LG 43LJ55 Schematic

LED TV

SERVICE MANUAL

CHASSIS : LA75M

MODEL : 43LJ55** 43LJ55**-U*

CAUTION

BEFORE SERVICING THE CHASSIS, READ THE SAFETY PRECAUTIONS IN THIS MANUAL.

P/NO : MFL69963002 (1703-REV01)

CONTENTS

CONTENTS .............................................................................................. 2

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

SERVICING PRECAUTIONS ................................................................... 4

SPECIFICATION ....................................................................................... 6

SOFTWARE UPDATE .............................................................................. 8

BLOCK DIAGRAM ................................................................................... 9

EXPLODED VIEW .................................................................................. 10

DISASSEMBLY GUIDE .......................................................................... 11

TROUBLE SHOOTING GUIDE ................................................ APPENDIX

- 2 -

SAFETY PRECAUTIONS

IMPORTANT SAFETY NOTICE

Many electrical and mechanical parts in this chassis have special safety-related characteristics. These parts are identified by in the Exploded View. It is essential that these special safety parts should be replaced with the same components as recommended in this manual to prevent Shock, Fire, or other Hazards. Do not modify the original design without permission of manufacturer.

General Guidance

An isolation Transformer should always be used during the servicing of a receiver whose chassis is not isolated from the AC power line. Use a transformer of adequate power rating as this protects the technician from accidents resulting in personal injury from electrical shocks.

It will also protect the receiver and it's components from being damaged by accidental shorts of the circuitry that may be inadvertently introduced during the service operation.

If any fuse (or Fusible Resistor) in this TV receiver is blown, replace it with the specified.

When replacing a high wattage resistor (Oxide Metal Film Resistor, over 1 W), keep the resistor 10 mm away from PCB.

Keep wires away from high voltage or high temperature parts.

Before returning the receiver to the customer,

always perform an AC leakage current check on the exposed metallic parts of the cabinet, such as antennas, terminals, etc., to be sure the set is safe to operate without damage of electrical shock.

Leakage Current Cold Check(Antenna Cold Check)

With the instrument AC plug removed from AC source, connect an electrical jumper across the two AC plug prongs. Place the AC switch in the on position, connect one lead of ohm-meter to the AC plug prongs tied together and touch other ohm-meter lead in turn to each exposed metallic parts such as antenna terminals, phone jacks, etc. If the exposed metallic part has a return path to the chassis, the measured resistance should be between 1 MΩ and 5.2 MΩ. When the exposed metal has no return path to the chassis the reading must be infinite. An other abnormality exists that must be corrected before the receiver is returned to the customer.

Leakage Current Hot Check (See below Figure)

Plug the AC cord directly into the AC outlet.

Do not use a line Isolation Transformer during this check. Connect 1.5 K / 10 watt resistor in parallel with a 0.15 uF capacitor between a known good earth ground (Water Pipe, Conduit, etc.) and the exposed metallic parts. Measure the AC voltage across the resistor using AC voltmeter with 1000 ohms/volt or more sensitivity. Reverse plug the AC cord into the AC outlet and repeat AC voltage measurements for each exposed metallic part. Any voltage measured must not exceed 0.75 volt RMS which is corresponds to

0.5 mA. In case any measurement is out of the limits specified, there is possibility of shock hazard and the set must be checked and repaired before it is returned to the customer.

Leakage Current Hot Check circuit

- 3 -

SERVICING PRECAUTIONS

CAUTION: Before servicing receivers covered by this service manual and its supplements and addenda, read and follow the

SAFETY PRECAUTIONS on page 3 of this publication. NOTE: If unforeseen circumstances create conict between the

following servicing precautions and any of the safety precautions on page 3 of this publication, always follow the safety precautions. Remember: Safety First.

General Servicing Precautions

1. Always unplug the receiver AC power cord from the AC power source before;

a. Removing or reinstalling any component, circuit board mod-

ule or any other receiver assembly.

b. Disconnecting or reconnecting any receiver electrical plug or

other electrical connection.

c. Connecting a test substitute in parallel with an electrolytic

capacitor in the receiver. CAUTION: A wrong part substitution or incorrect polarity installation of electrolytic capacitors may result in an explosion hazard.

2. Test high voltage only by measuring it with an appropriate high voltage meter or other voltage measuring device (DVM, FETVOM, etc) equipped with a suitable high voltage probe. Do not test high voltage by "drawing an arc".

3. Do not spray chemicals on or near this receiver or any of its assemblies.

4. Unless specied otherwise in this service manual, clean

electrical contacts only by applying the following mixture to the contacts with a pipe cleaner, cotton-tipped stick or comparable non-abrasive applicator; 10 % (by volume) Acetone and 90 % (by volume) isopropyl alcohol (90 % - 99 % strength)

CAUTION: This is a ammable mixture. Unless specied otherwise in this service manual, lubrication of

contacts in not required.

5. Do not defeat any plug/socket B+ voltage interlocks with which receivers covered by this service manual might be equipped.

6. Do not apply AC power to this instrument and/or any of its electrical assemblies unless all solid-state device heat sinks are correctly installed.

7. Always connect the test receiver ground lead to the receiver chassis ground before connecting the test receiver positive lead. Always remove the test receiver ground lead last.

