JVC THA75 - Service Manual Immediate Download

SERVICE MANUAL

No.22014

2003/02

TH-A75

DVD DIGITAL CINEMA SYSTEM

22014

2003

TH-A75

TABLE OF CONTENTS

Important Safety Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2

Disassembly method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5

Adjustment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-15

Description of major ICs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-16

STANDBY

COMPACT

SUPER VIDEO

DIGITAL¥EX

PRO LOGIC

PROGRESSIVE

PHONES

SOURCE

VOLUME

RMÐSTHA75U

DVD CINEMA SYSTEM

CHANNEL/ZOOM

VOLUME

TV VOL

TUNING

STOP

DIMMER

PAUSE

FF/

/REW

TV/VIDEO

MUTING

REC

PLAY

DOWN

MEMORY

STROBE

DVD

VCR 1

AUDIO

VCR/DBS

ANGLE

FM/AM

SUBTITLE

DECODE

RETURN

DIGEST

VFP

TOP MENU

CONTROL

EFFECT

S.WFR

TEST

SLEEP

VCR

SETTING

TV RETURN

ENTER

SCREEN

CHOICE

FM MODE

+10

100+

AUDIO

VCR

SOUND

AUDIO/

TV/VCR

CATV/DBS

PROGRESSIVE

SURROUND

OFF

DSP

CENTER

SURR-L

SURR-R

S-BACK

ADJUST

O.T.

REPLAY

XV-THA75

SP-XSA75

SP-WA75

SP-XCA75

Area Suffix

A ------------------------ Australia

TH-A75

1-2 (No.22014)

SECTION 1

Important Safety Precautions

1.1 Safety Precautions

(1) This design of this product contains special hardware and

many circuits and components specially for safety purposes.

For continued protection, no changes should be made to the

original design unless authorized in writing by the man-

ufacturer. Replacement parts must be identical to those

used in the original circuits. Services should be per-

formed by qualified personnel only.

(2) Alterations of the design or circuitry of the product should

not be made. Any design alterations of the product should

not be made. Any design alterations or additions will void

the manufacturers warranty and will further relieve the

manufacture of responsibility for personal injury or property

damage resulting therefrom.

(3) Many electrical and mechanical parts in the products have

special safety-related characteristics. These characteris-

tics are often not evident from visual inspection nor can the

protection afforded by them necessarily be obtained by us-

ing replacement components rated for higher voltage, watt-

age, etc. Replacement parts which have these special safety

characteristics are identified in the Parts List of Service Manu-

al. Electrical components having such features are iden-

tified by shading on the schematics and by ( ) on the

Parts List in the Service Manual. The use of a substitute re-

placement which does not have the same safety character-

istics as the recommended replacement parts shown in the

Parts List of Service Manual may create shock, fire, or oth-

er hazards.

(4) The leads in the products are routed and dressed with ties,

clamps, tubings, barriers and the like to be separated from

live parts, high temperature parts, moving parts and/or

sharp edges for the prevention of electric shock and fire

hazard. When service is required, the original lead routing

and dress should be observed, and it should be confirmed

that they have been returned to normal, after reassembling.

(5) Leakage shock hazard testing)

After reassembling the product, always perform an isolation

check on the exposed metal parts of the product (antenna

terminals, knobs, metal cabinet, screw heads, headphone

jack, control shafts, etc.) to be sure the product is safe to

operate without danger of electrical shock.

Do not use a line isolation transformer during this check.

· Plug the AC line cord directly into the AC outlet. Using a

"Leakage Current Tester", measure the leakage current

from each exposed metal parts of the cabinet, particular-

ly any exposed metal part having a return path to the

chassis, to a known good earth ground. Any leakage cur-

rent must not exceed 0.5mA AC (r.m.s.).

· Alternate check method

Plug the AC line cord directly into the AC outlet. Use an AC

voltmeter having, 1,000 ohms per volt or more sensitivity in

the following manner. Connect a 1,500 ohm 10W resistor

paralleled by a 0.15 µF AC-type capacitor between an

exposed metal part and a known good earth ground.

Measure the AC voltage across the resistor with the AC

voltmeter.

Move the resistor connection to each exposed metal part,

particularly any exposed metal part having a return path to

the chassis, and measure the AC voltage across the resistor.

Now, reverse the plug in the AC outlet and repeat each

measurement. Voltage measured any must not exceed 0.75

V AC (r.m.s.). This corresponds to 0.5 mA AC (r.m.s.).

1.2 Warning

(1) This equipment has been designed and manufactured to

meet international safety standards.

(2) It is the legal responsibility of the repairer to ensure that

these safety standards are maintained.

(3) Repairs must be made in accordance with the relevant

safety standards.

(4) It is essential that safety critical components are replaced

by approved parts.

(5) If mains voltage selector is provided, check setting for local

voltage.

1.3 Caution

Burrs formed during molding may be left over on some parts

of the chassis.

