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LG 55UN6950 Service Manual
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LG 55UN6950 Service Manual

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LED TV
SERVICE MANUAL
CHASSIS : UAX3E
MODEL : 55UN6950/6951ZUA
55UN6900/7000PUB/55UN7100PUA
55UN6955ZUF
CAUTION
BEFORE SERVICING THE CHASSIS, READ THE SAFETY PRECAUTIONS IN THIS MANUAL.
P/NO : MFL71703814 (2104-REV02)
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 © 2021 LG Electronics Inc. All rights reserved. Only training and service purposes.

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Summary of Contents for LG 55UN6950

  • 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 SOFTWARE UPDATE ................9 BLOCK DIAGRAM ................. 10 EXPLODED VIEW .................. 11 ASSEMBLY / DISASSEMBLY GUIDE ........... 13 TROUBLE SHOOTING GUIDE ..........APPENDIX - 2 - Copyright © LG Electronics Inc. All rights reserved. Only for 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. - 3 - Copyright © LG Electronics Inc. All rights reserved. Only for training and service purposes.

  • Page 4: Servicing Precautions

    - 4 - Copyright © LG Electronics Inc. All rights reserved. Only for 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. - 5 - Copyright © LG Electronics Inc. All rights reserved. Only for training and service purposes.

  • Page 6: Specification

    AV and DVI use same jack ; SPDIF out Optical Audio out Rear (1EA), HeadPhone HeadPhone out USB Input EMF, DivX HD, For SVC (download) JPEG, MP3, DivX HD - 6 - Copyright © LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 7 25.12 SDTV 480P 720*480 31.47 59.94 SDTV 480P 720*480 31.5 27.02 SDTV 480P 720*576 31.25 SDTV 576P 1280*720 44.96 59.94 74.17 HDTV 720P - 7 - Copyright © LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 8 8K Model Only. 7680*4320 1188 8K Model Only. 7680*4320 2376 8K Model Only. 7680*4320 263.74 59.94 2376 8K Model Only. 7680*4320 2376 8K Model Only. - 8 - Copyright © LG Electronics Inc. All rights reserved. Only for training and service purposes.

  • Page 9: Software Update

    (5) After finished the update, below Pop-up appear (6) Turn OFF the TV and On. Check the updated SW Version and Tool Option - 9 - Copyright © LG Electronics Inc. All rights reserved. Only for training and service purposes.

  • Page 10: Block Diagram

    BLOCK DIAGRAM - 10 - Copyright © LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 11 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. - 11 - Copyright © LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 12 EXPLODED VIEW(MODULE) IMPORTANT NOTICE MRC use only * MRC : Module Repair Center - 12 - Copyright © LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 13 It is easy to pull it if you put your finger in the groove. (3) Doing the step (4) at the opposite side also. - 13 - Copyright © LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 14 (Step 4) Case Top Screw disassemble (side screw) and Case Top disassemble * top 7ea / side L 5ea / side R 5ea / down 7ea - 14 - Copyright © LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 15 (Step 7) Optical Sheet disassemble (DS, Prism middle, Prism down, DP) (Step 8) DPS, LED Fixer disassemble & Reflector Sheet disassemble * rotate DPS (6ea) * push LED fixer in back (3ea) - 15 - Copyright © LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 16 2) Press the LED Array on the surface of Cover Bottom. 3) Connect the CNT to the LED Array. * Required LED Array Quantity Inch Q’ty(EA) * Finish the Attached LED Array - 16 - Copyright © LG Electronics Inc. All rights reserved. Only for training and service purposes.