8. Use with this receiver only the test xtures specied in this

service manual.

CAUTION: Do not connect the test xture ground strap to any

heat sink in this receiver.

Electrostatically Sensitive (ES) Devices

Some semiconductor (solid-state) devices can be damaged easily by static electricity. Such components commonly are called Electrostatically Sensitive (ES) Devices. Examples of typical ES

devices are integrated circuits and some eld-effect transistors

and semiconductor “chip” components. The following techniques should be used to help reduce the incidence of component damage caused by static by static electricity.

1. Immediately before handling any semiconductor component or semiconductor-equipped assembly, drain off any electrostatic charge on your body by touching a known earth ground. Alternatively, obtain and wear a commercially available discharging wrist strap device, which should be removed to prevent potential shock reasons prior to applying power to the unit under test.

2. After removing an electrical assembly equipped with ES devices, place the assembly on a conductive surface such as aluminum foil, to prevent electrostatic charge buildup or exposure of the assembly.

3. Use only a grounded-tip soldering iron to solder or unsolder ES devices.

4. Use only an anti-static type solder removal device. Some solder

removal devices not classied as “anti-static” can generate electrical charges sufcient to damage ES devices.

5. Do not use freon-propelled chemicals. These can generate

electrical charges sufcient to damage ES devices.

6. Do not remove a replacement ES device from its protective package until immediately before you are ready to install it. (Most replacement ES devices are packaged with leads electrically shorted together by conductive foam, aluminum foil or comparable conductive material).

7. Immediately before removing the protective material from the leads of a replacement ES device, touch the protective material to the chassis or circuit assembly into which the device will be installed. CAUTION: Be sure no power is applied to the chassis or circuit, and observe all other safety precautions.

8. Minimize bodily motions when handling unpackaged replacement ES devices. (Otherwise harmless motion such as the brushing together of your clothes fabric or the lifting of your

foot from a carpeted oor can generate static electricity sufcient to damage an ES device.)

General Soldering Guidelines

1. Use a grounded-tip, low-wattage soldering iron and appropriate tip size and shape that will maintain tip temperature within the range or 500 °F to 600 °F.

2. Use an appropriate gauge of RMA resin-core solder composed of 60 parts tin/40 parts lead.

3. Keep the soldering iron tip clean and well tinned.

4. Thoroughly clean the surfaces to be soldered. Use a mall wirebristle (0.5 inch, or 1.25 cm) brush with a metal handle. Do not use freon-propelled spray-on cleaners.

5. Use the following unsoldering technique

a. Allow the soldering iron tip to reach normal temperature.

(500 °F to 600 °F) b. Heat the component lead until the solder melts. c. Quickly draw the melted solder with an anti-static, suction-

type solder removal device or with solder braid.

CAUTION: Work quickly to avoid overheating the circuit

board printed foil.

6. Use the following soldering technique. a. Allow the soldering iron tip to reach a normal temperature

(500 °F to 600 °F)

b. First, hold the soldering iron tip and solder the strand against

the component lead until the solder melts.

c. Quickly move the soldering iron tip to the junction of the

component lead and the printed circuit foil, and hold it there only until the solder ows onto and around both the component lead and the foil. CAUTION: Work quickly to avoid overheating the circuit board printed foil.

d. Closely inspect the solder area and remove any excess or

splashed solder with a small wire-bristle brush.

- 4 -

IC Remove/Replacement

Some chassis circuit boards have slotted holes (oblong) through which the IC leads are inserted and then bent at against the circuit foil. When holes are the slotted type, the following technique should be used to remove and replace the IC. When working with boards using the familiar round hole, use the standard technique as outlined in paragraphs 5 and 6 above.

Removal

1. Desolder and straighten each IC lead in one operation by gently prying up on the lead with the soldering iron tip as the solder melts.

2. Draw away the melted solder with an anti-static suction-type solder removal device (or with solder braid) before removing the IC.

Replacement

1. Carefully insert the replacement IC in the circuit board.

2. Carefully bend each IC lead against the circuit foil pad and solder it.

3. Clean the soldered areas with a small wire-bristle brush. (It is not necessary to reapply acrylic coating to the areas).

"Small-Signal" Discrete Transistor Removal/Replacement

1. Remove the defective transistor by clipping its leads as close as possible to the component body.

2. Bend into a "U" shape the end of each of three leads remaining on the circuit board.

3. Bend into a "U" shape the replacement transistor leads.

4. Connect the replacement transistor leads to the corresponding leads extending from the circuit board and crimp the "U" with long nose pliers to insure metal to metal contact then solder each connection.

Power Output, Transistor Device Removal/Replacement

1. Heat and remove all solder from around the transistor leads.

2. Remove the heat sink mounting screw (if so equipped).

3. Carefully remove the transistor from the heat sink of the circuit board.

4. Insert new transistor in the circuit board.

5. Solder each transistor lead, and clip off excess lead.

6. Replace heat sink.

Diode Removal/Replacement

1. Remove defective diode by clipping its leads as close as possible to diode body.

2. Bend the two remaining leads perpendicular y to the circuit board.

3. Observing diode polarity, wrap each lead of the new diode around the corresponding lead on the circuit board.

4. Securely crimp each connection and solder it.

5. Inspect (on the circuit board copper side) the solder joints of the two "original" leads. If they are not shiny, reheat them and if necessary, apply additional solder.

