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LGE Internal Use Only

Copyright © 2007 LG Electronics. Inc. All right reserved. 
Only for training and service purposes

- 3 -

SAFETY PRECAUTIONS

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
Shock, Fire, or other Hazards. 
Do not modify the original design without permission of manufacturer.

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.

If any fuse (or Fusible Resistor) in this TV receiver is blown,
replace it with the specified.

When replacing a high wattage resistor (Oxide Metal Film Resistor,
over 1W), keep the resistor 10mm away from PCB.

Keep wires away from high voltage or high temperature parts.

Before returning the receiver to the customer,

always perform an 

AC leakage current check

on the exposed

metallic parts of the cabinet, such as antennas, terminals, etc., to
be sure the set is safe to operate without damage of electrical
shock. 

Leakage Current Cold Check(Antenna Cold Check)

With the instrument AC plug removed from AC source, connect an
electrical jumper across the two AC plug prongs. Place the AC
switch in the on position, connect one lead of ohm-meter to the AC
plug prongs tied together and touch other ohm-meter lead in turn to
each exposed metallic parts such as antenna terminals, phone
jacks, etc. 
If the exposed metallic part has a return path to the chassis, the
measured resistance should be between 1MΩ and 5.2MΩ. 
When the exposed metal has no return path to the chassis the
reading must be infinite.
An other abnormality exists that must be corrected before the
receiver is returned to the customer.

Leakage Current Hot Check

(See below Figure) 

Plug the AC cord directly into the AC outlet.

Do not use a line Isolation Transformer during this check.

Connect 1.5K/10watt resistor in parallel with a 0.15uF capacitor
between a known good earth ground (Water Pipe, Conduit, etc.)
and the exposed metallic parts.
Measure the AC voltage across the resistor using AC voltmeter
with 1000 ohms/volt or more sensitivity.
Reverse plug the AC cord into the AC outlet and repeat AC voltage
measurements for each exposed metallic part. Any voltage
measured must not exceed 0.75 volt RMS which is corresponds to
0.5mA.
In case any measurement is out of the limits specified, there is
possibility of shock hazard and the set must be checked and
repaired before it is returned to the customer.

Leakage Current Hot Check circuit

1.5 Kohm/10W

To Instrument's
exposed 
METALLIC PARTS

Good Earth Ground
such as WATER PIPE,
CONDUIT etc.

AC Volt-meter

IMPORTANT SAFETY NOTICE

0.15uF

Summary of Contents for 32LT75/76

Page 1: ...ERVICING THE CHASSIS READ THE SAFETY PRECAUTIONS IN THIS MANUAL CHASSIS LD74A MODEL 32LT75 76 32LT75 76 ZA North Latin America http aic lgservice com Europe Africa http eic lgservice com Asia Oceania http biz lgservice com Internal Use Only ...

Page 2: ... Electronics Inc All right reserved Only for training and service purposes CONTENTS CONTENTS 2 PRODUCT SAFETY 3 SPECIFICATION 6 ADJUSTMENT INSTRUCTION 10 TROUBLE SHOOTING 14 BLOCK DIAGRAM 23 EXPLODED VIEW 28 REPLACEMENT PARTS LIST 30 SVC SHEET ...

Page 3: ... operate without damage of electrical shock Leakage Current Cold Check Antenna Cold Check With the instrument AC plug removed from AC source connect an electrical jumper across the two AC plug prongs Place the AC switch in the on position connect one lead of ohm meter to the AC plug prongs tied together and touch other ohm meter lead in turn to each exposed metallic parts such as antenna terminals...

Page 4: ... on your body by touching a known earth ground Alternatively obtain and wear a commercially available discharging wrist strap device which should be removed to prevent potential shock reasons prior to applying power to the unit under test 2 After removing an electrical assembly equipped with ES devices place the assembly on a conductive surface such as aluminum foil to prevent electrostatic charge...

Page 5: ...the solder joints of the two original leads If they are not shiny reheat them and if necessary apply additional solder Fuse and Conventional Resistor Removal Replacement 1 Clip each fuse or resistor lead at top of the circuit board hollow stake 2 Securely crimp the leads of replacement component around notch at stake top 3 Solder the connections CAUTION Maintain original spacing between the replac...

