JVC LT-17AX5 Service Manual

YA351200511

SERVICE MANUAL

LCD FLAT TELEVISION

LT-17AX5, LT-17AX5/S, LT-17AX5/A, LT-23AX5, LT-23AX5

/S, LT-23AX5/A

TABLE OF CONTENTS

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

2 SPECIFIC SERVICE INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5

3 DISASSEMBLY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6

4 ADJUSTMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-21

5 TROUBLESHOOTING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-22

No.YA351

2005/11

SPECIFICATION

Item Contents

LT-17AX5 LT-23AX5

Dimensions (W × H × D) 54.1cm × 41.6cm × 9.2cm (TV only)

54.1cm × 47.7cm × 12.6cm (Included Stand)

Mass 9.0kg (TV only)

10.2kg (Included Stand)

TV RF System CCIR B/G, I, D/K, L

Color System PAL / SECAM / NTSC3.58 / NTSC4.43

Sound System A2 (B/G, D/K), NICAM (B/G, I, D/K), NTSC-M

Teletext System FLOF (Fastext), WST (World Standard System)

TV Receiving Channels

Power Input TV

Power Consumption 60W (Stand-by : 1W) 120W (Stand-by : 1W)

LCD Panel 17V wide aspect (15 : 9) 23V wide aspect (15 : 9)

Screen Size Diagonal : 43.4cm (H : 37.3cm × V : 22.4cm) Diagonal : 58.5cm (H : 50.2cm × V : 30.1cm)

Display Pixels Horizontal : 1280 pixels x Vertical : 768 pixels (W-XGA)

Audio Power Output 3W + 3W 5W + 5W

Speaker 5.4cm round type × 2 Antenna Terminal 75Ω unbalanced, coaxial

Video/Audio Input [VIDEO-1]

PC(VGA)Input VGA Input

Headphone 3.5mm mini jack × 1 Remote Control Unit RM-C1860 (AA/R6/UM-3 battery × 2)

AC Adapter DA-E061370334 DA-E056706411

VHF Low

VHF High

UHF

CATV

AC Adapter

S-Video

Video Audio

[VIDEO-2]

Component

Video

Audio

48.25MHz ~ 158MHz 160MHz ~ 442MHz 442MHz ~ 863.25MHz Mid : X ~ Z+2, S1 ~ S10 Super : S11 ~ S20 Hyper : S21 ~ S41

DC 12V AC 110V ~ AC 240V, 50Hz / 60Hz

Mini-DIN 4pin × 1 Y : 1V(p-p), positive (negative sync), 75Ω C : 0.286V(p-p), (Burst signal), 75Ω 1V(p-p), positive (negative sync), 75Ω, RCA pin jack × 1 500mV(rms), high inpedance, RCA pin jack × 2

RCA pin jack × 3 Y : 1V(p-p), positive (negative sync), 75Ω Pb/Pr : 0.7V(p-p), 75Ω 500mV(rms), high inpedance, RCA pin jack × 2

D-sub 15pin × 1

3.5mm mini jack

DC 24V AC 110V ~ AC 240V, 50Hz / 60Hz

NOTE : Design & specifications are subject to change without notice.

1-2 (No.YA351)

SECTION 1

PRECAUTION

1.1 SAFETY PRECAUTIONS

(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 (NEUTRAL) 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 the LIVE side GND and ISOLATED (NEUTRAL) side GND or EARTH side GND at the same time with a measuring apparatus (oscilloscope etc.). If above note will not be kept, a fuse or any parts will be broken.

(5) 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.

(6) 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 10kΩ

2W resistor to the anode button.

(7) 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.

a) 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.

b) 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

Ω per volt or more

sensitivity in the following manner. Connect a 1500

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.).

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

0.15 F AC-TYPE

PLACE THIS PROBE

1500 10W

GOOD EARTH GROUND

ON EACH EXPOSED ME TAL PAR T

Ω

(No.YA351)1-3

1.2 INSTALLATION

1.2.1 HEAT DISSIPATION

If the heat dissipation vent behind this unit is blocked, cooling efficiency may deteriorate and temperature inside the unit will rise. Therefore, please make sure pay attention not to block the heat dissipation vent as well as the ventilation outlet behind the unit and ensure that there is room for ventilation around it.

