QT-90W
SERVICE MANUAL
No. S6143QT90W///
STEREO RADIO CASSETTE RECORDER
MODEL
• 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-90W
CONTENTS
Page
SPECIFICATIONS ............................................................................................................................................................. 1
VOLTAGE SELECTION..................................................................................................................................................... 1
AC POWER SUPPLY CORD AND AC PLUG ADAPTOR ................................................................................................. 2
NAMES OF PARTS ........................................................................................................................................................... 2
HOW TO SET THE POINT "0" ON TUNER DIAL MEMORY............................................................................................. 2
DISASSEMBLY.................................................................................................................................................................. 3
REMOVING AND REINSTALLING THE MAIN PARTS..................................................................................................... 4
ADJUSTMENT ................................................................................................................................................................... 6
NOTES ON SCHEMATIC DIAGRAM ................................................................................................................................ 9
TYPES OF TRANSISTOR AND LED................................................................................................................................. 9
VOLTAGE .......................................................................................................................................................................... 9
SCHEMATIC DIAGRAM .................................................................................................................................................. 10
WIRING SIDE OF P.W.BOARD....................................................................................................................................... 12
BLOCK DIAGRAM OF IC................................................................................................................................................. 14
PARTS GUIDE/EXPLODED VIEW
SPECIFICATIONS
General
Power source
Power consumption
Output power
Speakers
Output terminal
Input terminal
Dimensions
Weight
Specifications for this model are subject to change without prior notice.
AC 110-127/220-240 V, 50/60 Hz
DC 15 V [“D” size (UM/SUM-1, R20 or HP-2) battery x 10]
40 W
MPO: 36 W (18 W + 18 W) (AC operation, 10 % T.H.D)
RMS: 20 W (10W + 10W) (DC operation, 10 % T.H.D)
8 cm (3-1/8”) full range speaker x 4
Headphones: 16 - 50 ohms (recommended: 32 ohms)
Mixing microphone: 600 ohms
Line input: 350 mV/47 kohms
Width: 520 mm (20-1/2”)
Height: 191 mm (7-1/2”)
Depth: 216 mm (8-1/2”)
4.7 kg (10.4 lbs.) without batteries
Radio
Frequency range
Tape recorder
Frequency response
Signal/noise ratio
Wow and flutter
Motor
Bias system
Erase system
FM: 88 - 108 MHz
SW1: 2.3 - 7.3 MHz
SW2: 7.3 - 22 MHz
MW: 526.5 - 1,606.5 kHz
60 - 12,000 Hz (Normal tape)
40 dB
0.3 % (WRMS)
DC 12 V electric governor
AC bias
Magnet erase
VOLTAGE SELECTION
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 selector with a screwdriver to the appropriate voltage number. (AC 110 - 127 V or AC 220 - 240 V)
This document has been published to be used
SHARP CORPORATION
– 1 –
for after sales service only.
The contents are subject to change without notice.
QT-90W
FOR A COMPLETE DESCRIPTION OF THE OPERATION OF THIS UNIT, PLEASE REFER
TO THE OPERATION MANUAL.
QACCA0004AW00
AC POWER SUPPLY CORD AND AC PLUG ADAPTOR
QPLGA0003AWZZ
QACCB0012AW00
QACCE0007AW00 QPLGA0004AWZZ
NAMES OF PARTS
01. Function/Beat Cancel Switch
02. Cassette Compartment
03. Record Button
04. Play Button
05. Rewind Button
06. Fast Forward Button
07. Stop/Eject Button
08. Pause Button
09. Volume Control
10. Band Selector
11. Extra Bass Control
12. Graphic Equalizer Controls
13. Built-in Microphone
14. Sound Level Meter
15. Surround Button
16. Fine Tuning Control
17. Tuning Control
18. Mixing Microphone Socket
19. Line Input Sockets
20. AC Voltage Selector
21. AC Input Socket
22. Battery Compartment
23. Headphone Socket
QACCL0002AW00/QACCL0008AW00
12345678910
11 12 13 14151617
18 19
22
2120
23
HOW TO SET THE POINT "0" ON TUNER DIAL MEMORY
1. Remove the front cabinet and main PWB. (Refer to page 3,
of disassembly section.)