3. Solder the connections. CAUTION: Maintain original spacing between the replaced component and adjacent components and the circuit board to prevent excessive component temperatures.

Circuit Board Foil Repair

Excessive heat applied to the copper foil of any printed circuit board will weaken the adhesive that bonds the foil to the circuit board causing the foil to separate from or "lift-off" the board. The following guidelines and procedures should be followed whenever this condition is encountered.

At IC Connections

To repair a defective copper pattern at IC connections use the following procedure to install a jumper wire on the copper pattern side of the circuit board. (Use this technique only on IC connections).

1. Carefully remove the damaged copper pattern with a sharp knife. (Remove only as much copper as absolutely necessary).

2. carefully scratch away the solder resist and acrylic coating (if used) from the end of the remaining copper pattern.

3. Bend a small "U" in one end of a small gauge jumper wire and carefully crimp it around the IC pin. Solder the IC connection.

4. Route the jumper wire along the path of the out-away copper pattern and let it overlap the previously scraped end of the good copper pattern. Solder the overlapped area and clip off any excess jumper wire.

At Other Connections

Use the following technique to repair the defective copper pattern at connections other than IC Pins. This technique involves the installation of a jumper wire on the component side of the circuit board.

1. Remove the defective copper pattern with a sharp knife. Remove at least 1/4 inch of copper, to ensure that a hazardous condition will not exist if the jumper wire opens.

2. Trace along the copper pattern from both sides of the pattern break and locate the nearest component that is directly connected to the affected copper pattern.

3. Connect insulated 20-gauge jumper wire from the lead of the nearest component on one side of the pattern break to the lead of the nearest component on the other side. Carefully crimp and solder the connections. CAUTION: Be sure the insulated jumper wire is dressed so the it does not touch components or sharp edges.

Fuse and Conventional Resistor Removal/Replacement

1. Clip each fuse or resistor lead at top of the circuit board hollow stake.

2. Securely crimp the leads of replacement component around notch at stake top.

- 5 -

SPECIFICATION

NOTE : Specifications and others are subject to change without notice for improvement

.

1. Application range

This specification is applied to the LED TV used LA75M chassis.

2. Test condition

Each part is tested as below without special appointment. (1) Temperature: 25 °C ± 5 °C, CST: 40 °C ± 2 °C (2) Relative Humidity: 65 % ± 10 % (3) Power Voltage

: Standard input voltage (AC 100-240 V~, 50/60 Hz) * Standard Voltage of each products is marked by models.

(4) Specification and performance of each parts are followed

each drawing and specification by part number in accordance with BOM.

(5) The receiver must be operated for about 5 minutes prior to

the adjustment.

