SHARP QT-CD131, QT-CD131C Service Manual

QT-CD131/131C

SERVICE MANUAL

No. S8870QTCD131/

QT-CD131 QT-CD131C

Illustration: QT-CD131

• In the interests of user-safety the set should be restored to its original condition and only parts identical to those specified should be used.

CONTENTS

IMPORTANT SERVICE NOTES (FOR QT-CD131 ONLY)................................................................................................ 2

SPECIFICATIONS ............................................................................................................................................................. 2

NAMES OF PARTS ........................................................................................................................................................... 3

DISASSEMBLY.................................................................................................................................................................. 4

REMOVING AND REINSTALLING THE MAIN PARTS..................................................................................................... 5

ADJUSTMENT ................................................................................................................................................................... 6

NOTES ON SCHEMATIC DIAGRAM ................................................................................................................................ 8

TYPES OF TRANSISTOR ................................................................................................................................................. 8

BLOCK DIAGRAM ............................................................................................................................................................. 9

SCHEMATIC DIAGRAM / WIRING SIDE OF P.W.BOARD............................................................................................. 12

WAVEFORMS OF CD CIRCUIT...................................................................................................................................... 21

TROUBLESHOOTING (CD SECTION) ........................................................................................................................... 22

FUNCTION TABLE OF IC................................................................................................................................................ 25

PARTS GUIDE/EXPLODED VIEW PACKING OF THE SET (FOR QT-CD131 ONLY)

Page

SHARP CORPORATION

– 1 –

This document has been published to be used for after sales service only. The contents are subject to change without notice.

QT-CD131/131C

FOR A COMPLETE DESCRIPTION OF THE OPERATION OF THIS UNIT, PLEASE REFER TO THE OPERATION MANUAL.

IMPORTANT SERVICE NOTES (FOR QT-CD131 ONLY)

BEFORE RETURNING THE AUDIO PRODUCT

(Fire & Shock Hazard) Before returning the audio product to the user, perform the following safety checks.

1. Inspect all lead dress to make certain that leads are not pinched or that hardware is not lodged between the chassis and other metal parts in the audio product.

2. Inspect all protective devices such as insulating materials, cabinet, terminal board, adjustment and compartment covers or shields, mechanical insulators etc.

3. To be sure that no shock hazard exists, check for leakage current in the following manner.

* Plug the AC line cord directly into a 120 volt AC outlet. * Using two clip leads, connect a 1.5k ohm, 10 watt resistor

paralleled by a 0.15µF capacitor in series with all exposed metal cabinet parts and a known earth ground, such as conduit or electrical ground connected to earth ground.

* Use a VTVM or VOM with 1000 ohm per volt, or higher,

sensitivity to measure the AC voltage drop across the resistor (See diagram).

* Connect the resistor connection to all exposed metal parts

having a return path to the chassis (antenna, metal cabinet, screw heads, knobs and control shafts, escutcheon, etc.) and measure the AC voltage drop across the resistor.

VTVM

AC SCALE

1.5k ohms 10W

0.15 µ F

TO EXPOSED METAL PARTS

All check must be repeated with the AC line cord plug connection reversed. Any reading of 0.3 volt RMS (this corresponds to 0.2 milliamp. AC.) or more is excessive and indicates a potential shock hazard which must be corrected before returning the audio product to the owner.

TEST PROBE

CONNECT TO KNOWN EARTH GROUND

SPECIFICATIONS

General

Power source: AC 120V, 60 Hz

DC 12 V [ "D" size (UM/SUM-1, R20 or HP-2) battery x 8] DC 3 V ["AA" size (UM/SUM-3, R6 or HP-7) battery x 2 for tuner memory]

Power consumption: 20 W Output power: FTC; 2.0 W min. RMS per channel (131) into 8 ohms from 150 Hz to 20 kHz,

with no more than 10 % total harmonic distortion. RMS; 2.3 W/CH (DC operation, 10 % T.H.D.)

