JVC AV-25L81(-BK), AV-29L81(-BK) Service Manual

SERVICE MANUAL

COLOUR TELEVISION

AV-25L81 AV-29L81

BASIC CHASSIS

AV-25L81 AV-29L81

POWER

DISPLAY

CHANNEL VOLUME

SYSTEM

COLOUR

SOUND MUTING

TV/VIDEO

123

I/II

456

PICTURE MODE

7809

RETURN

CHANNEL SCAN

-/--

OFF TIMER

ECO SENSOR

RM-C359 REMOTE CONTROL UNIT

RM-C359-1C

(-BK)

CONTENTS

a SPECIFICATIONS ....................................................................................................................................2

a SAFETY PRECAUTIONS ........................................................................................................................3

a FEATURES ..............................................................................................................................................4

a FUNCTIONS .............................................................................................................................................5

a SPECIFIC SERVICE INSTRUCTIONS ....................................................................................................6

¤ OPERATING INSTRUCTIONS (APPENDIX) ....................................................................................... 1-1

a SERVICE ADJUSTMENTS ....................................................................................................................16

¤ STANDARD CIRCUIT DIAGRAM (APPENDIX) .................................................................................. 2-1

a PARTS LIST ...........................................................................................................................................43

No. 51840 Sep. 2001

AV-25L81 AV-29L81

SPECIFICATIONS

Items

Dimensions (W × H × D) 68.2cm × 53.84cm × 47.75cm 73.2cm × 58.8cm × 51.8cm

Mass 30kg 47kg

TV RF System B, G, I, D, K

Colour System TV Mode PAL / SECAM

VIDEO Mode PAL / SECAM / NTSC3.58 / NTSC4.43

Stereo System A2 Bilingual

Receiving Frequency VHF (VL) 43.75MHz – 142.25MHz (AU0 – S6)

VHF (VH) 142.28MHz – 428.75MHz (S7 – S36)

UHF 428.78MHz – 865.75MHz (S37 – CHINA 57)

CATV

Intermediate VIF Carrier 38.0MHz

Frequency 31.5MHz (6.5MHz)

SIF Carrier 32.0MHz (6.0MHz)

Colour Sub Carrier Frequency PAL (4.43MHz), SECAM (4.40625MHz / 4.25MHz)

Aerial Input Terminal 75Ø Unbalanced

Power Input AC110 – 240V, 50 / 60Hz

Power Consumption 150W

Picture Tube Visible size : 60cm measured diagonally Visible size : 68cm measured diagonally

High Voltage 31kV ± 1kV (at cut-off in service mode) 32kV +1/–1.5kV (at cut-off in service mode)

Speaker 5 × 12cm Oval type ×2

Audio Output 5W ×2 7W ×2

Video / Audio Input (1 / 2 / 3) Video(1,3) : 1Vp-p, 75Ø (RCA pin jack)

Cable TVs of Mid (X-Z, S1-S10)

•

Super (S11-S20) & Hyper (S21-S41) bands receivable

32.5MHz (5.5MHz)

NTSC (3.58MHz / 4.43MHz)

(Max.)

Audio(1,2,3) : 500mVrms ( -4dBs ), High Impedance (RCA pin jack)

Component Input ( Input 2 )

Y : 1Vp-p positive (negative sync provided, when terminated with 75Ø)

CB/CR : 0.7Vp-p 75Ø

AV-25L81-BK AV-29L81-BK

/ 90W

(Avg.)

Contents

172W (Max.) / 108W (Avg.)

Video/Audio Output 1Vp-p, 75Ø (RCA pin jack)

500mVrms(-4dBs)

Low impedance (400Hz when modulated 100%) (RCA pin jack)

Headphone Jack Stereo mini jack (3.5φ)

Remote Control Unit RM-C359-1C

(Battery size: AA/R06/UM-3 × 2)

Design & specifications are subject to change without notice.

2 No. 51840

SAFETY PRECAUTIONS

AC VOLTMETER (HAVING 1000Ω/V, OR MORE SENSITIVITY)

PLACE THIS PROBE ON EACH EXPOSED ME TAL PAR T

1500Ω 10W

0.15µF AC-TYPE

GOOD EARTH GROUND

1. The design of this product contains special hardware, 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. Service should be performed by qualified personnel only.

2. Alterations of the design or circuitry of the products should not be made. Any design alterations or additions will void the manufacturer's warranty and will further relieve the manufacturer 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 Service manual. The use of a substitute replacement which

does not have the same safety characteristics as the recommended replacement part shown in the parts list of Service manual may cause shock, fire, or other hazards.

