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LG 42LB4D Troubleshooting Manual
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LG 42LB4D Troubleshooting Manual

Lcd flat panel
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See also: Owner's Manual
Troubleshooting
42LB4D
LCD Flat Panel
LCD TV - 2007

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Summary of Contents for LG 42LB4D

  • Page 1 Troubleshooting 42LB4D LCD Flat Panel LCD TV - 2007...

  • Page 2: General Guidance

    General Guidance An isolation Transformer should always be used during the servicing of a receiver whose chassis is not isolated from the AC power line. Use a transformer of adequate power rating as this protects the technician from accidents resulting in personal injury from electrical shocks. It will also protect the receiver and it's components from being damaged by accidental shorts of the circuitry that may be inadvertently introduced during the service operation.

  • Page 3: Servicing Precautions

    SERVICING PRECAUTIONS CAUTION: Before servicing receivers covered by this service manual and its supplements and addenda, read and follow the SAFETY PRECAUTIONS on page in this publication. NOTE: If unforeseen circumstances create conflict between the following servicing precautions and any of the safety precautions in this publication, always follow the safety precautions.
  • Page 4 SERVICING PRECAUTIONS continued Unless specified otherwise in this service manual, lubrication of contacts in not required. 5. Do not defeat any plug/socket B+ voltage interlocks with which receivers covered by this service manual, might be equipped. 6. Do not apply AC power to this instrument and/or any of its electrical assemblies unless all solid-state device heat sinks are correctly installed.

  • Page 5: Power Supply Troubleshooting

    Power Supply Troubleshooting LCD TV - 2007...
  • Page 6 Power Supply trouble shooting 42LB4DS Power Supply Power Supply Connectors With Test unit measurements Connector Connector Stan P201 Standby P202 18.86 3.0V 18.86 6.11 3.2V 3.2V 3.46 0.22V 2.753 11.99 3.2V 6.11 3.4V on 2.5V LCD TV - 2007...
  • Page 7 Power Supply trouble shooting Power Supply Ballast Connectors With Test unit measurements BALLAST / INVERTER P204 Label Standby Run Mode VBL - +24.12VDC 23.93V VBL - +24.12VDC 23.93V BALLAST / INVERTER VBL - +24.12VDC 23.93V P205 Label Standby RUN mode VBL - +24.12VDC 23.93V VBL - +24.12VDC...
  • Page 8 47LB1DA POWER SUPPLY Resistances with Board Connected Resistances with Board Disconnected P202 P201 P200 P202 P201 P200 ∞ AC_DET 100.7 KOhm 1.7 KOhm* 3.4V 1 KOhm* AC_DET 2 KOhm* 3.4V 1 KOhm* ∞ ∞ PWR_NF 1.7 KOhm* 3.4V 1 KOhm* PWR_NF 2 KOhm* 3.4V...
  • Page 9 Power Supply Voltage Distribution Diagram +19.0V +19.0V NTP3000 NTP3000 9.0V +12.0V KIA78R09 MC33078 +12.0V KIA78R09 MC33078 KIA78R09 KIA78R09 KIA78R09 KIA78R09 SC1565-2.5 SC1565-2.5 24C08 MST3369 MST3369 24C08 AZ1117H-3.3 AZ1117H-3.3 +5.0V +6.0V +6.0V PQ05DZ1U PQ05DZ1U CS4344 CS5340 TEA6420 FRC94XYH STMAV335 PQ05DZ1U AT/NT Tuner CS4344 CS5340 TEA6420...
  • Page 10 Power Supply trouble shooting I²C Bus Controller Block Diagram Stand-By Power Operation Dead Live I2C_CH1 (+3.3V_L & +5V_L) AT/NT Tuner 0xC2 I2C_CH2 (+3.3V_L & +5V_L) (X260) I2C Master Port Temp. Audio HDMI CS8416A Sensor Expander Switch U-Com 0X20(W) PDP Module (MST3361) (M62320) (LM75)
  • Page 11 Power Supply trouble shooting Check P701(MAIN PCB) Pin #3,8 Replace power board 5V Normal ? Check P702 (MAIN PCB) Check P702 wafers Replace Power board are all input & Connectors voltages Normal ? Normal ? Check SI3865( MAIN PCB) Check SI3865 Check X500 (18.43MHz) (Q702) pin 2,3 (Q702) Pin #5 2.5V...
  • Page 12 47LB4DS 47LB4DS 47LB4DS Video Trouble Shooting Guide Video Trouble Shooting Guide Video Trouble Shooting Guide LCD TV - 2007...