3. Test method

(1) Performance: LGE TV test method followed (2) Demanded other specification

- Safety : CE, IEC specification

- EMC : CE, IEC

4. General Specification

No Item Specication Remark

1 Market North America

2 Receiving system ATSC / NTSC-M, 64 & 256 QAM

3 Available Channel VHF : 02~13

UHF : 14~69

DTV : 02-69

CATV : 01~135

CADTV : 01~135

4 Input Voltage AC 100 ~ 240V@ 50/60Hz AC 120V, 50/60Hz on the label (USA)

5 Aspect Ratio 16:9

6 Tuning System FS Rear gender(1EA)

7 Operating Environment 1) Temp : 0 ~ 40 deg

2) Humidity : ~ 80 %

8 Storage Environment 1) Temp. : -20 ~ 60 deg

2) Humidity : ~ 85%

- 6 -

5. External Input Support Format

5.1. Component 2D input(Y, CB/PB)

No. Resolution H-freq(kHz) V-freq.(kHz) Pixel clock(MHz) Proposed

1 720*480 15.73 59.94 13.50 SDTV ,DVD 480I

2 720*480 15.75 60.00 13.5135 SDTV ,DVD 480I

3 720*480 31.47 59.94 27.00 SDTV 480P

4 720*480 31.50 60.00 27.027 SDTV 480P

5 1280*720 44.96 59.94 74.176 HDTV 720P

6 1280*720 45.00 60.00 74.25 HDTV 720P

7 1920*1080 33.72 59.94 74.176 HDTV 1080I

8 1920*1080 33.75 60.00 74.25 HDTV 1080I

9 1920*1080 67.432 59.94 148.352 HDTV 1080P

10 1920*1080 67.50 60.00 148.50 HDTV 1080P

5.2. HDMI Input (PC/DTV)

No. Resolution H-freq(kHz) V-freq.(kHz) Pixel clock(MHz) Proposed Remark

HDMI-PC DDC

1 640*350 @70Hz 31.46 70.09 25.17 EGA X

2 720*400 @70Hz 31.46 70.08 28.32 DOS O

3 640*480 @60Hz 31.46 59.94 25.17 VESA(VGA) O

4 800*600 @60Hz 37.87 60.31 40.00 VESA(SVGA) O

5 1024*768 @60Hz 48.36 60.00 65.00 VESA(XGA) O

6 1152*864 @60Hz 54.34 60.05 80.002 VESA O

7 1280*1024 @60Hz 63.98 60.02 108.0 VESA (SXGA) O FHD only

8 1360*768 @60Hz 47.71 60.01 85.50 VESA (WXGA) O

9 1920*1080 @60Hz 67.5 60.00 148.5 WUXGA(CEA 861D) O FHD only

No. Resolution H-freq(kHz) V-freq.(kHz) Pixel clock(MHz) Proposed

DTV

1 640*480 31.46 59.94 25.125 SDTV 480P

2 640*480 31.50 60.00 25.125 SDTV 480P

5 720*480 31.47 59.94 27.00 SDTV 480P

6 720*480 31.50 60.00 27.027 SDTV 480P

7 1280*720 44.96 59.94 74.176 HDTV 720P

8 1280*720 45.00 60.00 74.25 HDTV 720P

9 1920*1080 33.72 59.94 74.176 HDTV 1080I

10 1920*1080 33.75 60.00 74.25 HDTV 1080I

11 1920*1080 26.97 23.97 74.176 HDTV 1080P

12 1920*1080 27.00 24.00 74.25 HDTV 1080P

13 1920*1080 33.71 29.97 74.176 HDTV 1080P

14 1920*1080 33.75 30.00 74.25 HDTV 1080P

15 1920*1080 67.43 59.94 148.352 HDTV 1080P

16 1920*1080 67.50 60.00 148.50 HDTV 1080P

- 7 -

SOFTWARE UPDATE

1. USB

(1) Insert the USB memory Stick to the USB port (2) Automatically detect the SW Version and show the below

message

(3) Click [YES]: initiate the download and install of the update.

2. NSU

(This Function is needed to connect to the internet)

(1) Menu -> All Settings -> General -> About This TV

(2) Click [CHEK FOR UPDATES] : system check newest

version

(4) Click [Check Now]: move to “About This TV” page for

update

(5) TV is updating

(6) After finished the update, below Pop-up appear

(7) Click [Yes] : TV will be DC OFF -> ON (8) After TV turned on, Check the updated SW Version and

Tool Option

(3) Click [DOWNLOAD AND INSTALL] (4) TV is updating

(5) After finished the update, below Pop-up appear

(6) Turn OFF the TV and On. Check the updated SW Version

and Tool Option

- 8 -

IC101

M2R

Audio AMP

(DTA-2010)

Digital Demod

DIF (+/-)

Sub Micom

(R5F100GEAFB)

IR / KEY

IR

KEY

I2C

HDMI

MUX

LVDS

USB

SPDIF OUT

ETHERNET

USB1

USB2

OCP

1.5A

OCP

1.5A

HDMI1

HDMI2

(ARC)

REAR

OPTIC

LAN

51P(FHD)

DDR3 2133 4Gb x16

X_TAL

24MHz

WIFI Only

SUB

ASSY

USB_WIFI

DDR3 2133 4Gb x16

HDMI3

SIDE

CVBS/YPbPr

AV/COMP

REAR

EEPROM (256Kb)

eMMC 5.0 (4GB)

I2S

I2C

Analog Demod

1866

CVBS/SIF

X_TAL

32.768kHz

30P(HD)

BLOCK DIAGRAM

- 9 -

EXPLODED VIEW

200

400

800

540

521

120

820

LV1

530

900

121

500

570

571

AR1

700

A10

ARC1

IMPORTANT SAFETY NOTICE

Many electrical and mechanical parts in this chassis have special safety-related characteristics. These parts are identified by in the EXPLODED VIEW. It is essential that these special safety parts should be replaced with the same components as recommended in this manual to prevent Shock, Fire, or other Hazards. Do not modify the original design without permission of manufacturer.

- 10 -

DISASSEMBLY GUIDE

[Fig.1]

[Fig.2]

3

1

3

2

3

4

5

- 11 -

B

A

6

B

A

6

8

7

[Fig.3]

[Fig.4]

6

8

9

8

- 12 -

10

12

11

13

14 14

15

[Fig.5]

[Fig.6]

- 13 -

16 17

18

19

20

[Fig.7]

[Fig.8]

- 14 -

TROUBLE SHOOTING GUIDE

LGE Internal Use Only

Contents of Standard Repair Process

LGE Internal Use Only

No. Error symptom (High category) Error symptom (Mid category) Page Remarks

1

2 No video/No audio 2

3 Picture broken/ Freezing 3

4 Color error 4

5

6

7

8

9 Wrecked audio/discontinuation/noise 9

10

11

A. Video error

B. Power error

C. Audio error

No video/Normal audio 1

Vertical/Horizontal bar, residual image, light spot, external device color error

No power 6

Off when on, off while viewing, power

auto on/off

No audio/Normal video 8

Remote control & Local switch checking

MR15 operating checking 11

5

7

10

12

13 Camera operating checking 13

14 External device recognition error 14

15 E. Noise Circuit noise, mechanical noise 15

16 F. Exterior error Exterior defect 16

D. Function error

First of all, Check whether there is SVC Bulletin in GSCS System for these model.

Wifi operating checking 12

Standard Repair Process

LGE Internal Use Only

symptom

Error

A. Video error

No video/ Normal audio

Established

date

Revised date

First of all, Check whether all of cables between board is inserted properly or not.