  • Page 17: Troubleshooting Guide

    TROUBLE SHOOTING GUIDE Copyright © 2021 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 18 E. Noise Circuit noise, mechanical noise F. Exterior error Exterior defect First of all, Check whether there is SVC Bulletin in GSCS System for these model. Copyright © 2021 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 19 ☞A4 & A2 Always check & record S/W Version and White Replace Main Board Re-enter White Balance value Balance value before replacing the Main Board Copyright © 2021 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 20 ☞A18 Check various Check and No Video/ voltages of Power Normal replace No audio Board (13.2V…) voltage? MAIN B/D Replace Power Board and repair parts Copyright © 2021 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 21 1. Reconnection 2. Install Booster S/W Upgrade Contact with signal distributor Normal or broadcaster (Cable or Air) Picture? Normal Picture? Replace Main B/D Close Close Copyright © 2021 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 22 Component device/ Cable cable error normal Request repair for external device/cable Check external External HDMI device and Replace Main/T-con B/D device/ Cable error cable normal Copyright © 2021 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 23 Replace screen? HDMI/ Screen (Check normal operation of Main /T-con External Input, Component, normal? RGB and HDMI/DVI by connecting Jig, pattern Generator ,Set-top Box etc. Copyright © 2021 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 24 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 Copyright © 2021 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 25 Error? Normal? Abnormal Check for all 2- phase Replace Power B/D power out Abnormal Fix A/C cord & Outlet and check each 2 phase out Copyright © 2021 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 26 Reboot by SW down load function UNKNOWN No meaning (same as initial value) COMP_END OLED threshold voltage degradation(Compensation) completes. PNWASHDONE Power off by panel noise wash function complited. (OLED) Copyright © 2021 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 27 13.2V of Power Screen normal voltage Speaker off Board Cancel OFF Replace Power Board and repair parts Check Replace MAIN Board Disconnection Speaker disconnection Replace Speaker Copyright © 2021 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 28 (In case of Connect and check Normal External Input other external audio? signal error) device Check and fix external device Check and fix external device Copyright © 2021 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 29 Replace Main B/D (Power B/D don’t have problem) If R/C operate, Normal Close operating? Explain the customer cause is interference from light in room. Replace R/C Copyright © 2021 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 30 RF Receiver ver about 5sec Close is “00.00”? Replace MR20 Close Change the RF Receiver assy * If you conduct the loop at 3times, change the MR20. Copyright © 2021 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 31 1pin Main B/D INSTART menu “NG”? ☞A24 Close Check & Repair Wifi cable connection ☞A4 Wi-Fi Mac value Close is “NG”? Change the Wifi assy Copyright © 2021 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 32 Recognition error - S/W Version HDMI/ Check and fix DVI, Optical Replace Main B/D Fix in Recognition external device/cable accordance error with technical information Copyright © 2021 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 33 “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) Copyright © 2021 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 34 Revised date Zoom part with Module Replace module exterior damage damage Cabinet Replace cabinet damage Remote Replace remote control control damage Stand Replace stand dent Copyright © 2021 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 35 Exchange Module (1) ~ (3) Inverter/ Module A-8/11 A-9/11 ~ Only using Exchange T-Con (1) ~ (2) T-con model A-10/11 Exchange Power Board(PSU) A-11/11 Continue to the next page Copyright © 2021 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 36 Motion Remote operation checking method How to use the Service remote control A24-A26 E. Etc Check items after Main B/D replacement Adjustment Test pattern - ADJ Key Copyright © 2021 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 37 Check LCD back light with naked eye Content date After turning on the power and disassembling the case, check with the naked eye, whether you can see light from locations. Copyright © 2021 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 38 2. Enter into White Balance. 