JVC LT-26A70BJ Schematic

SERVICE MANUAL

WIDE LCD PANEL TELEVISION

YA492200611SERVICE MANUAL

LT-26A70BJ, LT-26A70BU, LT-26A70SJ, LT-26A70SU, LT-32A70BJ, LT-32A70BU, LT-32A70GU, LT-32A70SJ, LT-32A70SU

BASIC CHASSIS

FT2

TABLE OF CONTENTS

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

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

3 DISASSEMBLY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-11

4 ADJUSTMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-16

5 TROUBLESHOOTING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-21

No.YA492

2006/11

SPECIFICATION

Contents

Items

Dimensions ( W × H × D ) 68.6 cm × 51.4 cm × 24.4 cm [Included stand]

Mass 11.6 kg [Included stand]

Power Input AC220 V - AC240 V, 50 Hz

Power Consumption 106 W (Standby: 0.7 W) 114 W (Standby: 0.7 W)

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

Colour System

Stereo System NICAM (I) NICAM (B/G, I, D/K, L)

Teletext System

Receiving Frequency

Intermediate Frequency

Colour Sub Carrier Frequency

LCD panel 26V-inch wide aspect (16 : 9) 32V-inch wide aspect (16 : 9)

Screen Size

Display Pixels Horizontal : 1366 dots × Vertical : 768 dots (W-XGA)

Audio Power Output 5 W + 5 W

Speaker 12 cm × 12, oval type × 2 Aerial terminal (VHF/UHF) 75 Ω unbalanced, coaxial EXT-1 / EXT-2 (Input / Output) 21-pin Euro connector (SCART socket ) × 2 EXT-3 (Input) S-Video Mini-DIN 4 pin × 1

EXT-4 (Input)

HDMI Video HDMI 2-row 19pin connector × 1

Headphone 3.5 mm stereo mini jack × 1 Remote Control Unit RM-C1816S (AA/R6 dry cell battery × 2)

Design & specifications are subject to change without notice.

Component Video

1125i/750p

625p / 525p / 625i / 525i

VIF 38.9MHz (I)

SIF 32.9MHz (6.0MHz :I) 33.4MHz (5.5MHz :B/G)

PAL 4.43MHz

SECAM ---- 4.40625MHz / 4.25MHz ---- 4.40625MHz / 4.25MHz

NTSC 3.58MHz / 4.43MHz

Video 1 V (p-p), Positive (Negative sync provided), 75 Ω, RCA pin jack × 1 Audio 500 mV (rms), High impedance, RCA pin jack × 2

Audio Digital: HDMI 2-row 19pin connector × 1

LT-26A70BJ LT-26A70SJ

68.6 cm × 47.4 cm × 12.2 cm [TV only]

9.6 kg [TV only]

PAL, NTSC 3.58/4.43 [EXT only]

FLOF (Fastext) WST(World Standard system)

UHF: 470MHz - 862MHz VHF: 47MHz - 470MHz

Diagonal : 66 cm (H: 57.6 cm × V: 32.4 cm) Diagonal : 80 cm (H: 69.7 cm × V: 39.2 cm)

Y: 1 V (p-p), Positive (Negative sync provided), 75 Ω C: 0.286 V (p-p) (Burst signal), 75 Ω

RCA pin jack × 3 Y : 1 V (p-p) (Sync signal: ±0.35V(p-p), 3-value sync.), 75Ω , Pb/Pr : ±0.35V(p-p), 75 Ω Y : 1 V (p-p), Positive (Negative sync provided), 75 Ω, Cb/Cr : 0.7V(p-p), 75 Ω

(Digital-input terminal is not compatible with picture signals of personal computer)

LT-26A70BU LT-26A70SU

PAL, SECAM, NTSC 3.58/4.43 [EXT only]

A2 (B/G, D/K)

FLOF (Fastext) TOP WST(World Standard system)

UHF: 470MHz - 862MHz

38.9MHz (B/G, I, D/K, L)

32.9MHz (6.0MHz :I)

32.4MHz (6.5MHz :D/K)

LT-32A70BJ LT-32A70SJ

82.0 cm × 58.8 cm × 24.4 cm [Included stand]

82.0 cm × 55.1 cm × 12.7 cm [TV only]

14.6 kg [Included stand]

12.6 kg [TV only]

PAL, NTSC 3.58/4.43 [EXT only]

NICAM (I) NICAM (B/G, I, D/K, L)

