Sharp LC-C3742U Service Manual

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LC-C3742U

SERVICE MANUAL

No. SX6Y7LCC3742U

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.

LC-C3742U

OUTLINE

This model is based on the LC-37D42U and is changed some parts. This Service Manual covers the modifications alone. For the other points, refer to the LC-32/37D42U Service Manual.

CONTENTS

DIFFERENCES FROM BASE MODEL

LIST OF CHANGED PARTS...............................i

SAFETY PRECAUTION

IMPORTANT SERVICE SAFETY PRE-

CAUTION ...........................................................ii

PRECAUTIONS A PRENDRE LORS DE

LA REPARATION.............................................. iii

PRECAUTIONS FOR USING LEAD-FREE

SOLDER ........................................................... iv

PRECAUTIONS IN SERVICING THE

HDCP-KEY ROM ...............................................v

Parts Guide

Parts marked with " " are important for maintaining the safety of the set. Be sure to replace these parts with specified ones for maintaining the safety and performance of the set.

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

LC-C3742U

DIFFERENCES FROM BASE MODEL

Service Manual

LIST OF CHANGED PARTS

Ref. No. Description LC-37D42U LC-C3742U Note

PWB ASSEMBLIES

MAIN Unit DUNTKD862FM04 ← — R/C, LED Unit DUNTKD909FM02 ← — KEY Unit DUNTKD910FM02 ← — AV TERMINAL Unit DUNTKD999FM04 ← — POWER Unit RDENCA198WJQZ ← —

CABINET AND MECHANICAL PARTS Please refer to a Parts list.

PACKING PARTS AND ACCESSORIES Please refer to a Parts list.

LC-C3742U

SAFETY PRECAUTION

Service Manual

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: FO R C O N TI NU ED PROTECTION AGAINST A RISK OF FIRE REPLACE ONLY WITH SAME TYPE FUSE.

F7001 (250V 6.3A)

• 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 0.75 Vrms (this corresponds to 0.5 mA rms AC.) or more is excessive and indicates a potential shock hazard which must be corrected before returning the monitor to the owner.

DVM

BEFORE RETURNING THE RECEIVER (Fire & Shock Hazard)

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

3. 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.

4. 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.

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

• Plug the AC cord directly into a 120 volt AC outlet.

• 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.

///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

TO EXPOSED METAL PARTS

AC SCALE

1.5k ohm 10W

0.15µF

TEST PROBE

CONNECT TO KNOWN EARTH GROUND

SAFETY NOTICE

Many electrical and mechanical parts in LCD color 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 components having such features

are identified by " " and shaded areas in the Replacement Parts List and Schematic Diagrams.

For continued protection, replacement parts must be identical to those used in the original circuit.

The use of a 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.

LC-C3742U

PRECAUTIONS A PRENDRE LORS DE LA REPARATION

Ne peut effectuer la réparation qu' un technicien spécialisé qui s'est parfaitement accoutumé à toute vérification de sécurité et aux conseils suivants.

•

AVERTISSEMENT

N'entreprendre aucune modification de tout circuit. C'est dangereux.

Débrancher le récepteur avant toute réparation.

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

F7001 (250V 6.3A)

VERIFICATIONS CONTRE L'INCEN-DIE ET LE CHOC ELECTRIQUE

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

Inspecter tous les faisceaux de câbles pour s'assurer que les fils

3. ne soient pas pincés ou qu'un outil ne soit pas placé entre le châssis et les autres pièces métalliques du récepteur.

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 résistancecapacité, les isolateurs mécaniques, etc.

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

•

Brancher le cordon d'alimentation directem-ent à une prise de courant de 120V. (Ne pas utiliser de transformateur d'isolation pour cet essai).

A l'aide de deux fils à pinces, brancher une résistance de 1.5 kΩ 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 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 peut 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

SONDE D'ESSAI

AUX PIECES METALLIQUES EXPOSEES

BRANCHER A UNE TERRE CONNUE

AVIS POUR LA SECURITE

De nombreuses pièces, électriques et mécaniques, dans les téléviseur ACL présentent des caractéristiques spéciales relatives à la sécurité, qui 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 pièces électriques qui présentent ces particularités sont identifiées par la marque " " et hachurées dans la liste des pièces de remplacement et les diagrammes schématiques.

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, radiations X ou autres accidents.

iii

LC-C3742U

PRECAUTIONS FOR USING LEAD-FREE SOLDER

Employing lead-free solder

• “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:

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

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.

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

PARTS CODE

ZHNDAi123250E BL J φ0.3mm 250g (1roll) ZHNDAi126500E BK J φ0.6mm 500g (1roll) ZHNDAi12801KE BM J φ1.0mm 1kg (1roll)

PRICE RANK

PART

DELIVERY

DESCRIPTION

LC-C3742U

PRECAUTIONS IN SERVICING THE HDCP-KEY ROM

Applied part: HDCP-KEY ROM

IC8451 RH-IXB979WJQZY (updated ROM)

The HDCP-KEY ROM shall be protected and managed for its information inside. In servicing this ROM, therefore, take the following information protection/management measures.

1) When disposing of the component parts and PWBs, destruct the IC itself in a proper way.

(For repairing or replacing the component parts and PWBs as well as clearing those in stock)

2) In storing the component parts, protect and manage them against theft and disclosure.

(For storing the service parts, service units, etc.)

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