QT-120H (serv.man2) - Sharp Audio Service Manual (repair manual)

qt-120h (serv.man2) service manual
Model
QT-120H (serv.man2)
Pages
16
Size
820.74 KB
Type
PDF
Document
Service Manual
Brand
Device
Audio / Portable
File
qt-120h-sm2.pdf
Date

Read Sharp QT-120H (serv.man2) Service Manual online

QT-120H
SPECIFICATIONS
Specifications for this model are subject to change without
prior notice.
CONTENTS
Page
SPECIFICATIONS ............................................................................................................................................................... 1
MPORTANT SERVICE NOTES (FOR UK ONLY) ............................................................................................................... 2
VOLTAGE SELECTION (EXCEPT FOR UK) ...................................................................................................................... 2
AC POWER SUPPLY CORD ............................................................................................................................................... 2
NAMES OF PARTS ............................................................................................................................................................. 2
DISASSEMBLY .................................................................................................................................................................... 3
ADJUSTMENT ..................................................................................................................................................................... 4
NOTES ON SCHEMATIC DIAGRAM .................................................................................................................................. 5
TYPES OF TRANSISTOR ................................................................................................................................................... 5
SCHEMATIC DIAGRAM / WIRING SIDE OF P.W.BOARD ................................................................................................. 6
REPLACEMENT PARTS LIST / EXPLODED VIEW
PACKING OF THE SET (FOR UK ONLY)
QT-120H
SERVICE MANUAL
SHARP  CORPORATION
No. S9769QT120H//
• Note for users in UK
Recording and playback of any material may require consent
which SHARP is unable to give. Please refer particularly to the
provisions of Copyright Act 1956, the Dramatic and Musical
Performers Protection Act 1956, the Performers Protection Acts
1963 and 1972 and to any subsequent statutory enactments and
orders.
 General
Power source:
AC 230 V, 50 Hz
DC 12 V 
[
"D" size (UM/SUM-1, 
R20 or HP-2) battery 
×
  8
]
Power consumption:
30 W
Output power:
PMPO; 60 W (total)
(AC operation)
MPO (Max.); 20 W (10 W + 10 W)
(AC operation)
RMS; 10 W (5 W + 5 W)
(DC operation, 10 % T.H.D.)
 Radio section
Frequency range:
FM; 87.5 - 108 MHz
MW; 526.5 - 1,606.5 kHz
LW; 150 - 285 kHz
 Tape recorder section
Frequency response:
60 - 12,000 Hz (Normal tape)
Signal/noise ratio:
40 dB
Wow and flutter:
0.15 % (WRMS)
Motor:
DC 12 V electric governor
Bias system:
AC bias
Erase system:
Magnet erase
For U.K. customers
Speakers:
12 cm (4-3/4") free-edge speaker
×
  2
Tweeter 
×
  2
Output terminal:
Headphones; 16-50 ohms
(recommended; 32 ohms)
Dimensions:
Width; 515 mm (20-5/16")
Height; 173 mm (6-13/16")
Depth; 203 mm (8")
Weight:
3.7 kg (8.2 lbs.) without batteries
RMS; 10 W (5 W + 5 W)
(DC operation, 1 kHz, 10 % T.H.D.)
For Turkish customers
For customers in other
countries
MPO (Max.); 20 W (10 W + 10 W)
(AC operation)
RMS; 10 W (5 W + 5 W)
(DC operation, 1 kHz, 10 % T.H.D.)
 • 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.
QT-120H
NAMES OF PARTS
FOR A COMPLETE DESCRIPTION OF THE OPERATION OF THIS UNIT, PLEASE REFER
TO THE OPERATION MANUAL.
– 2 –
9FF24801830210 (EXCEPT FOR U.K. )
AC POWER SUPPLY CORD
9FF24801800281 (FOR U.K. )
VOLTAGE SELECTION (EXCEPT FOR UK)
Before operating the unit on mains, check the preset voltage. If the voltage is different from your local voltage, adjust the voltage
as follows: Slide the AC power supply socket  to the visible indication of the side of your local voltage.
