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LGE Internal Use Only

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

CAUTION: Before servicing receivers covered by this service
manual and its supplements and addenda, read and follow the

SAFETY PRECAUTIONS

on page 3 of this publication.

NOTE: 

If unforeseen circumstances create conflict between the

following servicing precautions and any of the safety precautions on
page 3 of this publication, always follow the safety precautions.
Remember: Safety First.

General Servicing Precautions
1.  Always unplug the receiver AC power cord from the AC power

source before;
a.  Removing or reinstalling any component, circuit board

module or any other receiver assembly.

b.  Disconnecting or reconnecting any receiver electrical plug or

other electrical connection.

c. Connecting a test substitute in parallel with an electrolytic

capacitor in the receiver.

CAUTION:

A wrong part substitution or incorrect polarity

installation of electrolytic capacitors may result in an
explosion hazard.

2.  Test high voltage only by measuring it with an appropriate high

voltage meter or other voltage measuring device (DVM,
FETVOM, etc) equipped with a suitable high voltage probe.
Do not test high voltage by "drawing an arc".

3.  Do not spray chemicals on or near this receiver or any of its

assemblies.

4. Unless specified otherwise in this service manual, clean

electrical contacts only by applying the following mixture to the
contacts with a pipe cleaner, cotton-tipped stick or comparable
non-abrasive applicator; 10% (by volume) Acetone and 90% (by
volume) isopropyl alcohol (90%-99% strength)

CAUTION:

This is a flammable mixture.

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.

7.  Always connect the test receiver ground lead to the receiver

chassis ground before connecting the test receiver positive
lead.
Always remove the test receiver ground lead last.

8. 

Use with this receiver only the test fixtures specified in this
service manual.

CAUTION:

Do not connect the test fixture ground strap to any

heat sink in this receiver.

Electrostatically Sensitive (ES) Devices

Some semiconductor (solid-state) devices can be damaged easily
by static electricity. Such components commonly are called

Electrostatically Sensitive (ES) Devices.

Examples of typical ES

devices are integrated circuits and some field-effect transistors and
semiconductor "chip" components. The following techniques
should be used to help reduce the incidence of component
damage caused by static by static electricity.
1.  Immediately before handling any semiconductor component or

semiconductor-equipped assembly, drain off any electrostatic
charge 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 buildup or
exposure of the assembly.

3.  Use only a grounded-tip soldering iron to solder or unsolder ES

devices.

4. Use only an anti-static type solder removal device. Some solder

removal devices not classified as "anti-static" can generate
electrical charges sufficient to damage ES devices.

5.  Do not use freon-propelled chemicals. These can generate

electrical charges sufficient to damage ES devices.

6.  Do not remove a replacement ES device from its protective

package until immediately before you are ready to install it.
(Most replacement ES devices are packaged with leads
electrically shorted together by conductive foam, aluminum foil
or comparable conductive material).

7.  Immediately before removing the protective material from the

leads of a replacement ES device, touch the protective material
to the chassis or circuit assembly into which the device will be
installed.

CAUTION: 

Be sure no power is applied to the chassis or circuit,

and observe all other safety precautions.

8. Minimize bodily motions when handling unpackaged

replacement ES devices. (Otherwise harmless motion such as
the brushing together of your clothes fabric or the lifting  of your
foot from a carpeted floor can generate static electricity
sufficient to damage an ES device.)

General Soldering Guidelines
1.  Use a grounded-tip, low-wattage soldering iron and appropriate

tip size and shape that will maintain tip temperature within the
range or 500

°F to 600°F.

2.  Use an appropriate gauge of RMA resin-core solder composed

of 60 parts tin/40 parts lead.

3.  Keep the soldering iron tip clean and well tinned.
4.  Thoroughly clean the surfaces to be soldered. Use a mall wire-

bristle (0.5 inch, or 1.25cm) brush with a metal handle.
Do not use freon-propelled spray-on cleaners.

5.  Use the following unsoldering technique

a.  Allow the soldering iron tip to reach normal temperature.

(500

°F to 600°F)

b.  Heat the component lead until the solder melts.
c.  Quickly draw the melted solder with an anti-static, suction-

type solder removal device or with solder braid.
CAUTION: Work quickly to avoid overheating the
circuitboard printed foil.

6.  Use the following soldering technique.

a.  Allow the soldering iron tip to reach a normal temperature

(500

°F to 600°F)

b.  First, hold the soldering iron tip and solder the strand against

the component lead until the solder melts.

c.

