LG Electronics 42LT640H-ZA A. Video error, Lcd Tv, Check Back Light On with naked eye

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Standard Repair Process

	Error	A. Video error	Established
LCD TV	Error	A. Video error	date
LCD TV	symptom	No video/ Normal audio	Revised date	1/13
		No video/ Normal audio	Revised date	1/13

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 audio

Normal Y audio

☞A1

Check Back Light On with naked eye

On Y

☞A4

Check Main Board 3.5V,12V,3.3V, 1.26V, 1.5V etc.

Normal Y voltage

Replace T-con Board or module

☞A28

Move to No video/No audio

☞A2 Check Power Board 24V,12V,3.5V output

Repair Power Board or parts

Normal Y voltage

Repair Power Board or parts

Replace Inverter or module

End

※Precaution ☞A7 & A3

Always check & record S/W Version and White Balance value before replacing the Main Board

Replace Main Board

Re-enter White Balance value

Copyright © 2012 LG Electronics. Inc. All rights reserved.	LGE Internal Use Only
Only for training and service purposes

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Contents http//biz.lgservice.com READ THE SAFETY PRECAUTIONS IN THIS MANUALhttp//aic.lgservice.com http//eic.lgservice.comSPECIFICATION CONTENTSSAFETY PRECAUTIONS SERVICING PRECAUTIONSIMPORTANT SAFETY NOTICE SAFETY PRECAUTIONSElectrostatically Sensitive ES Devices SERVICING PRECAUTIONSRemoval IC Remove/ReplacementReplacement Small-Signal Discrete Transistor Removal/Replacement3. Test method SPECIFICATION4. Model General Specification 1. Application rangeHDMI1-DTV/DVI RGB InputRGB-PC AnalogD-SUB 15PIN5. Video resolutions 2D 5.1. Component Input Y, CB/PB, CR/PR5.2. RGB Input PC PCDVI 5.3. HDMI InputPC/DTV1. Application Range ADJUSTMENT INSTRUCTIONBoot file Download After downloading, have to adjust Tool Option again3.2. Function Check 4. Total Assembly line process4.1. Adjustment Preparation 3.1. ADC ProcessManual W/B process using adjust Remote control 4.4. EDID data4.2. DDC EDID Write RGB 128Byte 4.3 DDC EDID Write HDMI 256Byte4.6.2. HI-POT auto-check 4.5. Outgoing condition Configuration4.6. HI-POT Test 4.6.1. HI-POT auto-check preparation5.3. Method & notice 5.1. Signal Table5. Model name & Serial number D/L 5.2. Comand Set6.1. Download Procedure 6. CI+ Key Download methodCI+ Key Value Half BLOCK DIAGRAMS7LR All rights reservedEXPLODED VIEW Copyright 2012 LG Electronics. Inc. All rights reserved EMEA INTERACTIVEGP4MSTAR 2011 . 08OLED THERMAL Step Up regulator 3 . 3V to 5VMAX 250mA+3.3VNormal FROM LIPS & POWER B/DPowerDET +1.5VDDRNTP-7500L IC501CONTROL IR & LED MIRROR Pol - change 51Pin LVDS Connector30Pin LVDS Connector For HD 60HzNormal For FHD 60/120HzSIDEHDMI HDMI1For CEC HDMI20 . 3 3 u F USBDIODES RGB/SPDIF/PC/HP/USBS7LRDIVXMS10 W25Q80BVSSIG IC1300MX25L8006EM2I-12G IC1300-*1P4RGLOBALTUNERBLOCK SI2176ATSC1INPUTHSI2156DVB1INPUTH IC1501 LGDT1001PILG1001 A2 Full Scart/ Comp1 EXTSPK OUT UART/I2C SWITCHEXTSPK AMP EXTSPKCONTROL/DEBUGREAL TIME CLOCKRTC EXTERNALPOWER OUT 5V/12VOption name of this page CI SLOT because of Hong Kong CI RegionSMD GASKET Page 1. Trouble Shooting Contents of LCD TV Standard Repair ProcessA2 Check Power Board 24V,12V,3.5V output A. Video errorMain B/D↔ Power B/D, LVDS Cable,Speaker Cable,IR B/D Cable LCD TVBoard voltages of PowerCheck various No VideoSignal strength Normal over 30% Signal Quality Normal over 30% A. Picture ProblemBy using Digital signal level meter By using Diagnostics menu on OSD Menu→Setup→Manual TuningLink Cable Check color by input -External Input COMPONENT -RGB※ Check and replaceCheck color condition by input -External Input -Component RGB Connect other external device and cableExternal device screen error-Color error Vertical/Horizontal bar, residual image, light spotCheck Power On ‘”High” B. Power errorStand-By Red Operating white Check Power LEDPOWEROFFCPUABNORMAL Check Power Off Starusinstart menuIf Power Off mode is not displayed Check Power B/D voltage POWEROFFABNORMAL1Check audio B+ C. Audio errorPower Board Check user menu Speaker offCheck audio B+ Voltage 20V or In case of External Input signal error Check and fix external deviceOutput signal D. General Function Problem1. Remote controlR/C operating error Check & Repair Cable connection Connector solderS/W Version D. Function errorCheck input signal Y Check technical Signal information input? - Fix informationIdentify nose type E. NoiseF. Exterior defect Standard Repair Process Detail Technical Manual A. Video errorVideo error, video lag/stopMENU -Æ red keycustomer support -Æ signal test -Æ select channel When the signal is strong, use the attenuator -10dB, -15dB, -20dB etcVersion 1. Checking method for remote controller for adjustmentPress the IN-START with the remote controller for adjustment ALL MODELSYou can view 6 types of patterns using the ADJ Key A. Video errorColor errorAppendix Exchange T-Con Board Appendix Exchange T-Con Board No picture/Sound Ok A - 3/5 Appendix Exchange PSULED driverNo Light Dim LightPress damage Appendix Exchange the ModuleUn-repairable Cases In this case please exchange the module Panel Mura, Light leakageUn-repairable Cases In this case please exchange the module Entry method 1. Press the IN-START button of the remote controller for adjustment2. Check the entry into adjustment item B. Power error Off when on, off whiling viewing2. Select the AUDIO function of the Menu C. Audio errorNo audio/Normal video1. Press the MENU button on the remote controller Checking method