QT-CD50H (serv.man3) - Sharp Audio Service Manual (repair manual)

• 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.

Page

IMPORTANT SERVICE NOTES ........................................................................................................................................  2
SPECIFICATIONS .............................................................................................................................................................  2
NAMES OF PARTS ...........................................................................................................................................................  3
FITTING OF DIAL POINTER .............................................................................................................................................  3
DISASSEMBLY ..................................................................................................................................................................  4
ADJUSTMENT ...................................................................................................................................................................  5
WIRING SIDE OF P.W.BOARD / SCHEMATIC DIAGRAM ...............................................................................................  6
NOTES ON SCHEMATIC DIAGRAM ..............................................................................................................................  14
TYPES OF TRANSISTOR AND LED ...............................................................................................................................  14
FUNCTION TABLE OF IC ................................................................................................................................................  15
PARTS GUIDE/EXPLODED VIEW
PACKING OF THE SET

Service Headquarters:         Sharp Plaza,         Mahwah, New Jersey  07430-2135

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

– 2 –

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 0.15

µ

F 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.

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.

50 - 14,000 Hz (Normal tape)

50 dB

0.25 % (WRMS)

DC 12 V electric governor

AC bias

Magnet Erase

Compact disc

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

2

16-bit linear quantization

4-tims oversampling digital filter

1-bit D/A converter

Unmeasurable
(less than 0.001% W. peak)

    General

AC 120V, 60 Hz
DC 12 V [ "D" size (UM/SUM-1,
R20 or HP-2) battery x 8]

20 W

FTC; 2.0 W minimum RMS per
channel into 8 ohms from 150 Hz to
20 kHz with no more than 10 % total
harmonic distortion.
RMS; 2.3 W (1.65 W + 1.65 W)
(DC operation, 10 % T.H.D)

4" (10 cm) full range speaker x 2

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

Width; 18-1/2" (470 mm)
Height; 6-1/2" (166 mm)
Depth; 8-7/8" (226 mm)

7.9 Ibs. (3.6 kg) without batteries

    Radio

FM; 87.6 - 108 MHz
AM; 530 - 1,720 kHz

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

AC SCALE

VTVM

1.5k ohms

10W

0.15

µ

F

TEST PROBE

TO EXPOSED
METAL PARTS

CONNECT TO
KNOWN EARTH
GROUND

– 3 –

PHONES

X-BASS

FUNCTION /

POWER

VOLUME

CD OPERATION

INDICATOR

TUNING

REPEAT

REVIEW /
DOWN

STOP

CUE     / 
UP

PLAY /

PAUSE

A

B

C

BEAT

CANCEL

REAR OF THE

UNIT

PLAY

STOP/EJECT

F FWD

REWIND

PAUSE

RECORD

1. Turn the tuning control shaft fully in the direction 

 A 

 shown

in Fig.3 and fix its dial pointer.

Pully (213)

Pully

Dial Pointer (211)

(213)

Pully (212)

Tuner
Frame (255)

Tuner Frame

''0''Point

Dial Pointer
(211)

Tunig Control
Knob(222)

Tuner PWB

Dial Drum
        (224)

7

2

3

4

5

6

A

8

1

708   5mm

Dial Cord Ass'y (245)

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.

– 4 –

1

Front Cabinet

1. Open the cassette holder.

4-1

(With LCD PWB)

2. Screw .................. (A1) x4

3. Screw .................. (A2) x3
4. Socket ................. (A3) x1

2

LCD PWB

1. Screw .................. (B1) x3

4-2

2. Holder ................. (B2) x1
3. Screw .................. (B3) x4

3

Tuner PWB

1. Screw .................. (C1) x1

4-3

(With Volume PWB) 2. Screw .................. (C2) x4

3. Screw .................. (C3) x1
4. Lug wire .............. (C4) x1

4

Top Cabinet

1. Screw .................. (D1) x2

4-3

(With CD Mechanism/

2. Screw .................. (D2) x4

Tape Mechanism/

3. Socket ................. (D3) x3

Beat Cut PWB)

5

Beat Cut PWB

1. Screw .................. (E1) x2

4-3

6

Volume PWB/

1. Knob .................... (F1) x2

4-3

Power Amp. PWB/

2. Socket ................. (F2) x1

Earphon PWB

3. Screw .................. (F3) x2

7

Volume PWB

1. Screw .................. (G1) x2

4-4

8

Power Amp. PWB/

1. Screw .................. (H1) x3

4-4

Earphon PWB

9

Tape Mechanism

1. Screw ................... (J1) x2

4-5

10

Deck PWB

1. Screw .................. (K1) x3

4-5

11

CD Servo PWB

1. Screw .................. (L1) x4

4-5

(With LCD PWB)

2. Socket ................. (L2) x1

(Note)

3. Flat Cable ........... (L3) x1
4. Screw .................. (L4) x1
5. Switch Bracket ..... (L5) x1

12

CD Mechanism

1. Screw ................. (M1) x4

4-5

(A2) x3
ø3 x36mm

(A1) x1
ø3 x18mm

(A1) x1
ø3 x18mm

(A1) x2
ø3 x18mm

Front Cabinet

Top Cabinet

Rear Cabinet

Cassette
Holder

Open

(A3) x1

Volume PWB

Power Amp.
PWB

(B3) x4
ø2.6 x6mm

(B1) x3
ø2.6 x6mm

(B2) x1

LCD
PWB

Front Cabinet

(J1) x2
ø3 x8mm

(L1) x4
ø2.6 x8mm

(M1) x4
ø2.6 x16mm

(L4) x1
ø2.6 x8mm

(L5) x1

SW1

(K1) x3
ø3 x8mm

Top Cabinet

(L2) x1

(L3) x1

CD Motor PWB

CD Servo PWB

Tape Mechanism

CD
 Mechanism

Deck
PWB

Note. After removing the connector for the optical pickup from

the connector wrap the conducitive aluminum foil around
the front end of connector so as to protect the optical
pickup from electrostatic damage.

(G1) x2
ø2.6 x8mm

Power Amp.
PWB

(H1) x3
ø3 x8mm

Pull

Earphone
 PWB

Pull

Volume
PWB

(C1) x1
ø3 x12mm

(C2) x2     
ø3 x10mm

(C2) x2
ø3 x10mm

(D2) x4
ø3 x10mm

CD Servo
 PWB

Beat Cut 
 PWB

Earphon
 PWB

Volume PWB

Power Amp. 
PWB

Tuner
 PWB (C3)x1

ø3x8mm

(E1) x2
ø2.6x12mm

(D3) x2

(F2) x1

(F3) x2
ø3 x12mm

(F1) x2

(D3) x1

Tape Mechanism

Washer

Lug Wire

(D1) x2
ø3 x8mm

Top Cabinet

CD Servo
 PWB

Rod 
Antenna

(C4)x1