Service manual

ManualsBrandsSharp ManualsTV20LK61M

20LK31M

20LK61M

COLOR TELEVISION

Chassis No. SN-70A

In the interests of user-safety (Required by safety regulations in some countries) the set should be restored to its

original condition and only parts identical to those specified should be used.

S80G420LK31M/

» ELECTRICAL SPECIFICATIONS.........................................................................................................1

» IMPORTANT SERVICE SAFETY PRECAUTION ................................................................................2

» LOCATION OF USER'S CONTROL.....................................................................................................4

» INSTALLATION AND SERVICE INSTRUCTIONS ...............................................................................5

» CHASSIS LAYOUT .............................................................................................................................10

» BLOCK DIAGRAM ..............................................................................................................................12

» SCHEMATIC DIAGRAMS...................................................................................................................14

» PRINTED WIRING BOARD ASSEMBLIES ........................................................................................21

» REPLACEMENT PARTS LIST ...........................................................................................................24

» PACKING OF THE SET......................................................................................................................31

Page

CONTENTS

ELECTRICAL SPECIFICATIONS

Specifications are subject to change without

prior notice.

SERVICE MANUAL

20LK31M

20LK61M

SHARP CORPORATION

MODELS

20LK61M

20LK31M

POWER INPUT ........................................110-220 V AC 50/60 Hz

POWER RATING

20LK31M............................................................................ 88 W

20LK61M............................................................................ 98 W

PICTURE SIZE .......................................... 1,194cm

(185sq inch)

CONVERGENCE ............................................................ Magnetic

SWEEP DEFLECTION .................................................... Magnetic

FOCUS .............................................. Hi-Bi-Potential Electrostatic

INTERMEDIATE FREQUENCIES

Picture IF Carrier Frequency .................................... 45.75 MHz

Sound IF Carrier Frequency ..................................... 41.25 MHz

Color Sub-Carrier Frequency ................................... 42.17 MHz

(Nominal)

AUDIO POWER

OUTPUT RATING

20LK31M........................................... 1.5W (at 10% distortion)

20LK61M........................................... 3.0W (at 10% distortion)

SPEAKER

SIZE ........................................................................ 9 cm × 5 cm

VOICE COIL IMPEDANCE

20LK31M ................................................... 16 ohm at 400 Hz

20LK61M ................................................... 32 ohm at 400 Hz

ANTENNA INPUT IMPEDANCE

VHF/UHF ................................................... 75 ohm Unbalanced

TUNING RANGES

VHF-Channels ............................................................. 2 thru 13

UHF-Channels ........................................................... 14 thru 69

CATV Channels ......................................................... 1 thru 125

Summary of content (30 pages)