4. Don't short between the LIVE side ground and ISOLATED (NEU-

TRAL) side ground or EARTH side ground when repairing.

Some model's power circuit is partly different in the GND. The difference of the GND is shown by the LIVE : ( ) side GND, the ISOLATED (NEUTRAL) : ( ) side GND and EARTH : ( ) side GND. Don't short between the LIVE side GND and ISOLATED (NEUTRAL) side GND or EARTH side GND and never measure with a measuring apparatus (oscilloscope etc.) the LIVE side GND and ISOLATED (NEUTRAL) side GND or EARTH side GND at the same time. If above note will not be kept, a fuse or any parts will be broken.

5. If any repair has been made to the chassis, it is recommended that the B1 setting should be checked or adjusted (See ADJUSTMENT OF B1 POWER SUPPLY).

6. The high voltage applied to the picture tube must conform with that specified in Service manual. Excessive high voltage can cause an increase in X-Ray emission, arcing and possible component damage, therefore operation under excessive high voltage conditions should be kept to a minimum, or should be prevented. If severe arcing occurs, remove the AC power immediately and determine the cause by visual inspection (incorrect installation, cracked or melted high voltage harness, poor soldering, etc.). To maintain the proper minimum level of soft X-Ray emission, components in the high voltage circuitry including the picture tube must be the exact replacements or alternatives approved by the manufacturer of the complete product.

AV-25L81 AV-29L81

8. When service is required, observe the original lead dress. Extra precaution should be given to assure correct lead dress in the high voltage circuit area. Where a short circuit has occurred, those components that indicate evidence of overheating should be replaced. Always use the manufacturer's replacement components.

9. Isolation Check

(Safety for Electrical Shock Hazard)

After re-assembling the product, always perform an isolation check on the exposed metal parts of the cabinet (antenna terminals, video/ audio input and output terminals, Control knobs, metal cabinet, screw heads, earphone jack, control shafts, etc.) to be sure the product is safe to operate without danger of electrical shock.

(1) Dielectric Strength Test

The isolation between the AC primary circuit and all metal parts exposed to the user, particularly any exposed metal part having a return path to the chassis should withstand a voltage of 3000V AC (r.m.s.) for a period of one second.

(. . . . Withstand a voltage of 1100V AC (r.m.s.) to an appliance rated

up to 120V, and 3000V AC (r.m.s.) to an appliance rated 200V or more, for a period of one second.) This method of test requires a test equipment not generally found in the service trade.

(2) Leakage Current Check

Plug the AC line cord directly into the AC outlet (do not use a line isolation transformer during this check.). Using a "Leakage Current Tester", measure the leakage current from each exposed metal part of the cabinet, particularly any exposed metal part having a return path to the chassis, to a known good earth ground (water pipe, etc.). Any leakage current must not exceed 0.5mA AC (r.m.s.). However, in tropical area, this must not exceed 0.2mA AC (r.m.s.).

● Alternate Check Method

Plug the AC line cord directly into the AC outlet (do not use a line isolation transformer during this check.). Use an AC voltmeter having 1000 ohms per volt or more sensitivity in the following manner. Connect a 1500Ø 10W resistor paralleled by a 0.15µF AC-type capacitor between an exposed metal part and a known good earth ground (water pipe, etc.). 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. Any voltage measured must not exceed 0.75V AC (r.m.s.). This corresponds to 0.5mA AC (r.m.s.). However, in tropical area, this must not exceed 0.3V AC (r.m.s.). This corresponds to 0.2mA AC (r.m.s.).

7. Do not check high voltage by drawing an arc. Use a high voltage meter or a high voltage probe with a VTVM. Discharge the picture tube before attempting meter connection, by connecting a clip lead to the ground frame and connecting the other end of the lead through a 10kØ 2W resistor to the anode button.

No. 51840 3

AV-25L81 AV-29L81

FEATURES

s New chassis design enables use of an interactive on-screen control. s Pure flat CRT produces fine textured picture in every detail. s Wide range voltage (110V ~ 240V) for AC power input. s With AUDIO/VIDEO/COMPONENT input terminals. s I 2 C bus control utilizes single chip ICs. s By means of AUTO PROGRAM, the TV stations can be selected

automatically and the TV channels can also be rearranged automatically.

s Built-in DIGITAL ECO MODE (ECONOMY, ECOLOGY).