2. Turn the gear dial in the arrowed direction until it stops so
that the " " mark comes to the front of main PWB.
3. When the tuning knob is set at 2, adjust it from above so that
its "0" point rib comes to the right of "0" point rib of the dial
drum when you face the unit.
4. Check the tuning display label by turning the tuning knob.
The frequency band will be FM 88 - 108 MHz when the dial
is turned counter-clockwise.
5. Reassemble the front cabinet.
– 2 –
Main PWB
Front Side
Dial Drum “0”
Point Rib
Dial Drum
Front Side
Tuning Knob
Bracket
Dial Drum “0” Point Rib
Mark “ ”
Top Side
2
Figure 2
Gear Dial
Mark “ ”
Tuning Knob
Tuning Knob
“ 0 ” Point Rib
“0” Point of Tuning Display
3
Tuning Knob
Tuning Knob “0” Point Rib
Main PWB
Dial Drum
DISASSEMBLY
QT-90W
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.
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 Rear Cabinet 1. Battery Lid............ (A1) x1 3-1
2. Screw ................... (A2) x6
3. Screw ................... (A3) x4
2 Front Cabinet 1. Knob..................... (B1) x1 3-1
2. Nut........................ (B2) x1
3. Socket .................. (B3) x4 3-2
3 Jack PWB 1. Socket ..................(C1) x2 3-2
2. Screw ...................(C2) x2
4 Volume PWB 1. Socket ..................(D1) x1 3-2
5 Battery PWB 1. Socket .................. (E1) x1 3-2
2. Hook..................... (E2) x1
6 Headphones PWB 1. Socket .................. (F1) x2 3-2
2. Screw ................... (F2) x1
7 Main PWB with 1. Screw ...................(G1) x2 3-2
Tape Mechanism 2. Screw ...................(G2) x1
8 Main PWB 1. Socket ..................(H1) x2 3-3
2. Screw ...................(H2) x4
3. Solder................... (H3) x2
9 Tape Mechanism 1. Open the cassette holder. 4-1
2. Screw ....................(J1) x4
10 Surroud PWB 1. Screw ................... (K1) x3 4-2
11 Graphic Equalizer 1. Screw ................... (L1) x2 4-2
PWB
(B1)x1
(B2)x1
Rear Cabinet
Headphones
(F2)x1
ø4x14mm
Battery
PWB
(E1)x1
(F1)x1
(B3)x1
(C1)x1
Volume
PWB
(F1)x1
(E2)x1
(B3)x1
PWB
(A3)x4
ø3x12mm
Figure 3-1
Tape Mechanism
(D1)x1
(C1)x1
(B3)x1
Handle
Main PWB
(G1)x2
ø3x12mm
(C2)x2
ø4x14mm
Front Cabinet
(A2)x6
ø3x30mm
(A1)x1
Lug Wire
(G2)x1
ø3x8mm
(B3)x1
Rear Cabinet
Jack PWB
How to attach the tuning display label
(See Fig. 3-4.)
Reference
1. Start Stick Label Matching
With Base Line
Base Line
10
108
1600
9
22.0
7.3
19.0
1400
6.0
104
1200
5.0
15.0
8
7
6
5
100
1000
800
4.0
12.0
Tuning Display Label
96
4
3.2
10.0
700
0
1
88
2
3
540
92
2.3
7.3
600
2.6
8.5
2. This Line Must Be
Stick Matching
Figure 3-4
Dial Drum
Figure 3-2
(H2)x4
ø3x10mm
(H1)x2
(H3)x2
Tape
Mechanism
Main PWB
Figure 3-3
– 3 –
QT-90W
(A1)x2
ø2x7mm
Record/Playback
Head
Hook
(A2)x2
Erase Head
PLAY
Button
Push
Lug Wire
Tape Mechanism
Stop/Eject Buttom
Push
Graphic Equalizer
PWB
Front Cabinet
Open
Cassette
Holder
(J1)x4
ø3x10mm
Figure 4-1
REMOVING AND REINSTALLING THE MAIN PARTS
TAPE MECHANISM SECTION
Perform steps 1 to 9 of the disassembly method to remove the
tape mechanism. (See page 3.)
