Sharp QTCD-250 Service manual

QT-CD250

SERVICE MANUAL

No. S2014QTCD250/

QT-CD250

• 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

Page

IMPORTANT SERVICE NOTEST (FOR U.S.A. ONLY) .................................................................................................... 2

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

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

OPERATION MANUAL ...................................................................................................................................................... 4

DISASSEMBLY.................................................................................................................................................................. 5

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

ADJUSTMENT ................................................................................................................................................................... 7

NOTES ON SCHEMATIC DIAGRAM .............................................................................................................................. 11

TYPES OF TRANSISTOR ............................................................................................................................................... 11

SCHEMATIC DIAGRAM .................................................................................................................................................. 12

WIRING SIDE OF P.W.BOARD....................................................................................................................................... 14

WAVEFORMS OF CD CIRCUIT...................................................................................................................................... 16

TROUBLESHOOTING (CD SECTION) ........................................................................................................................... 17

FUNCTION TABLE OF IC................................................................................................................................................ 21

PARTS GUIDE/EXPLODED VIEW PACKING OF THE SET (FOR U.S.A. ONLY)

SHARP CORPORATION

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

QT-CD250

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

IMPORTANT SERVICE NOTES (FOR U.S.A. 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 120 V, 60 Hz

DC 9 V [ "D" size (UM/SUM-1, R20 or HP-2) battery × 6] DC 4.5 V [ "AA" size (UM/SUM-3, R6 or HP-7) battery × 3 for backup memory]

Power consumption: 12 W Output power: FTC; 2.0 W min. RMS per channel

into 4 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.)

Speakers: 4" (10 cm) full-range speaker x 2 Output terminals: Dimensions: Width; 15-3/4" (400 mm)

Weight: 6.0 lbs. (2.7 kg) without batteries

Headphones; 16-50 ohms (recommended; 32 ohms)

Height; 6-1/4" (158 mm) Depth; 8-3/8" (212 mm)

● Compact disc player

Type: Compact disc Signal readout:

Non-contact, 3-beam semi-conductor laser pickup

Audio channels: 2 Quantization: 16-bit linear quantization Filter: 8-times oversampling digital filter D/A converter: 1-bit D/A converter Wow and flutter:

Unmeasurable (less than 0.001% W. peak)

● Radio Frequency

range:

FM; 87.5 - 108 MHz AM; 530 - 1,720 kHz

● Tape recorder Frequency

response: 50 - 14,000 Hz (Normal tape) Signal/noise ratio: 50 dB Wow and flutter: 0.25 % (WRMS) Motor: DC 9 V electric governor Bias system: AC bias Erase system: Magnet erase

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

– 2 –

234

NAMES OF P ARTS

QT-CD250

11.

(TAPE) Record Button

12.

(TAPE) Play Button

13.

(TAPE) Rewind Button

14.

(TAPE) Fast Forward Button

15.

(TAPE) Stop/Eject Button

16.

(TAPE) Pause Button

17.

Cassette Compartment

18.

CD Compartment

19.

(CD) Stop Button

(TUNER) Tuning Down Button

10.

(CD) Repeat Button

(TUNER) Band Selector Button

11.

(TUNER) Preset Memory Button

12.

Extra Bass Button

13.

(CD) Play/Pause Button

(TUNER) Tuning Up Button

14.

(CD) Track Up/Cue Button

(TUNER) Preset Up Button

15.

(CD) Track Down/Review Button

(TUNER) Preset Down Button

16.

Volume Up/Down Buttons

17.

Power/Function Switch

18.

(CD) Play Indicator

19.

(CD) Repeat Indicator

22 23

14 15

30 31

20.

(CD) Pause Indicator

21.

Extra Bass Indicator

22.

(TUNER) Memory Indicator

23.

(TUNER) FM Stereo Mode Indicator

24.

(TUNER) FM Stereo Indicator

25.

Battery Compartment

26.

FM Telescopic Rod Antenna

27.

Headphone Jack

28.

AC Power Input Jack

29.

Backup Memory Battery Compartment

30.

(CD) Play/Pause Button

(TUNER) Tuning Up Button

31.

(CD) Track Down/Review Button

(TUNER) Preset Down Button

32.

(CD) Stop Button

(TUNER) Tuning Down Button

33.

(CD) Repeat Button

(TUNER) Band Selector Button

34.

(TUNER) Memory Button

35.

(TUNER) Clear Button

36.

(CD) Track Up/Cue Button

(TUNER) Preset Up Button

37.

Extra Bass Button

38.

Volume Up/Down Buttons

27 28

35 36 37

REMOTE CONTROL

Remote Sensor

8" - 20' (0.2 m - 6 m)

Notes:

● Replace the batteries if the operating distance is reduced or if the operation becomes erratic.

