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LG 75NANO90UNA Service Manual
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LG 75NANO90UNA Service Manual

Chassis uax2a
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LED TV
SERVICE MANUAL
CHASSIS : UAX2A
MODEL : 75NANO90UNA
CAUTION
BEFORE SERVICING THE CHASSIS, READ THE SAFETY PRECAUTIONS IN THIS MANUAL.
P/NO : MFL71703904 (2003-REV00)
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 © 2020 LG Electronics Inc. All rights reserved. Only training and service purposes.

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Summary of Contents for LG 75NANO90UNA

  • 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 ........... 12 TROUBLE SHOOTING GUIDE ..........APPENDIX - 2 - Copyright © LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 3 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 - 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 AV and DVI use same jack ; SPDIF out(1EA) 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 (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 - 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 Holder 8 points Screw 17 Points Latch 4 Points Back Cover Curling shape Cover Bottom+ Holder B/C Assembly Module (Holder) + B/C (Curling) - 12 - Copyright © LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 13 (4) Using Plastic Scraper, Make space between B/C and Module. And with the back cover raised remove B/C using Plastic Scraper. (remove direction : under -> upper) Right Plastic Scraper Plastic Scraper Plastic Scraper <Step3> <Step2> <Step1> - 13 - Copyright © LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 14 <Step 2> (6) Two people grasp B/C, and remove B/C. (Grasp position : 600~800mm) (7) B/C Handling is refer to B/C Handling Guide. - 14 - Copyright © LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 15 (1) After set B/C above Module, Push Latch Point in B/C Bending. (Push slope direction of B/C for preventing transform) (2) Confirm Latch Assmble(If Latch is not assemble, Gap and lifting are made.) B/C-Module Gap - 15 - Copyright © LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 16 ▪ One person B/C Handling Guide - OK - 1 Person, 2 Hands Grasp - Stand and Top middle Grasp : Shoulder width 600 mm - 16 - Copyright © LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 17 - 2 People Grasp : Long side shoulder width 600~800mm - 2 people set up : 4-corner Handling ▪ Two people Handling Guide - NG - 17 - Copyright © LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 18 Worker 1 moves to left side of it holding top and Worker 2 also holds top of it. And then, Worker 1, 2 lift it to- gether. Position of hands - 18 - Copyright © LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 19 Step 9. Put down it on a Module (1) Worker 3 must prepare to receive of it on the opposite side. Worker 2 Worker 1 Worker 3 - 19 - Copyright © LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 20 2. Disassemble of Guide panel screws. *Disassemble the Screws (Up10ea / L 6ea / R 6ea) 3. Disassemble of Case Top screws. *Bottom Side screws 13ea. - 20 - Copyright © LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 21 *Fix the S-PCB to Panel(use the tape) . 5. Disassemble of down Hooks. *Disassemble Hooks with flat stick. 6. Disassemble of Up / Right /Left side Hooks. - 21 - Copyright © LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 22 7. Panel and Guide Panel disassembly(use adsorber) 8. Removal of Sheets and DP Sheet Down * Sheet 1ea, DP 1ea 9. Removal of DPS(28ea) - 22 - Copyright © LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 23 *Be careful not to damage the reflector sheet 11. Removal of LED Array *Press the CNT of extension B/D and then remove the LED array at an angle - 23 - Copyright © LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 24 * Assemble the reflector sheet bellow the lens with your fingers * In the case of corner and center, place the side marked UP on top. 3. Assemble the DPS(28ea) - 24 - Copyright © LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 25 5. Assemble the Panel and Guide Panel(use adsorber) * Assemble the upper left/right first and assemble the bottom left/right. 6. Assemble the Guide Panel hook. - 25 - Copyright © LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 26 7. Remove the fixed tape first, then assemble the case top. 8. Assemble the Case Top screws. *Bottom side screws 13ea. *When the left and right ends, hold Case Top by hand. - 26 - Copyright © LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 27 10. Assemble the Guide Panel. *Assemble the Screws Screw. - Guide Panel Screws(Up10ea / L 6ea / R 6ea) Cover Shield Screws(Left 4ea / Right 5ea). - 27 - Copyright © LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 28 TROUBLE SHOOTING GUIDE Copyright © 2020 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 29 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 © 2020 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 30 ☞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 © 2020 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 31 ☞A9 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 © 2020 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 32 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 © 2020 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 33 Replace Main/T-con B/D 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 © 2020 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 34 Normal (Check normal operation of HDMI/ Screen Main /T-con screen? External Input, Component, normal? RGB and HDMI/DVI by connecting Jig, pattern Generator ,Set-top Box etc. Copyright © 2020 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 35 Measure voltage of each output of Power B/D Normal? Normal Replace Main B/D voltage? Normal Close Check ST-BY 3.5V voltage? ☞A9 Replace Power B/D Replace Power Copyright © 2020 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 36 Normal Replace Main B/D Check Power B/D voltage? voltage ※ Caution Check and fix exterior Replace Power B/D of Power B/D Part Copyright © 2020 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 37 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 © 2020 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 38 > Power Board Screen normal voltage Speaker off Cancel OFF Replace Power Board and repair parts Check Speaker Replace MAIN Board Disconnection disconnection Replace Speaker Copyright © 2020 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 39 (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 © 2020 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 40 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 © 2020 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 41 MR20 Close Down load the Firmware * If you conduct the loop at 3times, change the MR20. * INSTART MENU14.RF Remote control Test3. Firmware download Copyright © 2020 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 42 Voltage? 