1.2.2 INSTALLATION REQUIREMENTS

Ensure that the minimal distance is maintained, as specified below, between the unit with and the surrounding walls. Install the unit on stable flooring or stands. Take precautionary measures to prevent the unit from tipping in order to protect against accidents and earthquakes.

Distance recommendations

Avoid improper installation and never position the unit where good ventilation is impossible. When installing this TV, distance recommendations must be maintained between the set and the wall, as well as inside a tightly enclosed area or

150 mm

200 mm 200 mm

150 mm

50 mm

piece of furniture. Keep to the minimum distance guidelines shown for safe operation.

1.3 PRECAUTIONS

(1) The picture brightness may become uneven on the entire screen according to the environmental temperature. Be sure to use

your monitor set in a specified temperature range for proper display presentation.

(2) Avoid disturbing the heat dissipation from the vent holes provided in the rear, on the top and at the sides. Failure to do so may

result in damaged electronics inside due to the accumulated heat within the unit.

(3) Be sure to install the unit in a well-ventilated place. Also make sure that the ambient temperature is kept in the range of 0 to 35°C.

(4) Avoid operation or storage in high temperature and humidity that exceed the specified limit. Otherwise, the display presentation

may be deteriorated.

(5) This monitor may display a blurred picture when exposed to an extreme environmental conditions. This phenomenon is due to

an intrinsic characteristic of the Liquid Crystal Display (LCD). This is not the failure.

(6) This monitor display uses a Cold Cathode Tube as a backlighting device. The brilliance of this tube (and the monitor display)

may be degraded by time.

1.4 CAUTIONS FOR TRANSPORTATION

The goods may be damaged during transportation caused by poor handling such as throwing, toppling, dropping, etc, giving an excess force against the LCD device. This may happen even if the packing is rigid and secured. To avoid such adverse situations, give a proper instruction to the freighter for secured handling. The LCD panel uses a glass plate, which is very fragile against an external force. Take utmost care to avoid vibration or shock to the panel.

1-4 (No.YA351)

SECTION 2

SPECIFIC SERVICE INSTRUCTIONS

2.1 ABOUT LIQUID CRYSTAL DISPLAY

2.1.1 STRUCTURE OF LIQUID CRYSTAL PANEL

The Liquid Crystal Display used for this unit is of a TFT (Thin Film Transistor) type panel. The structure of this panel is that a TFT array-formed substrate and the stripe pixel matrix type color filter substrate are pressed together with a liquid crystal filled in between these materials.

2.1.2 LONG-TERM AFTERIMAGE ON THE LCD

A minute amount of ionic material could be mingled into a liquid crystal substrate in the manufacturing process. By applying the electricity to the panel the ionic material may be migrated towards one part of the electrodes, causing a long-term afterimage to be displayed. In practice, when a still image is displayed for a long time, the afterimage may be developed and persisted. To cure this problem, turn off the unit and then turn on again and arrange displaying an appropriate still image on the portion where the afterimage is being superimposed.

2.1.3 RESPONSE SPEED OF THE LCD

The LCD is slower than the CRT in terms of the display refresh rate, causing a fast moving picture may be displayed blurred. This is not fault but caused by an intrinsic characteristic of the LCD.

2.1.4 VIEWING ANGLE OF THE LCD

This LCD uses a wide-angle liquid crystal panel, featuring a low rate of the brightness inversion. When viewed from a far outer angle, the screen may be displayed with hue variation. Again, this is not fault but caused by an intrinsic characteristic of the LCD.

2.1.5 PIXEL DEFICIENCY OF THE LCD

The liquid crystal panel is manufactured with precise engineering procedure. However, there is a possibility of yielding a little amount of defective pixels in part on the panel. This is unavoidable feature even if the latest technology is being used for manufacturing the LCD module.

2.2 IMPORTANT NOTICE WHEN REPLACING COMPONENT PARTS

2.2.1 REPLACING THE LCD MODULE

(1) The LCD panel is fragile against the static charge. Be sure to take an appropriate grounding using a grounding-strap etc. when

to replace the LCD panel. (2) The LCD is made of glass, which is fragile against the mechanical shock. Use utmost care when handling the LCD panel. (3) When replacing the panel, first place the panel on the base chassis and then make sure that there is no gap in between the panel

and the chassis. Fix the panel with fixing screws. Turn the unit on with an all-black signal being put in and check if the brightness

is even on the entire screen. If the brightness is not even in some part, slacken the fixing screw nearby until the brightness

becomes even with other parts. (4) A tightening torque for the fixing screws must be set to 0.294Nm or the less. Applying the torque larger than this limit may result

in the damage on the LCD panel. (5) Connecting or disconnecting the plugs with the set is being powered may cause the malfunction of the set. Makes sure that the

AC power plug is disconnected from the power source when attempting the replacement work.