FLOF (Fastext) WST(World Standard system)

UHF: 470MHz - 862MHz VHF: 47MHz - 470MHz

38.9MHz (I)

32.9MHz (6.0MHz :I) 33.4MHz (5.5MHz :B/G)

LT-32A70BU LT-32A70GU LT-32A70SU

PAL, SECAM, NTSC 3.58/4.43 [EXT only]

A2 (B/G, D/K)

FLOF (Fastext) TOP WST(World Standard system)

UHF: 470MHz - 862MHz

38.9MHz (B/G, I, D/K, L)

32.9MHz (6.0MHz :I)

32.4MHz (6.5MHz :D/K)

1-2 (No.YA492)

SECTION 1

PRECAUTION

1.1 SAFETY PRECAUTIONS [EXCEPT FOR UK]

(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) 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 1000Ω per volt or more sensitivity in the following manner. Connect a 1500Ω 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

GOOD EARTH GROUND

1500 10W

PLACE THIS PROBE ON EACH EXPOSED ME TAL PAR T

(No.YA492)1-3

1.2 SAFETY PRECAUTIONS [FOR UK]

(1) The 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 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 product 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 product have special safety-related characteristics. These characteristics are often

not evident from visual inspection nor can the protection afforded by them necessary 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 part shown in the Parts List of Service Manual may cause shock, fire, or other hazards.

(4) The leads in the products are routed and dressed with ties, clamps, tubing’s, 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 re-assembling.

WARNING

(1) The 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.

1-4 (No.YA492)

1.3 INSTALLATION

1.3.1 HEAT DISSIPATION

If the heat dissipation vent behind this unit is blocked, cooling efficiency may deteriorate and temperature inside the unit will rise. The temperature sensor that protects the unit will be activated when internal temperature exceeds the pre-determined level and power will be turned off automatically.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.

Ventilation hole

*Diagram differs from actual appearance.

1.3.2 INSTALLATION REQUIREMENTS

Ensure that the minimal distance is maintained, as specified below, between the unit with and the surrounding walls, as well as the floor etc.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.

1.3.3 INSTALLATION REQUIREMENTS

To ensure safety in an emergency such as an earthquake, and to prevent accidents, ensure that measures are taken to prevent the TV dropping or falling over.

It fixes in a band.

TV Stand

*Diagram differs from actual appearance.

1.3.4 NOTES ON HANDLING

(1) WHEN TAKING UNIT OUT OF A PACKING CASE

When taking the unit out of a packing case, do not grasp the upper part of the unit. If you take the unit out while grasping the upper part, the LCD PANEL may be damaged because of a pressure. Instead of grasping the upper part, put your hands on the lower backside or sides of the unit.

(2) AS FOR PRESSING OR TOUCHING A SPEAKER

Be careful not to press the opening of the speaker in the lower part of the unit and around them since the decorative sheet on the surface of the openings may be deformed.

200 mm

150 mm 50 mm

*Diagram differs from actual appearance.

150 mm 50 mm

(No.YA492)1-5

1.4 HANDLING LCD PANEL

1.4.1 PRECAUTIONS FOR TRANSPORTATION

When transporting the unit, pressure exerted on the internal LCD panel due to improper handling (such as tossing and dropping) may cause damages even when the unit is carefully packed. To prevent accidents from occurring during transportation, pay careful attention before delivery, such as through explaining the handling instructions to transporters. Ensure that the following requirements are met during transportation, as the LCD panel of this unit is made of glass and therefore fragile:

(1) USE A SPECIAL PACKING CASE FOR THE LCD PANEL

When transporting the LCD panel of the unit, use a special packing case (packing materials). A special packing case is used when a LCD panel is supplied as a service spare part.

(2) ATTACH PROTECTION SHEET TO THE FRONT

Since the front (display part) of the panel is vulnerable, attach the protection sheet to the front of the LCD panel before transportation. Protection sheet is used when a LCD panel is supplied as a service spare part.

(3) AVOID VIBRATIONS AND IMPACTS

The unit may be broken if it is toppled sideways even when properly packed. Continuous vibration may shift the gap of the panel, and the unit may not be able to display images properly. Ensure that the unit is carried by at least 2 persons and pay careful attention not to exert any vibration or impact on it.

(4) DO NOT PLACE EQUIPMENT HORIZONTALLY

Ensure that it is placed upright and not horizontally during transportation and storage as the LCD panel is very vulnerable to lateral impacts and may break. During transportation, ensure that the unit is loaded along the traveling direction of the vehicle, and avoid stacking them on one another. For storage, ensure that they are stacked in 2 layers or less even when placed upright.