1pin Main B/D INSTART menu ☞A15 Close Check & Repair Wifi cable connection ☞A4 Wi-Fi Mac Close value is “NG”? Change the Wifi assy Copyright © 2020 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 43 Recognition error - S/W Version HDMI/ Check and fix DVI, Optical Replace Main B/D Fix in external device/cable Recognition accordance error with technical information Copyright © 2020 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 44 “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 © 2020 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 45 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 © 2020 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 46 Exchange Module (1) ~ (3) A-6/11 ~ A-8/11 Inverter/ Module Exchange T-Con (1) ~ (2) A-9/11 ~ A-10/11 Exchange Power Board(PSU) A-11/11 Continue to the next page Copyright © 2020 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 47 How to use the Service remote control A16-A18 Check items after Main B/D replacement E. Etc Adjustment Test pattern – ADJ Key Main Board JIG Point Copyright © 2020 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 48 Check Back Light On with naked eye Content date If the Black light LED assemble is ‘OK’, you can see the lights on each points. Copyright © 2020 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 49 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 © 2020 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 50 All settings  Programmes  Programme Tuning & settings  Manual Tuning When the signal is strong, use the attenuator (-10dB, -15dB, -20dB etc.) Copyright © 2020 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 51 Revised Version checking method Content date 1. Checking method for remote control for adjustment Version Press the IN-START with the remote control for adjustment Copyright © 2020 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 52 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 © 2020 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 53 Revised Content connection diagram date As the part connecting to the external input, check the screen condition by signal Copyright © 2020 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 54 A. Video error_Color error symptom date Revised Content Check Link Cable(VX1/EPI) reconnection condition date Check the contact condition of the Link Cable, especially dust or mis insertion. Copyright © 2020 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 55 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 © 2020 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 56 LVDS cable connection problem CABLE Color spread LVDS cable connection problem Due to foreign substance withi nLVDS CABLE Screen stop cable PIN A - 2/11 Copyright © 2020 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 57 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 © 2020 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 58 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 © 2020 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 59 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 © 2020 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 60 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 © 2020 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 61 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 © 2020 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 62 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 © 2020 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 63 T-Con is defective and the picture below T-CON image broken the screen is broken A - 9/11 Copyright © 2020 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 64 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 © 2020 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 65 Appendix : Exchange Power Board (PSU) No Light No picture/Sound Ok A - 11/11 Copyright © 2020 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 66 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 © 2020 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 67 8.4Vrms (typ) 17mA(0~17mA) 13.2V 12.54V ~ 13.86V 4.0A (0.1~4.0A) 18.00V ~ 22.00V 1.0A (0.1~1.0A) Check Voltage DC 13.2V line ST-BY All condition meets, Power Board OK. Copyright © 2020 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 68 LED blank 7 times Local data error (Checksum & Data Length) Slim Direct V-sync signal error LED blank 8 times V-sync signal is low Slim Direct Copyright © 2020 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 69 POWER OFF MODE checking method date Entry method 1. Press the IN-START button of the remote control for adjustment. 2. Check the entry into adjustment item 3. Copyright © 2020 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 70 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 © 2020 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 71 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 © 2020 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 72 2. Check the standby 3.5V on the terminal (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 © 2020 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 73 Checking order to check motion remote/wifi MIC_CLK Checking order 1.Check BT/Wifi cable condition between BT/Wifi assy & Main board. 2.Check the 3.5V on the terminal 1 pin Copyright © 2020 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 74 Standard Repair Process Detail Technical Manual Error Established E. Etc symptom date Revised Content How to use the Service remote control date 1. How to access the remote control Copyright © 2020 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 75 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 © 2020 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 76 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 © 2020 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 77 - 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 © 2020 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 78 You can view 11 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 © 2020 LG Electronics Inc. All rights reserved. Only for training and service purposes.
  • Page 79 Main Board / T-CON Voltage Check Point Content date +1.25V VTERM +D13.2V VCC18 +1.88V +5.69V VCOM1 +A13V +7.91V HVDD (20V) +16.61V +5.8V VCOM2 VGL1 -15V VGL2 +28V Copyright © 2020 LG Electronics Inc. All rights reserved. Only for training and service purposes.