SHARP LC20S4US Service Manual

LC-20S4U-S

SUPPLEMENT

SERVICE MANUAL

S05P1LC20S4US

SUPPLEMENT

LCD COLOR TELEVISION

MODEL

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.

OUTLINE

The LCD panel of this model has been redesigned. With this redesign, the main and analog PWB unit as well as the LCD panel-related and other mechanical parts have also been modified and these parts are not interchangeable with those of previous LCD panel models in servicing. This Supplement covers the modified points from the previous Supplement. For other technical points, refer to the Service Manual for previous LCD panel model LC-20S4U-S (S2F1LC20S4US) as well as the Supplement for LC-20S4U-S (S65K1LC20S4US).

The previous LCD panel models and the new model can be identified with the following markings.

• The

• The B character is also added at the end of the model name on the number label (barcode label) of the

• The serial product numbers (in the 5th thru 9th digits) are 81112 and on.

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

» REMOVING OF MAJOR PARTS .................................................................................................................. 5

» OVERALL WIRING DIAGRAM .....................................................................................................................8

» SCHEMATIC DIAGRAM

» REPLACEMENT PARTS LIST....................................................................................................................30

» PACKING OF THE SET ..............................................................................................................................39

B character is added at the end of the model name on the model label.

packing case.

CONTENTS

ËMAIN Unit .................................................................................................................................................10

ËANALOG Unit...........................................................................................................................................22

LC-20S4U-S

Page

SHARP CORPORATION

This document has been published to be used for after sales service only. The contents are subject to change without notice.

LC-20S4U-S

SUPPLEMENT

IMPORTANT SERVICE SAFETY PRECAUTION

Service work should be performed only by qualified service technicians who are thoroughly familiar with all safety checks and the servicing guidelines which follow:

WARNING

1. For continued safety, no modification of any circuit should be attempted.

2. Disconnect AC power before servicing.

CAUTION: FOR CONTINUED PROTECTION AGAINST A RISK OF FIRE REPLACE ONLY WITH SAME

A V

TYPE F3701 (2.5A, 250V) AND F3702 (2.0A, 250V) FUSE.

BEFORE RETURNING THE RECEIVER (Fire & Shock Hazard)

Before returning the receiver to the user, perform the following safety checks:

1. Inspect all lead dress to make certain that leads are not pinched, and check that hardware is not lodged between the chassis and other metal parts in the receiver.

2. Inspect all protective devices such as non-metallic control knobs, insulation materials, cabinet backs, adjustment and compartment covers or shields, isolation resistor-capacitor networks, mechanical insulators, etc.

3. To be sure that no shock hazard exists, check for leakage current in the following manner.

• Plug the AC cord directly into a 110~240 volt AC outlet, and connect the DC power cable into the receiver's DC jack. (Do not use an isolation transformer for this test).

• Using two clip leads, connect a 1.5k ohm, 10 watt resistor paralleled by a 0.15µF capacitor in series with all exposed metal cabinet parts and a known earth ground, such as electrical conduit or electrical ground connected to an earth ground.

• Use an AC voltmeter having with 5000 ohm per volt, or higher, sensitivity or measure the AC voltage drop across the resistor.

• 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, etc.) and measure the AC voltage drop across the resistor. All checks must be repeated with the AC cord plug connection reversed. (If necessary, a nonpolarized adaptor plug must be used only for the purpose of completing these checks.) Any reading of 0.75V peak (this corresponds to 0.5 mA. peak AC.) or more is excessive and indicates a potential shock hazard which must be corrected before returning the monitor to the owner.

DVM

AC SCALE

1.5k ohm 10W

0.15 µF

TEST PROBE

TO EXPOSED METAL PARTS

CONNECT TO KNOWN EARTH GROUND

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SAFETY NOTICE

Many electrical and mechanical parts in LCD television have special safety-related characteristics. These characteristics are often not evident from visual inspection, nor can protection afforded by them be necessarily increased by using replacement components rated for higher voltage, wattage, etc. Replacement parts which have these special safety characteristics are identified in this manual; electrical

and shaded areas in the

Schematic Diagrams

For continued protection, replacement parts must be identical to those used in the original circuit. The use of substitute replacement parts which do not have the same safety characteristics as the factory recommended replacement parts shown in this service manual, may create shock, fire or other hazards.

components having such features are identified by " å"

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Replacement Parts Lists

and

LC-20S4U-S

SUPPLEMENT

PRECAUTIONS A PRENDRE LORS DE LA REPARATION

La réparation ne peut être effectuée que par un technicien spécialisé qui s'est parfaitement accoutumé à toute vérification de sécurité et aux conseils suivants.