1.4.2 OPTICAL FILTER (ON THE FRONT OF THE LCD PANEL)

(1) Avoid placing the unit under direct sunlight over a

prolonged period of time. This may cause the optical filter to deteriorate in quality and COLOUR.

(2) Clean the filter surface by wiping it softly and lightly with a

soft and lightly fuzz cloth (such as outing flannel).

(3) Do not use solvents such as benzene or thinner to wipe the

filter surface. This may cause the filter to deteriorate in quality or the coating on the surface to come off. When cleaning the filter, usually use the neutral detergent diluted with water. When cleaning the dirty filter, use water-diluted ethanol.

(4) Since the filter surface is fragile, do not scratch or hit it with

hard materials. Be careful enough not to touch the front surface, especially when taking the unit out of the packing case or during transportation.

1.4.3 PRECAUTIONS FOR REPLACEMENT OF EXTERIOR PARTS

Take note of the following when replacing exterior parts (REAR COVER, FRONT PANEL, etc.):

(1) Do not exert pressure on the front of the LCD panel (filter

surface). It may cause irregular COLOUR.

(2) Pay careful attention not to scratch or stain the front of the

LCD panel (filter surface) with hands.

(3) When replacing exterior parts, the front (LCD panel) should

be placed facing downward. Place a mat, etc. underneath to avoid causing scratches to the front (filter surface).

1-6 (No.YA492)

SECTION 2

SPECIFIC SERVICE INSTRUCTIONS

2.1 FEATURES

T-V LINK

When you have a T-V LINK compatible VCR connected to the EXT-2 Terminal on the TV, it is easier to set up the VCR and to view videos.

PICTURE MODE

This function can adjust the picture settings automatically.

2.2 MAIN DIFFERENCE LIST

Item LT-26A70BJ LT-26A70SJ LT-26A70BU LT-26A70SU

Paint Color Black Silver Black Silver

Broadcasting System I (UHF / VHF)

RF System PAL

Video System PAL, NTSC

Teletext FLOF / WST

Plug Type UK Type (3 Pins)

Item LT-32A70SJ LT-32A70BJ LT-32A70SU LT-32A70BU LT-32A70GU

Paint Color Black Silver Black Silver Titanium

Broadcasting System I (UHF / VHF)

RF System PAL

Video System PAL, NTSC

Teletext FLOF / WST

Plug Type UK Type (3 Pins)

← ← ← ← ←

ZOOM

This function can change the screen size according to the picture aspect ratio.

DIGITAL VNR

This function cuts down the amount of noise in the original picture.

B/G, D/K, I, L

PAL,SECAM

PAL, SECAM, NTSC

FLOF / TOP / WST

EU Type (2 Pins)

B/G, D/K, I, L

PAL,SECAM

PAL, SECAM, NTSC

FLOF / TOP / WST

EU Type (2 Pins)

← ← ← ← ←

←← ←← ←← ←← ←←

(No.YA492)1-7

2.3 21-PIN EURO CONNECTOR (SCART) : EXT-1 / EXT-2

Pin No. Signal designation Matching value EXT-1 EXT-2

1 AUDIO R output 500mV(rms) (Nominal), Low impedance Used (TV OUT) Used (LINE OUT)

2 AUDIO R input 500mV(rms) (Nominal), High impedance Used (R1) Used (R2)

3 AUDIO L output 500mV(rms) (Nominal), Low impedance Used (TV OUT) Used (LINE OUT)

4 AUDIO GND Used Used

5 GND (B) Used Used

6 AUDIO L input 500mV(rms) (Nominal), High impedance Used (L1) Used (L2)

7 B input 700mV

8 FUNCTION SW

(SLOW SW)

Low : 0V-3V High : 8V-12V, High impedance

, 75Ω Used Used

(B-W)

Used Used

9 GND (G) Used Used

10 SCL / T-V LINK Not used Used

(SCL2 / TV-LINK)

11 G input 700mV

, 75Ω Used Used

(B-W)

12 SDA Not used Used (SDA2)

13 GND (R) Used Used

14 GND (YS) Used Not used

15 R / C input R : 700mV

C : 300mV

(B-W) (P-P)

, 75Ω

Used (R) Used (C2/R)