(Main B/D↔ Power B/D, LVDS Cable, Speaker Cable, IR B/D Cable,,,)

☞A18 ☞A1

N

Y

Check Back Light On with naked eye

☞A18

Check Power Board 13V output

On

Normal voltage

N

Repair Power Board or parts

Y N Check Power

Board 13V etc.

Replace Inverter

Y

or module

Normal

voltage

N

Repair Power Board or parts

End

Y

Replace T-con/Main Board or module

No video Normal audio

Normal

audio

Move to No video/No audio

1/16

※Precaution

Always check & record S/W Version and White Balance value before replacing the Main Board

☞A4 & A2

Replace Main Board

1

Re-enter White Balance value

Standard Repair Process

LGE Internal Use Only

symptom

Error

A. Video error

No video/ No audio

Established

date

Revised date

2/16

☞A18

No Video/ No audio

Check various voltages of Power Board (13V…)

Normal

voltage?

N

Replace Power Board and repair parts

Y

Check and replace MAIN B/D

End

2

Standard Repair Process

LGE Internal Use Only

☞ A3

Check RF Signal level

Normal Signal?

N

Check RF Cable

Connection

1. Reconnection

Normal

Picture?

Y

Close

Y

N

Error

symptom

A. Video error

Picture broken/ Freezing

Established

date

Revised date

. By using Digital signal level meter . By using Diagnostics menu on OSD

( Setting→ Channels→ Channel Tuning→ Manual Tuning → Check the Signal )

- Signal strength (Normal : over 50%)

- Signal Quality (Normal: over 50%)

Check whether other equipments have problem or not.

(By connecting RF Cable at other equipment)

→ DVD Player ,Set-Top-Box, Different maker TV etc

☞ A4

Normal

Picture?

Contact with signal distributor

or broadcaster (Cable or Air)

Y

S/W Version

N

Check

SVC

Bulletin?

S/W Upgrade

Normal

Picture?

Y

N

Y

N

Check

Tuner soldering

N

Replace

Main B/D

3/16

Y

Close

3

Standard Repair Process

LGE Internal Use Only

☞A6

Check color by input

-External Input

-COMPONENT

-AV

-HDMI

☞A8

Check Test pattern

Error

symptom

Color

error?

Check error color input mode

☞ A7

※ Check

and replace

Y

Link Cable (LVDS) and

N

contact condition

External Input/

Component

error

A. Video error

Color error

Color

error?

Check external device and cable

N

Y

Replace Main B/D

Established

date

Revised date

External device

/Cable

normal

N

Color

error?

End

Y

4/16

Y

Replace module

N

Replace Main/T-con B/D

HDMI error

Check external

device and cable

4

Request repair

for external

device/cable

N

External device

/Cable

normal

Y

Replace Main/T-con B/D

Standard Repair Process

LGE Internal Use Only

symptom

Vertical / Horizontal bar, residual image,

Error

A. Video error

light spot, external device color error

Vertical/Horizontal bar, residual image, light spot

☞A6

Check color condition by input

-External Input

-Component

-HDMI

☞A8

Check Test pattern

Screen

normal?

N

Replace module

Check external

Y

device connection condition

Normal?

N

Request repair

for external device

External device screen error-Color error

Check screen condition by input

Check S/W Version

Check

version

Y

S/W Upgrade

N

-External Input

-Component

-HDMI/DVI

Component

☞ A7

Check and

Y

replace Link Cable

External

Input

error

Established

date

Revised date

Screen

normal?

N

Replace Main/T-con B/D

For LGD panel

Y

End

Replace Main B/D

For other panel

Connect other external device and cable

(Check normal operation of External Input, Component, RGB and HDMI/DVI by connecting Jig, pattern Generator ,Set-top Box etc.

Screen

normal?

Request repair for external device

N

Y

5/16

Replace Module

N

Screen

normal?

Y

End

Replace Main/T-con B/D

Normal

screen?

End

N

Y

5

HDMI/

DVI

Connect other external device and cable

(Check normal operation of External Input, Component, RGB and HDMI/DVI by connecting Jig, pattern

Generator ,Set-top Box etc.

Y

Screen

normal?

N

Replace Main /T-con B/D

Standard Repair Process

LGE Internal Use Only

symptom

☞A17

Check Logo LED

. Stand-By: Red or Turn On . Operating: Turn Off

Power LED

Check Power cord was inserted properly

Error

On?

N

Normal?

Y

Close

Y

Check ST-BY 7.8V

☞A18

B. Power error

No power

DC Power on by pressing Power Key On Remote control

Normal

voltage?

Y

N

Established

date

Revised date

☞A18

Y

N

Check Power On ‘”High”

Replace Main B/D

Normal

operation?

☞A18

Measure voltage of each output of Power B/D

N

Y

Replace Main B/D

Normal

voltage?

Replace Power B/D

OK?

Y

6/16

Replace

Power B/D

Replace Power B/D

6

Standard Repair Process

LGE Internal Use Only

Check A/C cord

Error

symptom

Fix A/C cord

Error?

Y

B. Power error

Off when on, off while viewing, power auto on/off

☞A19

N

Check Power Off Mode

☞A18

(If Power Off mode is not displayed) Check Power B/D voltage

※ Caution Check and fix exterior of Power B/D Part

Abnormal

Established

date

Revised date

CPU

1

Normal

voltage?