AVERTISSEMENT

1. Pour la sécurité continue, n'entreprendre aucune modification de tout circuit.

2. Débrancher l'alimentation CA avant la réparation.

PRECAUTION: POUR LA PROTECTION CONTINUE CONTRE LES RISQUES D'INCENDIE, REMPLACER LE

A V

FUSIBLE PAR UN FUSIBLE DE MEME TYPE F3701 (2.5A, 250V) ET F3702 (2.0A, 250V).

AVANT DE RENDRE LE RECEPTEUR A L’UTILISATEUR (Incendie et choc électrique)

Avant de rendre le récepteur à l'utilisateur, effectuer les vérifications suivantes.

1. Inspecter tous les faisceaux de câbles pour s'assurer que les fils ne soient pas pincés ou qu'un outil ne soit pas placé entre le châssis et les autres pièces métalliques du récepteur.

2. Inspecter tous les dispositifs de protection comme les boutons de commande non-métalliques, les isolants, le dos du coffret, les couvercles ou blindages de réglage et de compartiment, les réseaux de résistance-capacité, les isolateurs mécaniques, etc.

3. S'assurer qu'il n'y ait pas de danger d'électrocution en vérifiant la fuite de courant, de la facon suivante:

• Enficher le cordon d’alimentation directement dans une prise de 110-240V CA, et brancher le câble d’alimentation CC à la prise CC du récepteur. (Ne pas utiliser de transformateur d’isolation pour cet essai.)

• A l'aide de deux fils à pinces, brancher une résistance de 1.5kΩ 10 watts en parallèle avec un condensateur de 0.15µF en série avec toutes les pièces métalliques

exposées du coffret et une terre connue comme une conduite électrique ou une prise de terre branchée à la terre.

• Utiliser un voltmètre CA d'une sensibilité d'au moins 5000Ω/V pour mesurer la chute de tension CA en travers de la résistance.

• Toucher avec la sonde d'essai les pièces métalliques exposées qui présentent une voie de retour au châssis (antenne, coffret métallique, tête des vis, arbres de commande et des boutons, écusson, etc.) et mesurer la chute de tension CA en travers de la résistance. Toutes les vérifications doivent être refaites après avoir inversé la fiche du cordon d'alimentation. (Si nécessaire, une prise d'adpatation non polarisée doit être utilisée dans le but de terminer ces vérifications.) La tension de pointe mesurèe ne doit pas dépasser

0.75V (correspondante au courant CA de pointe de

0.5mA). Dans le cas contraire, il y a une possibilité de choc électrique qui doit être supprimée avant de rendre le récepteur au client.

DVM

ECHELLE CA

1.5k ohm 10W

0.15 µF

SONDE D'ESSAI

AUX PIECES METALLIQUES EXPOSEES

BRANCHER A UNE TERRE CONNUE

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AVIS POUR LA SECURITE

De nombreuses pièces, électriques et mécaniques, dans les téléviseurs de l'afficharge à cristaux liquides présentent des caractéristiques spéciales relatives à la sécurité. Ces caracténstiques ne sont souvent pas évidentes à vue. Le degré de protection ne peut pas être nécessairement augmentée en utilisant des pièces de remplacement étalonnées pour haute tension, puissance, etc. Les pièces de remplacement qui présentent ces caractéristiques sont identifiées dans ce manuel; les

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pièces électriques qui présentent ces particularités sont identifiées par la marque " å " et hachurées dans la

des pièces de remplacement schématiques

et les

diagrammes

liste

Pour assurer la protection, ces pièces doivent être identiques à celles utilisées dans le circuit d'origine. L'utilisation de pièces qui n'ont pas les mêmes caractéristiques que les pièces recommandées par l'usine, indiquées dans ce manuel, peut provoquer des électrocutions, incendies ou autres accidents.

LC-20S4U-S

SUPPLEMENT

Precautions for using lead-free solder

1 Employing lead-free solder

"All PWBs" of this model employs lead-free solder. The LF symbol indicates lead-free solder, and is attached on the PWBs and service manuals. The alphabetical character following LF shows the type of lead-free solder. Example:

L Fa

Indicates lead-free solder of tin, silver and copper.

2 Using lead-free wire solder

When fixing the PWB soldered with the lead-free solder, apply lead-free wire solder. Repairing with conventional lead wire solder may cause damage or accident due to cracks. As the melting point of lead-free solder (Sn-Ag-Cu) is higher than the lead wire solder by 40°C, we recommend you to use a dedicated soldering bit, if you are not familiar with how to obtain lead-free wire solder or soldering bit, contact our service station or service branch in your area.