Output power: RMS; 2.3 W/CH (131C) (DC operation, 10 % T.H.D.) Speakers: 4" (10 cm) full-range speaker x 2 Output terminals: Headphones; 16-50 ohms

(recommended; 32 ohms)

Dimensions: Width; 18-15/16" (480 mm)

Height; 6-1/16" (153 mm) Depth; 10" (254 mm)

Weight: 7.1 Ibs. (3.2 kg) without batteries

Radio

Frequency range: FM; 87.5 - 108 MHz

AM; 530 - 1,702 kHz

Tape recorder

Frequency response: 50 - 14,000 Hz (Normal tape) Signal/noise ratio: 50 dB Wow and flitter: 0.25 % (WRMS) Motor: DC 12 V electric governor Bias system: AC bias Erase system: Magnet erase

Compact disc player

Disc: Compact disc Signal readout: Non-contact, 3-beam semi-

conductor laser pickup

Audio channels: 2 Quantization: 16-bit linear quantization Filter: 4-tims oversampling digital filter D/A converter: 1-bit D/A converter Wow and flutter: Unmeasurable

(less than 0.001% W. peak)

Specifications for this model are subject to change without prior notice.

– 2 –

QT-CD131/131C

1. Cassette Compartment

2. CD Compartment

3. (TAPE) Record Button:

4. (TAPE) Play Button:

5. (TAPE) Rewind Button:

6. (TAPE) Fast Forward Button:

7. (TAPE) Stop/Eject Button:

8. (TAPE) Pause Button:

9. FM Stereo Mode Indicator: ST

10. FM Stereo Indicator:

11. Band Indicator: FM/AM

12. Memory Indicator

13. Preset Number Indicator

14. Frequency Indicator

15. (CD) Play Indicator:

16. (CD) Repeat Indicator:

17. (CD) Track Number Indicator

NAMES OF PARTS

5678

10 11 12

18. (TUNER) Preset Down Button:

19. (TUNER) Preset Up Button:

20. (TUNER) Band Selector Button

21. (TUNER) Preset Memory Button

22. (TUNER) Tuning Down Button:

23. (TUNER) Tuning Up Button:

24. Volume Control

25. Stand-by, On/Function Switch

26. Extra Bass Button: X-BASS

27. (CD) Track Down/Review Button:

28. (CD) Track Up/Cue Button:

29. (CD) Stop Button:

30. (CD) Play/Repeat Button:

31. FM Telescopic Rod Aerial

32. Headphone Socket

33. Battery Compartment

34. AC Power Input Socket

15 16

19 20 21 22 23

24 25 26 27 28 29 30

– 3 –

3231

33 34

QT-CD131/131C

DISASSEMBLY

Caution on Disassembly

Follow the below-mentioned notes when disassembling the unit and reassembling it, to keep it safe and ensure excellent performance:

1. Take cassette tape and compact disc out of the unit.

2. Be sure to remove the power supply plug from the wall outlet before starting to disassemble the unit.

3. Take off nylon bands or wire holders where they need be removed when disassembling the unit. After servicing the unit, be sure to rearrange the leads where they were before disassembling.

4. Take suffcient care on static electricity of integrated circuits and other circuits when servicing.

STEP REMOVAL PROCEDURE FIGURE

1 Rear Cabinet 1. Screw ................. (A1) x10 4-1

2. Socket .................. (A2) x2 4-2

2 Top Cabinet 1. Knob..................... (B1) x1 4-2

(with CD Mechanism/

Tape Mechanism/ 3. Socket .................. (B3) x2

Main PWB)