Replace Power B/D

Replace Main B/D

Y

N

Replace Power B/D

Replace Main B/D

Normal?

N

7/16

Y

End

* Please refer to the all cases which can be displayed on power off mode.

Status Power off List Explanation

"POWEROFF_REMOTEKEY" Power off by REMOTE CONTROL

"POWEROFF_OFFTIMER" Power off by OFF TIMER

"POWEROFF_SLEEPTIMER" Power off by SLEEP TIMER "POWEROFF_INSTOP" Power off by INSTOP KEY "POWEROFF_AUTOOFF" Power off by AUTO OFF

Normal

Abnormal

"POWEROFF_ONTIMER" Power off by ON TIMER "POWEROFF_RS232C" Power off by RS232C "POWEROFF_RESREC" Power off by Reservated Record "POWEROFF_RECEND" Power off by End of Recording "POWEROFF_SWDOWN" Power off by S/W Download

"POWEROFF_UNKNOWN" Power off by unknown status except listed case

"POWEROFF_ABNORMAL1" Power off by abnormal status except CPU trouble "POWEROFF_CPUABNORMAL" Power off by CPU Abnormal

7

Standard Repair Process

LGE Internal Use Only

No audio Screen normal

Error

C. Audio error

symptom

No audio/ Normal video

☞A20 ☞A21+A18

Check user menu > Speaker off

Off

Y

Cancel OFF

Check Main B+

N

13V of Power Board

Established

date

Revised date

Normal voltage

Replace Power Board and repair parts

Y

N

8/16

Check Speaker disconnection

Disconnection

Y

Replace Speaker

8

N

Replace MAIN Board

End

Standard Repair Process

LGE Internal Use Only

Check input signal

-RF

-External Input

signal

Error

symptom

C. Audio error

Wrecked audio/ discontinuation/noise

Established

date

Revised date

→ abnormal audio/discontinuation/noise is same after “Check input signal” compared to No audio

☞A21+A18

Check audio B+ Voltage (13V)

Y

Normal

voltage?

N

Replace Power B/D

Replace Main B/D

N

Y

Signal

normal?

N

Y

(When RF signal is not received)

Request repair to external

cable/ANT provider

(In case of

External Input

signal error) Check and fix external device

Wrecked audio/

Discontinuation/

Noise for

all audio

Wrecked audio/

Discontinuation/

Noise only

for D-TV

Wrecked audio/

Discontinuation/

Noise only

for Analog

Wrecked audio/

Discontinuation/

Noise only

for External Input

Check and replace speaker and connector

Replace Main B/D

Connect and check other external device

Normal

audio?

9/16

End

Check and fix external device

9

Standard Repair Process

LGE Internal Use Only

Error

symptom

D. Function error

Remote control & Local switch checking

1. Remote control(R/C) operating error

☞A22

Check R/C itself

Operation

Check R/C Operating

When turn off light

in room

If R/C operate,

Explain the customer

cause is interference

from light in room.

operating?

Normal

Y

N

Check & Replace

Baterry of R/C

Normal

operating?

Replace R/C

Check & Repair Cable connection Connector solder

Y

Close

N

Normal

operating?

Y

Close

☞A22

N

Check B+ 13V

On Main B/D

Established

date

Revised date

☞A22

N

Y

Check IR

Output signal

Normal

Voltage?

☞A18

Check 13v on Power B/D

Replace Power B/D or

Replace Main B/D

(Power B/D don’t have problem)

10/16

Replace

Main B/D

Normal

Signal?

N

Repair/Replace

IR B/D

Y

10

Standard Repair Process

LGE Internal Use Only

Error

symptom

3.Wifi operating error

☞A4

Check the

INSTART menu

Wi-Fi Mac value

is “NG”?

☞A24

Check & Repair

Y

Wifi cable

connection

☞A4

Wi-Fi Mac value

is “NG”?

D. Function error

Wifi operating checking

☞A24

N

Check the Wifi wafer

N

Close

1pin

Established

Revised date

Normal

Voltage?

Y

Close

date

N

12/16

Replace

Main B/D

Change the Wifi

Y

assy

12

Standard Repair Process

LGE Internal Use Only

Check input signal

symptom

Signal

input?

N

Check technical

Y

information

- Fix information

- S/W Version

Check and fix

external device/cable

Error

D. Function error

External device recognition error

Technical

information?

Fix in

accordance

with technical

information

N

Y

External Input and

Component

Recognition error

DVI, Optical

Recognition error

Established

Revised date

HDMI/

date

14/16

Replace Main B/D

14

Standard Repair Process

LGE Internal Use Only

Identify nose type

Error

symptom

Circuit

noise

Mechanical

noise

※ Mechanical noise is a natural phenomenon, and apply the 1st level description. When the customer does not agree, apply the process by stage. ※ Describe the basis of the description in “Part related to nose” in the Owner’s Manual.