In accordance with the brightness in a room, the brightness and/or contrast of the picture can be adjusted automatically to make the optimum picture which is easy on the eye.

s Built-in ON TIMER & RETURN +.

4 No. 51840

FUNCTIONS

a FRONT PANEL

[AV-25L81-BK]

a FRONT PANEL

[AV-29L81-BK]

L/MONOVR

IN (VIDEO-3)

AV-25L81 AV-29L81

a REAR PANEL

VIDEO-1

INPUT

MONO

COMPONENT

(

VIDEO-2

INPUT

RRC

)

MONO

OUTPUT

a REMOTE CONTROL UNIT

RM-C359-1C

DISPLAY

CHANNEL VOLUME

SYSTEM

SOUND MUTING

COLOUR

TV/VIDEO

I/II

PICTURE MODE

CHANNEL SCAN

RETURN

ECO SENSOR

RM-C359 REMOTE CONTROL UNIT

POWER

123

456

7809

-/--

OFF TIMER

No. 51840 5

AV-25L81

SPECIFIC SERVICE INSTRUCTIONS

DISASSEMBLY PROCEDURE [AV-25L81-BK]

REMOVING THE REAR COVER

1. Unplug the AC power cord.

2. Remove the 9 screws marked Å and 4 screws maked ı as shown in Fig.1.

3. Withdraw the Rear cover toward you.

[CAUTION]

When reinstalling the rear cover, carefully push it inward after in-

•

serting the Main PWB into the rear cover groove.

REMOVING THE MAIN PW BOARD

After removing the rear cover.

•

1. Slightly raise the both sides of the Main PWB by hand, take off the PB stopper marked

2. Withdraw the Main PWB backward. (If necessary, take off the wire clamp and connectors, etc.)

from the front cabinet.

REMOVING THE SPEAKER

After removing the rear cover.

•

1. Remove the 2 screws marked Î and 2 screws maked ´ as shown in Fig.1.

2. Follow the same steps when removing the other hand speaker.

CHECKING THE MAIN PW BOARD

1. To check the back side of the Main PWB.

1) Pull out the Main PWB. (Refer to REMOVING THE MAIN PW

BOARD).

2) Erect the Main PWB vertically so that you can easily check its

back side.

[CAUTION]

Before turning on power, make sure that the CRT earth wire and

•

other connectors are properly connected. When repairing, connect the Deg. coil to the DEG. connector on the

•

Main PWB.

WIRE CLAMPING AND CABLE TYING

1. Be sure to clamp the wire.

2. Never remove the cable tie used for tying the wires together. Should it be inadvertently removed, be sure to tie the wires with a new cable tie.

6 No. 51840

FRONT CABINET

PICTURE TUBE

(×2)

SPEAKER

CRT SOCKET PWB

MAIN PWB

AV-25L81

(×2)

SPEAKER

(×2)

REAR COVER

PB STOPPER

(×9)

(×4)

Fig.1

No. 51840 7

AV-29L81

DISASSEMBLY PROCEDURE [AV-29L81-BK]

REMOVING THE REAR COVER

1. Unplug the AC power cord.

2. Remove the 16 screws marked

3. Withdraw the Rear cover toward you.

[CAUTION]

When reinstalling the rear cover, carefully push it inward after in-

•

serting the Main PWB into the rear cover groove.

as shown in Fig.2.

REMOVING THE CHASSIS (CHASSIS BASE AND CONTROL BASE)

After removing the rear cover.

•

1. Slightly raise the both sides of the chassis by hand and remove the 2 claws marked in Fig.2.

2. Withdraw the chassis backward.

(If necessary, take off the wire clamp, connector’s etc.)

When conducting a check with power supplied, be sure to confirm

that the CRT earth wire is connected to the CRT Socket PWB and the Main PWB.

under the chassis from the front cabinet as shown

REMOVING THE AV TERMINAL BOARD

After removing the rear cover.

•

1. Remove the 4 screws marked Ç as shown in Fig.2.

2. When you pull out the AV Terminal board in the direction of arrow marked Î as shown in Fig.2, it can be removed.

CHECKING THE MAIN PW BOARD

1. To check the back side of the Main PWB.

1) Pull out the chassis. (Refer to REMOVING THE CHASSIS).

2) Erect the chassis vertically so that you can easily check the back side of the Main PWB.

