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Sharp WQ-790W Service Manual

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SPECIFICATIONS ............................................................................................................................................................... 1
VOLTAGE SELECTION ....................................................................................................................................................... 2
AC POWER SUPPLY CORD AND PLUG ........................................................................................................................... 2
FITTING OF DIAL POINTER ............................................................................................................................................... 2
NAMES OF PARTS ............................................................................................................................................................. 3
DISASSEMBLY .................................................................................................................................................................... 4
ADJUSTMENT ..................................................................................................................................................................... 5
NOTES ON SCHEMATIC DIAGRAM .................................................................................................................................. 6
VOLTAGE ............................................................................................................................................................................ 7
TYPES OF TRANSISTOR AND LED ................................................................................................................................... 7
SCHEMATIC DIAGRAM / WIRING SIDE OF P.W.BOARD ................................................................................................. 8
PARTS GUIDE / EXPLODED VIEW
General
Power source:
AC 110-127 V/220-240 V,
50/60 Hz
DC 15 V ["D" size (UM/SUM-
1, R20 or HP-2) battery × 10]
Power consumption:
20 W
Output power:
PMPO; 120 W (60 W + 60 W)
(AC operation)
MPO (Max.); 30 W
(15 W + 15 W) (AC operation)
RMS; 15 W (7.5 W + 7.5 W)
(DC operation, 10 % T.H.D.)
Speakers:
12 cm (4-3/4") free-edge
speaker × 2
5 cm (2") surround speaker × 2
Input terminal:
MIC 1/2; 1 mV/600 ohms
CD/LINE; 350 mV/47 kohms
Output terminal:
Headphones; 16-50 ohms
(recommended; 32 ohms)
Dimensions:
Width; 630 mm (24-13/16")
Height; 205 mm (8-1/8")
Depth; 215 mm (8-1/2")
Weight:
5.3 kg (11.7 lbs.) without bat-
teries
SERVICE MANUAL
CONTENTS

SPECIFICATIONS

Frequency range:
Frequency response:
Signal/noise ratio:
Wow and flutter:
Motor:
Bias system:
Erase system:
SHARP CORPORATION
WQ-790W
• 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.
Radio section
FM; 88 - 108 MHz
SW1; 2.3 - 7.3 MHz
SW2; 7.3 - 22 MHz
MW; 526.5 - 1,606.5 kHz
Tape recorder section
60 - 12,000 Hz (Normal tape)
40 dB (TAPE 1, recording/playback)
55 dB (TAPE 2, playback)
0.15 % (WRMS)
DC 15 V electric governor
AC bias
Magnet erase
Specifications for this model are subject to change without
prior notice.
This document has been published to be used
for after sales service only.
The contents are subject to change without notice.
WQ-790W
No. S7852WQ790W//
Page

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  Summary of Contents for Sharp WQ-790W

  • Page 1: Table Of Contents

    WQ-790W SERVICE MANUAL No. S7852WQ790W// WQ-790W • 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 SPECIFICATIONS ................................1 VOLTAGE SELECTION ............................... 2 AC POWER SUPPLY CORD AND PLUG ...........................
  • Page 2: Voltage Selection

    WQ-790W FOR A COMPLETE DESCRIPTION OF THE OPERATION OF THIS UNIT, PLEASE REFER TO THE OPERATION MANUAL. 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 AC power supply socket to the visible indication of the side of your local voltage.
  • Page 3: Names Of Parts

    WQ-790W NAMES OF PARTS 14 15 7 8 9 10 11 12 17 18 19 20 21 22 23 24 35 36 38 39 (TAPE 1) Cassette Compartment (TAPE 2) Cassette Compartment Power/(TAPE 2) Play Direction Indicators (TAPE 1) Record Button:...
  • Page 4: Disassembly

    WQ-790W DISASSEMBLY Open Caution on Disassembly Casette Holder Follow the below-mentioned notes when disassembling (Left/Right) the unit and reassembling it, to keep it safe and ensure Open excellent performance: 1. Take cassette tape out of the unit. (B1)x1 2. Be sure to remove the power supply plug from the wall ø3x20mm...
  • Page 5: Adjustment

    WQ-790W ADJUSTMENT MECHANISM SECTION TUNER SECTION • Driving Force Check fL: Low-range frequency fH: High-renge frequency Specified Value Torque Meter • FM IF/RF Play: TW-2412 Tape 1: Over 60 g Tape 2: Over 50 g Specified Value/ Instrument Test Stage...
  • Page 6: Notes On Schematic Diagram

