LG 43LJ55 U Series Service Manual
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LG 43LJ55 U Series Service Manual

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LED TV
SERVICE MANUAL
CHASSIS : LA75M
MODEL : 43LJ55**
CAUTION
BEFORE SERVICING THE CHASSIS, READ THE SAFETY PRECAUTIONS IN THIS MANUAL.
P/NO : MFL69963002 (1703-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.
Copyright © 2017 LG Electronics Inc. All rights reserved.
Only training and service purposes
CONFIDENTIAL
43LJ55**-U*

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Summary of Contents for LG 43LJ55 U Series

  • 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 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 -...

  • Page 3: Safety Precautions

    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.

  • Page 4: Servicing Precautions

    SERVICING PRECAUTIONS CAUTION: Before servicing receivers covered by this service 2. After removing an electrical assembly equipped with ES manual and its supplements and addenda, read and follow the devices, place the assembly on a conductive surface such as SAFETY PRECAUTIONS on page 3 of this publication. aluminum foil, to prevent electrostatic charge buildup or expo- NOTE: If unforeseen circumstances create conflict between the sure of the assembly.
  • Page 5 IC Remove/Replacement 3. Solder the connections. Some chassis circuit boards have slotted holes (oblong) through CAUTION: Maintain original spacing between the replaced which the IC leads are inserted and then bent flat against the cir- component and adjacent components and the circuit board to cuit foil.

  • Page 6: Specification

    SPECIFICATION NOTE : Specifications and others are subject to change without notice for improvement. 1. Application range 3. Test method This specification is applied to the LED TV used LA75M (1) Performance: LGE TV test method followed chassis. (2) Demanded other specification - Safety : CE, IEC specification - EMC : CE, IEC 2.
  • Page 7 5. External Input Support Format 5.1. Component 2D input(Y, C Resolution H-freq(kHz) V-freq.(kHz) Pixel clock(MHz) Proposed 720*480 15.73 59.94 13.50 SDTV ,DVD 480I 720*480 15.75 60.00 13.5135 SDTV ,DVD 480I 720*480 31.47 59.94 27.00 SDTV 480P 720*480 31.50 60.00 27.027 SDTV 480P 1280*720 44.96...

  • Page 8: Software Update

    SOFTWARE UPDATE 1. USB 2. NSU (1) Insert the USB memory Stick to the USB port (This Function is needed to connect to the internet) (2) Automatically detect the SW Version and show the below message (1) Menu -> All Settings -> General -> About This TV (3) Click [YES]: initiate the download and install of the update.

  • Page 9: Block Diagram

    BLOCK DIAGRAM - 9 -...

  • Page 10: Exploded View

    EXPLODED VIEW 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.

  • Page 11: Disassembly Guide

    DISASSEMBLY GUIDE [Fig.1] [Fig.2] - 11 -...
  • Page 12 [Fig.3] [Fig.4] - 12 -...
  • Page 13 [Fig.5] [Fig.6] - 13 -...
  • Page 14 [Fig.7] [Fig.8] - 14 -...