● Periodically clean the transmitter LED on the remote control and the sensor on the main unit with a soft cloth.

● Exposing the sensor on the main unit to strong light may interfere with operation. Change the lighting or the direction of the unit.

● Keep the remote control away from moisture, excessive heat, shock, and vibrations.

– 3 –

QT-CD250

Preparation for use /

Preparación para su uso

■ AC power

■

Funccionamiento con corriente alterna

■ Battery power

■

Funccionamiento con pilas

To an AC socket

A un tomacorriente de CA

T o AC INPUT

A la toma AC INPUT

AC 120 V, 60 Hz

120 V de CA, 60 Hz

● 6 “D” size batteries

(UM/SUM-1, R20, HP-2 or similar)

●

6 pilas del tamaño “D”

(UM/SUM-1,R20,HP-2 o similares)

● Batteries are not included.

●

Las pians no están incluidas.

■ Headphones

■

Auriculares

■ Turning the power ON

and to OFF

■

Conexión(ON) y

desconexión(OFF) de la

alimentación

TUNER

OFF POWER

■ Volume control

■

Control del volumen

Quick Guide /

Guía rápida

Listening to a CD /

Audictión de discos CD

To stop the playback

Press the ■ button.

TUNING

PLAY / PAUSE

OFF POWER

● Label side up.

●

Con el lado de

la etiqueta

encarada hacia

arriba.

Para detener la

reproducción

Pulse el botón

■

TUNER

Listening to a tape

Audictión de una cinta

TUNER

OFF POWER

Listening to the radio /

Audictión de la radio

Recording from CDs /

Grabaciones de discos CD

TUNER

OFF POWER

● Load the disc to be

recorded.

●

Introduzca el disco que

va a grabar.

123

134

BAND

REPEAT

TUNING

PLAY / PAUSE

TUNER

OFF POWER

TUNING

PLAY / PAUSE

Para detener la

reproducción

Pulse el botón

To stop the playback

Press the button.

To stop the recording

Press the button.

Para detener la

grabación

Pulse el botón

OPERATION MANUAL

– 4 –

DISASSEMBLY

Top Cabinet

AC Socket

(B1)x2 ø3x12mm

(D2)x7 ø3x12mm

(C1)x2 ø3x12mm

(C4)x4 ø3x10mm

(D3)x1 ø2.5x8mm

Main PWB

Power PWB

(D4)x3

(B3)x1

(B2)x2

(B4)x2

(D1)x1

CD Lid Switch

Power Transformer

Terminal PWB

(C3)x2

Switch PWB

(C2)x1

(E1)x3 ø2.5x10mm

(F1)x4 ø3x10mm

(D5)x1

(D5)x2

Top Cabinet

(D6)x6 ø3x8mm

(D7)x2

Washer

CD Mechanism

CD Control PWB

Tape Mechanism

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 to be removed when disassembling the unit. After servicing the unit, be sure to rearrange the leads where they were before disassembling.

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

STEP REMOVAL PROCEDURE FIGURE

1 Top Cabinet/ 1. Screw ................... (A1) x7 5-1

Front Cabinet 2. Socket .................. (A2) x1

2 Power PWB/ 1. Screw ................... (B1) x2 5-2

Terminal PWB 2. Hook..................... (B2) x2

3 Switch PWB 1. Screw ................... (C1) x2 5-2

4 Main PWB/ 1. Socket .................. (D1) x1 5-2

CD Control PWB 2. Screw ...................(D2) x7

(Note) 3. Screw ................... (D3) x1

5 CD Mechanism 1. Screw ................... (E1) x3 5-3

6 Tape Mechanism 1. Screw ................... (F1) x4 5-3

Top Cabinet

3. Screw ................... (A3) x1

3. Socket .................. (B3) x1

4. Hook..................... (B4) x2

2. Socket .................. (C2) x1

3. Hook..................... (C3) x2

4. Screw ................... (C4) x4

4. Solder................... (D4) x3

5. Socket .................. (D5) x3 5-3

6. Screw ................... (D6) x6

7. Hook..................... (D7) x2

SP202

R-CH

QT-CD250

Figure 5-2

CD MECHANISM SECTION

Perform steps 1 to 4 of the disassembly method to remove the CD mechanism.

How to remove the pickup (See Fig. 5-4.)

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

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

3. Remove the pickup.

Note : (Figure 5-3 and Figure 5-4)

After removing the connector for the optical pickup from the

(A3)x1 ø3x10mm

Front Cabinet

Main PWB

(A2)x1

(A1)x4 ø3x12mm

x1 pc. (A4) x 1 pc.

REMOVING AND REINSTALLING THE MAIN PARTS

(A1)x3 ø3x12mm

connector, wrap the conductive aluminium foil around the front end of connector to protect the optical pickup from electrostatic damage.