2.2.2 REPLACING THE FUSE

Be sure to use the rated fuse. After replacing the fuse, confirm that the insulator is stuck on the shielding surface for secure insulation.

(No.YA351)1-5

SECTION 3

DISASSEMBLY

3.1 DISASSEMBLY PROCEDURE

CAUTION:

• Prior to disassembly, unplug the power cord and AC

adapter from the AC outlet without fail. (Turn the power "off".)

• When exchanging parts etc. with the front side (LCD

side) facing down, please place a protection sheet below before starting, so as to prevent scratches on the front side.

A x4

3.1.1 REMOVING THE CABLE COVER (L/R) AND NECK COVER (Fig.1)

(1) Remove the 4 claws [A]. (2) Remove the CABLE COVER (L), CABLE COVER (R) and

NECK COVER.

CABLE COVER (L)

CABLE COVER (R) NECK COVER

1-6 (No.YA351)

Fig.1

3.1.2 REMOVING THE STAND ASS'Y (Fig.2)

• Remove the NECK COVER. (1) Remove the 4 screws [B] and remove the STAND ASS’Y.

3.1.3 REMOVING THE TUNER MODULE (Fig.2)

• Remove the CABLE COVER (R). (1) Remove the DUMMY COVER by pulling the claw [C]. (2) Remove the 1 claw [C] and remove the TUNER COVER. (3) Remove the TUNER MODULE by pulling carefully.

3.1.4 REMOVING THE AV JACK MODULE (Fig.2)

• Remove the CABLE COVER (L). (1) Loosen the 2 screws [D]. (2) Remove the AV JACK MODULE by pulling carefully.

Dx2

DUMMY COVER

TUNER COVER

Bx4

TUNER MODULE

STAND ASS'Y

AV JACK MODULE

Fig.2

(No.YA351)1-7

3.1.5 REMOVING THE REAR COVER (Fig.3)

• Remove the CABLE COVER (L/R) and NECK COVER.

• Remove the STAND ASS’Y.

• Remove the TUNER MODULE.

• Remove the AV JACK MODULE. (1) Remove the 4 screws [E] and remove the REAR COVER.

Ex4

1-8 (No.YA351)

REAR COVER

Fig.3

3.1.6 REMOVING THE MAIN PWB SHIELD (Fig.4, 5)

• Remove the REAR COVER. (1) Remove the 1 screw [F] and remove the D-SUB COVER.

(Fig.4)

(2) Remove the 1 screw [G] and remove the AUDIO COVER.

(Fig.4)

(3) Remove the 2 screws [H] and remove the MODULE

BRACKETS. (Fig.4) (4) Remove the 4 screws [I] and the 2 screws [J]. (Fig.5) (5) Remove the MAIN PWB SHIELD by sliding to downside.

(Fig.5)

MODULE

BRACKET

D-SUB COVER

AUDIO COVER

Fig.4

(No.YA351)1-9

MAIN PWB SHIEELD

Ix2

Fig.5

1-10 (No.YA351)

3.1.7 REMOVING THE MAIN PWB (Fig.6)

• Remove the REAR COVER.

• Remove the MAIN PWB SHIELD. (1) Remove the 1 screw [K]. (2) Disconnect the connectors [P004] / [P006] / [P009] / [P014]

from the MAIN PWB.

(3) Disconnect the connector [P613] from the FRONT

CONTROL PWB.

(4) Remove the 6 screws [L] and remove the MAIN PWB.

NOTE:

• EIt is advisable to take note of the connecting location

(connector number) of the removed connectors.

[P004]

[P006]

[P009]

[P017]

MAIN PWB

FRONT CONTROL PWB

Lx6

[P613]

Fig.6

(No.YA351)1-11

3.1.8 REMOVING THE LCD PANEL UNIT [LT-17AX5, LT-17AX5/S, LT-17AX5/A] (Fig.7, 8)

• Remove the REAR COVER.

• Remove the MAIN PWB SHIELD.

• Remove the MAIN PWB.