  • Page 15: Troubleshooting Guide

    TROUBLE SHOOTING GUIDE LGE Internal Use Only Copyright 2017 LG Electronics Inc. All rights reserved. Only for training and service purposes...
  • Page 16 Circuit noise, mechanical noise F. Exterior error Exterior defect First of all, Check whether there is SVC Bulletin in GSCS System for these model. LGE Internal Use Only Copyright 2017 LG Electronics Inc. All rights reserved. Only for training and service purposes...
  • Page 17 Always check & record S/W Version and White Replace Main Board Re-enter White Balance value Balance value before replacing the Main Board LGE Internal Use Only Copyright 2017 LG Electronics Inc. All rights reserved. Only for training and service purposes...
  • Page 18 Check and No Video/ Normal voltages of Power replace No audio voltage? Board (13V…) MAIN B/D Replace Power Board and repair parts LGE Internal Use Only Copyright 2017 LG Electronics Inc. All rights reserved. Only for training and service purposes...
  • Page 19 1. Reconnection S/W Upgrade Normal Contact with signal distributor or broadcaster (Cable or Air) Picture? Normal Picture? Replace Main B/D Close Close LGE Internal Use Only Copyright 2017 LG Electronics Inc. All rights reserved. Only for training and service purposes...
  • Page 20 Request repair for external device/cable Check external External device device and Replace Main/T-con B/D HDMI /Cable cable error normal LGE Internal Use Only Copyright 2017 LG Electronics Inc. All rights reserved. Only for training and service purposes...
  • Page 21 Screen (Check normal operation of normal? Main /T-con External Input, Component, RGB and HDMI/DVI by connecting Jig, pattern Generator ,Set-top Box etc. LGE Internal Use Only Copyright 2017 LG Electronics Inc. All rights reserved. Only for training and service purposes...
  • Page 22 Measure voltage of each output of Power B/D Normal? Normal Replace Main B/D voltage? Normal Check ST-BY 7.8V Close voltage? ☞A18 Replace Power B/D Replace Power LGE Internal Use Only Copyright 2017 LG Electronics Inc. All rights reserved. Only for training and service purposes...
  • Page 23 Power off by unknown status except listed case "POWEROFF_ABNORMAL1" Power off by abnormal status except CPU trouble Abnormal "POWEROFF_CPUABNORMAL" Power off by CPU Abnormal LGE Internal Use Only Copyright 2017 LG Electronics Inc. All rights reserved. Only for training and service purposes...
  • Page 24 Screen normal voltage Speaker off Board Cancel OFF Replace Power Board and repair parts Check Replace MAIN Board Disconnection Speaker disconnection Replace Speaker LGE Internal Use Only Copyright 2017 LG Electronics Inc. All rights reserved. Only for training and service purposes...
  • Page 25 Connect and check Normal External Input other external audio? signal error) device Check and fix external device Check and fix external device LGE Internal Use Only Copyright 2017 LG Electronics Inc. All rights reserved. Only for training and service purposes...
  • Page 26 (Power B/D don’t have problem) If R/C operate, Normal Close Explain the customer operating? cause is interference from light in room. Replace R/C LGE Internal Use Only Copyright 2017 LG Electronics Inc. All rights reserved. Only for training and service purposes...
  • Page 27 1pin Main B/D ☞A24 Close Check & Repair Wifi cable connection ☞A4 Wi-Fi Mac value is “NG”? Close Change the Wifi assy LGE Internal Use Only Copyright 2017 LG Electronics Inc. All rights reserved. Only for training and service purposes...
  • Page 28 - S/W Version HDMI/ Check and fix Replace Main B/D DVI, Optical Fix in external device/cable Recognition error accordance with technical information LGE Internal Use Only Copyright 2017 LG Electronics Inc. All rights reserved. Only for training and service purposes...
  • Page 29 “Part related to nose” in the Owner’s then proceed as shown in the solution manual Manual. (For models without any fix information, provide the description) LGE Internal Use Only Copyright 2017 LG Electronics Inc. All rights reserved. Only for training and service purposes...
  • Page 30 Zoom part with Module Replace module exterior damage damage Cabinet Replace cabinet damage Remote control Replace remote control damage Stand Replace stand dent LGE Internal Use Only Copyright 2017 LG Electronics Inc. All rights reserved. Only for training and service purposes...
  • Page 31 Defected Type caused by T-Con/ Exchange Power Board (PSU) A-3/5 Inverter/ Module Exchange Module (1) A-4/5 Exchange Module (2) A-5/5 Continue to the next page LGE Internal Use Only Copyright 2017 LG Electronics Inc. All rights reserved. Only for training and service purposes...
  • Page 32 Voltage and speaker checking method when there is no audio Remote control operation checking method D. Function error Wifi operation checking method LGE Internal Use Only Copyright 2017 LG Electronics Inc. All rights reserved. Only for training and service purposes...