Page 6: ...Half scart and support MNT OUT Video Input 2EA PAL SECAM NTSC 4 System PAL SECAM NTSC PAL60 S Video Input 1EA PAL SECAM NTSC 4 System PAL SECAM NTSC PAL60 Component Input 1EA Y Cb Cr Y Pb Pr RGB Input RGB PC RGB DTV HDMI Input 2EA HDMI PC HDMI DTV SOUND Audio Input 4 EA PC Audio Component AV 2EA L R Input Item Specification Remark Display Screen Device 32 wide Color Display Module LCD Aspect Ratio...

Page 7: ... 0 284 0 286 Y 0 606 0 615 0 614 Blue X 0 145 0 144 0 146 Y 0 064 0 063 0 061 Contrast ratio W O PC mode 600 800 32 LPL 0 RT Luminance Variation 1 3 7 3 Chroma Brightness LCD Module LPL 4 Component Video Input Y PB PR No Specification Proposed Resolution H freq kHz V freq Hz 1 720 480 15 73 60 00 SDTV DVD 480i 2 720 480 15 63 59 94 SDTV DVD 480i 3 720 480 31 47 59 94 480p 4 720 576 15 625 50 00 SD...

Page 8: ...odel only Input 1920 1200 60Hz 1600 1200 60Hz Display 12 1920 1080 66 647 59 988 138 625 WUXGA Reduced Blanking Timing No Resolution H freq kHz V freq Hz Pixel clock MHz Proposed Remark 1 720 480 31 47 59 94 27 00 SDTV 480P 4 3 PC mode 640 480 60Hz Display 2 720 480 31 50 60 27 027 SDTV 480P 4 3 3 640 480 31 469 59 94 25 175 SDTV 480P 4 3 4 640 480 31 469 60 00 25 20 SDTV 480P 4 3 5 720 480 31 47 ...

Page 9: ...60 31 40 00 VESA 46 875 75 00 49 50 4 832 624 49 725 74 55 57 283 Macintosh 5 1024 768 48 363 60 00 65 00 VESA XGA 56 470 70 00 75 00 60 123 75 029 78 75 6 1280 768 47 78 59 87 79 5 WXGA PC mode only 7 1360 768 47 72 59 8 84 75 WXGA 8 1366 768 47 56 59 6 84 75 WXGA 9 1280 1024 63 595 60 0 108 875 SXGA FHD Model only 10 1400 1050 65 160 60 0 122 50 SXGA FHD Model only 11 1600 1200 74 077 60 0 130 3...

Page 10: ...x0C0x0D 0x0E 0x0F 0x00 00 FF FF FF FF FF FF 00 1E 6D ⓐ ⓑ 0x01 ⓒ 01 03 01 46 27 78 EA D9 B0 A3 57 49 9C 25 0x02 11 49 4B A5 6E 00 31 40 45 40 61 40 D1 C0 01 01 0x03 01 01 01 01 01 01 1B 21 50 A0 51 00 1E 30 48 88 0x04 35 00 BC 86 21 00 00 1C 26 36 80 A0 70 38 1F 40 0x05 50 20 85 04 BC 86 21 00 00 18 ⓓ 0x06 ⓓ 00 00 00 FD 0x07 00 3C 4B 1D 43 0E 00 0A 20 20 20 20 20 20 00 ⓔ 1 For Analog EDID 0x000x010...

Page 11: ...Balance 1 Input the Video Signal 7 Color Bar signal into AV3 2 Set the PSM to Dynamic mode in the Picture menu 3 Press IN START key on R C for adjustment 4 Press the G Vol key to operate the set then it becomes automatically 5 Auto RGB OK means the adjustment is completed 6 2 Adjustment of Component 1 Required Equipments Remote controller for adjustment MSPG 925FS Pattern Generator Which has 720p ...

Page 12: ...of White Balance the pattern will come out Auto adjustment Map RS 232C Auto control interface and directions 1 Adjust in the place where the influx of light like floodlight around is blocked illumination is less than 10ux 2 Adhere closely the Color Analyzer CA 210 to the module less than 10cm distance keep it with the surface of the Module and Color Analyzer s Prove vertically 80 100 3 Aging time ...

