LG 28LJ400B Service Manual

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Easy setup manual (45 pages)

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LED TV

SERVICE MANUAL

CHASSIS :

CAUTION

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

P/NO : MFL70041014 (1802-REV01)

Any reproduction, duplication, distribution (including by way of email, facsimile or other electronic means), publication,

modification, copying or transmission of this Service Manual is STRICTLY PROHIBITED unless you have obtained the prior

written consent of the LG Electronics entity from which you received this Service Manual. The material covered by this

prohibition includes, without limitation, any text, graphics or logos in this Service Manual.

OU70A

MODEL : 28LJ400B

28LJ430B

CONFIDENTIAL

28LJ400B-PU

28LJ430B-PU

Table of Contents

Summary of Contents for LG 28LJ400B

Page 1 Service Manual is STRICTLY PROHIBITED unless you have obtained the prior written consent of the LG Electronics entity from which you received this Service Manual. The material covered by this prohibition includes, without limitation, any text, graphics or logos in this Service Manual.
Page 2: Table Of Contents
SOFTWARE UPDATE PROCEDURE............8 BLOCK DIAGRAM ................. 10 EXPLODED VIEW .................. 12 DISASSEMBLE..................13 TROUBLE SHOOTING GUIDE ..........APPENDIX ADJUSTMENT INSTRUCTION ..........APPENDIX Copyright ⓒ 2017 LG Electronics Inc. All rights reserved. - 2 - Only training and service purposes.
Page 3: Safety Precautions
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. Copyright ⓒ 2017 LG Electronics Inc. All rights reserved. - 3 - Only training and service purposes.
Page 5 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. Copyright ⓒ 2017 LG Electronics Inc. All rights reserved. - 5 - Only training and service purposes.
Page 6: Specification
Bottom : CVBS(Y), Pb, Pr Component + AV posite Input Bottom : Audio L/R HDMI2 Side HDMI Input HDMI1 Bottom Side (USB 2.0) Copyright ⓒ 2017 LG Electronics Inc. All rights reserved. - 6 - Only training and service purposes.
Page 7 60.00 1920*1080p 26.97 23.976 1920*1080p 27.00 24.00 1920*1080p 33.716 29.976 1920*1080p 33.75 30.00 1920*1080p 56.25. 50.00 1920*1080p 67.432 59.94 1920*1080p 67.50 60.00 Copyright ⓒ 2017 LG Electronics Inc. All rights reserved. - 7 - Only training and service purposes.
Page 8: Software Update Procedure
3. Select “YES” button and press “OK” key if you want to update TV software, the update OSD will be displayed. Copyright ⓒ 2017 LG Electronics Inc. All rights reserved. - 8 - Only training and service purposes.
Page 9 Upgrade succeed: The TV will prompt to restart immediately.After restart, The TV will prompt From what version of the TV will be prompted to upgrade to what version. Copyright ⓒ 2017 LG Electronics Inc. All rights reserved. - 9 - ...
Page 10: Block Diagram
SYSTEM FUNCTION BLOCK DIAGRAM FLASH LVDS/miniLVDS DDR3 TPA5733l 128MB USB 2.0 MSD3553 I2C&AGC NTSC/ATSC IR & KEY HDMI1 YPBPR CVBS & Audio IN Copyright ⓒ 2017 LG Electronics Inc. All rights reserved. - 10 - Only training and service purposes.
Page 11 1.15V MSD3553 Tuner TAS5733 DC-DC 700mA 200mA 68mA LC2127 1000mA 1000mA USB2.0 8ohm 5W TAS5733L 200mA 3V3_STB 200mA MSD3553 150mA D-LDO VCC-PANEL POW_EN Copyright ⓒ 2017 LG Electronics Inc. All rights reserved. - 11 - Only training and service purposes.
Page 12: 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. Copyright ⓒ 2017 LG Electronics Inc. All rights reserved. - 12 - Only training and service purposes.
Page 13: Disassemble
1 1 . . Rated regulations : WEEE directive, EPEAT Fig.0 Picture of front side. Fig.1 Put the MNT on the clean vinyl Copyright ⓒ 2017 LG Electronics Inc. All rights reserved. - 13 - Only training and service purposes.
Page 14 Fig.2 unlock the base Screw (4EA,By using screw driver) and disassemble the stand body Fig 3 unlock the back cover Screw (11 EA,By using screw driver) and disassemble the back cover Copyright ⓒ 2017 LG Electronics Inc. All rights reserved. - 14 -...
Page 16 Fig 6 unlock the Power board Screw (4 EA,By using screw driver) and disassemble the Power board Fig 7 Disassemble the LVDS then take it away Copyright ⓒ 2017 LG Electronics Inc. All rights reserved. - 16 - Only training and service purposes.
Page 18 Fig 10 unlock the Hanging Screw (2 EA,By using screw driver) and disassemble the Hanging Bracket Fig11 unlock the PCBA Screw (3 EA,By using screw driver) Copyright ⓒ 2017 LG Electronics Inc. All rights reserved. - 18 - Only training and service purposes.