Check location of noise

Circuit noise, mechanical noise

E. Noise

Replace PSU

※ When the nose is severe, replace the module (For models with fix information, upgrade the

S/W or provide the description)

OR

※ If there is a “Tak Tak” noise from the cabinet, refer to the KMS fix information and then proceed as shown in the solution manual (For models without any fix information, provide the description)

Established

date

Revised date

15/16

15

Standard Repair Process

LGE Internal Use Only

Error

symptom

Zoom part with exterior damage

Module

damage

Cabinet

damage

Remote

control

damage

F. Exterior defect

Exterior defect

Replace module

Replace cabinet

Replace remote control

Established

date

Revised date

16/16

Stand

dent

Replace stand

16

Contents of Standard Repair Process Detail Technical Manual

LGE Internal Use Only

No. Error symptom Content Page Remarks

1

A. Video error_ No video/Normal audio

2 Check White Balance value A2

4

A. Video error_ video error /Video lag/stop

5 Version checking method A4

6 Tuner Checking Part A5

A. Video error _Vertical/Horizontal bar,

7

residual image, light spot

8

A. Video error_ Color error

9 Adjustment Test pattern - ADJ Key A8

10

11 Exchange Main Board (2) A-2/5

12 Exchange Power Board (PSU) A-3/5

Defected Type caused by T-Con/ Inverter/ Module

13 Exchange Module (1) A-4/5

Check LCD back light with naked eye A1

TUNER input signal strength checking method

Connection diagram A6

Check Link Cable (EPI) reconnection condition

Exchange Main Board (1) A-1/5

A3

A7

14 Exchange Module (2) A-5/5

Continue to the next page

Contents of Standard Repair Process Detail Technical Manual

LGE Internal Use Only

Continued from previous page

No. Error symptom Content Page Remarks

16

B. Power error_ No power

17 Check power input Voltage & ST-BY 3.5V A18

18

19

20

21

22 Wifi operation checking method A23

B. Power error_Off when on, off

while viewing

C. Audio error_ No audio/Normal video

D. Function error

Check front display LED A17

POWER OFF MODE checking method A19

Checking method in menu when there is no audio

Voltage and speaker checking method when there is no audio

Remote control operation checking method

A20

A21

A22

Standard Repair Process Detail Technical Manual

LGE Internal Use Only

Error

symptom

Content

A. Video error_No video/Normal audio

Check LCD back light with naked eye

Established

date

Revised

date

A1

After turning on the power and disassembling the case, check with the naked eye, whether you can see light from locations.

A1

Standard Repair Process Detail Technical Manual

LGE Internal Use Only

Error

symptom

Content

A. Video error_No video/Normal audio

Check White Balance value

Established

date

Revised

date

A2

Entry method

1. Press the ADJ button on the remote control for adjustment.

2. Enter into White Balance of item 10.

3. After recording the R, G, B (GAIN, Cut) value of Color Temp (Cool/Medium/Warm), re-enter the value after replacing the MAIN BOARD.

A2

Standard Repair Process Detail Technical Manual

LGE Internal Use Only

Error

symptom

Content

A. Video error_Video error, video lag/stop

TUNER input signal strength checking method

Established

date

Revised

date

All Setting  Channels  Channel Tuning Manual Tuning

A3

When the signal is strong,

use the attenuator (-10dB, -

15dB, -20dB etc.)

A3

Standard Repair Process Detail Technical Manual

LGE Internal Use Only

Error

symptom

Content

A. Video error_Video error, video lag/stop

Version checking method

Established

date

Revised

date

A4

1. Checking method for remote control for adjustment

Version

Press the IN-START with the remote control for adjustment

A4

Standard Repair Process Detail Technical Manual

LGE Internal Use Only

Error

symptom

Content

A. Video error_Video error, video lag/stop

TUNER checking part

Established

date

Revised

date

A5

Checking method:

1. Check the signal strength or check whether the screen is normal when the external device is connected.

2. After measuring each voltage from power supply, finally replace the MAIN BOARD.

A5

Standard Repair Process Detail Technical Manual

LGE Internal Use Only

Error

symptom

Content

A. Video error _Vertical/Horizontal bar,

residual image, light spot

Connection diagram (1)

Established

date

Revised

date

A6

As the part connecting to the external input, check the screen condition by signal

A6

Standard Repair Process Detail Technical Manual

LGE Internal Use Only

Error

symptom

Content

Check Link Cable(VX1) reconnection condition

A. Video error_Color error

Established

date

Revised

date

A7

Check the contact condition of the Link Cable, especially dust or mis insertion.

A7

Standard Repair Process Detail Technical Manual

LGE Internal Use Only

Error

symptom

Content

A. Video error_Color error

Adjustment Test pattern - ADJ Key

Established

date

Revised

date

A8

You can view 6 types of patterns using the ADJ Key Checking item : 1. Defective pixel 2. Residual image 3. MODULE error (ADD-BAR,SCAN BAR..)

4.Video error (Classification of MODULE or Main-B/D!)