3 Main PWB/ 1. Screw ................... (C1) x8 4-3

Switch PWB 2. Socket .................. (C2) x4 4-3,5-2

Tuner Display PWB/

Switch PWB

5 Tape Mechanism 1. Screw ................... (E1) x4 5-2

6 CD Mechanism 1. Screw ................... (F1) x3 5-2

7 Terminal PWB 1. Screw ...................(G1) x5 5-3

8 Battery PWB 1. Hook..................... (H1) x2 5-4

2. Screw ................... (B2) x3

1. Screw .................. (D1) x3 5-1

2. Hook..................... (G2) x1

(A1)x6 ø3x20mm

(B2)x3 ø3x10mm

(A1)x3 ø3x12mm

(A2)x1

(A1)x1 ø3x12mm

Figure 4-1

Top Cabinet

Front Cabinet

Rear Cabinet

(B1)x1

(C1)x6 ø3x10mm

(C1)x2 ø3x10mm

Headphones PWB

(A2)x1

(C2)x1

Top Cabinet

Main PWB

Figure 4-2

Figure 4-3

(B3)x1

Front Cabinet

Switch PWB

Main PWB

– 4 –

(D1)x2

(G1)x2 ø3x10mm

(G1)x1 ø3x10mm

(G1)x2 ø3x10mm

Terminal PWB

Driver

Push

(G2)x1

Rear Cabinet

ø3x12mm

(E1)x4 ø3x10mm

QT-CD131/131C

Switch PWB

Tuner Display PWB

Front Cabinet

(D1)x1 ø3x10mm

Figure 5-1

Figure 5-3

(F1)x3 ø2.5x10mm

Tape Mechanism

(C2)x2

Top Cabinet

CD Mechanism

Figure 5-2

(C2)x1

REMOVING AND REINSTALLING THE MAIN PARTS

CD MECHANISM SECTION

Perform steps 1, 2, 3 and 6 of the disassembly method to remove the CD mechanism.

How to remove the pickup (See Fig. 5-5.)

1. Remove the screws (A1) x 2 pcs., to remove the shaft (A2) x1 pc.

2. Remove the stop washer (A3) x1 pc., to remove the gear (A4) x 1 pc.

3. Remove the pickup.

Pull

(H1)x1

Battery PWB

Pickup

Rear Cabinet

(H1)x1

Pull

Figure 5-4

(A1) x2

2.6 x6mm CD

Mechanism

– 5 –

Shaft (A2) x1

Figure 5-5

Gear (A4) x1

Stop Washer (A3) x1

QT-CD131/131C

ADJUSTMENT

MECHANISM SECTION

• Driving Force Check

Torque Meter

PLAY: TW-2412 Over 120 g

• Torque Check

Torque Meter

Play: TW-2111 25 to 65 g.cm Fast Forward: TW-2231 60 to 130 g.cm Rewind: TW-2231 60 to 130 g.cm

• Head Azimuth

Torque Meter

MTT-114 Output: Speaker Terminal

(CNP201 Load resistance: 8 ohms)

• Tape Speed

Test

Tape

MTT-111 In motor 3,000 ± 90 Hz Output: Speaker

Adjusting

Point

Specified

TAPE SECTION

Position of each switch or control

Volume control Max Function switch Tape/Power Off X-BASS On

• Bias Oscillation

Adjustment Point

L301 82 kHz ± 6 kHz Pin 2 of CNP201

• Playback Amplifier Sensitivity Check

Test Tape

MTT-118 1.8 V ± 3 dB Speaker Terminal

AM TRACKING

fL fH

AM BAR

ANTENNA

FM RF

Specified Value

– 6 kHz

Specified Value

TC1

TP1

FM IF

IC1

COVERAGE

Specified Value

Instrument

Value

Instrument Connection

(Load resistance: 8 ohms)

FM ROD ANTENNA

AM BAND

FM BAND

COVERAGE

Connection

Teaminal (CNP201 Load resistance: 8 ohms)

Instrument

Connection

R26

FM DET.