16 Ys input (FAST SW) Low : 0V-0.4V, High : 1V-3V, 75Ω Used Used

17 GND (VIDEO output) Used Used

18 GND (VIDEO input) Used Used

19 VIDEO output 1V

20 VIDEO / Y input 1V

(Negative sync), 75Ω Used (TV OUT) Used (LINE OUT)

(P-P)

(Negative sync), 75Ω Used Used

(P-P)

21 COMMON GND Used Used

(P-P= Peak to Peak, B-W= Blanking to white peak)

[Pin assignment]

20 18 16 14 12 10 8 6 4 2

21 19 17 15 13 11 9 7 5 3 1

1-8 (No.YA492)

2.4 TECHNICAL INFORMATION

2.4.1 LCD PANEL

This unit uses the flat type panel LCD (Liquid Crystal Display) panel that occupies as little space as possible, instead of the conventional CRT (Cathode Ray Tube), as a display unit. Since the unit has the two polarizing filter that are at right angles to each other, the unit adopts "normally black" mode, where light does not pass through the polarizing filter and the screen is black when no voltage is applied to the liquid crystals.

2.4.1.1 SPECIFICATIONS

The following table shows the specifications of this unit.

Item

Maximum dimensions ( W × H × D )

Weight 4.5 kg 6.9 kg

Effective screen size Diagonal: 660 mm (H: 576 mm × V: 324 mm) Diagonal: 800 mm (H: 697 mm × V: 392 mm)

Aspect ratio 16 : 9

Drive device / system a-Si-TFT active matrix system

Resolution Horizontally 1366 × Vertically 768 × RGB < W-XGA > 3147264 dots in total

Pixel pitch (pixel size) Horizontally: 0.4215 mm, Vertically: 0.4215 mm Horizontally: 0.51075 mm, Vertically: 0.51075 mm

Displayed colour 16777216 colours 256 colours for R G and B

Brightness 500cd/m2

Contrast ratio 1200 : 1

Response time (Tr) less than 8 ms

View angle (Horizontally) 176° View angle (Vertically) 176°

Surface polarizer Anti-Glare type Low reflective coat

Colour filter Vertical stripe

Backlight Cold cathode fluorescent lamp × 6 Cold cathode fluorescent lamp × 12

Power supply voltage in LCD 5 V

Power supply voltage in inverter

Panel interface system LVDS (Low Voltage Differential Signaling)

62.6 cm × 37.3 cm × 4.8 cm 76.0 cm × 45.0 cm × 4.5 cm

24 V

26V LCD PANEL UNIT 32V LCD PANEL UNIT

Specifications

2.4.1.2 PIXEL FAULT

There are three pixel faults - bright fault , dark fault and flicker fault - that are respectively defined as follows.

 BRIGHT FAULT

In this pixel fault, a cell that should not light originally is lighting on and off. For checking this pixel fault, input ALL BLACK SCREEN and find out the cell that is lighting on and off.

 DARK FAULT

In this pixel fault, a cell that should light originally is not lighting or lighting with the brightness twice as brighter as originally lighting. For checking this pixel fault, input 100% of each R/G/B colour and find out the cell that is not lighting.

 FLICKER FAULT

In the pixel fault, a cell that should light originally or not light originally is flashing on and off. For checking this pixel fault, input ALL BLACK SCREEN signal or 100% of each RGB colour and find out the cell that is flashing on and off.