Page 13: ...0 and adjust other two lower than 80 When R G B GAIN are all 80 it is the FULL DYNAMIC Range of Module 8 Scart RGB DVR Adjustment Mode Required Equipments Remote controller for adjustment MSPG 925FS Pattern Generator Which has Video Signal Color Bar Pattern shown in Fig 2 Model 232 Pattern 80 1 Input the Video Signal Color Bar signal into AV1 Using Full Scart Cable 2 Set the PSM to Dynamic mode in...

Page 14: ...lug in the power cord Yes No Is the Line Filter and Power Board Cable connected Connect the Cable Yes No Is the appropriate Fuse F100 on the Power Board Replace the Fuse Yes No Is the Power Board and 13P of VSC Board Cable connected Connect the Cable Yes No After removing the cables connect them to the Power Board except the SC101 connection cable and change the AC voltage marking to manual When S...

Page 15: ...nector do they operate normally No Yes Yes Is the VSC Board normal Is the output voltage normal after removing P900 P901 of VSC Board If it operates normally after removing the P900 P901 Replace the VSC Board No Yes Does minute discharge at Module Is the LVDC cable normal Is the inverter on Check the LCD Module Yes No YES Yes Reconnect the LVDS cable in P1901 No Is the IC700 FLI8548 Output normal ...

Page 16: ...play 1 Symptom 1 LED is green 2 The minute discharge is continuously accomplished from the module 2 Procedure check Is the LVDS cable normal Is the VSC Board normal Is the LVDS cable connected Insert the Cable Yes No No Yes Does the FIL8548 IC IC700 operate Replace the FIL8548 IC IC700 No Is the Ctrl Board of Module normal Replace the Ctrl B D No No Yes Replace the VSC B D Replace the cable Yes ...

Page 17: ...eo AV mode 5 In case of an unusual display in Component RGB mode Is the Tuner normal Is the CXA2069Q normal Is the Tuner Cable connected Re insert the cable Yes No No Yes Is the FIL8548 normal Replace the Tuner No Are the Input voltage IIC Communication and CVBS output normal Yes Are the Input voltage IIC Communication and HV sync normal No Replace the IC No Are the input voltage IIC Communication...

Page 18: ...al display in SCART1 mode 8 In case of an unusual display in SCART2 mode Is the HDMI002 IC1004 normal Yes Same as Block A Are Input voltage IIC Communication and HV sync normal No Is the Video input of the A V Jack J1200 normal Yes Same as Block A Check the input source No Replace the IC No Is the Video input of the A V Jack J1201 normal Yes Same as Block A Check the input source No ...

Page 19: ...t diagram No Is there no sound only for specific input except HDMI DTV RF Check the signal before CAX2069 refer to circuit diagram No YES YES Is there no sound only for RF Check the Tuner IN OUT No YES YES Is there no sound only for AV component PC input Is the output of CXA2069 normal No YES Is the IC1300 operating normally Replace the IC1300 MSP4450 No Is the IC1301 operating normally Replace th...

Page 20: ...on No Is time shift mode on Menu Are the cables connected well P1500 P1501 Insert cables well Yes Power and Data Cable is normal P1500 P1501 Change the power and Data cable No Is HDD normal Change the HDD Assy No No YES Check BU9580KVT IC IC1504 Is it ok Replace STI5100 IC IC100 YES Yes Power s operation is normal No Power s operation is normal Yes No Check STI5100 IC IC100 NEC61151F IC1600 NEC640...

Page 21: ...e time shift or recorded TV Go on 19page in the document Yes No MUTE key on Turn off the mute key Yes No Sound cable is ok No No No Connect speak cable sound is ok Are power cable connected well Connect power cables power B D No Check speakers Are they ok No No Check MSP IC1300 Audio AMP IC1301 Is it ok Is Data cable P1501 ok Connect Data cable Yes Yes Yes Change the speakers Yes Change the ICs Is...