  • Page 13: Video Troubleshooting

    Video Trouble Shooting Video Trouble Shooting Stand-By Mode IC Operation Block Diagram Cable 24C512 DDR1 TP_IN1 Flash 120Hz AT/NT 16MB LGDT3303 (NOR 32MB) DDR2 RGB odd FRC94xyH 64MBx2 Latchx2 Flex Bus M_SIF 1080P RGB even Video CVBS(NT Main) LVDS 63LVD1023 Scaler AV1, Y/C1 Analog...
  • Page 14 NO VIDEO / OSD Video Trouble Shooting Video Trouble Shooting Check Replace Power board Check L729(2.5V) Power connector Check THC63LVD1023 (IC601)#9(DE), Check X260 (IC101) #15(Clk), 3.3V #47(DISP_E #7(Hsync),#8(Vsync) Check P600 Check THC63LVD1023 #(Clk) : 74.25MHz (IC601) #47(DISP_EN), #33(TXAC-) , #33 (TXAC-) : 74.25MHz #32(TXAC+) , #17(TXBC-) ,...
  • Page 15 Video Trouble Shooting Video Trouble Shooting LCD Control Board LCD Control Board Video Data to LCD Panel. Video Data to LCD Panel. Test points From LCD Test points From LCD control board control board LCD TV - 2007...