– 5 –

(A1) x2

ø2.6 x6mm

Pickup

Shaft (A2) x1

Figure 5-3Figure 5-1

Gear (A4) x1

Figure 5-4

CD Mechanism

Stop Washer (A3) x1

QT-CD250 TAPE MECHANISM SECTION

Perform steps 1 to 6 of the disassembly method to remove the tape mechanism. (See page 5.)

How to remove the record / playback and erase heads (See Fig. 6-1.)

1. Remove the screws (A1) x 2 pcs., to remove the record/ playback head.

2. Remove the hooks (A2) x 2 pcs., toward the center position

as shown in Fig. 6-1. and then extract the erase head upward.

Note:

After replacing the heads and performing the azimuth adjustment, be sure to apply screwlock.

How to remove the pinch roller (See Fig. 6-2.)

1. Carefully bend the pinch roller pawl in the direction of the

arrow <A>, and remove the pinch roller (B1) upwards.

Hook (A2)x2

Erase Head

Pinch Roller (B1)x1

(A1) x1 ø2x7mm

(A1) x1 ø2x3mm

Record/Playback Head

Figure 6-1

<A>

Pinch Roller Pawl

Figure 6-2

How to remove the belts (See Fig. 6-3.)

1. Remove the main belt (C1) x 1 pc., from the motor pulley.

2. Remove the FF/REW belt (C2) x 1 pc., from the REW/FF

roller.

3. Put on the belts in the reverse order of removal.

Note:

When putting on the belt, ascertain that the belt is not twisted, and clean it.

How to remove the motor (See Figs. 6-4.)

1. Remove the mainbelt.

2. Remove the screw (D1) x 1 pc., to remove the motor mount.

3. Remove the screws (D2) x 2 pcs., to remove the motor.

Note:

When mounting the motor, pay attention to the motor mounting angle.

How to remove the flywheel (See Fig. 6-5.)

1. Remove the belt.

2. Remove the stop washer (E1) x 1 pc., with a small precision

screwdriver to extract the flywheel from the capstan metal.

Note:

When the stop washer is deformed or damaged, replace it with a new one.

Flywheel

FF/REW Belt (C2)x1

Motor

Motor Mount

(E1) x 1 Stop Washer

Main Belt (C1)x1

Washer

Flywheel

Figure 6-3

(D2)x2 Special Screw

(D1)x1 Special Screw

Figure 6-4

Motor

REW/FF Clutch Ass'y

Motor Mount

Motor

How to reinstall the parts

Install each part in the reverse order of the removal with care.

Figure 6-5

– 6 –

ADJUSTMENT

SW102

CNP101

L301

CNP602

IC1

TC1

HPJ201 HEADPHONE

IC101

CNP201

123

FM IF

AM BAND COVERAGE fL

TP1

L3 AM BAR ANTENNA

AM TRACKING fL

AM TRACKING fH

AM IF

FM BAND COVERAGE fL

BIAS OSC.

MAIN PWB

QT-CD250

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: 4 ohms)

• Tape Speed

Test

Tape

Adjusting

Point

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

resistor in Teaminal motor. (M601) (CNP201 Load

TAPE SECTION

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

Position of each switch or control

Specified

Value

Specified Value

Instrument

Connection

resistance: 4 ohms)

• AM IF/RF

Signal generator: 400 Hz, 30%, AM modulated

Test Stage

Frequency Frequency

Display

AM IF 450 kHz 1,720 kHz T3 *1 AM Band — 530 kHz (fL): L4 *3

Coverage 1.0 ±0.05V AM Tracking 600 kHz 600 kHz (fL): L3 *2

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

Setting/

Adjusting

Parts

*1. Input: Antenna, Output: Pin 16 of IC1 *2. Input: Antenna, Output: Speaker Terminal

*3. Input: Input is not connected, Output: TP1

Instrument

Connection

• Bias Oscillation

Adjustment Point

Specified Value

L301 82 kHz ± 6 kHz Pin 2 of CNP201

- 6 kHz

Instrument

Connection

• Playback Amplifier Sensitivity Check

Test Tape

Specified Value

MTT-118 1.1 V ± 3 dB Speaker Terminal

Instrument Connection

(Load resistance: 4 ohms)

TUNER SECTION

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

• FM RF

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

Test Stage

Frequency

Display

Serring/

Adjusting

Point

FM Band — 87.5 MHz (fL): L2 *1

(10-30 dB)

Coverage 1.7 V ± 0.05V FM RF 98.0 MHz 98.0 MHz L1 *2

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

Instrument

Connection

Figure 7 ADJUSTMENT POINTS

– 7 –

QT-CD250

A. CD TEST MODE

Set the function switch to "CD" when pressing the "REVIEW(PRESET DOWN )" button together with "STOP(TUNING DOWN)" button.