1
1.
Cassette Compartment
1
2.
Record Button: 
1
3.
Play Button: 
1
4.
Rewind Button: 
1
5.
Fast Forward Button: 
1
6.
Stop/Eject Button: 
1
7.
Pause Button: 
1
8.
Tuning Control
1
9.
Extra Bass Control: X-BASS
10.
Stand-by
On/Function/FM Mode Switch
11.
Headphone Socket
12.
Volume Control
13.
Graphic Equalizer Controls
14.
Band Selector Switch
15.
Built-in Microphone
16.
Tweeter
17.
Full-Range Speaker
18.
FM Telescopic Rod Aerial
19.
Battery Compartment
20.
Beat Cancel Switch
21.
AC Power Input Socket
IMPORTANT SERVICE NOTES (FOR UK ONLY)
Before returning the unit to the customer after completion of a repair or adjustment it is necessary for the following withstand voltage
test to be applied to ensure the unit is safe for the customer to use.
Setting of Withstanding Voltage Tester and set.
NG: The “NG” lamp lights and the buzzor sounds.
OK: The “GOOD” lamp lights.
Judgment
Unit
Set current (Cutoff current)
Set time
Set name
Withstanding Voltage Tester
Test voltage
Set value
4,240 VPEAK
3,000 VRMS
6 secs
4 mA
PROBE
AC
OUT
UNIT
SHORT-CIRCUT
AC POWER
SUPPLY CORD
CONNECT THE PROBE
TO GND OF BATTERY 
SPRING
WITHSTANDING
VOLTAGE TESTER
1
2 3 4 5 6 7
8
9
10
11
12
13
14
17
18
19
21
20
15
16
QT-120H
– 3 –
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  out of the unit.
2. Be sure to remove the power supply plug from the wall
outlet before starting to disassemble the unit and remove
the batteries from 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 sufficient care on static electricity of integrated
circuits and other circuits when servicing.
STEP
REMOVAL
PROCEDURE
FIGURE
1
Back Cabinet
1. Battery Compartment Lid.
3-1
................................. (A1)x1
2. Screw ................... (A2)x8
3. Screw ................... (A3)x1
4. Lug wire ............... (A4)x1
5. Socket .................. (A5)x1
2
Top Cabinet
1. Socket .................. (B1)x2
3-2
2. Screw ................... (B2)x2
3
Tape mechanism 1. Open the cassette Door.
3-2
2. Screw ................... (C1)x4
4
Tuning Bracket
1. Knob ..................... (D1)x1
3-3
2. Screw ................... (D2)x5
3. Socket .................. (D3)x1
5
Main PWB
1. Socket .................. (E1)x1
3-4
2. Screw ................... (E2)x2
3. Plug ...................... (E3)x1
4. Mic ....................... (E4)x1
6
Power AMP.PWB 1. Screw ................... (F1)x2
3-4
7
Graphic Equalizer 1. Socket .................. (G1)x1
3-4
PWB
2. Screw ................... (G2)x1
8
Power Supply
1. Screw ................... (H1)x1
3-5
PWB
2. Bracket ................. (H2)x1
Figure 3-5
Figure 3-2
Figure 3-1
Figure 3-4
Figure 3-3
(H1) x1
ø3 x8mm
(H2) x1
Pull
Power 
Transformer
Back 
  Cabinet
Pawl
Driver
Push
Power
Supply
PWB
(A2) x8
ø3 x20mm
(A3) x1
ø3 x8mm
Top Cabinet
Front
  Cabinet
Back  Cabinet
(A4)x1
Main 
PWB
(A5)x1
Power
AMP.PWB
(A1) x1
(C1) x4
ø3 x8mm
(B1) x2
Front
  Cabinet