  • Page 16: Lcd Control Board

    Video Trouble Shooting Video Trouble Shooting LCD Control Board LCD Control Board Check: Video data from LVDS Transmitter (IC601). The diagram shown, points out the test points for the Video Data transmitted to the LCD Control PCB. Points highlighted are above the LVDS cable connection LCD TV - 2007...
  • Page 17 NO RF VIDEO (ATSC) Video Trouble Shooting Video Trouble Shooting AT/NT/ LGDT TUNER 3303 Check Antenna Cable Check Tuner 5V, Video out VSB1/QAM TP TP A Check CVBS Video Path FRC9445H TP C TP B / 656 CVBS X260 Check X260 inputs CVBS M_TU_CVBS(C2117) AV1/2...
  • Page 18 Video Trouble Shooting NO RF VIDEO (NTSC) Video Trouble Shooting AT/NT/ LGDT TUNER 3303 Check Antenna Cable Check Tuner 5V, Video out VSB1/QAM TP TP A FRC9445H Check CVBS Video Path TP C TP B / 656 X260 CVBS Check X260 inputs CVBS M_TU_CVBS(C2117) AV1/2...
  • Page 19 Video Trouble Shooting Video Trouble Shooting NO RF VIDEO 1: Check Antenna cable (RF switch, Tuners..) Check Antenna Cable 2: Check Tuners Vcc and IF out Appears to be noise Check Tuner(TU600), 5V, IF out 3: Check X260 Input (CLK, SOP, Valid, Error, Data) Check LGDT3303(IC604) inputs power pins, Osc(25Mhz), IF pin...
  • Page 20 Video Trouble Shooting Video Trouble Shooting AT/NT/ LGDT TUNER 3303 VSB1/QAM TP TP A FRC9445H TP C TP B / 656 CVBS X260 CVBS AV1/2 AV1/2 Y/C1, Y/C2 Y/C1, Y/C2 YCbCr1 YCbCr2 YCbCr or RGB Comp1/2 HS,VS HS,VS 3361 HDMI TMDS341A 1/2/3 LCD TV - 2007...
  • Page 21 Video Trouble Shooting Video Trouble Shooting AT/NT/ LGDT TUNER 3303 VSB1/QAM TP TP A FRC9445H TP C TP B / 656 X260 CVBS CVBS AV1/2 AV1/2 Y/C1, Y/C2 Y/C1, Y/C2 YCbCr1 YCbCr2 YCbCr or RGB Comp1/2 HS,VS HS,VS 3361 HDMI TMDS341A 1/2/3 LCD TV - 2007...
  • Page 22 Video Trouble Shooting Video Trouble Shooting AT/NT/ LGDT TUNER 3303 VSB1/QAM TP TP A FRC9445H TP C TP B / 656 X260 CVBS CVBS AV1/2 AV1/2 Y/C1, Y/C2 Y/C1, Y/C2 YCbCr1 YCbCr2 YCbCr or RGB Comp1/2 HS,VS HS,VS 3361 HDMI TMDS341A 1/2/3 LCD TV - 2007...
  • Page 23 Video Trouble Shooting Video Trouble Shooting 1. Check Signal format (ref. owner’s manual) Check Signal format 2. Check STMAV335(IC403) Power Input Signal (supported format?) Check STMAV335(IC403) Power Pins, Comp1(#2,#5,#11), Comp2(#3,#6,#10), RGB(#9,#4,#7) RGB_V,H(R400,R401) Check STMAV335(IC403) outputs #14(MUX_OUT_Y), #13(MUX_OUT_Pb), #8(MUX_OUT_Pr) Check MST3361(IC402) OSC, Power pins,#44( Y_in), 3 : Check STMAV335(IC403) outputs Signal shape is same...
  • Page 24 Video Trouble Shooting Video Trouble Shooting AT/NT/ LGDT TUNER 3303 VSB1/QAM TP TP A FRC9445H TP C TP B / 656 X260 CVBS CVBS AV1/2 AV1/2 Y/C1, Y/C2 Y/C1, Y/C2 YCbCr1 YCbCr2 YCbCr or RGB Comp1/2 HSync, / VSync HS,VS 3361 HDMI TMDS341A...
  • Page 25 Video Trouble Shooting Video Trouble Shooting AT/NT/ LGDT TUNER 3303 VSB1/QAM TP TP A FRC9445H TP C TP B / 656 CVBS X260 CVBS AV1/2 AV1/2 Y/C1, Y/C2 Y/C1, Y/C2 YCbCr1 YCbCr2 YCbCr or RGB Comp1/2 H Sync, V Sync HS,VS 3361 HDMI...
  • Page 26 Video Trouble Shooting Video Trouble Shooting 1. Check Signal format (ref. owenr’s manual) Check Signal format 2. Check STMAV335(IC403) Power Input Signal (supported format?) Check STMAV335(IC403) Power Pins, Comp1(#2,#5,#11), Comp2(#3,#6,#10), RGB(#9,#4,#7) RGB_V,H(R400,R401) Check STMAV335(IC403) outputs #14(MUX_OUT_Y), #13(MUX_OUT_Pb), #8(MUX_OUT_Pr) Check MST3361(IC402) 3 : Check STMAV335(IC403) outputs Signal shape is same (above) OSC, Power pins,#44( Y_in),...

  • Page 27: Hdmi Signal Path

    Video Trouble Shooting HDMI Signal Path Video Trouble Shooting HDMI Signal Path EVEREST3 BASIC HDMI/DVI AT/NT/ TUNER LGDT 3303 VSB1/QAM TP TP A FRC9445H TP C TP B / 656 CVBS X260 CVBS AV1/2 AV1/2 Y/C1, Y/C2 Y/C1, Y/C2 YCbCr1 YCbCr2 YCbCr or RGB Comp1/2...
  • Page 28 Video Trouble Shooting Video Trouble Shooting EVEREST3 BASIC HDMI/DVI 1 : _Check HDCP Error Power off and on Snow noise (White dot) ? (TV or STB/DVD…) _Retry power off and on (TV or STB/DVD…) _Check MST3361(IC402) HDCP IIC line (#69,#70) SCL : Check HDCP Power SDA :...
  • Page 29 47LB4DS 47LB4DS 47LB4DS Audio Trouble Shooting Guide Audio Trouble Shooting Guide Audio Trouble Shooting Guide LCD TV - 2007...

  • Page 30: Audio Troubleshooting

    Audio Troubleshooting Audio Path Audio Path VSB TP AT/NT ANT/Cable LGDT TP A TUNER 3303 TP C SIF IN 1 SIF IN 2 X260 MSP4450K I2SO 1 I2S IN 1 EXT1/2 I2S IN 2 MCLK COMP 1/2 3000 I2S OUT 1 I2SI 3 SC 2 SPDIF 出...

