms/div CH1=2V CH2=2V CH3=2V CH4=2V 50us/div CH1=1V CH2=2V CH3=500mV 2ms/div...

  • Page 37: Trouble Shooting

    MD-MT20/20C/20W TROUBLE SHOOTING It is advisable to use the TEST mode (refer to Error Data Display Mode, P19) indicating the causes of troubles before starting repair. Causes of operation errors (up to 10 errors) are recorded as error codes. This information is useful for repair.
  • Page 38 MD-MT20/20C/20W • Abnormal display Is waveform output from CN482 pins 6 to 8? Is waveform output from IC401 pins 9,11,13? Are the pin 4 (VCC) and pin 5 (GND) normal? Check the periphery of IC401. Check between IC401 and CN482.
  • Page 39 MD-MT20/20C/20W • The spindle motor fails to run.Does the head move Check the IC201 periphery. Does the waveform appear on the IC201 pins 24 and 25 after TEST mode AUTO2 completion and in this state? Replace. IC601 Does waveform appear on the IC601 pin 13? Does waveform appear on IC901 pins 1, 19 and 20? L608, IC201, IC901, CN601 and flex, etc.

  • Page 40: Function Table Of Ic

    MD-MT20/20C/20W FUNCTION TABLE OF IC IC401 RH-iX0298AWZZ: System Microcomputer (IX0298AW) (1/3) Port Name Terminal Name Input/Output Function Pin No. P12/TCLKA Input Track cross signal/focus drive detection TCLKB SPIN Input Spindle motor FG pulse detection input CHGON Output Ni-MH battery charge ON output...
  • Page 41 MD-MT20/20C/20W IC401 RH-iX0298AWZZ: System Microcomputer (IX0298AW) (2/3) Port Name Terminal Name Input/Output Function Pin No. Input Operation mode selection input 1 INNSW Input Mechanism inner SW position detection input WDTOVF WDTOVF Output Watch dog timer (not used) Input Operation mode selection input 2...

  • Page 42: Circuit Description

    MD-MT20/20C/20W IC401 RH-iX0298AWZZ: System Microcomputer (IX0298AW) (3/3) System LSI expansion output port (6th generation: LR37811) Terminal Name Input/Output Pin No. Port Name Function Remarks EXPORT0 LDCNT1 Output Recording head raising-lowering control output 1 See the separate table *3. EXPORT1 LDCNT2...
  • Page 43 MD-MT20/20C/20W Battery voltage measurement When the battery is being used or while it is being charged, the output of pin 17 should be H (battery voltage measurement output). The output should be held L in the power-off mode and in the other modes. However, when it is necessary to measure the battery voltage, pull pin 17 (battery voltage measurement output) H temporarily, to make the measurement.
  • Page 44 MD-MT20/20C/20W –– MEMO –– – 44 –...
  • Page 45 “HOW TO ORDER REPLACEMENT PARTS” To have your order filled promptly and correctly, please furnish the For U.S.A. only following information. Contact your nearest SHARP Parts Distributor to order. 1. MODEL NUMBER 2. REF. No. 3. PART NO. 4. DESCRIPTION For location of SHARP Parts Distributor, Please call Toll-Free;...
  • Page 46 MD-MT20/20C/20W PRICE PRICE DESCRIPTION PARTS CODE PARTS CODE DESCRIPTION RANK RANK INTEGRATED CIRCUITS L702~704 RCILC0353AFZZ AB Tip Solid Induction,100mA L711~714 RCILC0353AFZZ AB Tip Solid Induction,100mA IC101 VHIIR3R55//-1 AQ RF Signal,Processor,IR3R55 AC 0.47 µH L719 VPBNNR47K0000 IC200 VHI62FP2002-1 AE 2.0V Regulator,62FP2002 AC 22 µH,Choke...
  • Page 47 AA 68 ohms,1/16W R206 VRS-CY1JB274F AA 270 kohms,1/16W R765,766 VRS-CY1JB180J AA 18 ohms,1/16W [MD-MT20W] R207 VRS-CY1JB681J AA 680 ohms,1/16W R765,766 VRS-CY1JB8R2J AA 8.2 ohms,1/16W [MD-MT20/20C] R222 VRS-CY1JB105J AA 1 Mohm,1/16W R767,768 VRS-CY1JB102J AA 1 kohm,1/16W R250,251 VRS-TV2AB1R0F AB 1 ohm,1/10W R769,770 VRS-CY1JB153J...
  • Page 48 QSW-M0170AFZZ AD Switch,Push Type [Disc Protect] PSHEZ0045AWZZ AB Sheet D,LCD PCUSZ0017AWZZ J AB Cushion,Cartridge MECHANICAL PARTS GFTAU3008AWSA J AS Bottom Cabinet [MD-MT20-S] GFTAU3009AWSA J AS Bottom Cabinet [MD-MT20C-S] NGERH0597AFZZ AC Wheel,Drive GFTAU3010AWSA J AS Bottom Cabinet [MD-MT20W-S] NSFTD0334AFZZ AD Screw,Drive...
  • Page 49 AB Caution,Headphones New Zealand] [MD-MT20 Only] TLABE0304AWZZ AB Label,Bar Code [MD-MT20W-S TINSE0254AWZZ AE Operation Manual [MD-MT20] TINSZ0429AWZZ AB Quick Guide [MD-MT20 Only] for Australia/New Zealand/ Taiwan Only] UBAGC0001AWZZ J AK Battery Carrying Case TLABE0305AWZZ AB Label,Bar Code [MD-MT20W-GL UBAGC0002AWSA J...
  • Page 50 MD-MT20/20C/20W 501x2 508x2 8-3(PH901) (SW902) 502x3 M901 M903 503x2 M902 Figure 5 MD MECHANISM EXPLODED VIEW – 5 –...
  • Page 51 MD-MT20/20C/20W 229x2 202-1 202-2 603x2 201-1 603x2 PWB-A2 201-2 602x3 PWB-A1 MD-MT20W Only 216x2 603x2 MD-MT20W Only MD MECHANISM 603x2 603x2 Figure 6 CABINET EXPLODED VIEW – 6 –...
  • Page 52 MD-MT20/20C/20W PACKING OF THE SET (MD-MT20 ONLY) Optical Digital Cable Setting position of switches and knobs UNIT HOLD Remote Control HOLD CANCEL Operation Manual AC Adaptor Headphones Caution SPAKZ0485AWZZ Quick Guide AC Adaptor Pad Carying Case Remote Control Connecting Cord...

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