JVC TH-A85 Service Manual

SERVICE MANUAL

DVD DIGITAL CINEMA SYSTEM

MB04020039

TH-A85

Area suffix

B ------------------------------- U.K. E ----------- Continental Europe EN ------------ Northern Europe

TABLE OF CONTENTS

1 PRECAUTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3

2 SPECIFIC SERVICE INSTRUCTIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-7

3 DISASSEMBLY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-8

4 ADJUSTMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-25

5 TROUBLESHOOTING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-26

No.MB040

2003/11

SPECIFICATION

Center Unit

Audio Audio Input Sensitivity/Impedance (1 kHz), Total Harmonic Distortion 0.01%

Analog input AUX IN 360 mV/47 kΩ Digital input* Optical -21 dBm to -15 dBm (660 nm ±30 nm) * Corresponding to Linear PCM, Dolby Digital, and DTS Digital Surround (with sampling frequency - 32 kHz, 44.1 kHz, 48 kHz).

Video Color System PAL

Horizontal Resolution 500 lines Signal-to-Noise Ratio 64 dB(Composite signal when "RGB" is selected) Video Output Level Composite video 1 V(p-p)/75 Ω

S-video (Y: luminance) : 1 V(p-p)/75 Ω

(C: chrominance, burst) : 0.286 V(p-p)/75 Ω

Tuner Tuning Range FM 87.5 MHz to 108.0 MHz

AM(MW) 552 kHz to 1629 kHz

General Power Requirements AC 230 over, 50 Hz

Power Consumption 20 W (at operation) 2.5 W (in standby mode) Dimensions (W × H × D) 398 mm × 70 mm × 265 mm Mass 2.7 kg

Subwoofer

Amplifier Front/Center/Surround 80 W per channel, RMS at 6 Ω at 1kHz, with 10% total harmonic distortion.

Subwoofer 100 W, RMS at 4 Ω at 100Hz, with 10% total harmonic distortion.

General Power Requirements AC 230 over, 50 Hz

Power Consumption 150 W (at operation) 0 W (in standby mode) Dimensions (W × H × D) 235 mm × 335 mm × 492 mm Mass 13.0 kg

Sparker

Satellite Power Handing Capacity 80W

Impedance 6 Ω Dimensions (W × H × D) 250 mm × 1103 mm × 250 mm Mass 3.77 kg

Center Power Handing Capacity 80W

Impedance 6 Ω Dimensions (W × H × D) 258 mm × 75 mm × 81 mm Mass 0.95 kg

Designs & Specifications are subject to change without notice.

1-2 (No.MB040)

SECTION 1

PRECAUTION

1.1 Safety Precautions

(1) This design of th is product contains special hardw are 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 manufacturer. Replacement parts must be identical to those used in the original circuits. Services should be performed 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 characteristics are often not evident from visual inspection nor can the protection afforded by them necessarily be obtained by using replacement components rated for higher voltage, wattage, etc. Replacement parts which have these special safety characteristics are identified in the Parts List of Service Manual. Electrical components having such features are identified by shading on the schematics and by ( ) on the Parts List in the Service Manual. The use of a substitute replacement which does not have the same safety characteristics as the recommended replacement parts shown in the Parts List of Service Manual may create shock, fire, or other 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, particularly any exposed metal part having a return path to the chassis, to a known good earth ground. Any leakage current 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, 1,000Ω per volt or more sensitivity in the following manner. Connect a 1,500Ω 10W resistor paralleled by a 0.15µF 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.).

AC VOLTMETER (Having 1000 ohms/volts, or more sensitivity)

0.15 F AC TYPE

Place this probe on

Good earth ground

1.2 Warning

(1) This equipment has been designed and manufactured to

meet international safety standards.

(2) It is the legal resp onsibility 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 compone nts 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 preforming 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. (This regulation dose not Except the J and C version)

each exposed metal part.

(No.MB040)1-3

1.5 Safety Precautions (U.K only)

(1) This design of this product contains special hardware and many circuits and components specially for safety purposes. For con-

tinued protection, no changes should be made to the original design unless authorized in writing by the manufacturer. Replacement parts must be identical to those used in the original circuits.

(2) Any unauthorised design alterations or additions will void the manufacturer's guara ntee; furthermore the manu facturer cannot

accept responsibility for personal injury or property damage resulting therefrom.