(No.YA492)1-9

2.4.2 MAIN CPU PIN FUNCTION [IC3

Pin Pin name I/O Function Pin Pin name I/O Function

1 P9_4 O PANEL_POWER_CONTROL 51 A17 O Program ROM address for CPU

2 P9_3 O POWER 52 A16 O Program ROM address for CPU

3 P9_2 O SC_RGB_CONTROL 53 A15 O Program ROM address for CPU

4 P9_1 O SOUNDAMP_POWER 54 A14 O Program ROM address for CPU

5 HP_DET I HEADPHONE_DETECT 55 A13 O Program ROM address for CPU

6 BYTE I BYTE 56 A12 O Program ROM address for CPU

7 CNVSS I CNVSS 57 A11 O Program ROM address for CPU

8 XCIN - Not used 58 A10 O Program ROM address for CPU

9 XCOUT - Not used 59 A9 O Program ROM address for CPU

10 CPU_RESET I /RESET 60 VCC2 I 3.3V

11 XOUT O XOUT 61 A8 O Program ROM address for CPU

12 VSS - VSS 62 VSS - VSS

13 XIN I XIN 63 A7 O Program ROM address for CPU

14 VCC1 I 3.3V 64 A6 O Program ROM address for CPU

15 P8_5 - Not used 65 A5 O Program ROM address for CPU

16 P8_4 - Not used 66 A4 O Program ROM address for CPU

17 /INT1 I PX_INT# 67 A3 O Program ROM address for CPU

18 /INT0 I REMOCON 68 A2 O Program ROM address for CPU

19 P8_1 - Not used 69 A1 O Program ROM address for CPU

20 P8_0 O LED_ON 70 A0 O Program ROM address for CPU

21 P7_7 O HDMI_DETECT 71 P1_7 - Not used

22 P7_6 O SOUNDAMP MUTE 72 P1_6 - Not used

23 P7_5 I DEBUG 73 P1_5 I TV_LINK_IN

24 P7_4 O BACKLIGHT_CONTROL 74 P1_4 O EDID_WP

25 P7_3 O HDMI_DAC_MUTE 75 P1_3 - Not used

26 P7_2 - Not used 76 P1_2 O TV_LINK_CONTROL

27 P7_1 I/O SCL_EEP 77 P1_1 O TV_LINK_OUT

28 P7_0 I/O SDA_EEP 78 P1_0 I HDMI_PICTURE_SIGNAL_INDICATON

29 P6_7 I/O TX 79 D7 I/O Program ROM data for CPU

30 P6_6 I/O RX 80 D6 I/O Program ROM data for CPU

31 P6_5 I/O DEBUG3 81 D5 I/O Program ROM data for CPU

32 P6_4 I/O DEBUG2 82 D4 I/O Program ROM data for CPU

33 P6_3 I/O SDA_DEVICE 83 D3 I/O Program ROM data for CPU

34 P6_2 I/O SCL_DEVICE 84 D2 I/O Program ROM data for CPU

35 P6_1 O RESET_for_PX 85 D1 I/O Program ROM data for CPU

36 P6_0 O RESET_for_MSP 86 D0 I/O Program ROM data for CPU

37 P5_7 - Not used 87 AN7 I TUNER AGC

38 ALE O PX,FLASH_ALE 88 AN6 I TUNER AFT

39 P5_5 I/O DEBUG6 89 AN5 I LOW VOLTAGE_PROTECTION

40 P5_4 - Not used 90 AN4 I HDMI_PROTECTION

41 P5_3 - Not used 91 AN3 I POWER_DET

42 /RD O PX,FLASH_RD# 92 AN2 I KEYA

43 /WRH /BHE O RY_BY 93 AN1 I KEYB

44 /WR O PX,FLASH_WR# 94 VSS - VSS

45 /CS3 - Not used 95 AN0 - Not used

46 /CS2 O PX_CHIPSELECT# 96 VREF I 3.3V

47 /CS1 - Not used 97 AVCC I 3.3V

48 /CS0 O FLASH_CHIPSELECT# 98 P9_7 O AUDIO_MUTE

49 A19 O Program ROM address for CPU 99 P9_6 O BACKLIGHT_POWER

50 A18 O Program ROM address for CPU 100 P9_5 O EEP_WP

: MAIN PWB]

1-10 (No.YA492)

SECTION 3

DISASSEMBLY

3.1 DISASSEMBLY PROCEDURE

CAUTION AT DISASSEMBLY:

• Make sure that the power cord is disconnected from the outlet.

• Pay special attention not to break or damage the parts.

• When removing each board, remove the connectors as required. Taking notes of the connecting points (connector numbers) makes service procedure manageable.

• Make sure that there is no bent or stain on the connectors before inserting, and firmly insert the connectors.

3.1.1 REMOVING THE STAND

(1) Remove the 4 screws [A], then remove the STAND ASS'Y.

3.1.2 REMOVING THE REAR COVER AND BACK BRACKET

• Remove the STAND. (1) Remove the 8 screws [B], 3 screw [C]. (2) Remove the REAR COVER. (3) Remove the 4 screws [D]. (4) Remove the BACK BRACKET.

3.1.3 REMOVING THE POWER PWB

• Remove the STAND.

• Remove the REAR COVER.

• Remove the POWER CORD. (1) Remove the 4 screws [E]. (2) Remove the POWER PWB.

3.1.4 REMOVING THE MAIN PWB

• Remove the STAND.