  • Page 33 After turning on the power and disassembling the case, check with the naked eye, whether you can see light from locations. LGE Internal Use Only Copyright 2017 LG Electronics Inc. All rights reserved. Only for training and service purposes...
  • Page 34 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. LGE Internal Use Only Copyright 2017 LG Electronics Inc. All rights reserved. Only for training and service purposes...
  • Page 35  All Setting  Channels Channel Tuning Manual Tuning When the signal is strong, use the attenuator (-10dB, - 15dB, -20dB etc.) LGE Internal Use Only Copyright 2017 LG Electronics Inc. All rights reserved. Only for training and service purposes...
  • Page 36 Content date <ALL MODELS> 1. Checking method for remote control for adjustment Version Press the IN-START with the remote control for adjustment LGE Internal Use Only Copyright 2017 LG Electronics Inc. All rights reserved. Only for training and service purposes...
  • Page 37 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. LGE Internal Use Only Copyright 2017 LG Electronics Inc. All rights reserved. Only for training and service purposes...
  • Page 38 Revised Content Connection diagram (1) date <ALL MODELS> As the part connecting to the external input, check the screen condition by signal LGE Internal Use Only Copyright 2017 LG Electronics Inc. All rights reserved. Only for training and service purposes...
  • Page 39 Content Check Link Cable(VX1) reconnection condition date <ALL MODELS> Check the contact condition of the Link Cable, especially dust or mis insertion. LGE Internal Use Only Copyright 2017 LG Electronics Inc. All rights reserved. Only for training and service purposes...
  • Page 40 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!) LGE Internal Use Only Copyright 2017 LG Electronics Inc. All rights reserved. Only for training and service purposes...
  • Page 41 Solder defect, CNT Broken Solder defect, CNT Broken T-Con Defect, CNT Broken Abnormal Power Section Solder defect, Short/Crack Solder defect, Short/Crack A - 1/5 LGE Internal Use Only Copyright 2017 LG Electronics Inc. All rights reserved. Only for training and service purposes...
  • Page 42 Abnormal Power Section Solder defect, Short/Crack Abnormal Display Fuse Open, Abnormal power section Solder defect, Short/Crack Noise GRADATION GRADATION A - 2/5 LGE Internal Use Only Copyright 2017 LG Electronics Inc. All rights reserved. Only for training and service purposes...
  • Page 43 Appendix : Exchange Power Board (PSU) No Light Dim Light Dim Light Dim Light No picture/Sound Ok A - 3/5 LGE Internal Use Only Copyright 2017 LG Electronics Inc. All rights reserved. Only for training and service purposes...
  • Page 44 Appendix : Exchange the Module (1) Press damage Press damage Press damage Un-repairable Cases In this case please exchange the module. Crosstalk Crosstalk A - 4/5 LGE Internal Use Only Copyright 2017 LG Electronics Inc. All rights reserved. Only for training and service purposes...
  • Page 45 Un-repairable Cases In this case please exchange the module. Horizontal Block Gate TAB IC Defect Gate TAB IC Defect A - 5/5 LGE Internal Use Only Copyright 2017 LG Electronics Inc. All rights reserved. Only for training and service purposes...
  • Page 46 B. Power error _No power symptom date Revised Content Check front Power Indicator date ST-BY condition: On or Off Power ON condition: Turn Off LGE Internal Use Only Copyright 2017 LG Electronics Inc. All rights reserved. Only for training and service purposes...
  • Page 47 Check power input voltage and ST-BY 3.5V date Values Backlight Symbol Unit Forward Voltage Check the DC 13.2V. 43LJ5500-UA 65.94 72.45 49LJ5500-UA 113.4 122.4 55LJ5500-UA 125.2 127.2 142.4 LGE Internal Use Only Copyright 2017 LG Electronics Inc. All rights reserved. Only for training and service purposes...
  • Page 48 <ALL MODELS> Entry method 1. Press the IN-START button of the remote control for adjustment 2. Check the entry into adjustment item 3 LGE Internal Use Only Copyright 2017 LG Electronics Inc. All rights reserved. Only for training and service purposes...
  • Page 49 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 LGE Internal Use Only Copyright 2017 LG Electronics Inc. All rights reserved. Only for training and service purposes...
  • Page 50 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. LGE Internal Use Only Copyright 2017 LG Electronics Inc. All rights reserved. Only for training and service purposes...
  • Page 51 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. LGE Internal Use Only Copyright 2017 LG Electronics Inc. All rights reserved. Only for training and service purposes...
  • Page 52 Checking order to check WiFi KEY1 Checking order 1.Check IR/Wifi cable condition between Wifi assy & Main board. 2.Check the 3.5V on the terminal LGE Internal Use Only Copyright 2017 LG Electronics Inc. All rights reserved. Only for training and service purposes...

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