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LG 42LB550A Service Manual
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LG 42LB550A Service Manual

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LED TV
LED TV
SERVICE MANUAL
SERVICE MANUAL
CHASSIS : LB45B
CHASSIS : LB45B
MODEL : 42LB550A
MODEL : 42LB550A
42LB552A
42LB552A
CAUTION
CAUTION
BEFORE SERVICING THE CHASSIS,
BEFORE SERVICING THE CHASSIS,
READ THE SAFETY PRECAUTIONS IN THIS MANUAL.
READ THE SAFETY PRECAUTIONS IN THIS MANUAL.
North/Latin
North/Latin
America
America
Europe/Africa
Europe/Africa
 Asia/Oceania
 Asia/Oceania
42LB550A-TA
42LB550A-TA
42LB552A-TB
42LB552A-TB
Internal Use Only
Internal Use Only
http://aic.lgservice.com
http://aic.lgservice.com
http://eic.lgservice.com
http://eic.lgservice.com
http://biz.lgservice.com
http://biz.lgservice.com

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  • Page 1  Asia/Oceania  Asia/Oceania http://biz.lgservice.com http://biz.lgservice.com LED TV LED TV SERVICE MANUAL SERVICE MANUAL CHASSIS : LB45B CHASSIS : LB45B MODEL : 42LB550A MODEL : 42LB550A 42LB550A-TA 42LB550A-TA 42LB552A 42LB552A 42LB552A-TB 42LB552A-TB CAUTION CAUTION BEFORE SERVICING THE CHASSIS, BEFORE SERVICING THE CHASSIS, READ THE SAFETY PRECAUTIONS IN THIS MANUAL.
  • Page 2 CONTENTS CONTENTS CONTEN CONTENTS ......................................SAFETY PRECA SAFETY PRECAUTIONS UTIONS ..............................SERVI SERVICING CING PRECAUT PRECAUTIONS IONS ............................SPECIFIC SPECIFICA TION TION ....................................
  • Page 3 SAFETY PRECAUTIONS SAFETY PRECAUTIONS IMPORTANT SAFETY NOTICE IMPORTANT SAFETY NOTICE Many el Many electrical ectrical and mechanic mechanical parts al parts in this in this chassis chassis have spec have special safety safety-related characteristi -related characteristics. These parts These parts are identified are identified in the...
  • Page 4 SERVICING PRECAUTIONS SERVICING PRECAUTIONS CAUTION: Before servicing receivers covered by this CAUTION: Before servicing receivers covered by this service service 2. After removing an electrical assembly equipped with ES 2. After removing an electrical assembly equipped with ES manual and its supplements and addenda, read and manual and its supplements and addenda, read and follow the follow the...
  • Page 5 IC Remove/Replacement IC Remove/Replacement 3. Solder the connections. 3. Solder the connections. Some chassis circuit boards have slotted holes (oblong) through Some chassis circuit boards have slotted holes (oblong) through CAUTION: Maintain original spacing between the replaced CAUTION: Maintain original spacing between the replaced which the IC leads are inserted and then which the IC leads are inserted and then bent at against the cir-...
  • Page 6 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 LB45B chassis. 1) Performance: LGE TV test method followed 2) Demanded other specification - Safety : CE, IEC specification 2.
  • Page 7 5. Component Video Input(Y, P Resolution H-freq. (kHz) V-freq. (Hz) Pixel clock (MHz) Proposed 720*480 15.73 59.94 13.500 SDTV, DVD 480I(525I) 720*480 15.75 60.00 13.514 SDTV, DVD 480I(525I) 720*576 15.625 50.00 13.500 SDTV, DVD 576I(625I) 50Hz 720*480 31.47 59.94 27.000 SDTV 480P 720*480 31.50...