• Remove the REAR COVER. (1) Remove the 3 screws [F] and 2 screws [G]. (2) Remove the TERMINAL BASE. (3) Remove the 8 screws [H] and 1 screw [J]. (4) Remove the SHIELD COVER. (5) Remove the 4 screws [K] . (6) Remove the MAIN PWB.

3.1.6 REMOVING THE IR PWB

• Remove the STAND.

• Remove the REAR COVER. (1) Remove the 2 screws [M]. (2) Remove the IR PWB.

3.1.7 REMOVING THE SPEAKER HOLDER AND SPEAKER

• Remove the STAND.

• Remove the REAR COVER. (1) Remove the 2 screws [P]. (2) Remove the SPEAKER with the SPEAKER HOLDER. (3) Remove the 4 screws [N]. (4) Remove the SPEAKER. (5) The other SPEAKER HOLDER AND SPEAKER are

removed according to similar procedure.

3.1.8 REMOVING THE LCD PANEL UNIT

• Remove the STAND.

• Remove the REAR COVER.

• Remove the TERMINAL BASE. (1) Remove the 2 screws [Q] and 1 screw [R]. (2) Remove the STAND BRACKET. (3) Remove the 4 screws [S]. (4) Remove the MAIN BASE. (5) Remove the 6 screws [T]. (6) Remove the LCD PANEL UNIT.

3.1.5 REMOVING THE CONTROL KNOB ASS'Y AND CONTROL PWB

• Remove the STAND.

• Remove the REAR COVER.

(1) Remove the 2 screws [L]. (2) Remove the CONTROL PWB with the CONTROL KNOB

ASS'Y.

(3) Remove the CONTROL PWB from the CONTROL KNOB

ASS'Y.

(No.YA492)1-11

BACK BRACKET

STAND ASS'Y

REAR SIDE

REAR COVER

RATING LABEL

POWER PWB

INSULATOR

SHIELD COVER

MAIN PWB

STNAD

BRACKET

POWER CORD

TERMINAL BASE

LCD PANEL UNIT

FRONT BASE

CONTROL PWB

The terminal of a connector is turned up and connected.

+PUGTVCPFNQEMUWTGN[

terminal side

Check that connector is inserted completly.

(Don't insert aslant)

SPEAKER

MAIN BASE

SPEAKER

HOLDER

CONTROL KNOB ASS'Y IR PWB

1-12 (No.YA492)

Fig.1

SPEAKER

HOLDER

This illustration is LT-32A70 series.

3.2 MEMORY IC REPLACEMENT

S001 5I R OF 126 PAL50 FULL STD H

SERVICE MENU

1.ADJUST

2.SELF_CHECK

3.I2C STOP

4.OPTION

• This model uses the memory IC.

• This memory IC stores data for proper operation of the video and drive circuits.

• When replacing, be sure to use an IC containing this (initial value) data.

3.2.1 MEMORY IC REPLACEMENT PROCEDURE

1. Power off

Switch off the power and disconnect the power plug from the AC outlet.

2. Replace the memory IC

Be sure to use the memory IC written with the initial setting values.

3. Power on

Connect the power plug to the AC outlet and switch on the power.

4. Receiving channel setting

Refer to the OPERATING INSTRUCTIONS and set the receive channels (Channels Preset) as described.

5. User setting

Check the user setting items according to the given in page later. Where these do not agree, refer to the OPERATING INSTRUCTIONS and set the items as described.

6. SERVICE MODE setting

Verify what to set in the SERVICE MODE, and set whatever is necessary (Fig.1). Refer to the SERVICE ADJUSTMENT for setting.

3.2.2 SERVICE MODE SETTING

SERVICE MODE SCREEN

NOTE:

As self check feature is not used in this TV, "2.SELF_CHECK" and "4.OPTION" cannot be selected (screen display only).

SETTING ITEM

Setting

items

Setting items Settings Item No.