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. Copyright © 2021 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 39 All Setting  Programmes  Programme Tuning & Settings  Manual Tuning All Settings When the signal is strong, use the attenuator (-10dB, - 15dB, -20dB etc.) Copyright © 2021 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 40 Version checking method Content date <ALL MODELS> 1. Checking method for remote control for adjustment 65UN81006LB Version Press the IN-START with the remote control for adjustment Copyright © 2021 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 41 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. Copyright © 2021 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 42 Revised Content connection diagram (1) date <ALL MODELS> As the part connecting to the external input, check the screen condition by signal Copyright © 2021 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 43 Revised Content Check Link Cable(Vx1/EPI) reconnection condition date 43/49/55/65UN69& 43/49/55/65UN71 Check the contact condition of the Link Cable, especially dust or mis insertion. Copyright © 2021 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 44 Screen darkness to disconnection of the FFC cable pin. G color transient due to poor FFC cable CABLE G Color Excessive connection A - 1/11 Copyright © 2021 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 45 CABLE Color spread FFC connection problem CABLE Color spread FFC connection problem Due to foreign substance within CABLE Screen stop FFC PIN A - 2/11 Copyright © 2021 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 46 Main IC problem Main Dark picture Dark left-side screen Top/bottom screen part Main Broken picture Picture problem due to tuner Inner side quality problem A - 3/11 Copyright © 2021 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 47 Screen spread Screen corner appears blurry Main Color Spread Color spread on the screen Main Blurry Screen Blurry picture on the screen A - 4/11 Copyright © 2021 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 48 Screen picture spread problem Screen problem No problem at the initial stage. Right-side Main During Heat run, right-side picture picture problem problem A - 5/11 Copyright © 2021 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 49 BLU internal foreign matter inflow MODULE Internal matter 6 block image broken MODULE Image broken MODULE Image broken Screen sync signal broken A - 6/11 Copyright © 2021 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 50 BLU Vertical spreading on cube screen in no MODULE Vertical smear signal MODULE Over color Screen contour part brightly Over color A - 7/11 Copyright © 2021 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 51 Center of the screen 1 block dark MODULE Screen darkness MODULE Vertical bar Center Vertical Bar Darkness at the MODULE bottom of the MODULE internal BLU breakage screen A - 8/11 Copyright © 2021 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 52 T-Con is defective and the picture below T-CON image broken the screen is broken A - 9/11 Copyright © 2021 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 53 The entire screen is dark and bit noise T-CON Image Broken occurs The entire screen is dark and bit noise T-CON Image Broken occurs A - 10/11 Copyright © 2021 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 54 Appendix : Exchange Power Board (PSU) No Light No picture/Sound Ok A - 11/11 Copyright © 2021 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 55 Established 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 Copyright © 2021 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 56 전압 SK100 (AC input) ※ Depending on Model Power Board is different. all condition meets, Power Board OK. But Interface(P801, P201) and Spec is same Copyright © 2021 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 57 <ALL MODELS> 65UN81006LB K6LP Entry method 1. Press the IN-START button of the remote control for adjustment. 2. Check the entry into adjustment item 3. Copyright © 2021 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 58 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 Copyright © 2021 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 59 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. Copyright © 2021 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 60 2. Check the standby 3.5V on the terminal 6 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. Copyright © 2021 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 61 Checking order to check motion remote/wifi KEY1 Checking order 1. Check BT/Wifi cable condition between BT/Wifi assy & Main board. 2. Check the 3.5V on the terminal 22. Copyright © 2021 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 62 Error Established E. Etc symptom date Revised Content How to use the Service remote control date 1. How to access the remote control 65UN81006LB K6LP Copyright © 2021 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 63 Digital EYE function ON/OFF For some Model, access to the Test Pattern TILT Used for screen tilting change (Access to the old PDP control mode) Copyright © 2021 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 64 Connects to external input 1,2,3 COMP1,2 (Added function) Connects to Component 1,2 HDMI1,2,3,4 Connects to HDMI 1,2,3,4 (Add function) DVI (Add function) Connects to DVI Copyright © 2021 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 65 - Record the R, G, B (GAIN, Cut) value of the color temperature before main board replacement. After replacing the main board, key in the recorded value. Copyright © 2021 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 66 You can view 9 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!) Copyright © 2021 LG Electronics Inc. All rights reserved. Only for training and service purposes.

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