IC2

AM IF

MAIN PWB

TP2

VR1

VCO

TUNER SECTION

fL: Low-range frequency fH: High-renge frequency

• FM RF

Signal generator: 1 kHz, 75 kHz dev., FM modulated

Test Stage

Band — 87.5 MHz (fL): L2 *1 Coverage 2.0 ± 0.1 V

RF 90.0 MHz 90.0 MHz L1 *2

Frequency

(10~30 dB)

*1. Input: Antenna, Output: TP1 *2. Input: Antenna, Output: Speaker Terminal

• Detection

Signal generator: 10.7 MHz, FM sweep generator

Test

Stage

IF 10.7 MHz 98.00 MHz T1(Turn Input: Pin 1 of

Frequency

• AM IF/RF

Signal generator: 400 Hz, 30%, AM modulated

Test Stage

IF 450 kHz 1,720 kHz T3 *1

Band — 530 kHz (fL): L4 *3

Coverage 1.0 ± 0.1 V Tracking 600 kHz 600 kHz (fL): L3 *2

Frequency Frequency

1,400 kHz 1,400 kHz (fH):TC1

*1. Input: Antenna, Output: Pin19 of IC2 *2. Input: Antenna, Output: Speaker Terminal *3. Input: Input is not connected, Output: TP1

• VCO Frequency

Adjusting Point

VR1 76 kHz ± 200 Hz Pin 13, pin 21 and

Note:

After preparing the test circuit shown in Fig. 6-1, connect the Pin 13, Pin 21 and ground of the IC2 with the test circuit, and measure the value. At this time, apply a standard unmodulated signal input and adjust the VCO.

Pin 13 of IC2 Pin 21 of IC2

Figure 6-1 VCO FREQUENCY TEST CIRCUIT

Frequency

Display

Frequency

Display

Specified

Value

Setting/

Adjusting

Setting/

Adjusting

Parts

the core of IC1 T1 fully Output: TP2 counterclockwise.

Setting/

Adjusting

FET : 2SK19 or 2SK54

10 kohm

Instrument

Connection

Parts

Instrument

Connection

Instrument

Connection

Parts

Instrument

Connection

ground of IC2

TO FREQUENCY COUNTER

Figure 6-2 ADJUSTMENT POINTS

– 6 –

CD SECTION

Since this CD system incorporates the following automatic adjustment function, when the pickup is replaced, it is necessary to reajust it. Since this CD unit does not need adjustment, the combination of PWB and laser pickup unit is not restricted.

TEST MODE

QT-CD131/131C

Start

Note

Operation

LCD MODE

Start

Display

While holding down the "STOP" button, move the FUNCTION/POWER switch to "CD". Then, release the "STOP" button and, within 0.5 second, connect the TEST POINT to GND (within 0.5 second). (See Fig. 7)

1. When the CD LID switch is in the OFF position, the unit will be able to enter the test mode. However, playback cannot be performed in this mode.

2. You can only move the pickup.

3. The LCD display should be the same as it is for normal CD operations. The use of the "UP/CUE" button will move the pickup to the outermost position.

The use of the "DOWN/REVIEW" button will move the pickup to the innermost position. When the "PLAY" button is pressed, the laser will be lit, and when the "STOP" button is pressed, it will be

turned off. Playback will also start and stop when these buttons are pressed. a. If the "PLAY" button is pressed while in the stop mode, the laser will simply be turned on at first.

b. If the laser is lit and the "PLAY" button is pressed again, playback will start from the current pickup position. c. If the "STOP" button is pressed, playback will stop. When pressed again, the laser will be turned off.

Turning the tracking servo on or off.

a. Each time the PAUSE button is pressed during playback, the tracking servo will be turned on or off. (Note: If the PLAY button is pressed while in the stop mode, the tracking servo will automatically be turned on.)

While holding down the "STOP" button, move the FUNCTION/POWER switch to "CD". Then, release the "STOP" button and, within 0.5 second, press the REVIEW/DOWN button.

1 second1 second

* After the number 3 has appeared in the display, each time the "UP/CUE" button is pressed, the display will switch

in the following order: 1, 2, and then 3.