[CAUTION]

When erecting the chassis, be careful so that there will be no con-

•

tacting with other PW Board. Before turning on power, make sure that the CRT earth wire and

•

other connectors are properly connected. When repairing, connect the Deg. coil to the DEG. connector on the

•

Main PWB.

WIRE CLAMPING AND CABLE TYING

1. Be sure to clamp the wire.

2. Never remove the cable tie used for tying the wires together. Should it be inadvertently removed, be sure to tie the wires with a new cable tie.

REMOVING THE CONTROL BASE

After removing the rear cover and the chassis.

•

1. While pushing down the 2 claws maked ´ as shown in Fig. 3.

2. When you pull out the Control base in the direction of arrow maked as shown in Fig. 3.

(If necessary, take off the wire, connector’s etc.)

REMOVING THE SPEAKER

After removing the rear cover.

•

1. Remove the 4 screws marked ˝ as shown in Fig.2.

2. Withdraw the speaker backward.

3. Follow the same steps when removing the other hand speaker.

8 No. 51840

AV-29L81

FRONT CABINET

FRONT CONTROL PWB (1/2)

(×4)

SPEAKER

CONTROL BASE

PICTURE TUBE

CRT SOCKET PWB

Fig.2

SPEAKER

(×4)

FRONT CONTROL PWB (2/2)

MAIN PWB

CLAW B

AV TERMINAL BOARD

REAR COVER

CHASSIS BASE

(×4)

CLAW B

(×1)

(×4)

(×6)

[FRONT SIDE]

CONTROL BASE

CHASSIS BASE

Fig.3

Fig.2

No. 51840 9

AV-25L81 AV-29L81

REMOVING THE CRT

* Replacement of the CRT should be performed by 2 or more persons.

After removing the rear cover, chassis etc.,

•

1. Putting the CRT change table on soft cloth, the CRT change table

should also be covered with such soft cloth (shown in Fig. 4).

2. While keeping the surface of CRT down, mount the TV set on the

CRT change table balanced will as shown in Fig. 5.

3. Remove 4 screws marked by arrows with a box type screwdriver as

shown in Fig. 5. Since the cabinet will drop when screws have been removed, be sure

•

to support the cabinet with hands.

4. After 4 screws have been removed, put the cabinet slowly on cloth

(At this time, be carefully so as not to damage the front surface of the cabinet) shown in Fig. 6. The CRT should be assembled according to the opposite sequence

•

of its dismounting steps.

* The CRT change table should preferably be smaller that the CRT sur-

face, and its height be about 35cm.

CRT CHANGE TABLE

CLOTH

CRT CHANGE TABLE

Fig. 4

CRT

APPROX. 35cm

BOX TYPE SCREW DRIVER

COATING OF SILICON GREASE FOR ELECTRICAL INSULATION ON THE CRT ANODE CAP SECTION.

Subsequent to replacement of the CRT and HV transformer or repair

•

of the anode cap, etc. by dismounting them, be sure to coat silicon grease for electrical insulation as shown in Fig. 7.

1. Wipe around the anode button with clean and dry cloth. (Fig. 7)

2. Coat silicon grease on the section around the anode button. At this

time, take care so that any silicon greases dose not sticks to the anode button. (Fig. 8)

夝 Silicon grease product No. KS - 650N

CRT

Anode button

CABINET

Approx. 20mm (Do not coat grease on this section

Fig. 5

CRT

CRT CHANGE TABLE

Fig. 6

Silicon grease should be coated by 5mm or more from the outside diameter of anode cap.

Silicon grease

coating

Fig. 7

10 No. 51840

Anode button (No sticking of silicon grease)

Coating position of silicon grease

Anode cap

Fig. 8

REPLACEMENT OF MEMORY IC

AV-25L81 AV-29L81

1. MEMORY IC

This TV uses the following memory IC.

Memory IC: IC1702 on MAIN PW Board

The memory IC memorizes data for correctly operating the video and deflection circuits. When replacing the memory IC, be sure to use the same type IC written with the initial values of data. In other words, use the specific IC listed in “PRINTED WIRING BOARD PARTS LIST”. For its mounting location, refer to “ADJUSTMENT LOCATIONS”.

2. PROCEDURE FOR REPLACING MEMORY IC

(1) Power off

Switch the power off and unplug the power cord from the wall outlet.

(2) Replacing the memory IC

Replace the memory IC with new one. Be sure to use the memory IC written with the initial data values.

(3) Power on

Plug the power cord into the wall outlet and switch the power on.