3 Soldering

As the melting point of lead-free solder (Sn-Ag-Cu) is about 220°C which is higher than the conventional lead solder by 40°C, and as it has poor solder wettability, you may be apt to keep the soldering bit in contact with the PWB for extended period of time. However, Since the land may be peeled off or the maximum heat-resistance temperature of parts may be exceeded, remove the bit from the PWB as soon as you confirm the steady soldering condition. Lead-free solder contains more tin, and the end of the soldering bit may be easily corroded. Make sure to turn on and off the power of the bit as required. If a different type of solder stays on the tip of the soldering bit, it is alloyed with lead-free solder. Clean the bit after every use of it. When the tip of the soldering bit is blackened during use, file it with steel wool or fine sandpaper.

Be careful when replacing parts with polarity indication on the PWB silk.

Lead-free wire solder for servicing

Part No. ★ Description Code ZHNDAi123250E J φ0.3mm 250g(1roll) BL ZHNDAi126500E J φ0.6mm 500g(1roll) BK ZHNDAi12801KE J φ1.0mm 1kg(1roll) BM

REMOVING OF MAJOR PARTS

Cabinet B

Carrying Handle

Cabinet A

Terminal Cover (R)

Terminal Cover (L)

Stand

Stand Cover

1. Remove the stand cover fixing screws (1 pc.)

2. Remove the stand fixing screws (4 pcs.).

3. Remove the carrying handle fixing screws (4 pcs.).

4. Remove the terminal covers (left and right).

5. Remove the terminal screws (6 pcs.).

6. Remove the cabinet B fixing screws (8 pcs.).

7. Remove the cabinet B after opening from the direction of an arrow.

8. Remove the stand angle fixing screws (3 pcs.).

9. Disconnect all the connectors from all the PWBs.

LC-20S4U-S

SUPPLEMENT

Analog PWB

SC1201

CN1

P4001

Stand Angle

Operation PWB

Main PWB

SC2001

SC3401

SC701

P3702

SC4052

P3701

SC4051

SC6701

P6706

P6705

P6704

P6703

P3402

P3401

P6702

R/C, LED PWB

Inverter PWB

LC-20S4U-S

SUPPLEMENT

10. Remove the 3 lock screws from the main PWB, and undo the claws a and b. Detach the main PWB by lifting the area around the claws and pulling the PWB out.

11. Remove the 3 lock screws from the analog PWB, and undo the claws c and d. Detach the chassis frame (right) from the analog PWB by pulling out the terminals. In the same way, undo the claws e and f, and detach the chassis frame (left) from the analog PWB by pulling out the terminals.

Note: When detaching the main PWB and analog PWB, be careful not to break the PWB-fixing claws.

12. Remove the operation PWB fixing screws (5 pcs.)

13. Remove the inverter PWB fixing screws (2 pcs.)

14. Remove the R/C, LED PWB fixing screws (2 pcs.)

15. Remove the 3 lock screws each from the right and left speakers and take out both the speakers.

Main PWB

Chassis Frame (R)

Analog PWB

Operation PWB

Chassis Frame (L)

Speaker (R)

Inverter PWB

Speaker (L)

R/C, LED PWB

LC-20S4U-S

SUPPLEMENT

» Precautions in handling the LCD panels

1. Work in a clean room (with humidities below 50%).

2. Be sure to wear an anti-static armband.

3. Handle the panels on an electro-conductive mat.

4. Be careful not to fall, shake and shock the panels.

16. Detach the back shield.

17. Remove the 5 lock screws from the bezel and detach the bezel. Note: Carefully undo the hooks in the four directions.

18. Detach the LCD panel from the backlight case.

Note1: Carefully undo the hooks in the four directions. Note2: Do not remove the LCD panel from the panel chassis. Be careful not to touch the LCD panel's glass faces,

driver IC, PWBs and other components with bare hands. (Otherwise defects may be caused in the production line.)

19. Remove the diffusion sheets (top), lens sheet, diffusion sheet (bottom) and diffusion plate. Note: Fit the diffusion plate and sheets tightly in the backlight casing. If set out of position, the panel may get cracked.

20. Detach the lamp unit from the backlight case.

Back shield (PSLDMA810WJN1)

Lens Sheet (POFMA0220TPZZ)

Diffusion Plate (PSLDK2553TPZZ)

Back light Case (LHLDZ3104TPZA)

Lamp Unit, x5 (RLMPC2401TPZZ)

Diffusion Sheet (Bottom) (PSLDK2554TPZZ)

Diffusion Sheet (Top), x2 (PSLDK2567TPZZ)

20" LCD Panel

Bezel (LANGK3261TPZA)

LC-20S4U-S

121110987654321

SUPPLEMENT

OVERALL WIRING DIAGRAM

LC-20S4U-S

121110987654321

SUPPLEMENT

SCHEMATIC DIAGRAM

MAIN Unit-1/6

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