  • Page 31: Audio Out

    Audio Troubleshooting Audio Out Audio Out Monitor L,R Out All Source Speaker Out Digital Audio Out If DTV or HDMI input Check X260 (IC101) Output R153(SCLK), R154(LRCLK), Check X260 (IC101) Output R155(DATA) R153(SCLK), R154(LRCLK), Check CS8416 (IC501) Power Check MSP4450K (IC508) Input R155(DATA), R156(MCLK) R5059(SCLK) R5060(LRCLK), R5061(DATA)
  • Page 32 Audio Troubleshooting TV RF Sound TV RF Sound VSB TP ANT/Cable AT/NT LGDT TUNER TP A 3303 TP C SIF IN 1 SIF IN 2 X260 MSP4450K MSP4450K I2SO 1 I2SO 1 I2S IN 1 EXT1/2 I2S IN 2 COMP 1/2 MCLK 3000 I2S OUT 1...
  • Page 33 TV RF No Sound TV RF No Sound Check Antenna Cable Check Tuner (TU600) 5V (3,5,9,17 pin), SIF(18 pin) Check SIF lines C6025, C6026 Check MSP4450K (IC508) inputs C5016, #67pin Check MSP4450K (IC508) outputs R5039(SCLK), R5040(LRCLK), R5043(DATA) Check MSP4450K (IC508) Power Check X260 (IC101) Intputs R175(SCLK), R176(LRCLK), R177(DATA)
  • Page 34 Audio Troubleshooting DTV No Sound DTV No Sound VSB TP ANT/Cable AT/NT LGDT TUNER TP A 3303 TP C SIF IN 1 SIF IN 2 X260 MSP4450K I2SO 1 I2S IN 1 EXT1/2 I2S IN 2 MCLK COMP 1/2 3000 I2S OUT 1 I2SI 3 SC 2...
  • Page 35 Audio Troubleshooting AV/Component/RGB No Sound AV/Component/RGB No Sound VSB TP ANT/Cable AT/NT LGDT TUNER TP A 3303 TP C SIF IN 1 SIF IN 2 X260 MSP4450K I2SO 1 I2S IN 1 EXT1/2 I2S IN 2 MCLK COMP 1/2 3000 I2S OUT 1 I2SI 3 SC 2...
  • Page 36 Audio Troubleshooting HDMI No Sound HDMI No Sound ANT/Cable Check HDMI Cable VSB TP AT/NT LGDT Check MST3361 (IC402) output TUNER TP A 3303 HDMI_SPDIF (R409) TP C Check CS8416 (IC501) inputs SIF IN 1 HDMI_SPDIF (C5005) Check CS8416 (IC501) outputs SIF IN 2 DATA(#26), SCLK(#27), LRCLK(#28)
  • Page 37 EVEREST3 BASIC USB BLOCK 1. USB 1.1 Block Diagram For EMF 5V_USB X260 USB_PWR_DOWN VBUS_5V DC/DC Converter DEVICE USB1.1_OVRCUR USB_ link (IC712) Side B/D (HDD or Memory) (IC101) Cable DP,DM USB 1.1 cable 2. Check Sequence If the device is HDD, check Check the device Cable.Is Check the device a external power adaptor.

  • Page 38: Exploded View

    Exploded View LCD TV - 2007...
  • Page 39 LCD,Module-TFT, LC370WX2-SLD1 WXGA 37.0INCH 1366X768 500CD COLOR 72% 16/9 1000:1(basic) 120Hz,0RT Pol. ABJ31872405 Cabinet Assembly, 37LB4DS-UA LP78A 37" 37LB4DS-UA CABINET ASSY(C/SKD) ACQ31873408 Cover Assembly, Rear, 37LB4DS-UA LA73A 37" 405AF LG ONLY BACK COVER ASS'Y(C/SKD) EBR35343001 PCB Assembly, Sub, SUB T.T LA73A 37LB4DS-UA AUSLLHX 37LB4DS-UAControl key total MES32421701 Indicator, MOLD PMMA LED&PRE AMP 26LC4D-AA PMMA 2 PHY -...

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