SWITCH PWB – A2

R771

3.9K

R772

TEST

POINT

2.7K

R773

1.8K

R774

1.5K

R776

10K

SW774

TRACK DOWN/

REVIEW

SW773

TRACK UP/

CUE

SW771

PLAY

SW7712

STOP

TO CD SECTION

Figure 7

– 7 –

QT-CD131/131C

NOTES ON SCHEMATIC DIAGRAM

• Resistor: To differentiate the units of resistors, the symbol as K and M are used: the symbol K means 1000 ohm and the symbol M means 1000 kohm and the resistor without any symbol is an ohm resistor. The resistor designated "Fusible" is a fuse type resistor

• Capacitor: To indicate the unit of capacitor, a symbol P is used: this symbol P means micro-micro-farad and the unit of the capacitor without such a symbol is microfarad. As to electrolytic capacitor, the expression “capacitance/withstand voltage” is used. (CH), (TH), (RH), (UJ): Temperature compensation (ML): Mylar type (P.P.): Polypropylene type

• The indicated voltage in each section is the one measured by Digital Multimeter between such a section and the chassis with no signal given.

REF. NO DESCRIPTION POSITION

SW102 RECODE/PLAYBACK OFF—ON SW201 FUNCTION/POWER TAPE—TUNER—CD/

OFF—ON SW203 X-BASS OFF—ON SW501 BAND OFF—ON SW502 TUNER DOWN OFF—ON SW503 TUNER UP OFF—ON SW504 MEMORY OFF—ON SW505 PRESET UP OFF—ON

1. Tuner ( ): AM mode Marking except for ( ): FM mode

2. CD ( ): Play mode Marking except for ( ): Stop state

3. Deck section ( ): Record mode Marking except for ( ): Playback mode Display / Control section: ( ): Active state Marking except for ( ): CD Function mode at stop state

• Schematic diagram and Wiring Side of P.W.Board for this model are subject to change for improvement without prior notice.

• Parts marked with “ ” ( ) are important for

maintaining the safety of the set. Be sure to replace these parts with specified ones for maintaining the safety and performance of the set.

REF. NO DESCRIPTION POSITION

SW506 PRESET DOWN OFF—ON SW601 TAPE MAIN OFF—ON SW702 PICKUP IN OFF—ON SW761 CD LID OPEN/CLOSE OFF—ON SW771 PLAY/REPEAT OFF—ON SW772 STOP OFF—ON SW773 TRACK UP/CUE OFF—ON SW774 TRACK DOWN/REVIEW OFF—ON

FRONT

VIEW

ECB

S8050D

FRONT

VIEW

ECB (S)(G)(D) (1) (2) (3)

2SA673-C 2SC1815 GR 2SC1674 K

Figure 8 TYPES OF TRANSISTOR

FRONT

VIEW

EBC

S9012H

– 8 –

3955385433

8 42

+5V

FOCUS COIL

TRACKING COIL

PICKUP UNIT

19 23 25

171118

50 52 5351

Q804

+5V

634364

104412

61 58

CL, DAT, SELIAL CONTROL

CONSTANT

VOLTAGE

REGULATOR

MOTOR

SLIDE

MOTOR

SPIN

123

~~ 1714

XIN

XOUT

OPERATION

KEY

SW771~SW774

LID

SW761

OPEN/CLOSE

242728

60 41 44 33 22 23

CD LCD

LCD701

PICKUP IN

PU-IN SW

SL+

SL–

+7.4V

(CD)

123

GND (A)

R-CH

L-CH

GND (D)

POWER GND

+7.4V (D)

SECTION

MAIN

VVDD

XIN

XOUT

VDD

XVDD

EFMO

EFMIN

CLV+

CLV–

V/P

HFL

TES

TOFF

JP–

JP+

TGL

RES. CQCK. COIN

SQOUT. RWC. WRQ

LCHO

LC78622E

IC802

SERVO/SIGNAL

CONTROL

16.93MHz

XL801

SLI

SLC

CV+

JP–

DRF CE DAT CL CLK THLD/DEF

SLD

SLEO

SPO FD TO

SL+

SL–

FEFIN1

FIN2

64 62

+5V

Q805

VCC1

LDO

LASER

DRIVER

SERVO AMP.

