C. Audio error, Lcd Tv, Check audio B+ | LG Electronics 42LT640H-ZA

Standard Repair Process

	Error	C. Audio error	Established
LCD TV	Error	C. Audio error	date
LCD TV	symptom	No audio/ Normal video	Revised date	8/13
		No audio/ Normal video	Revised date	8/13

No audio Screen normal

☞A24

Check user menu > Speaker off

Off

Cancel OFF

☞A25

Check audio B+	Normal	Y
20V or 24V of	Normal
20V or 24V of	voltage
Power Board	voltage
Power Board

Replace Power Board and repair parts

Check		N
Check		Disconnection
Speaker		Disconnection
Speaker
disconnection
		Y
		Y

		Replace Speaker

Replace MAIN Board

End

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LG Electronics 42LT640H-ZA C. Audio error, Lcd Tv, Check user menu Speaker off, Check audio B+, Normal, 20V or 24V of

Contents

http//eic.lgservice.com READ THE SAFETY PRECAUTIONS IN THIS MANUALhttp//aic.lgservice.com http//biz.lgservice.com SERVICING PRECAUTIONS CONTENTSSAFETY PRECAUTIONS SPECIFICATION SAFETY PRECAUTIONS IMPORTANT SAFETY NOTICE SERVICING PRECAUTIONS Electrostatically Sensitive ES Devices Small-Signal Discrete Transistor Removal/Replacement IC Remove/ReplacementReplacement Removal 1. Application range SPECIFICATION4. Model General Specification 3. Test method AnalogD-SUB 15PIN RGB InputRGB-PC HDMI1-DTV/DVI 5.1. Component Input Y, CB/PB, CR/PR 5. Video resolutions 2D5.2. RGB Input PC 5.3. HDMI InputPC/DTV PCDVI After downloading, have to adjust Tool Option again ADJUSTMENT INSTRUCTIONBoot file Download 1. Application Range 3.1. ADC Process 4. Total Assembly line process4.1. Adjustment Preparation 3.2. Function Check 4.3 DDC EDID Write HDMI 256Byte 4.4. EDID data4.2. DDC EDID Write RGB 128Byte Manual W/B process using adjust Remote control 4.6.1. HI-POT auto-check preparation 4.5. Outgoing condition Configuration4.6. HI-POT Test 4.6.2. HI-POT auto-check 5.2. Comand Set 5.1. Signal Table5. Model name & Serial number D/L 5.3. Method & notice 6. CI+ Key Download method 6.1. Download ProcedureCI+ Key Value All rights reserved BLOCK DIAGRAMS7LR Half EXPLODED VIEW 2011 . 08 EMEA INTERACTIVEGP4MSTAR Copyright 2012 LG Electronics. Inc. All rights reserved OLED Step Up regulator 3 . 3V to 5VMAX 250mA THERMAL +1.5VDDR FROM LIPS & POWER B/DPowerDET +3.3VNormal IC501 NTP-7500L CONTROL IR & LED For FHD 60/120Hz 51Pin LVDS Connector30Pin LVDS Connector For HD 60HzNormal MIRROR Pol - change HDMI2 HDMI1For CEC SIDEHDMI 0 . 3 3 u F RGB/SPDIF/PC/HP/USB USBDIODES S7LRDIVXMS10 IC1300-*1 IC1300MX25L8006EM2I-12G W25Q80BVSSIG SI2176ATSC1INPUTH P4RGLOBALTUNERBLOCKSI2156DVB1INPUTH LGDT1001 IC1501PILG1001 A2 Full Scart/ Comp1 EXTSPKCONTROL/DEBUG UART/I2C SWITCHEXTSPK AMP EXTSPK OUT EXTERNALPOWER OUT 5V/12V REAL TIME CLOCKRTC CI Region Option name of this page CI SLOT because of Hong Kong SMD GASKET Page Contents of LCD TV Standard Repair Process 1. Trouble Shooting LCD 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 output No Video voltages of PowerCheck various Board By 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 Cable Vertical/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 RGB Check 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 POWEROFFCPUABNORMAL Check 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 or Check & Repair Cable connection Connector solder D. General Function Problem1. Remote controlR/C operating error Output signal Y Check technical Signal information input? - Fix information D. Function errorCheck input signal S/W Version E. Noise Identify nose type F. 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 Manual ALL MODELS 1. Checking method for remote controller for adjustmentPress the IN-START with the remote controller for adjustment Version A. Video errorColor error You can view 6 types of patterns using the ADJ Key Appendix Exchange T-Con Board Appendix Exchange T-Con Board Dim Light Appendix Exchange PSULED driverNo Light No picture/Sound Ok A - 3/5 Panel Mura, Light leakage Appendix Exchange the ModuleUn-repairable Cases In this case please exchange the module Press damage Appendix 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 method Checking method C. Audio errorNo audio/Normal video1. Press the MENU button on the remote controller 2. Select the AUDIO function of the Menu

C. Audio error

Check user menu > Speaker off

Check audio B+

Normal

20V or 24V of

voltage

Power Board