Tape
  Mechanism
Top
  Cabinet
Cassette
  Door
Stop/Eject Button
Open
Push
Main PWB
(B2) x2
ø3 x8mm
(D2) x5
ø3 x12mm
(D1) x1
Tuning
Bracket
Main PWB
Power
AMP. PWB
(D3) x1
Front
Cabinet
(E2) x2
ø3 x8mm
(G2) x1
ø2 x8mm
(F1) x2
ø3 x8mm
(G1) x1
(E1) x1
Power
AMP. PWB
Tuning
Bracket
(E3) x1
Graphic Equalizer
PWB
Sheild
Paper
(E4) x1
Lug
Main 
PWB
QT-120H
– 4 –
ADJUSTMENT
Figure 4 VCO FREQUENCY TEST CIRCUIT
TUNER SECTION
fL: Low-range frequency
fH: High-renge frequency
Specified value
Instrument Connection
VR101
76 kHz 
±
 200 Hz
Pin 13, Pin 21 and ground
of IC102
• FM IF/RF
Specified Value/
Adjusting
Point
• AM IF/RF
Test Stage
Specified Value/
Adjusting
Point
Instrument
Connection
Test Stage
IF
T101
Input: FM Antenna
Detection
T102
Output:Pin 9 of IC102
Band
fL: L103
Input: Antenna
Coverage
fH: TC2
Output: Headphone Socket
Tracking
fL(88 MHz): L102
(Load resistance:
fH(108 MHz): TC1
32 ohms)
Specified Value
Play: TW-2412
Over 120 g
MECHANISM SECTION
• Driving Force Check
Specified Value
• Torque Check
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
MTT-114
Output: Speaker Terminal
(Load resistance:
 3 ohms)
Instrument Connection
• Tape Speed
Instrument
Connection
Normal
MTT-111
3,000 
±
Speaker
Speed
30 Hz
terminal
(Load
resistance:
6 ohms)
* Open the cassette holder, and load the test tape directly into
the mechanism. (Do not load the tape into the cassette
holder.)
Specified Value
Beat Cancel
A: 80 kHz + 10 kHz/ – 6kHz
B: – 3 
±
 1 kHz for A
C: – 5 
±
 2 kHz for A
DECK SECTION
• Bias Oscillation
Torque Meter
Torque Meter
Test Tape
Specified Value
Test Tape
• Beat Cancel Switch: A
T201
80 kHz + 10 kHz
Pin 2 of CNP201
            – 6 kHz
Adjustment Point
Specified value
Instrument
Connection
IF
T103
MW Band
fL: L107
Coverage
fH: TC4
MW Tracking fL(600 kHz): L104
fH(1,400 kHz): TC3
LW Band
fL: L108
Coverage
fH: TC103
LW
fL(170 kHz): L105
Tracking
fH(270 kHz): TC102
 Input: Antenna
 Output: Pin 9 of IC102
Input: Antenna
 Output: Headphone Socket
(Load resistance
32 ohms)
Adjustment
Point
• VCO Frequency
Note:
After preparing the test circuit shown in Fig. 4, connect the Pin
13, Pin 21 and ground of the IC102 with the test circuit, and
measure the value.
10 pF
1M ohm
10K ohm
0.1
˚
TO FREQUENCY
      COUNTER
Pin 13 of IC102
Pin 21 of IC102
FET: 2SK212
      (or Other 2SK Type FET.)
G
D
S
Instrument
Connection
Page of 16
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Here you can read online and download Sharp QT-120H (serv.man2) Service Manual in PDF. QT-120H (serv.man2) service manual will guide through the process and help you recover, restore, fix, disassemble and repair Sharp QT-120H (serv.man2) Portable. Information contained in service manuals typically includes schematics / circuit diagrams, wiring diagrams, block diagrams, printed wiring boards, exploded views, parts list, disassembly / assembly, pcb.