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Sharp 37GQ-20S Service Manual

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ELECTRICAL SPECIFICATION.......................2
IMPORTANT SERVICE NOTES.......................3
PRINTED WIRING BOARDS...........................11

SHARP CORPORATION

SERVICE MANUAL

PAL SYSTEM COLOUR TELEVISION
37GQ-20S
37GQ-21S
MODELS:
In the interests of user safety (required by safety
regulations in some countries) the set should restored
to its original condition and only parts identical to
those specified should be used.
CONTENTS
PART LIST.......................................................18
TROUBLESHOOTING TABLES......................23
1
37GQ-20S
37GQ-21S
SEJB37GQ2*S02
Issued: 9th June '00
SQUAD
CHASSIS
This document has been published to
be used for after sales service only.

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Summary of Contents for Sharp 37GQ-20S

  • Page 1: Table Of Contents

    37GQ-20S 37GQ-21S SERVICE MANUAL SEJB37GQ2*S02 Issued: 9th June ‘00 SQUAD CHASSIS PAL SYSTEM COLOUR TELEVISION 37GQ-20S 37GQ-21S MODELS: In the interests of user safety (required by safety regulations in some countries) the set should restored to its original condition and only parts identical to those specified should be used.

  • Page 2: Electrical Specification

    37GQ-20S 37GQ-21S ELECTRICAL SPECIFICATIONS •Sound Carrier Trap •Power Input .......220V-240 Volts AC 50Hz B/G............33.4MHz •Power Consumption Normal Operating........30W •Adjacent Sound Carrier Trap Stand-by Operating........7.5W B/G.............40.4MHz (Method IEC60107) •Audio Power Output Rating .....2W (MPO) •Adjacent Picture Carrier Trap B/G............30.9MHz Ω Speaker......32 2W, 8cm Round, 1pc Convergence......Self Converging System...

  • Page 3: Important Service Notes

    37GQ-20S 37GQ-21S IMPORTANT SERVICE NOTES Maintenance and repair of this receiver should be done by qualified service personnel only. SERVICING OF HIGH VOLTAGE SYSTEM AND PICTURE TUBE When servicing the high voltage system, remove static charge from it by connecting a 10K ohm resistor in series with an insulated wire (such as test probe) between picture tube ground tag and high voltage lead.

  • Page 4: Service Adjustment

    37GQ-20S 37GQ-21S SERVICE ADJUSTMENT •SERVICE MODE FUNCTION This mode funtion is provided to assist with the settings of those adjustments that may vary from one Picture Tube to another, or between models. In order to use the Service Mode 1. Press main switch to OFF.
  • Page 5 37GQ-20S 37GQ-21S Bear in mind that, for storage location indication a hexadecimal numerical system is used, instead of a decimal system. 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F, 10, 11, ..19, 1A, 1B, 1C, 1D, 1E, 1F, 20, 21, .., 99, 9A, 9B, 9C, 9D, 9E, 9F, A0, A1, .., B0, .., C0, .., D0, ..E0, .., F0, F1, F2, F3, F4, F5, F6, F7, F8, F9, FA,...
  • Page 6 37GQ-20S 37GQ-21S ONE CHIP REGISTER 00: ONE CHIP REGISTER 01: ONE CHIP REGISTER 02: ONE CHIP REGISTER 03: ONE CHIP REGISTER 04: ONE CHIP REGISTER 05: ONE CHIP REGISTER 06: ONE CHIP REGISTER 07: ONE CHIP REGISTER 08: ONE CHIP REGISTER 09:...
  • Page 7 37GQ-20S 37GQ-21S VH F1HIGH : U PPER WIND OW LIM IT FOR V HF1 PRG _NUM B ER: CU RREN T PRO GRA M ME NU MBE R W AITSUP : U PPER L IM IT DE LAY TIME FOR A UTO SEAR CH.
  • Page 8 37GQ-20S 37GQ-21S VHF1_SP: STEP FOR AUTO SEARCH IN VHF1 BAND VHF3_SP: STEP FOR AUTO SEARCH IN VHF3 BAND UHF_SP: STEP FOR AUTO SEARCH IN VHF BAND OLD_PROGRAM: FOR FLASHBACK RETURN UHFHIGH: UPPER WINDOW LIMIT FOR UHF VHF3HIGH: UPPER WINDOW LIMIT FOR VHF3...
  • Page 9 37GQ-20S 37GQ-21S BG_COARSE: THICK TUNING ADJUSTMENT FOR L AND BG 0AH BG_FINE: FINE TUNING ADJUSTMENT FOR L AND BG LP_FINE: FINE TUNING ADJUSTMENT FOR L’ DELAY SEARCH: XXXXXXX0 -> SHOWS ‘PROGRAMME –‘ DURING AUTOSEARCH. XXXXXXX1 -> DHOWS ‘AUTO SEARCH’ DURING AUTOSEARCH...
  • Page 10 37GQ-20S 37GQ-21S •GEOMETRY ADJUSTMENT PROCEDURE 1. HOR POS a) Receive Philips pattern signal. ∧ b) When button is pressed, picture moves to the left. ∨ c) When button is pressed, picture moves to the right. d) Adjust the horizontal location to obtain picture centering (Fig.1).