A8

Appendix : Exchange Main Board (1)

LGE Internal Use Only

Solder defect, CNT Broken

T-Con Defect, CNT Broken

Solder defect, CNT Broken

T-Con Defect, CNT Broken

Solder defect, CNT Broken

Abnormal Power Section

Solder defect, Short/Crack

Abnormal Power Section Solder defect, Short/Crack

A - 1/5

Appendix : Exchange Main Board (2)

LGE Internal Use Only

Abnormal Power Section

Solder defect, Short/Crack

Abnormal Power Section

Fuse Open, Abnormal power section

Solder defect, Short/Crack

Abnormal Display

GRADATION

Noise

A - 2/5

GRADATION

Appendix : Exchange Power Board (PSU)

LGE Internal Use Only

No Light

Dim Light

No picture/Sound Ok

A - 3/5

Appendix : Exchange the Module (1)

LGE Internal Use Only

Press damage Press damage

Crosstalk Crosstalk

Press damage

Un-repairable Cases In this case please exchange the module.

A - 4/5

Appendix : Exchange the Module (2)

LGE Internal Use Only

Vertical Block

Source TAB IC Defect

Horizontal Block

Gate TAB IC Defect

Vertical Line

Source TAB IC Defect

Horizontal Block

Gate TAB IC Defect

Vertical Block

Source TAB IC Defect

Horizontal line

Gate TAB IC Defect Gate TAB IC Defect

Un-repairable Cases In this case please exchange the module.

Horizontal Block

Gate TAB IC Defect

A - 5/5

Standard Repair Process Detail Technical Manual

LGE Internal Use Only

Error

symptom

Content

ST-BY condition: On or Off Power ON condition: Turn Off

B. Power error _No power

Check front Power Indicator

Established

date

Revised

date

A17

Standard Repair Process Detail Technical Manual

Backlight

Forward Voltage

Symbol

Values

Unit

Min

Typ

Max

43LJ5500-UA

Vf

-

65.94

72.45

Vdc

49LJ5500-UA

Vf

-

113.4

122.4

Vdc

55LJ5500-UA

Vf

125.2

127.2

142.4

Vdc

LGE Internal Use Only

Error

symptom

Content

B. Power error _No power

Check power input voltage and ST-BY 3.5V

Check the DC 13.2V.

Established

date

Revised

date

A18

Standard Repair Process Detail Technical Manual

LGE Internal Use Only

Error

symptom

Content

B. Power error _Off when on, off whiling viewing

POWER OFF MODE checking method

Established

date

Revised

date

A19

Entry method

1. Press the IN-START button of the remote

control for adjustment

2. Check the entry into adjustment item 3

A19

Standard Repair Process Detail Technical Manual

LGE Internal Use Only

Error

symptom

Content

C. Audio error_No audio/Normal video

Checking method in menu when there is no audio

Established

date

Revised

date

A20

Checking method

1. Press the Setting button on the remote control

2. Select the Sound function of the Menu

3. Select the Sound Out

4. Select TV Speaker

A20

Standard Repair Process Detail Technical Manual

1

SPK_R-

2

SPK_R+

3

SPK_L-

4

SPK_L+

LGE Internal Use Only

Error

symptom

Content

C. Audio error_No audio/Normal video

Voltage and speaker checking method when there is no audio

Established

date

Revised

date

A21

Checking order when there is no audio

1.Check the contact condition of or 13.2V connector of Main Board

2. Measure the 13.2V input voltage supplied from Power Board (If there is no input voltage, remove and check the connector)

3.Connect the tester RX1 to the speaker terminal and if you hear the Chik Chik sound when you touch the

GND and output terminal, the speaker is normal.

A21

Standard Repair Process Detail Technical Manual

LGE Internal Use Only

Error

symptom

Content

Remote control operation checking method

D. Function error

Established

date

Revised

date

A22

① IR & EYE Sensor

IR & LOGO light Rear

IR

LED

Eye

②

Checking order to check remote control

Checking order

1.Check IR cable condition between IR & Main board.( Check picture number① and ②)

2.Check the standby 3.5V on the terminal 22 pin (③)

3.AS checking the Pre-Amp(IR LED light) , the power is in ON condition, an Analog Tester needle should move slowly, otherwise, it’s defective.

③

P4001

1 +3.4V_WIFI

2 WIFI_DM 3 WIFI_DP 4 GND 5 WOL/WIFI_POWER_ON 6 +3.4V_WIFI 7 NC 8 GND

9 NC 10 NC 11 GND 12 GND 13 NC 14 NC 15 NC 16 I2C_SDA_EYE 17 I2C_SCL_EYE 18 GND 19 IR

20 LED_R

21 GND 22 +3.4V_ST 23 KEY2 24 KEY1 25 GND

A22

Standard Repair Process Detail Technical Manual

LGE Internal Use Only

Error

symptom

Content

Wifi operation checking method

D. Function error

Established

date

Revised

date

A23

WiFi AC only Model

① Wifi Assy Front

② Wifi Assy Rear

②

Checking order to check WiFi

Checking order

1.Check IR/Wifi cable condition between Wifi assy & Main board.

2.Check the 3.5V on the terminal

③

P4001

1 +3.4V_WIFI

2 WIFI_DM

3 WIFI_DP

4 GND

5 WOL/WIFI_POWER_ON

6 +3.4V_WIFI

7 NC

8 GND

9 NC 10 NC 11 GND 12 GND 13 NC 14 NC 15 NC 16 I2C_SDA_EYE 17 I2C_SCL_EYE 18 GND 19 IR

20 LED_R

21 GND 22 +3.4V_ST 23 KEY2 24 KEY1 25 GND

A23

LG 43LJ553T, 43LJ55 Schematic