(1) Remove the 5 screws [M]. (Fig.7) (2) Remove the 1 claw [N], 4 claws [O] and 1 claw [P] and

remove the LCD PANEL UNIT and LCD BRACKET. (Fig.7)

(3) Remove the 4 screws [Q] and remove LCD BRACKET.

(Fig.8)

Ox4

1-12 (No.YA351)

Mx5

Fig.7

LCD BRACKET

Qx2

Fig.8

(No.YA351)1-13

3.1.9 REMOVING THE LCD PANEL UNIT [LT-23AX5, LT-23AX5/S, LT-23AX5/A] (Fig.9, 10)

• Remove the REAR COVER.

• Remove the MAIN PWB SHIELD.

• Remove the MAIN PWB.

(1) Remove the 6 screws [R]. (Fig.9) (2) Remove the 3 claws [S], 4 claws [T], 3 claws [U] and 2

claws [V] and remove the LCD PANEL UNIT and LCD BRACKET. (Fig.9)

(3) Remove the 8 screws [W] and remove LCD BRACKET.

(Fig.10)

Sx3

Ux3

Tx4

1-14 (No.YA351)

Fig.9

Vx2

Rx6

LCD BRACKET

Wx4

Fig.10

(No.YA351)1-15

3.1.10 REMOVING THE INVERTER PWB [LT-17AX5, LT-17AX5/S, LT-17AX5/A] (Fig.11)

• Remove the REAR COVER.

• Remove the MAIN PWB SHIELD.

• Remove the MAIN PWB.

• Remove the LCD BRACKET.

(1) Remove the 4 screws [X]. (2) Disconnect the connectors from the INVERTER PWB and

remove the INVERTER PWB.

NOTE:

• It is advisable to take note of the connecting location

(connector number) of the removed connectors.

Xx4

INVERTER PWB

1-16 (No.YA351)

Fig.11

3.1.11 REMOVING THE SPEAKERS (Fig.12)

• Remove the REAR COVER. (1) Disconnect the connector [P612] from the FRONT

CONTROL PWB.

(2) Strip off the sponges and remove the SPEAKERS.

NOTE:

• It is advisable to take note of the connecting location

(connector number) of the removed connectors.

[P612]

FRONT CONTROL PWB

SPONGE

SPEAKER

SPONGE

SPEAKER

Fig.12

(No.YA351)1-17

3.1.12 REMOVING THE FRONT CONTROL PWB (Fig.13)

• Remove the REAR COVER. (1) Disconnect the connector [P611] from the FRONT

CONTROL PWB. (2) Remove the 2 screws [Y]. (3) Remove the 3 screws [Z] and remove the FRONT

CONTROL PWB.

NOTE:

• EIt is advisable to take note of the connecting location

(connector number) of the removed connectors.

3.1.13 REMOVING THE IR SENSOR PWB (Fig.13)

• Remove the REAR COVER. (1) Remove the 1 screw [a]. (2) Disconnect the connector [P005] from the IR SENSOR

PWB.

NOTE:

• It is advisable to take note of the connecting location

(connector number) of the removed connectors.

Zx3

[P611]

FRONT CONTROL PWB

[P005]

IR SENSOR PWB

Fig.13

1-18 (No.YA351)

3.2 FIRMWARE VERSION CHECK

3.2.1 PROCEDURE FOR FIRMWARE VERSION CHECK

(1) Press the [MUTING] key and the [DISPLAY] key

simultaneously, and the FACTORY MODE screen Fig.1 will be displayed.

(2) The FIRMWARE VERSION is displayed in the upperleft on

the FACTORY MODE screen.

(3) Press the [POWER] key or the [BACK] key to exit the

FACTORY MODE.

CAUTION:

• Do not change setting values of FACTORY MODE

screen.

3.2.2 SERVICE CONTROL KEY LAYOUT ON THE REMOTE CONTROL UNIT

FACTORY MODE SCREEN

FIRMWARE Ver.

Build Date:Fab 16 2005 Time:20:52:58

V23JLBJ F/W Ver. 3.83

Factory Mode

PICTURE ADC TCD3 Scalar Display Color Process

: SELECT

OK : OPERATE

VIDEO STATUS

POWER

INPUT

SLEEP

MTS

TIMER

POWER

NUTING

MUTING

100+

ASPECT

C.C.

DISPLAY BACK

(No.YA351)1-19

+ 44 hidden pages