Page 20 Fig 14 Disassemble Guide Panel and Films. Fig 15 unlock the Light-bar Screw (9 EA,By using screw driver) and disassemble the Reflector Fig 16 Disassemble Light-bar. Copyright ⓒ 2017 LG Electronics Inc. All rights reserved. - 20 - Only training and service purposes.
Page 21 No backlight Exchange Module itself (1) Appendix-1 Appendix: Defected Type caused by T-Con/Module Exchange Module itself (2) Appendix-2 1 1 5 Appendix : ADJUSTMENT INSTRUCTION ADJUSTMENT Appendix-3 Copyright ⓒ 2017 LG Electronics Inc. All rights reserved. Only training and service purposes.
Page 22 5V_M,UL1 for VCC_DDR 3.+1.15V–- check UD1 and peripheral components Repair the abnormal circuit : 1. . 5V_M heck power supply ,and QM32 circuit 2. . CC_DDR–- check UL1 Copyright ⓒ 2017 LG Electronics Inc. All rights reserved. Only training and service purposes.
Page 23 Check if the panel is OK for panel Check if the output circuit from Change panel U1(MSD3553) to the jack is normal Software error or Repair this circuit U1(MSD3553) damage Copyright ⓒ 2017 LG Electronics Inc. All rights reserved. Only training and service purposes.
Page 24 Check if the voltage of panel power supply is normal(depend on panel) Check output signal Check the circuit of QM1 from U1(MSD3553) Change the panel Change U1(MSD3553) or the cable to panel Copyright ⓒ 2017 LG Electronics Inc. All rights reserved. Only training and service purposes.
Page 25 Check if the control circuit between PWM_DIM and PWM/ADJ is normal ? Check if the power supply Repair the circuit for inverter is normal? Check the inverter board Copyright ⓒ 2017 LG Electronics Inc. All rights reserved. Only training and service purposes.
Page 26 Check the output signal to AMP Check the circuit between output jack Check the circuit from AMP to the jack and AMP chip, Change AMP chip Copyright ⓒ 2017 LG Electronics Inc. All rights reserved. Only training and service purposes.
Page 27 Standard Repair Process Established A4-1 Function error 201 . Error date LED TV symptom Revised date TV video error 6 Function Trouble TV video TV can’t search any channel/no picture Check input RF signal Check the RF source Check tuner power Check if IIC work Check power supply circuit Check IIC circuit...
Page 28 Check the signal at the jack Check the signal on the Check the external source Corresponding of U1 Check the circuit from jack to Change U1(MSD3553) U1(MSD3553) Copyright ⓒ 2017 LG Electronics Inc. All rights reserved. Only training and service purposes.
Page 29 AC/DC Output Power convertor filter power amplifier The main IC Screen voltage output and so on Feed back 19V/24V/ LED driver 32V/50V output VCC_Panel PWM_DIM Copyright ⓒ 2017 LG Electronics Inc. All rights reserved. Only training and service purposes.
Page 30 Check if UB101 PIN5 Change damage RB101,RB102 voltage is about 15V resistors open Go to check Main Check the rectifier board Check if output short Change function UB101 Copyright ⓒ 2017 LG Electronics Inc. All rights reserved. Only training and service purposes.
Page 31 Check if UB801 PIN1 voltage is about 12V Check QB801/DB801 damage or not Remove Check Correct short/open Main the LED status Change board cable Change UB801 QB801/DB801 function Copyright ⓒ 2017 LG Electronics Inc. All rights reserved. Only training and service purposes.
Page 32 Appendix : Exchange the Module (1) Press damage Crosstalk Press damage Press damage Crosstalk Un-repairable Cases In this case please exchange the module. Copyright ⓒ 2017 LG Electronics Inc. All rights reserved. Only training and service purposes.
Page 34 9) SYSTEM INFO: System parameter 10) BOARD INIT: Factory reset (Don’t touch) 11) SW UPGRADE: Software upgrade 13) LG SYSTEM INFO: System parameter for LGE（Detail -> 2） 14) LG EZ ADJUST: LG EZ adjust（Detail -> 3） Bin Name:the name of current bin name...
Page 35 Appendix : ADJUSTMENT INSTRUCTION 2. LG SYSTEM INFO LG SYSTEM INFO Display some system parameters, no adjustable items Copyright ⓒ 2017 LG Electronics Inc. All rights reserved. Only training and service purposes.
Page 37 Appendix : ADJUSTMENT INSTRUCTION Output Operation Guide SHIPPING INIT: Press Right key to execute TV initialization, TV will be reset. Copyright ⓒ 2017 LG Electronics Inc. All rights reserved. Only training and service purposes.

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LG 28LJ400B Service Manual

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