  • Page 8 7. HDMI input (DTV) Resolution H-freq. (kHz) V-freq. (Hz) Pixel clock(MHz) Proposed Remarks 720*480 15.73 59.94 13.500 SDTV, DVD 480I(525I) 720*480 15.75 60.00 13.514 SDTV, DVD 480I(525I) Spec. out but display. 720*576 15.625 50.00 13.500 SDTV, DVD 576I(625I) 50Hz 720*480 31.469 59.94 SDTV 480P...
  • Page 9 ADJUSTMENT INSTRUCTION 1. Application Range 4. EDID Download This specification sheet is applied to all of the LED TV with 4.1. Overview LB45B chassis. - It is a VESA regulation. A PC or a MNT will display an optimal resolution through information sharing without any necessity of user input.
  • Page 10 5. White Balance Adjustment 5.4. Adjustment Command (Protocol) (1) RS-232C Command used during auto-adj. 5.1. Overview RS-232C COMMAND 5.1.1. W/B adj. Objective & How-it-works Explanation DATA (1) Objective: To reduce each Panel’s W/B deviation Begin White Balance adjustment (2) How-it-works: When R/G/B gain in the OSD is at 192, it End White Balance adjustment  ...
  • Page 11 (2) Medium / Warm Mode - AUO/ INX/ COST/ SHARP/ BOE Module which cool spec is 1) Purpose : Adjust the color temperature to reduce the 13000K deviation of the module color temperature. cool Warm 2) Principle: To adjust the white balance without the saturation, - In Medium mode, Fix to G gain to 192 and change the spec others(R/B Gain)(20LB45X model)
  • Page 12 9.3. Checkpoint 11. Optional adjustments (1) Test voltage 11.1. Manual ADC Calibration - GND: 1.5 KV / min at 100 mA ■ Enter ‘EZ ADJUST’ mode by pressing ‘ADJ’ key. - SIGNAL: 3 KV / min at 100 mA ■ Enter Internal ADC calibration mode by pressing ‘OK’ key at (2) TEST time: 1 second ‘3.
  • Page 14 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 Schematic Diagram and EXPLODED VIEW. It is essential that these special safety parts should be replaced with the same components as recommended in this manual to prevent X-RADIATION, Shock, Fire, or other Hazards.
  • Page 15 R123 SYMBOL MARK OF THIS SCHEMETIC DIAGRAM INCORPORATES SPECIAL FEATURES IMPORTANT FOR PROTECTION FROM X-RADIATION. FIRE AND ELECTRICAL SHOCK HAZARDS, WHEN SERVICING IF IS 32/42LB550A 2013/08/15 ESSENTIAL THAT ONLY MANUFACTURES SPECIFIED PARTS BE USED FOR THE CRITICAL COMPONENTS IN THE SYMBOL MARK OF THE SCHEMETIC.
  • Page 16 IP4294CZ10-TBR SYMBOL MARK OF THIS SCHEMETIC DIAGRAM INCORPORATES SPECIAL FEATURES IMPORTANT FOR PROTECTION FROM X-RADIATION. FIRE AND ELECTRICAL SHOCK HAZARDS, WHEN SERVICING IF IS 32/42LB550A 2013/08/15 ESSENTIAL THAT ONLY MANUFACTURES SPECIFIED PARTS BE USED FOR INPUT2 THE CRITICAL COMPONENTS IN THE...
  • Page 17 6800pF SYMBOL MARK OF THIS SCHEMETIC DIAGRAM INCORPORATES SPECIAL FEATURES IMPORTANT FOR PROTECTION FROM X-RADIATION. FIRE AND ELECTRICAL SHOCK HAZARDS, WHEN SERVICING IF IS 32/42LB550A 2013/08/15 ESSENTIAL THAT ONLY MANUFACTURES SPECIFIED PARTS BE USED FOR AUDIO THE CRITICAL COMPONENTS IN THE...