How to remove the record / playback and erase
heads (See Fig. 4-3.)
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. 4-3. and then extract the erase head
upward.
Note:
After replacing the heads and performing the azimuth
adjustment, be sure to apply screwlock.
Surround PWB
Figure 4-2
(L1)x2
ø2.6x8mm
(K1)x3
ø2.6x8mm
How to remove the pinch roller (See Fig. 4-4.)
1. Remove the screw (B1) x 1 pc., and remove the pinch roller
upwards.
Figure 4-3
(B1)x1
ø1.5x2.5mm
Pinch Roller
Figure 4-4
– 4 –
QT-90W
How to remove the belts (See Fig. 5-1.)
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 Fig. 5-2.)
1. Remove the main belt. (See Fig. 5-1.)
2. Remove the screws (D1) x 2 pcs., to remove the motor
bracket.
3. Remove the screws (D2) x 2 pcs., to remove the motor.
Note:
When mounting the motor, pay attention to the motor bracket
angle.
Main Belt
(C1)x1
Flywheel
FF/REW Belt
(C2)x1
Figure 5-1
(D1)x1
ø2x4mm
Motor
Motor
Motor Pulley
REW/FF
Roller
Motor Bracket
(D1)x1
ø2x4mm
How to remove the flywheel (See Fig. 5-3.)
1. Remove the belt. (See Fig. 5-1.)
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.
(D2)x2
ø2.6x1.6mm
Special Screw
(E1)x 1
Stop Washer
Washer
Washer
Flywheel
Motor Bracket
Motor
Figure 5-2
Driver
How to reinstall the parts
Install each part in the reverse order of the removal with care.
Figure 5-3
– 5 –
QT-90W
ADJUSTMENT
TUNER SECTION
fL: Low-range frequency
fH: High-range frequency
FM Section
Step
1 FM IF: (1) FM IF sweep Inject the IF Signal are taken Adjust T106, T108 (1) Band SW in FM.
2 FM BAND (1) FM RF sweep Inject the RF Same as step 1 Adjust P.V.C. (TC1) Same as step 1
3 FM BAND Same as step 2 Same as step 2 Same as step 1 Adjust L103 to get Tune P.V.C. to low
4 Repeat step 2, 3 until no further improvement can be made.
5 FM TRACKING Same as step 2 Same as step 2 Same as step 1 Adjust P.V.C. (TC2) to Tune P.V.C. to
6 FM TRACKING Same as step 2 Same as step 2 Same as step 1 Adjust L102 to get MAX. Tune P.V.C. to
7 Repeat step 5, 6 and then step 2, 3, 5, 6 until no further improvement can be made.
Alignment
Frequency
10.7 MHz generator sweep signal out from point TP3 and repeat to get (2) VOL. & TONE
(T108) (2) Alignment through 300 pF best "S" curve with control in MIN.
FM oscilloscope capacitor to point center at 10.7 MHz position
DETECTION: (3) Power supply TP2 (3) Tune P.V.C. to
(T106) high end
COVERAGE fH: generator signal directly to get MAX. output
108.2 MHz (2) Alignment point TP1
COVERAGE fL: MAX. output end
87.4 MHz
fH: 106 MHz get MAX. output 106 MHz
fL: 90 MHz output 90 MHz
Test Equipment
oscilloscope
(3) Power supply
Signal-in
Signal-out
Adjust
Remark
FM Stereo Section
Step
1 VCO: 75 kHz (1) Frequency counter Inject MONO Through test Adjust VR102 let (1) FM and stereo
Alignment
Frequency
Test Equipment
(2) Power supply signal at 98 MHz circuit as Fig 6. Frequency counter position
(3) FM Signal directly to point value: 76 K ± 200 Hz. (2) Tune radio to
generator TP1 and ground 98 MHz
Pin 13 of IC102
Signal-in Signal-out
Pin 21 of IC102
Adjust
Remark
D
G
FET: 2SK212
(or other 2SK type FET.)
10 pF
S
1M ohm
0.1 µF
To frequency
counter
10K ohm
Figure 6
– 6 –
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