1.ADJUST Video system setting -1 Adjust S001 - S096

Video system setting -2 Fixed D001 - D020

SERVICE MODE SCREEN

D031 - D099

Audio System Setting -1 Fixed A001 - A003

SERVICE MENU

1.ADJUST

2.SELF_CHECK

3.I2C STOP

4.OPTION

Not used (Display only)

Audio system setting -2 Fixed SD10 - SD15

Option Setting Fixed O001 - O004

1. ADJUST

S001 5I R OF 126 PAL50 FULL STD H

Fig.1

(No.YA492)1-13

3.2.3 SETTINGS OF FACTORY SHIPMENT

3.2.3.1 BUTTON OPERATION 3.2.3.2 REMOTE CONTROL DIRECT OPERATION

Setting item Setting position

POWER Off

CHANNEL PR1

VOLUME 10

TV/AV TV

3.2.3.3 REMOTE CONTROL MENU OPERATION

(1) PICTURE

Setting item Setting position

PICTURE MODE BRIGHT

COLOUR TEMP. COOL

FEATURES

DIGITAL VNR AUTO (LOW)

COLOUR SYSTEM TV Depends on PR/CH

EXT AUTO

4:3 AUTO ASPECT PANORAMIC

(2) SOUND

Setting item Setting position

STEREO / I•II Stereo sound

BASS Centre

TREBLE Centre

BALANCE Centre

3D SOUND OFF

CHANNEL PR1

VOLUME 10

ZOOM AUTO

3D SOUND OFF

SUB POWER OFF

(4) FEATURES

SLEEP TIMER OFF

CHILD LOCK ID NO.0000, All CH off

APPEARANCE TYPE A

BLUE BACK ON

FAVOURITE SETTING Reset

(5) SET UP

AUTO PROGRAM TV channel automatically set

EDIT/MANUAL PRESET CH only

LANGUAGE ENGLISH

DECODER (EXT-2) OFF

EXT SETTING

S-IN BLANK

ID BLANK

DUBBING EXT-1 → EXT-2

Setting item Setting position

1-14 (No.YA492)

3.3 REPLACEMENT OF CHIP COMPONENT

3.3.1 CAUTIONS

(1) Avoid heating for more than 3 seconds. (2) Do not rub the electrodes and the resist parts of the pattern. (3) When removing a chip part, melt the solder adequately. (4) Do not reuse a chip part after removing it.

3.3.2 SOLDERING IRON

(1) Use a high insulation soldering iron with a thin pointed end of it. (2) A 30w soldering iron is recommended for easily removing parts.

3.3.3 REPLACEMENT STEPS

1. How to remove Chip parts

2. How to install Chip parts

[Resistors, capacitors, etc.]

(1) As shown in the figure, push the part with tweezers and

alternately melt the solder at each end.

(2) Shift with the tweezers and remove the chip part.

[Transistors, diodes, variable resistors, etc.]

(1) Apply extra solder to each lead.

SOLDER

[Resistors, capacitors, etc.]

(1) Apply solder to the pattern as indicated in the figure.

(2) Grasp the chip part with tweezers and place it on the

solder. Then heat and melt the solder at both ends of the chip part.

[Transistors, diodes, variable resistors, etc.]

(1) Apply solder to the pattern as indicated in the figure. (2) Grasp the chip part with tweezers and place it on the

solder.

(3) First solder lead A as indicated in the figure.

(2) As shown in the figure, push the part with tweezers and

alternately melt the solder at each lead. Shift and remove the chip part.

NOTE :

After removing the part, remove remaining solder from the pattern.

(4) Then solder leads B and C.

(No.YA492)1-15

SECTION 4

SERVICE MENU

1.ADJUST

2.SELF_CHECK

3.I2C STOP

4.OPTION

ADJUSTMENT

4.1 ADJUSTMENT PREPARATION

(1) The adjustment using the REMOTE CONTROL UNIT is

made on the basis of the initial setting values. The setting values which adjust the screen to the optimum condition can be different from the initial setting values.

(2) Make sure that connection is correctly made AC to AC

power source.

(3) Turn on the power of the TV and measuring instruments for

warming up for at least 30 minutes before starting adjustments.

(4) If the receive or input signal is not specified, use the most

appropriate signal for adjustment.

(5) Never touch the parts (such as variable resistors,

transformers and condensers) not shown in the adjustment items of this service adjustment.

4.2 PRESET SETTING BEFORE ADJUSTMENTS

Unless otherwise specified in the adjustment items, preset the following functions with the REMOTE CONTROL UNIT.