  • Page 18 SYMBOL MARK OF THIS SCHEMETIC DIAGRAM INCORPORATES SPECIAL FEATURES IMPORTANT FOR PROTECTION FROM X-RADIATION. 2013/08/15 FIRE AND ELECTRICAL SHOCK HAZARDS, WHEN SERVICING IF IS 32/42LB550A ESSENTIAL THAT ONLY MANUFACTURES SPECIFIED PARTS BE USED FOR TUNER & THE CRITICAL COMPONENTS IN THE...
  • Page 20 SYMBOL MARK OF THIS SCHEMETIC DIAGRAM INCORPORATES SPECIAL FEATURES IMPORTANT FOR PROTECTION FROM X-RADIATION. FIRE AND ELECTRICAL SHOCK HAZARDS, WHEN SERVICING IF IS 2013/08/15 32/42LB550A ESSENTIAL THAT ONLY MANUFACTURES SPECIFIED PARTS BE USED FOR THE CRITICAL COMPONENTS IN THE SYMBOL MARK OF THE SCHEMETIC.
  • Page 21 MMBT3904(NXP) SYMBOL MARK OF THIS SCHEMETIC DIAGRAM INCORPORATES SPECIAL FEATURES IMPORTANT FOR PROTECTION FROM X-RADIATION. FIRE AND ELECTRICAL SHOCK HAZARDS, WHEN SERVICING IF IS 32/42LB550A 2013/08/15 ESSENTIAL THAT ONLY MANUFACTURES SPECIFIED PARTS BE USED FOR THE CRITICAL COMPONENTS IN THE SYMBOL MARK OF THE SCHEMETIC.
  • Page 23 Standard Repair Process Established A. Video error  2013. 01 .24 Error date LCD TV symptom No video/ Normal audio Revised date 1/14 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,,,) No video Normal Check Back Light...
  • Page 24 Standard Repair Process Established A. Video error  2013. 01 .24 Error date LCD TV symptom No video/ No audio Revised date 2/14 Check various voltages Check and No Video/ Normal of Power Board replace No audio voltage? ( 3.5V,12V,20V or 24V…) MAIN B/D Replace Power Board and repair...
  • Page 25 Standard Repair Process Established A. Video error 2013. 01 .24 Error date LCD TV symptom Picture broken/ Freezing Revised date 3/14  A5 Check RF Signal level  Y Check whether other equipments have problem or not. Normal (By connecting RF Cable at other equipment) Signal? →...
  • Page 26 Standard Repair Process Established A. Video error 2013. 01 .24 Error date LCD TV symptom Tuning fail, Picture broken/ Freezing Revised date 4/14 Check RF signal cable  A5 Check whether other equipments have problem or not. Check RF Signal level (By connecting RF Cable at other equipment) →...
  • Page 27 Standard Repair Process Established A. Video error  2013. 01. 24 Error date LCD TV symptom Color error Revised date 5/14  A8/ A9  Check and Check color by input replace Link Color Cable Color Color Replace module Replace Main B/D error? -COMPONENT error? (LVDS) and...
  • Page 28 Standard Repair Process A. Video error  Established 2013. 01 .24 Error date LCD TV symptom Vertical / Horizontal bar, residual image, Revised date 6/14 light spot, external device color error Vertical/Horizontal bar, residual image, light spot Replace Module  A8/ A9 Check color condition by input Check external Check and...
  • Page 29 Standard Repair Process Established B. Power error  2013. 01 .24 Error date LCD TV symptom No power Revised date 7/14 DC Power on Replace Check Power LED Normal Check Power by pressing Power Key Power Power LED operation? On ‘”High” On Remote control .
  • Page 30 Standard Repair Process Established B. Power error  2013. 01 .24 Error date LCD TV symptom Off when on, off while viewing, power auto on/off Revised date 8/14 Check outlet Check Power Off Check A/C cord Error? Replace Main B/D Normal? Mode Abnormal Check for all 3- phase...
  • Page 31 Standard Repair Process Established C. Audio error  2013. 01 .24 Error date LCD TV symptom Revised date No audio/ Normal video 9/14 Check user Check audio B+ 24V No audio Normal menu > of Power Board Screen normal voltage Speaker off Replace Power Board and repair parts Cancel OFF Check Speaker...