(4) Check and setting of SYSTEM CONSTANT SET:

1) Press the DISPLAY key and the PICTURE MODE key on the remote control unit simultaneously. The SERVICE MENU screen will be displayed.(See Fig.1.)

2) In the SERVICE MENU, press the DISPLAY key and PICTURE MODE key simultaneously. Then, the SYSTEM CONSTANT SET screen will be displayed.(See Fig.2.)

3) Check whether the setting values of the SYSTEM CONSTANT SET are the same as those indicated in Table1. If the value is different, select the setting item with the MENU &/^ key, and set the correct value with the MENU –/+key.

4) Press the DISPLAY key twice to return to the normal screen.

(5) Receive channel setting

Refer to the OPERATING INSTRUCTIONS and set the receive channels (channels preset).

(6) User setting

Check the user setting values in Table 2, and if setting value is different, set the correct value. For setting, refer to the OPERATING INSTRUCTIONS.

(7) Setting of SERVICE MENU

Verify the setting for each setting item in the SERVICE MENU.(See Table 3.) If readjustment is necessary, perform adjustment referring to “SERVICE ADJUSTMENTS”.

SERVICE MENU

1. IF

3. DEF

5. PRESET PLUG & PLAY (OFF)

1-6 : SELECT DISPLAY : EXIT

2. VC

4. VSM PRESET

******* **** ***** ***** **** **** *** ***

Fig. 1

SYSTEM CONSTANT-

SYSTEM CONSTANT SET 1

SYSTEM COMB TILT TEXT SUPER BASS LANGUAGE

89 : SEL

+ : OPE DISP : EXIT

MULTI NO NO YES NO E / R / C

NAME OF REMOTE CONTROL KEYS

DISPLAY

PICTURE MODE

DISPLAY

CHANNEL VOLUME

SYSTEM

SOUND MUTING

COLOUR

TV/VIDEO

PICTURE MODE

CHANNEL SCAN

123

I/II

456

7809

RETURN

ECO SENSOR

POWER

OFF TIMER

SYSTEM CONSTANT-

SYSTEM CONSTANT SET 2

MSP

BILINGUAL B / B SOUND TUNER COLOUR AUTO

89 : SEL

+ : OPE DISP : EXIT

SYSTEM CONSTANT-

SYSTEM CONSTANT SET 3

-/--

LOCK 1 MHz

156.25 kHz

31.25 kHz

89 : SEL

500 kHz 250 kHz

+ : OPE DISP : EXIT

ΙΙ

NO NO NO MU NO

ΙΙΙ

020 020 020 015 015

Fig. 2

No. 51840 11

AV-25L81 AV-29L81

SETTING OF SYSTEM CONSTANT SET

Setting item Setting content

SYSTEM

COMB

TILT

TEXT

SUPPER BASS

LANGUAGE

MSP

BILINGUAL

B/B SOUND

TUNER

COLOUR AUTO

EASTERN UKRANIAN RUSSIAN

NO PAN EURO ARABK

MULTI TRIPLE

VIET PAL

E/T E/V E

YES NO

MU MA

YES NO

Setting value

AV-25L81-BK AV-29L81-BK

TRIPLE

E/T

YES

LOCK 1MHz

500KHz

250KHz

156.25KHz

31.25KHz

000 024

020

015

Table 1

12 No. 51840

USER SETTING VALUES

Setting item Setting value

SUB POWER ON

CHANNEL POSITION 1 POSITION

CHANNEL PRESET REFER TO OPERATING INSTRUCTIONS

VOLUME

TV/VIDEO TV

VNR OFF

COMPRESS (16:9) OFF

AUTO SHUTOFF OFF

CHILD LOCK OFF

BLUE BACK ON

VIDEO-2 SET VIDEO

LANGUAGE THAI

MONO SURROUND OFF

AI VOLUME ON

ON SCREEN DISPLAY POSITION INDICATION

COLOUR SYSTEM PAL

SOUND SYSTEM B/G

PICTURE MODE-VSM BRIGHT

OFF TIMER 00

ECO SENSOR OFF

BILINGUAL MODE Ι (Ι/ΙΙ)

BASS CENTRE

TREBLE CENTRE

BALANCE CENTRE

PICTURE TILT 00 [AV-29L81-BK]

15 ± 2 [AV-25L81-BK]

10 ± 2 [AV-29L81-BK]

AV-25L81 AV-29L81

Table 2

No. 51840 13

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