(3) Essential safety critical components are identified by ( ) on the Parts List and by shading on the schematics, and must never

be replaced by parts other than those listed in the man ual. Please note however that many el ectrical and mechanical parts in the product have special safety related characteristics. These characteristics are often not evident from visual inspection. Parts other than specified by the manufacturer may not have the same safety characteristics as the recommended replacement parts shown in the Parts List of the Service Manual and may create shock, fire, or other 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 sh ock and fire ha zard. When se rvice is required, the original lead routing and dress should be observed, and it should be confi rmed that they have been returned to normal, after re-assembling.

1.5.1 W arning

(1) Service should be performed by qualified personnel only. (2) This equipment has been designed and manufactured to meet international safety standards. (3) It is the legal responsibility of the repairer to ensure that these safety standards are maintained. (4) Repairs must be made in accordance with the relevant safety standards. (5) It is essential that safety critical components are replaced by approved parts. (6) If mains voltage selector is provided, check setting for local voltage.

Burrs formed during molding may be left over on some parts of the chassis. Therefore, pay attention to such burrs in the case of preforming repair of this system.

1-4 (No.MB040)

1.6 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.

1.6.1 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 conducti ve 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.

(caption) Anti-static wrist strap

Conductive material (conductive sheet) or iron palate

(3) Handling the optical pickup

• In order to maintain quality during transport and before insta llation, both sides of the lase r diode on the replacement o ptical 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.

1.7 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

replacement 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.

1.8 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.

Flexible wire

Short land sections

DVD servo board

DVD mechanism assembly

CN101

(No.MB040)1-5

1.9 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.

Please use enough caution not to see the beam directly or touch it in case of an adjustment or operation check.

REPRODUCTION AND POSITION OF LABEL and PRINT

WARNING LABEL and PRINT

CLASS 1 LASER PRODUCT

CAUTION LABEL

1-6 (No.MB040)

SECTION 2

SPECIFIC SERVICE INSTRUCTIONS

This service manual does not describe SPECIFIC SERVICE INSTRUCTIONS.

(No.MB040)1-7

SECTION 3

DISASSEMBLY

3.1 Main body section

3.1.1 R emoving the top plate (See Fig.1)

(1) From the top side of the main body, remove the four screws

A attaching the top plate.

(2) Remove the top plate from main body.

3.1.2 Removing the rear cover (See Figs.2 and 3)

• Prior to performing the following procedures, remove the top

plate. (1) From the rear side of the main body, remove the three

screws B attaching the rear cover. (See Fig.2)

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

C and two screws D attaching the rear cover. (See Fig.3)

(3) Remove the rear cover upward.

Top plate

Fig.1

Rear cover

3.1.3 Removing the rear panel (See Fig.4)

• Prior to performing the following procedures, remove the top

plate and rear cover. (1) From the rear side of the main body, remove the nine

screws E and screw F attaching the rear panel.

(2) Remove the rear panel from main body.

Fig.2

Rear cover

Fig.3

1-8 (No.MB040)

Rear panel

Fig.4

3.1.4 Removing the front panel assembly

(See Figs.5 and 6)

• Prior to performing the following procedures, remove th e top

plate. (1) From the top side of the head phone board, remove the

three screws G attaching the front panel assembly. (See Fig.5)

(2) Disconnect the card wires from the connectors CN408

on the main board. (See Fig.5)

CN412

(3) Extend the side of the front panel assembly in the direction

of the arrows a. (See Fig.5)

(4) Remove the front panel assembly in the direction of the ar-

rows c, while releasing the claw b. (See Fig.6)

and

Main board

Fig.5

Front panel assembly

CN412

CN408

Head phone board

Front panel assembly

3.1.5 Removing the DVD mechanism assembly

(See Figs.7 and 8)

• Prior to performing the following procedures, remove th e top

plate and rear cover. (1) From the top side of the main body, remove the two screws

H and screw J on the DVD mechanism assembly. (See Fig.7)

(2) Disconnect the connectors CN502

servo board from the connectors CN405 main board while lifting the DVD mechanism assembly upward. (See Fig.8)

(3) Take out the DVD mechanism assembly from the main

board.

and CN503 on the DVD

and CN406 on the

DVD servo board

CN502

claw

Fig.6

Fig.7

DVD mechanism assembly

CN503

CN406

Fig.8

CN405

Main board

(No.MB040)1-9

+ 19 hidden pages