LA9240M

IC801

+7.4V

756

261327

IC804

BA5914FP

FOCUS/TRACKING

/SPIN/SLIDE

DRIVER

M701

M702

SW702

RES

SL–

DRF

WRQ

RESET

VLC3

VDD

+5V

(D)

4MHz

X701

IC701

IX0105AW

SYSTEM

MICROCOMPUTER

COM0

SEG1 SEG4

COM3

CD LID

MUTE

QT-CD131/131C

Figure 9 BLOCK DIAGRAM (1/3)

– 9 –

QT-CD131/131C

23456

IC202

LA4597

POWER AMP.

VOLUME

X-BASS

SW203

A,B

VR201

A,B

STANBY

IC203

KIA7808P

VOLTAGE

REGULATOR

+B2

+B1

SP501

SPEAKERS

SP502

SO651

SW201-C

POWER/

FUNCTION

AM / FM

SELECT

FM +B

SW201-D

POWER /

FUNCTION

RADIO

TAPE

REC

POWER/

FUNCTION

SW201-A,B

FROM TUNER

SECTION

IC2-9,10PIN

EC / PB

SW102

A,F

P. B

REC

IC101

EQULIZER

AMP.

BA331IL

REC

P.B

P.B P.B

SW102

REC / PB

B.D

REC / PB

SW102

C,E

L-CH

REC / PB

HEAD

R-CH

(AUDIO GND)

+7.4V

+B2

(DIGITAL GND)

(POWER GND)

FROM

CD/DISPLAY

SECTION

R-CH

ERASE

HEAD

SW102-H

REC / PB

BIAS

OSC.

C201

L201

SW102-G

REC / PB

+B1

M601

TAPE

MOTOR

SW601

MAIN

D651~D654

RECTIFIER

TUNER

BACK UP

T601

POWER

TRANSFORMER

BATTERY

DC12V

["D" SIZE (UM/SUM-1,

R20 or HP-2)BATTERYx8]

BATTERY

DC3V

["AA" SIZE (UM/SUM-3,

R6 or HP-7)BATTERYx2

FOR TUNER MEMORY]

AC INPUT

AC 120V

60Hz

L-CH

MUTE

L-CH

R-CH

Figure 10 BLOCK DIAGRAM (2/3)

– 10 –

X IN

FM IN

X OUT

VSS

AM IN

IF IN

AM MIX OUT

4.5MHz

DOUT

DATA

CLOCK

PERIDO

OF1

CF2

AM IF IN

AM OSC

AM MIX OUT

FM IF IN

AM IF IN

GND

AM RF IN

FM DET

DET OUT

STEREO

TUNER

MPX VCO

MPX IN

R-CH OUT

L-CH OUT

MO/ST

FM DET

VR1

VCO

FM+B

FM RIPPLE

FILTER

TO MAIN

SECTION

CF1

B.P.F

VD1

FM RF

VD2

FM OSC

FM IF

Q1 RF AMP.

FM+B

FM ROD

ANTENA

SWITCHING

MUTE

15 9

6 5

3 4

IC3

TC9216P

PLL CONTROLLER

IC2

LA1805

FM IF DET.

/FM MPX./AM IF

IC1

TA7358AP

FM FRONT END

AM IF

Q10

AM OSC OUT

VT CONTROL

AM ANT.

VD3-1

TC1

AM OSC.

VD3-2

SW504

MEMORY

SW503

TUNER UP

SW502

TUNER DOWN

SW501

BAND

SW505

PRESET UP

SW506

PRESET DOWN

LCD501

LCD DISPLAY

11 10

9 8 7 6 5 4 3 2 1

1213

MONO/ST

IC501

TUNER

MICROCOMPUTER

Q501

Q502

TUNER

IC502

RESET

A-GND

AUDIO

+12V

+5V

VOLTAGE

REGULATOR

ZD1

D GND

TUNER +B

QT-CD131/131C

Figure 11 BLOCK DIAGRAM (3/3)

– 11 –

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