  • Page 32 Standard Repair Process Established C. Audio error  2013. 01 .24 Error date LCD TV symptom Wrecked audio/ discontinuation/noise Revised date 10/14 → abnormal audio/discontinuation/noise is same after “Check input signal” compared to No audio Wrecked audio/ Check and replace Discontinuation/ Check audio speaker and Noise for...
  • Page 33 Standard Repair Process D. Function error Established 2013. 02. 02 Error date LCD TV symptom Remote control & Local switch checking Revised date 11/14 1. Remote control(R/C) operating error Replace Main B/D Check & Repair  Y  Y Check R/C itself Normal  Y Normal...
  • Page 34 Standard Repair Process Established D. Function error  2013. 02. 02 Error date LCD TV symptom External device recognition error Revised date 12/14 Check technical Check External Input and information Signal Technical input Replace Main B/D Component input? - Fix information information? Recognition error signal...
  • Page 35 Standard Repair Process Established E. Noise 2013. 02. 02 Error date LCD TV symptom Circuit noise, mechanical noise Revised date 13/14 Replace PSU(with LED driver) Identify Check location Circuit nose type of noise noise Replace LED driver Mechanical Check location of noise noise  When the nose is severe, replace the module...
  • Page 36 Standard Repair Process Established F. Exterior defect 2013. 02. 02 Error date LCD TV symptom Exterior defect Revised date 14/14 Zoom part with Module Replace module exterior damage damage Cabinet Replace cabinet damage Remote controller Replace remote controller damage Stand Replace stand dent...
  • Page 37 Contents of LCD TV Standard Repair Process Detail Technical Manual Check LCD back light with naked eye LED driver B+ measuring method A. Video error_ No video/Normal audio Check White Balance value Power Board voltage measuring method TUNER input signal strength checking method A.
  • Page 38 Contents of LCD TV Standard Repair Process Detail Technical Manual Continued from previous page Check front display LED Check power input Voltage & ST-BY 3.5V B. Power error_No power Checking method when power is ON POWER BOARD voltage measuring method B.
  • Page 39 Standard Repair Process Detail Technical Manual Error Established A. Video error_No video/Normal audio 2013. 02.15 symptom date LCD TV Revised Content Check Back Light On with naked eye date <ALL MODELS> Power On -> disjoint back case -> check lighting from the module...
  • Page 40 Standard Repair Process Detail Technical Manual Error Established A. Video error_No video/Normal audio 2013. 02 .15 symptom date LCD TV Revised Content Inverter B+ 24V measuring method date <ALL MODELS> *Output Voltage is depend on inch 32 inch : 65.6~86.9V 39 inch : 117.3~142.2V Measure DC Voltage applying to Module from Power Board.
  • Page 41 Standard Repair Process Detail Technical Manual Error Established A. Video error_No video/Normal audio 2013. 02.15 symptom date LCD TV Revised Content Check White Balance value date <ALL MODELS> Entry method 1. Press the ADJ button on the remote controller for adjustment. 2.
  • Page 42 Standard Repair Process Detail Technical Manual Error Established A. Video error_No video/ Audio 2013. 02.15 symptom date LCD TV Revised Content Power Board voltage measuring method date Edge LED Check the DC 24V, 12V, 3.5V.
  • Page 43 Standard Repair Process Detail Technical Manual Error Established A. Video error_Video error, video lag/stop 2013. 02.15 symptom date LCD TV Revised LCD-TV Version checking method Content date <ALL MODELS> 1. Checking method for remote controller for adjustment Version Press the IN-START with the remote controller for adjustment...
  • Page 44 Standard Repair Process Detail Technical Manual Error A. Video error _Vertical/Horizontal bar, residual Established 2013. 02.15 symptom date image, light spot LCD TV Revised Content LCD TV connection diagram (1) date <ALL MODELS> As the part connecting to the external input, check the screen condition by signal...
