LG Electronics 42LT640H-ZA Contents of LCD TV Standard Repair Process, Trouble Shooting

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1. Trouble Shooting

Contents of LCD TV Standard Repair Process

No.	Error symptom (High category)	Error symptom (Mid category)	Page	Remarks

1		No video/Normal audio	1

2		No video/No audio	2

3	A. Video error	Video error, video lag/stop	3
	A. Video error
4		Color error	4

5		Vertical/Horizontal bar, residual image,	5
5		light spot, external device color error	5
		light spot, external device color error

6		No power	6
	B. Power error
7	B. Power error	Off when on, off while viewing, power auto	7
		Off when on, off while viewing, power auto
		on/off
		on/off

8	C. Audio error	No audio/Normal video	8

9		Wrecked audio/discontinuation/noise	9
9		Wrecked audio/discontinuation/noise	9

10		No response in remote controller, key error,	10
10	D. Function error	recording error, memory error	10
		recording error, memory error

11		External device recognition error	11

12	E. Noise	Circuit noise, mechanical noise	12

13	F. Exterior error	Exterior defect	13

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

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Contents http//eic.lgservice.com READ THE SAFETY PRECAUTIONS IN THIS MANUALhttp//aic.lgservice.com http//biz.lgservice.comSERVICING PRECAUTIONS CONTENTSSAFETY PRECAUTIONS SPECIFICATIONSAFETY PRECAUTIONS IMPORTANT SAFETY NOTICESERVICING PRECAUTIONS Electrostatically Sensitive ES DevicesSmall-Signal Discrete Transistor Removal/Replacement IC Remove/ReplacementReplacement Removal1. Application range SPECIFICATION4. Model General Specification 3. Test methodAnalogD-SUB 15PIN RGB InputRGB-PC HDMI1-DTV/DVI5.2. RGB Input PC 5. Video resolutions 2D5.1. Component Input Y, CB/PB, CR/PR 5.3. HDMI InputPC/DTV PCDVIAfter downloading, have to adjust Tool Option again ADJUSTMENT INSTRUCTIONBoot file Download 1. Application Range3.1. ADC Process 4. Total Assembly line process4.1. Adjustment Preparation 3.2. Function Check4.3 DDC EDID Write HDMI 256Byte 4.4. EDID data4.2. DDC EDID Write RGB 128Byte Manual W/B process using adjust Remote control4.6.1. HI-POT auto-check preparation 4.5. Outgoing condition Configuration4.6. HI-POT Test 4.6.2. HI-POT auto-check5.2. Comand Set 5.1. Signal Table5. Model name & Serial number D/L 5.3. Method & noticeCI+ Key Value 6.1. Download Procedure6. CI+ Key Download method All rights reserved BLOCK DIAGRAMS7LR HalfEXPLODED VIEW 2011 . 08 EMEA INTERACTIVEGP4MSTAR Copyright 2012 LG Electronics. Inc. All rights reservedOLED Step Up regulator 3 . 3V to 5VMAX 250mA THERMAL+1.5VDDR FROM LIPS & POWER B/DPowerDET +3.3VNormalIC501 NTP-7500LCONTROL IR & LED For FHD 60/120Hz 51Pin LVDS Connector30Pin LVDS Connector For HD 60HzNormal MIRROR Pol - changeHDMI2 HDMI1For CEC SIDEHDMI0 . 3 3 u F RGB/SPDIF/PC/HP/USB USBDIODESS7LRDIVXMS10 IC1300-*1 IC1300MX25L8006EM2I-12G W25Q80BVSSIGSI2156DVB1INPUTH P4RGLOBALTUNERBLOCKSI2176ATSC1INPUTH PILG1001 A2 IC1501LGDT1001 Full Scart/ Comp1 EXTSPKCONTROL/DEBUG UART/I2C SWITCHEXTSPK AMP EXTSPK OUTEXTERNALPOWER OUT 5V/12V REAL TIME CLOCKRTCCI Region Option name of this page CI SLOT because of Hong KongSMD GASKET Page Contents of LCD TV Standard Repair Process 1. Trouble ShootingLCD TV A. Video errorMain B/D↔ Power B/D, LVDS Cable,Speaker Cable,IR B/D Cable A2 Check Power Board 24V,12V,3.5V outputNo Video voltages of PowerCheck various BoardBy using Diagnostics menu on OSD Menu→Setup→Manual Tuning A. Picture ProblemBy using Digital signal level meter Signal strength Normal over 30% Signal Quality Normal over 30%and replace Check color by input -External Input COMPONENT -RGB※ Check Link CableVertical/Horizontal bar, residual image, light spot Connect other external device and cableExternal device screen error-Color error Check color condition by input -External Input -Component RGBCheck Power LED B. Power errorStand-By Red Operating white Check Power On ‘”High”POWEROFFABNORMAL1 Check Power Off Starusinstart menuIf Power Off mode is not displayed Check Power B/D voltage POWEROFFCPUABNORMALCheck user menu Speaker off C. Audio errorPower Board Check audio B+In case of External Input signal error Check and fix external device Check audio B+ Voltage 20V orCheck & Repair Cable connection Connector solder D. General Function Problem1. Remote controlR/C operating error Output signalY Check technical Signal information input? - Fix information D. Function errorCheck input signal S/W VersionE. Noise Identify nose typeF. Exterior defect When the signal is strong, use the attenuator -10dB, -15dB, -20dB etc A. Video errorVideo error, video lag/stopMENU -Æ red keycustomer support -Æ signal test -Æ select channel Standard Repair Process Detail Technical ManualALL MODELS 1. Checking method for remote controller for adjustmentPress the IN-START with the remote controller for adjustment VersionA. Video errorColor error You can view 6 types of patterns using the ADJ KeyAppendix Exchange T-Con Board Appendix Exchange T-Con Board Dim Light Appendix Exchange PSULED driverNo Light No picture/Sound Ok A - 3/5Panel Mura, Light leakage Appendix Exchange the ModuleUn-repairable Cases In this case please exchange the module Press damageAppendix Exchange the Module B. Power error Off when on, off whiling viewing 1. Press the IN-START button of the remote controller for adjustment2. Check the entry into adjustment item Entry methodChecking method C. Audio errorNo audio/Normal video1. Press the MENU button on the remote controller 2. Select the AUDIO function of the Menu