  • Page 11: Printed Wiring Boards

    37GQ-20S 37GQ-21S F7281BMN1A PRINTED WIRING BOARD Component side. J302 RMC001 K7287BM D1001 F7287BMN1 S1001 S1002 S1003 C1009 S1004 S701 J301 R864 C701 JL1, R885 C878 F7310BMN0 F7296BMN1 Q885 C876 (SH) (S). R883 (SH) (S). Q302 R862 Q883 Q301 JF12 C874...
  • Page 12 37GQ-20S 37GQ-21S F7281BMN1A PRINTED WIRING BOARD Copper side. J302 RMC001 C313 F7287BMN1 C1009 S1004 S1003 S1002 S1001 R319 C314 S701 R864 C878 J301 J301 R898 R320 C310 C310 C701 JF16 D862 F7288BMN1 C861 R893 R885 Q885 Q304 C876 F7310BMN0 R883...

  • Page 13: Schematic Diagram, Wave Forms

    37GQ-20S 37GQ-21S DESCRIPTION OF SCHEMATIC DIAGRAM NOTE: SAFETY NOTE: 1. The unit of resistance «ohm»is omitted (K=1000 1. DISCONNECT THE AC PLUG FROM THE AC ohms. M= Megaohm). OUTLET BEFORE REPLACING PARTS. 2. All resistors are 1/8 watt. unless otherwise noted.
  • Page 14 37GQ-20S 37GQ-21S Page 16...
  • Page 15 37GQ-20S 37GQ-21S Page 17...
  • Page 16 37GQ-20S 37GQ-21S...
  • Page 17 37GQ-20S 37GQ-21S R OUT R IN L OUT L IN V OUT V IN...

  • Page 18: Part List

    37GQ-20S 37GQ-21S REF No. PARTS DESCRIPTION PART LIST SN CODE EX CODE Q 0707 RH-TX0217BMZZ TRT BC337 PHILIPS S AA REPLACEMENT PARTS Q 0708 VS2SC2412KQ-1 TRT 2SC2412 ROHM S AA Q 1001 RH-TX0111BMZZ TRT PH-2369 PHILIPS S AA Replacement parts which have special safety characteristics are identi- fied in this manual.
  • Page 19 37GQ-20S 37GQ-21S REF No. PARTS DESCRIPTION REF No. PARTS DESCRIPTION SN CODE EX CODE SN CODE EX CODE L 0601 VP-CF4R7K0000 PEAK COIL 4,7UH 10% S AB C 0703 RC-KZ0029CEZZ CERAM C 10NF 80,20% 250V S AC L 0602 VP-CF220K0000...
  • Page 20 37GQ-20S 37GQ-21S REF No. PARTS DESCRIPTION REF No. PARTS DESCRIPTION SN CODE EX CODE SN CODE EX CODE R 0222 VRS-TV1JD224J 2125 220KOHM 5% 1/10W SMD S AA R 0611 VRD-RA2HD270J RES 27 OHM 5% 1/2W S AA R 0301 VRD-RA2HD472J RES 4.7KOHM 5% 1/2W...
  • Page 21 37GQ-20S 37GQ-21S REF No. PARTS DESCRIPTION REF No. PARTS DESCRIPTION SN CODE EX CODE SN CODE EX CODE R 1011 VRD-RA2HD472J RES 4.7KOHM 5% 1/2W S AA DIODES R 1012 VRD-RA2HD472J RES 4.7KOHM 5% 1/2W S AA D 0811 RH-DX0551BMZZ...
  • Page 22 JBTN-1047BMSC UP/DOWN BUTTON YELLOW "EM" S AA JBTN-1046BMSA POWER BUTTON BLACK S AA JBTN-1046BMSD POWER BUTTON 37GQ20SDES METALLIC BLUE 026 S AA JBTN-1046BMSC POWER BUTTON YELLOW "EM" S AA GCABB1107BMKA REAR CAB. 37GQ-20S/21S BLACK S AH GCABB1107BMKB REAR CAB. 37GG21SESY YELOW S AH...

  • Page 23: Troubleshooting Tables

    37GQ-20S 37GQ-21S TROUBLESHOOTING TABLES. NO PICTURE Check Picture setting by R/C. Signal should be received. Check the tuner supply and band biases. Both must be approx. 5V DC Normal Is tuning voltage normal at Pin (2) of Tuner? Check Q1001,...
  • Page 24 37GQ-20S 37GQ-21S NO SOUND Check Sound setting by R/C. Signal should be received. Does approx. 20V DC appear on C710? Check D707, C710 Does Sound Signal appear at Pin(6) of IC801? Check IC801, C301 Audio Amplifier muted? Check IC1001, Q305...
  • Page 25 37GQ-20S 37GQ-21S NO RASTER Fuse Blown Check F701 Normal Check Voltage on C705 Replace Fuse (Approx. 325V DC) Fuse Blown Normal again Check Voltage on C711 Check IC701 Approx. 0V Abnormal (Approx. 105V DC) Normal Normal Check D708, D717 Check CRT connector K1...
  • Page 26 37GQ-20S 37GQ-21S NO VERTICAL SCAN Is IC501 bias normal? Check R510, Q501, Check D709, D710, IC501 Q502, Q503 NEITHER VERTICAL NOR HORIZONTAL SYNCHRONIZATION Check IC801, C815, C816, R818 DEFECTIVE VERTICAL AMP. AND VERTICAL LINEARITY Readjust Vertical Size. Vertical size is abnormal...
  • Page 27 37GQ-20S 37GQ-21S NO SPECIFIC COLOUR some colour produced in B/W Broadcast reception? Check IC801, C812, C813, R813, X801 the white balance properly adjusted? The Picture Colour is The Picture Colour is The Picture Colour is Red or cyan. green or magenta.
  • Page 28 37GQ-20FP RECICLED PAPER PRINTED BY:...

This manual is also suitable for:

37gq-21s

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