  • Page 45 Standard Repair Process Detail Technical Manual Error Established  A. Video error_Color error 2013. 02.15 symptom date LCD TV Revised Content A8/A9 Check and replace Link Cable(LVDS) and contact condition date <ALL MODELS> 1. Check and replace LVDS Cable 2. Check LVDS connection condition...
  • Page 46 Standard Repair Process Detail Technical Manual Error Established A. Video error_Color error 2013. 02.15 symptom date LCD TV Revised Adjustment Test pattern - ADJ Key Content date You can view 6 types of patterns(with White and Full White) using the ADJ Key Checking item : 1.
  • Page 47 Appendix : Exchange T-Con Board (1) Solder defect, CNT Broken Solder defect, CNT Broken Solder defect, CNT Broken T-Con Defect, CNT Broken T-Con Defect, CNT Broken  Abnormal Power Section Solder defect, CNT Broken Solder defect, CNT Broken T-Con Defect, CNT Broken  Abnormal Power Section Solder defect, Short/Crack Solder defect, Short/Crack...
  • Page 48 Appendix : Exchange T-Con Board (2)  Abnormal Power Section  Abnormal Power Section Solder defect, Short/Crack  Abnormal Display Fuse Open, Abnormal power section Solder defect, Short/Crack Noise GRADATION GRADATION...
  • Page 49 Appendix : Exchange PSU(LED driver) No Light Dim Light Dim Light Dim Light No picture/Sound Ok...
  • Page 50 Appendix : Exchange the Module (1) Panel Mura, Light leakage Panel Mura, Light leakage Press damage Crosstalk Press damage Crosstalk Un-repairable Cases In this case please exchange the module. Press damage...
  • Page 51 Appendix : Exchange the Module (2) Vertical Line Vertical Block Vertical Block Source TAB IC Defect Source TAB IC Defect Source TAB IC Defect Horizontal Block Horizontal line Horizontal Block Gate TAB IC Defect Gate TAB IC Defect Gate TAB IC Defect Gate TAB IC Defect Gate TAB IC Defect Un-repairable Cases...
  • Page 52 Standard Repair Process Detail Technical Manual Error Established B. Power error _No power  2013. 02.15 symptom date LCD TV Revised Content Check front display LED date ST-BY condition: Red...
  • Page 53 Standard Repair Process Detail Technical Manual Error Established B. Power error _No power  2013. 02.15 symptom date LCD TV Revised Content Check power input voltage and ST-BY 3.5V date Edge LED Check the DC 24V, 12V, 3.5V.
  • Page 54 Standard Repair Process Detail Technical Manual Error Established B. Power error _No power  2013. 02.15 symptom date LCD TV Revised Content Checking method when power is ON date Edge LED Check the DC 24V, 12V, 3.5V.
  • Page 55 Standard Repair Process Detail Technical Manual Error Established B. Power error  _Off when on, off whiling viewing 2013. 02. 15 symptom date LCD TV Revised Content POWER OFF MODE checking method date <ALL MODELS> Entry method 1. Press the IN-START button of the remote controller for adjustment 2.
  • Page 56 Standard Repair Process Detail Technical Manual Error Established C. Audio error_No audio/Normal video 2013. 02.15 symptom date LCD TV Revised Content Checking method in menu when there is no audio date <ALL MODELS> Checking method 1. Press the MENU button on the remote controller 2.
  • Page 57 Standard Repair Process Detail Technical Manual Error Established C. Audio error_No audio/Normal video 2013. 02. 15. symptom date LCD TV Revised Voltage and speaker checking method Content date when there is no audio <ALL MODELS> Check the DC 24V, 12V, 3.5V.
  • Page 58 Standard Repair Process Detail Technical Manual Error D. Function error_ No response in remote controller, Established 2013. 01 .09 symptom key error date LCD TV Revised Content Remote controller operation checking method date <ALL MODELS> ② ③ ①  Checking order 1, 2.

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