Page 22: ...g and service purposes Check data cable P1501 Is it ok Connect data cable P1501 Remove the recorded lists and Record one more time and Play again Is it ok No Yes Yes 1 Are the cable connected well P1500 P1501 No Connect cable well No Check STI5100 IC IC100 NEC61151F IC600 NEC64015A Is it ok No Change HDD Is it ok Check BU9580KVT IC1504 Is it ok Yes 2 Replace VSC B D No No ...

Page 23: ...CX157 SPDIF out ST SPDIF MSP SPDIF DDRRAM 256MB DTV_out CVBS L R MSP4450K Audio SW Tone Control AV_LR PC_Audio Comp_LRin TV_L Rout SIF STA333W TV_L Rout AV_LR uPD64015 Video Decoder 24 576M HY57V161610ET SDRAM 2MB uPD61151 MPEG Encoder 656 Comp CS5331 I2S IN MCLK 16bit 32bit HY57V641620ET SDRAM 8MB 2 HY57V641620ET STm5100 TP Dec Mpeg Decoder Audio Dec 74LCX541 Addr Data Buffer For Hot Plugg in CI ...

Page 24: ...Strobe LDWE Write Enable LDCLKE Clock Enable LDCLK Clock LDCLKN Inverted Clock TS0_DATA 0 7 TS0_DATA_CLK TS0_DATA_VAL TS0_DATA_SYN YUV_D 0 7 YUV_PIXCLK CI_EN CI_RST I2C_SDA0 SCL0 I2C_SDA1 SCL1 Array R DIGIT_D 0 7 CLK_DIGIT EEPROM TS_SEL DTV_AUDIO_MUTE PIO_286 PIO_287 Tr REC_B FOR SCART PIN8 OUT_LEFT OUT_RIGHT CVBS Buffer Buffer DTV_LOUT DTV_ROUT SP_CVBS DTV_AUDIO_MUTE_BUF ST5100 GPIO 27M 32 768Khz...

Page 25: ...face Microprocessor CI_TS_DATA Descrambled TS Scart 1 Scart 1 Scart 2 Scart 2 cxa2069q cxa2069q MSP4450K MSP4450K TV_L R out 3 1pin DTV MNT_LROUT 3 1pin Scart1_Lrin 6 2pin Comp J1200 Comp J1200 PC audio J1100 PC audio J1100 PC_Audio LR Comp_Rin Lin Av2 J1201 Av2 J1201 Side AV P1400 Side AV P1400 AV2_Lin Rin Lin5 Rin5 AV_L R out ANX 9021 ANX 9021 STi5100 STi5100 DTV_Lout DTV_Rout 74LCX157 MUX 74LCX...

Page 26: ...rtez Plus TU600 A D tuner SW_TU_SCL SW_TU_SDA SDA_5V SCL_5V IC1300 MSP4450k IC1400 CXA2069Q 4 7K 5 0V SDA SCL 4 7K P_3 3V IC1301 STA335BW 0X38 P801 P1901 PDP PANEL IC407 LM75 SDA_EEPR SCL_EEPR 4 7K IC702 HDCP EEPROM IC701_24LC256 NVRAM 3 3V_CTZ SDA_HDMI SCL_HDMI 4 7K IC1004 STHDMI002A 5VST IC1002 AT24C028 J1000 HDMI JACK SDA_HDMI_0 SCL_HDMI_0 DDC_SDA_0 DDC_SCL_0 IC1002 AT24C028 J1000 HDMI JACK SDA...

Page 27: ... 27 MEMO LGE Internal Use Only Copyright 2007 LG Electronics Inc All right reserved Only for training and service purposes ...

Page 28: ...ctrical 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 Do not modify the original design without permission of manufactu...

Page 29: ...LGE Internal Use Only Copyright 2007 LG Electronics Inc All right reserved Only for training and service purposes ...

Page 30: ...LGE Internal Use Only Copyright 2007 LG Electronics Inc All right reserved Only for training and service purposes ...

Page 31: ...LGE Internal Use Only Copyright 2007 LG Electronics Inc All right reserved Only for training and service purposes ...

Page 32: ...LGE Internal Use Only Copyright 2007 LG Electronics Inc All right reserved Only for training and service purposes ...

Page 33: ...Aug 2007 Printed in Korea P NO MFL39435601 ...

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