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20LK31M 20LK61M SERVICE MANUAL S80G420LK31M/ COLOR TELEVISION LK LK Chassis No. SN-70A 20LK31M 20LK61M MODELS 20LK31M 20LK61M In the interests of user-safety (Required by safety regulations in some countries) the set should be restored to its original condition and only parts identical to those specified should be used. CONTENTS Page » ELECTRICAL SPECIFICATIONS .........................................................................................................
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0LK31M 20LK61M IMPORTANT SERVICE SAFETY PRECAUTION Ë Service work should be performed only by qualified service technicians who are throughly familiar with all safety checks and the servicing guidelines which follow: WARNING X-RADIATION AND HIGH VOLTAGE LIMITS 1. For continued safety, no modification of any circuit should be attempted. 2. Disconnect AC power before servicing. 3. Semiconductor heat sinks are potential shock hazards when the chassis is operating. 4.
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20LK31M 20LK61M IMPORTANT SERVICE SAFETY PRECAUTION (Continued) » Connect the resistor connection to all exposed metal parts having a return to the chassis (antenna, metal cabinet, screw heads, knobs and control shafts, escutcheon and etc.) and measure the AC voltage drop across the resistor. AII checks must be repeated with the AC line cord plug connection reversed. (If necessary, a nonpolarized adapter plug must be used only for the purpose of completing these check.
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20LK31M 20LK61M LOCATION OF USER'S CONTROL Front Panel 20LK31M 20LK61M LK LK VIDEO/AUDIOIN TERMINALS POWER Press → On. Press again → Off. VIDEO/AUDIOIN TERMINALS CHANNEL UP/DOWN ( ) Selects next higher channel. ( ) Selects next lower channel. VOLUME UP/DOWN (+) Increases sound. (–) Decreases sound. POWER Press → On. Press again → Off. CHANNEL UP/DOWN ( ) Selects next higher channel. ( ) Selects next lower channel. VOLUME UP/DOWN (+) Increases sound. (–) Decreases sound.
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20LK31M 20LK61M INSTALLATION AND SERVICE INSTRUCTIONS Note: (1) When performing any adjustments to resistor controls and transformers use non-metallic screwdrivers or TV alignment tools. (2) Before performing adjustments, the TV set must be on at least 15 minutes. CIRCUIT PROTECTION HIGH VOLTAGE CHECK The receiver is protected by a 4.0A fuse (F701), mounted on PWB-A, wired into one side of the AC line input.
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20LK31M 20LK61M For adjustments of this model, the bus data is converted to various analog signals by the D/A converter circuit. Note: There are still a few analog adjustments in this series such as focus and master screen voltage. Follow the steps below whenever the service adjusment is required. To enter the service mode and exit service mode. While pressing the Vol-up and Ch-up buttons at the sametime, plug the AC cord into a wall socket. Now, the TV set is switched on and enters the service mode.
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20LK31M 20LK61M Below are the adjustments ranges and initial values for FIX VALUE category.
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20LK31M 20LK61M Ë SERVICE ADJUSTMENT RF AGC Adjustment White Balance Adjustment. 1. Receive a good local channel. 2. Enter the service mode signal category and select the service adjustment "S01". 3. Set the data value to point where no noise or beat appears. 4. Select another channel to confirm that no noise or beat appears. Note: You have to exit the service mode first to select another channel. 1. Receive a good local channel. 2.
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20LK31M 20LK61M Vertical-Size, V-Linearity and V-S Correction Adjustments Ë MTS ADJUSTMENT 1. Receive a good local channel. 2. Enter the service mode DEF category and select the adjustment "D02" for Vertical Size, "D05" for VLinearity and "D06" for V-S Correction Adjustment. 3. Set in order "D05" for V-Linearity, "D06" for V-S Correction and set the data to get the best linearity. 4. Then adjust "D02" data unitl it become a proper vertical size. 1.
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20LK31M 20LK61M MODEL 20LK31M CHASSIS LAYOUT H PWB-B PWB-C G PWB-A F E D C B A 1 2 3 4 10 5 6
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20LK31M 20LK61M MODEL 20LK61M CHASSIS LAYOUT H PWB-B PWB-C G PWB-A F E D C B A 1 2 3 4 11 5 6
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20LK31M 20LK61M MODEL 20LK31M BLOCK DIAGRAM H G F E D C B A 1 2 3 4 12 5 6
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20LK31M 20LK61M MODEL 20LK61M BLOCK DIAGRAM H G F E D C B A 1 2 3 4 13 5 6
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20LK31M 20LK61M DESCRIPTION OF SCHEMATIC DIAGRAM WAVEFORM MEASUREMENT CONDITIONS: 1. Photographs taken on a standard gated color bar signal, the tint setting adjusted for proper color. The wave shapes at the red, green and blue cathodes of the picture tube depend on the tint, color level and picture control. 2. indicates waveform check points (See chart, waveforms are measured from point indicated to chassis ground.) NOTES: 1. The unit of resistance "ohm" is omitted. (K=kΩ=1000Ω, M=MΩ) 2.
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20LK31M 20LK61M SCHEMATIC DIAGRAM: CRT and FRONT AV Unit H G F E D Ë 20LK31M Ë 20LK61M C B A 1 2 3 4 15 5 6
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20LK31M 20LK61M MODEL 20LK31M SCHEMATIC DIAGRAM: MAIN Unit H G F E D C B A 1 2 3 16 4 5 6 7 8 9 10 11 17 12
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20LK31M 20LK61M MODEL 20LK61M SCHEMATIC DIAGRAM: MAIN-1 Unit H G F E D C B A 1 2 3 18 4 5 6 7 8 9 10 11 19 12
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20LK31M 20LK61M MODEL 20LK61M SCHEMATIC DIAGRAM: MAIN-2 Unit H G F E D C B A 1 2 3 4 20 5 6
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20LK31M 20LK61M PRINTED WIRING BOARD ASSEMBLIES H G F PWB-B: CRT Unit (Wiring Side) E D C PWB-C: FRONT AV Unit (Wiring Side) B A 1 2 3 4 21 5 6
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LK31M 20LK61M H G F E D C B A PWB-A: MAIN Unit (Wiring Side) 1 2 3 4 22 5 6
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20LK31M 20LK61M H G F E D C B A PWB-A: MAIN Unit (Component Side) 1 2 3 4 23 5 6
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20LK31M 20LK61M Ref. No. Part No. ★ Description PARTS LIST Code Ref. No. Replacement parts which have these special safety characteristics identified in this manual; electrical components having such features are identified by å and shaded areas in the Replacement Parts Lists and Schematic Diagrams.
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20LK31M 20LK61M Ref. No. ★ Part No. Description Code Ref. No.
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20LK31M 20LK61M Ref. No. Part No. ★ Description Code Ref. No.
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20LK31M 20LK61M Ref. No. Part No. ★ Description Code Ref. No.
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20LK31M 20LK61M Ref. No. ★ Part No. Description Code Ref. No.
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20LK31M 20LK61M Ref. No. ★ Part No. Description Code Ref. No.
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20LK31M 20LK61M Ref. No. Part No. ★ Description Code Ref. No.
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20LK31M 20LK61M Ref. No. Part No. ★ Description Code No. Part No. PACKING OFRef. THE SET ★ Description ★ Polyethylene Bag Operation Manual Infrared R/C Unit Rod Antenna Antenna Adapter ★ Batteries ★ Polyethylene Foam Wrap ★ Buffer Material FRONT ★ Packing Case Use tapes to fix the packing case. REAR ★ MARK : Not Replacement Items.
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20LK31M 20LK61M Ref. No. Part No. ★ Description Code Ref. No. ★ Part No. Description Code COPYRIGHT © 2000 BY SHARP CORPORATION ALL RIGHTS RESERVED. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without prior written permission of the publisher.