Setting item Settings position

PICTURE MODE STANDARD

PICTURE adjustments Centre

COLOUR TEMP. NORMAL

4.3 MEASURING INSTRUMENT AND FIXTURES

• Signal generator (Pattern generator)[PAL]

• Remote control unit

4.4 ADJUSTMENT ITEMS

 VIDEO CIRCUIT

• WHITE BALANCE (HIGH LIGHT) adjustment

4.5 BASIC OPERATION OF SERVICE MODE

4.5.1 SERVICE MODE SELECT KEY LOCATION

MUTING

NUMBER

INFORMATION

FUNCTION /

VCR/TV/DVD switch

FUNCTION /

4.5.2 HOW TO ENTER THE SERVICE MODE

(1) Press [INFORMATION] key and [MUTING] key on the

remote control unit simultaneously to enter the SERVICE MODE SCREEN. (Fig.1)

SERVICE MODE SCREEN

SERVICE MENU

1.ADJUST

2.SELF_CHECK

3.I2C STOP

4.OPTION

Not used

(Display only)

Fig.1

NOTE:

• As self check feature is not used in this TV, "2.SELF_CHECK" and "4.OPTION"cannot be selected (screen display only).

• Before entering the SERVICE MODE, confirm that the setting of VCR/TV/DVD switch is at the "TV" side. If the switches have not been properly set, you cannot enter the SERVICE MODE.”

4.5.3 HOW TO EXIT THE SERVICE MODE Press the [MENU] key to exit the Service mode.

4.5.4 CHANGE AND MEMORY OF SETTING VALUE

SELECTION OF SETTING ITEM

• [FUNCTION /] key. For scrolling up / down the setting items.

CHANGE OF SETTING VALUE (DATA)

• [FUNCTION /] key. For scrolling up / down the setting values.

MEMORY OF SETTING VALUE (DATA)

Changed setting value is memorized by pressing [MUTING] key.

4.5.5 ADJUSTMENT MODE

This mode is used to adjust the VIDEO CIRCUIT.

4.5.5.1 HOW TO ENTER THE ADJUSTMENT MODE

When the SERVICE MENU SCREEN of SERVICE MODE is displayed, press [1] key to enter the ADJUSTMENT MODE (Fig.2).

NOTE:

• When a number key other than the [1] key is pressed in the SERVICE MODE SCREEN, the other relevant screen may be displayed. This is not used in the adjustment procedure. Press the [MENU] key to return to the SERVICE MODE SCREEN.

1-16 (No.YA492)

4.5.5.2 DESCRIPTION OF STATUS DISPLAY

S001 5I R OF 126 PAL50 FULL STD H

SETTING VALUE (DATA)SETTINGITEM No. SETTING ITEM

S001 5I R OF 126 PAL50 FULL STD H

SIGNAL SYSTEM

ZOOM MODE

PICTURE MODE

(1) SIGNAL SYSTEM

The signal displayed on the screen is displayed.

PAL50 : PAL50Hz PAL60 : PAL60Hz SECAM : SECAM NTSC3 : NTSC3.58 NTSC4 : NTSC4.43 H525I : 525i(Component/HDMI) H625I : 625i(Component/HDMI) H525P : 525p(Component/HDMI) H625P : 625p(Component/HDMI) H750P : 750p(Component/HDMI) H125I : 1125i(Component/HDMI) VGA : VGA(HDMI)

COLOUR TEMP.

(4) WHITE BALANCE

State of the colour temperature is displayed.

NOTE:

In ADJUSTMENT MODE, the colour temperature can be set only to "NORMAL". When it is entered to ADJUSTMENT MODE, it is automatically changed to "NORMAL", even if the setting is in other colour temperature.

(5) SETTING ITEM NAME

Setting item name are displayed. The setting item numbers to be displayed are listed below.

Item No. Setting item

S001 - S043 Video system setting -1

D001 - D020

Video system setting -2 [Do not adjust]

D031 - D099

A001 - A003 Audio system setting -1 [Do not adjust]

SD10 - SD15 Audio system setting -2 [Do not adjust]

O001 - O004 Option data setting [Not used]

(6) SETTING ITEM NO.

Setting item numbers are displayed. For the setting item names to be displayed, refer to "INITIAL SETTING VALUES IN THE SERVICE MODE".

(7) SETTING VALUE (DATA)

The SETTING VALUE is displayed.

(2) ZOOM MODE

State of the screen mode is displayed.

NOTE:

In ADJUSTMENT MODE, the screen mode can be set only to "FULL". When it is entered to ADJUSTMENT MODE, it is automatically changed to "FULL", even if the setting is in other screen mode.

(3) PICTURE MODE

State of the picture mode is displayed.

NOTE:

In ADJUSTMENT MODE, the picture mode can be set only to "STANDARD". When it is entered to ADJUSTMENT MODE, it is automatically changed to "STANDARD", even if the setting is in other picture mode.

(No.YA492)1-17

+ 39 hidden pages