Step-1. CD Pickup can be move when press the "CUE" button either "REVIEW" button. "CUE" button : CD Pickup move to out side of disc. "REVIEW" button : CD Pickup move to in side of disc. (CD Pickup can't move any more, if reach to most in side.) Note: If the CD Lid open (SW810 open), the unit can be operate Step-1 only and the unit can't operate from Step-2 to Step-5.

Step-2. The LASER light up when press the "PLAY/PAUSE" button.

Step-3. CD disc can be playing mode when press the "PLAY/PAUSE" button during the LASER ON.

The LCD displays indicate the "Track Number" and the "Playing Time".

Step-4. CD disc will be stop and the LASER goes out when pressing the "STOP" button, and return back to Step-1. (CD Pickup position keeps at that point).

Step-5. It can be control to ON/OFF of the Tracking Servo when press the "MEMORY" button during the CD playing mode. (The Servo will be ON when playing mode again, if to make stop mode during the Servo OFF condition.)

The LCD displays indicate the playing time of CD Pickup point. (The LCD displays indicate the playing time at that point when Pickup moving, if press the "CUE" button or press the "REVIEW" button.)

– 8 –

QT-CD250

B. TUNER TEST MODE

Set the function switch to "TUNER" when pressing the "REVIEW(PRESET DOWN )" button together with "BAND(REPEAT)" button.

The LCD displays indicate the "TunEr" for several seconds. after that, the LCD displays indicate to the normal frequency.

PRESET.

P-01 FM 87.5 MHz STEREO P-02 FM 108.0 MHz STEREO P-03 FM 98.0 MHz STEREO P-04 FM 90.0 MHz STEREO P-05 FM 106.0 MHz STEREO P-06 AM 530 KHz P-07 AM 1720 KHz P-08 AM 990 KHz P-09 AM 600 KHz P-10 AM 1400 KHz P-11 FM 106.0 MHz MONO P-12 FM 90.0 MHz MONO P-13 FM 98.0 MHz MONO P-14 FM 108.0 MHz MONO P-15 FM 87.5 MHz MONO

U.S.A.

FM MODE

Note:

1. The Preset Channel can be change when press the "PRESET UP (CUE) button either "PRESET DOWN (REVIEW)" button. PRESET UP button is pressed : P-01 -> P-02 -> > > > > P-15 -> P-01 PRESET DOWN button is pressed : P-15 -> P-14 -> > > > > P-01 -> P-15

2. The Tuner Mode can be change when press the "BAND (REPEAT)" button. BAND button is pressed : FM stereo -> FM mono -> AM -> FM stereo

C. LCD TEST MODE

Set the function switch to "TUNER (or CD)" when pressing the "REVIEW(PRESET DOWN )" button together with "MEMORY" button.

All of the segments will light up.

– 9 –

QT-CD250

D. VOLUME TEST MODE

Set the function switch to "POWER ON (TAPE PLAY, TUNER or CD)" when pressing the "REVIEW(PRESET DOWN )" button together with "PLAY/PAUSE (TUNING UP)" button. The LCD display do not indicate the VOLUME level at this time. But, the VOLUME level is "12" which is defaults level.

The VOLUME LEVEL can be change when press the "VOLUME UP" button either press the "VOLUME DOWN" button. "VOLUME UP" button is pressed : (12 VoL) -> 30 VoL -> 30 VoL (30 is flashing)

"VOLUME DOWN" button is pressed : (12 VoL) -> 1 VoL-> 0 VoL -> 0 VoL (0 is flashing)

– 10 –

NOTES ON SCHEMATIC DIAGRAM

QT-CD250

• 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

SW102 RECODE/PLAYBACK REC—P.B. SW201 FUNCTION SELECTOR TAPE/OFF—

SW601 TAPE MAIN OFF—ON SW702 PICKUP IN OFF—ON SW801 PLAY/PAUSE/ OFF—ON

SW802 STOP/TUNING DOWN OFF—ON SW803 REPEAT/BAND OFF—ON SW804 TUNER/MEMORY OFF—ON SW805 CUE/PRESET UP OFF—ON SW806 REVIEW/ OFF—ON

SW807 VOLUME UP OFF—ON SW808 VOLUME DOWN OFF—ON SW809 X-BASS OFF—ON SW810 CD LID OFF—ON

DESCRIPTION

TUNING UP

PRESET DOWN

POSITION

TUNER/ON—CD/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.

FRONT

VIEW

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

KRA102 M KRC107 M KTA1046 Y KTA1266 GR KTA1273 Y KTC3199 GR

Figure 11 TYPES OF TRANSISTOR

– 11 –

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