Therefore, pay attention to such burrs in the case of pre-

forming repair of this system.

1.4 Critical parts for safety

In regard with component parts appearing on the silk-screen

printed side (parts side) of the PWB diagrams, the parts that are

printed over with black such as the resistor (

), diode (

)

and ICP (

) or identified by the "

" mark nearby are critical

for safety.

When replacing them, be sure to use the parts of the same type

and rating as specified by the manufacturer. (Except the JC version)

TH-A75

(No.22014)1-3

1.5 Preventing static electricity

Electrostatic discharge (ESD), which occurs when static electricity stored in the body, fabric, etc. is discharged,

can destroy the laser diode in the traverse unit (optical pickup). Take care to prevent this when performing repairs.

1.5.1

Grounding to prevent damage by static electricity

Static electricity in the work area can destroy the optical pickup (laser diode) in devices such as DVD players.

Be careful to use proper grounding in the area where repairs are being performed.

(1) Ground the workbench

Ground the workbench by laying conductive material (such as a conductive sheet) or an iron plate over it before placing the

traverse unit (optical pickup) on it.

(2) Ground yourself

Use an anti-static wrist strap to release any static electricity built up in your body.

(3) Handling the optical pickup

· In order to maintain quality during transport and before installation, both sides of the laser diode on the replacement optical

pickup are shorted. After replacement, return the shorted parts to their original condition.

(Refer to the text.)

· Do not use a tester to check the condition of the laser diode in the optical pickup. The tester's internal power source can easily

destroy the laser diode.

1.6 Handling the traverse unit (optical pickup)

(1) Do not subject the traverse unit (optical pickup) to strong shocks, as it is a sensitive, complex unit.

(2) Cut off the shorted part of the flexible cable using nippers, etc. after replacing the optical pickup. For specific details, refer to the replace-

ment procedure in the text. Remove the anti-static pin when replacing the traverse unit. Be careful not to take too long a time

when attaching it to the connector.

(3) Handle the flexible cable carefully as it may break when subjected to strong force.

(4) I t is not possible to adjust the semi-fixed resistor that adjusts the laser power. Do not turn it.

1.7 Attention when traverse unit is decomposed

*Please refer to "Disassembly method" in the text for the DVD pickup unit.

· Apply solder to the short land sections before the flexible wire is disconnected from the connector CN101 on the DVD servo board.

(If the flexible wire is disconnected without applying solder, the DVD pickup may be destroyed by static electricity.)

· In the assembly, be sure to remove solder from the short land sections after connecting the flexible wire.

DVD mechanism assembly

CN101

DVD servo board

Short land sections

Flexible wire

TH-A75

1-4 (No.22014)

1.8 Important for laser products

(1) CLASS 1 LASER PRODUCT

(2) DANGER : Invisible laser radiation when open and inter

lock failed or defeated. Avoid direct exposure to beam.

(3) CAUTION : There are no serviceable parts inside the

Laser Unit. Do not disassemble the Laser Unit. Replace the

complete Laser Unit if it malfunctions.

(4) CAUTION : The compact disc player uses invisible laser

radiation and is equipped with safety switches which

prevent emission of radiation when the drawer is open and

the safety interlocks have failed or are de feated.

It is dangerous to defeat the safety switches.

(5) CAUTION : If safety switches malfunction, the laser is able

to function.

(6) CAUTION : Use of controls, adjustments or performance of

procedures other than those specified herein may result in

hazardous radiation exposure.

CAUTION

Please use enough caution not to see the beam directly

or touch it in case of anadjustment or operation check.

VARNING

Osynlig laserstrålning är denna del är öppnad och spårren är

urkopplad. Betrakta ej strålen.

VARO

Avattaessa ja suojalukitus ohitettaessa olet alttiina näkymät-

tömälle lasersäteilylle. Älä katso säteeseen.

ADVARSEL

Usynlig laserstråling ved åbning, når sikkerhedsafbrydere er

ude af funktion. Undgå udsasttelse for stråling.

ADVARSEL

Usynlig laserstråling ved åpning, når sikkerhetsbryteren er avs-

lott. unngå utsettelse for stråling.

REPRODUCTION AND POSITION OF LABELS

WARNING LABEL

CLASS 1

LASER PRODUCT

TH-A75

(No.22014)1-5

SECTION 2

Disassembly method

2.1 Main body section

2.1.1 Removing the top cover (See Figs.1 to 4)

(1) From the right and left sides of the main body, remove the

four screws A attaching the top cover. (See Figs.1 and 2)

(2) From the back side of the main body, remove the two

screws B attaching the top cover. (See Fig.3)

(3) Lift the rear section of the top cover, slide the top cover

slightly in the direction of the arrow. (See Fig.4)

(4) Disengage the engagement sections a of the top cover

from the main body. (See Fig.4)

Fig.1

Fig.2

Fig.3

Fig.4

Top cover

Rear panel

Top cover