    WQ-790W CNS110 T301 BIAS OSCILLATION FM BAND COVERAGE FM IF T201 SW1 BAND TRACKING COVERAGE T203 CNS108 IC201 AM IF L201 L203 L202 MW BAND COVERAGE IC202 L204 T202 VR201 207 TC DETECTION SW2 BAND TC210 COVERAGE TC209 L205 TRACKING...
  • Page 7: Types Of Transistor And Led

    WQ-790W CNS110 T301 BIAS OSCILLATION FM BAND COVERAGE FM IF T201 SW1 BAND TRACKING COVERAGE T203 CNS108 IC201 AM IF L201 L203 L202 MW BAND COVERAGE IC202 L204 T202 VR201 207 TC DETECTION SW2 BAND TC210 COVERAGE TC209 L205 TRACKING...
  • Page 8: Voltage

    WQ-790W VOLTAGE TRANSISTOR RADIO TAPE PLAY TAPE REC IC101-105 (AN6884): Spectrum Analyzer Q101 0.63V 3.27V 0.63V 3.27V RADIO 6.13V 6.16V 6.5V Q102 0.63V 3.35V 0.63V 3.35V TAPE PLAY 6.5V Q103 7.36V 6.52V 7.28V 7.36V 6.52V 7.28V TAPE REC 6.5V Q106 0.69V...
  • Page 9 WQ-790W R207 820K IC201 C220 470P LA1186N C218 C212 T202 0.022 0.0047(ML) FM FRONT END SW201 FM/SW R209 R210 C222 BAND SELECTOR R205 R208 ROD ANTENNA 150K 3.3/50 MIC/FM M 220K FM DETECTION 3.9K C201 NORMAL/FM STE 0.001 HIGH/FM STE...
  • Page 10 WQ-790W SW403 DUBBING SPEED/ BUILT-IN MICROPHONE/ R531 FM MODE MIC/FM MONO SW403-A R565 R552 R344 R345 MAL/FM STEREO 5.6K 4.7K 4.7K MIC2 R557 R346 GH/FM STEREO C533 C344 470K R556 C341 4.7/50 4.7/50 150K 4.7/50 R211 Q303 VR301 9014 C 50K(B) MIC AMP.
  • Page 11 WQ-790W CNS2 TAPE 2 SW504 HEAD TAPE2 PLAYBACK SW502 FLEXIBLE PWB CNS1 DIRECTION HEAD (300-6) TAPE1 MAIN SW501 TAPE2 MAIN SW503 CNH107 TAPE2 PLAY RECORD/PLAYBACK ERASE HEAD(300-5) HEAD(300-4) TAPE 1 A B + - M501 TAPE MOTOR TAPE MECHANISM CN207...
  • Page 12 WQ-790W 1 2 3 4 CNH108 CNH109 MIC101 BUILT-IN MICROPHONE C347 R351 R350 L303 L304 SW302 RECORD/ 1 2 3 4 R333 PLAYBACK R343 CNS108 C515 R330 PALY REC. C353 C321 C352 R545 R553 R344 R552 CNS107 R555 R558 T1.25A L 250V...
  • Page 13 WQ-790W FM SIGNAL GRAPHIC EQUALIZER VR102-A VR103-A VR105-A VR104-A X-BASS VR102-B VR103-B VR105-B VR104-B VR101-A 330Hz 1kHz 3.3kHz 10kHz VR101-B R138 3.9K C176 R130 R112 R124 R106 R118 500P 8.2K 3.3K 4.7K R136 680K C103 470/16 R101 R103 C126 1/50...
  • Page 14 WQ-790W IC101~IC105 AN6884 SPECTRUM ANALYZER IC106~IC108 IC101 BA4458 AN6884 OPE AMP. R141 220K R177 C128 (1/2) 1/50 C126 C155 – C127 1/50 1/50 IC106 BA4558 R176 C154 8.2K 10/16 IC102 R144 C130 AN6884 0.15(ML) 390K C129 0.033(ML) R143 (2/2) 2.2K R173 –...
  • Page 15 WQ-790W SO501 AC POWER INLET SOCKET AC110V-127V POWER PWB-C 50/60Hz AC220V-240V 50/60Hz CNH110 TO MAIN PWB CNS110 P11 7-B D504 C504 D501 C501 D502 COLOR TABLE C502 BROWN T501 R D ( R ) POWER D503 TRANSFORMER ORANGE C503 YELLOW...