Quickly move the soldering iron tip to the junction of the

component lead and the printed circuit foil, and hold it there
only until the solder flows onto and around both the
component lead and the foil.

CAUTION:

Work quickly to avoid overheating the circuit

board printed foil.

d. Closely inspect the solder area and remove any excess or

splashed solder with a small wire-bristle brush.

SERVICING PRECAUTIONS

Summary of Contents for 42LY99

Page 1: ...LCD TV SERVICE MANUAL CAUTION BEFORE SERVICING THE CHASSIS READ THE SAFETY PRECAUTIONS IN THIS MANUAL CHASSIS LD75C MODEL 42LY99 42LY99 ZC website 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 21 EXPLODED VIEW 22 REPLACEMENT PARTS LIST 24 SVC SHEET ...

Page 3: ...fe 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 term...

Page 4: ...e 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 charg...

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 repla...

Page 6: ...2 SECAM L L 3 DVB T 3 Receiving system Analog Upper Heterodyne Digital COFDM 4 Scart Jack 2EA PAL SECAM Scart 2 Jack MNT DTV output 5 Video Input 1EA PAL SECAM NTSC 4 System PAL SECAM NTSC PAL60 6 S Video Input 1EA PAL SECAM NTSC 4 System PAL SECAM NTSC PAL60 7 Component Input 1EA Y Cb Cr Y Pb Pr 8 RGB Input 1EA RGB PC 9 HDMI Input 3 EA HDMI DTV SOUND 10 Audio Input 3 EA PC Audio Component AV L R ...

Page 7: ... 250 HDTV 1080I 12 1920 1080 28 125 50 00 74 250 HDTV 1080I 13 1920 1080 67 50 60 00 148 50 HDTV 1080P No Item Min Typ Max Unit Remark 1 Viewing Angle CR 10 R L 178 U D 178 2 White average brightness 400 500 cd m 100IRE Full White Pattern 255 gray Picture Dynamic Cool 3 Brightness uniformity 1 3 cd m 100IRE Full White Pattern 255 gray Picture Dynamic Cool 4 Color Coordinate White X Typ 0 279 Typ 8...

Page 8: ...duced Blanking Timing 6 HDMI input DTV No Resolution H freq kHz V freq Hz Pixel clock MHz Proposed Remarks 1 720 480 31 47 59 94 27 00 SDTV 480P 4 3 PC mode Display 640 480 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 59 94 27 000 SDTV 480P 16 9 6 720 480 31 50 60 00 27 027 SDTV 480P 16 9 7 720 576 31...

Page 9: ...00 37 879 60 31 40 00 VESA 46 875 75 00 49 50 4 832 624 49 725 74 55 57 283 Mcintosh 5 1024 768 48 363 60 00 65 00 VESA XGA 56 476 70 00 75 00 60 023 75 03 78 75 6 1280 768 47 693 59 99 80 125 WXGA 7 1360 768 47 649 59 94 84 625 WXGA 8 1366 768 47 649 59 94 84 625 WXGA 9 1280 1024 63 595 60 0 108 875 SXGA 10 1400 1050 65 160 60 0 122 50 SXGA 11 1600 1200 74 077 60 0 130 375 UXGA Reduced Blanking T...

Page 10: ...ution System control RS 232 Host should be PC for adjustment Before AV ADC Calibration execute the Module selection 4 1 Adjustment of RF AV S VIDEO 1 Required Equipments Remote controller for adjustment MSPG 925FS Pattern Generator Which has Video Signal 7 Color Bar Pattern shown in Fig 1 Model 202 Pattern 65 2 Method of Auto RF AV S VIDEO Color Balance 1 Input the Video Signal 7 Color Bar signal ...

Page 11: ...80 90 40 0x30 A9 40 D1 C0 01 01 1A 36 80 A0 70 38 1F 40 30 20 0x40 35 00 E8 26 32 00 00 1A 1B 21 50 A0 51 00 1E 30 0x50 48 88 35 00 BC 86 21 00 00 1C 00 00 00 FD 00 39 0x60 4B 1F 54 12 00 0A 20 20 20 20 20 20 0x70 01 2 0x80 02 03 21 F1 4E 81 02 03 15 12 13 04 14 05 20 21 0x90 22 1F 10 23 09 07 07 83 01 00 00 65 03 0C 00 10 0xA0 00 01 1D 00 80 51 D0 1C 20 40 80 35 00 BC 88 21 0xB0 00 00 1E 8C 0A D0...

Page 12: ... Aging time After aging start keep the power on no suspension of power supply and heat run over 15 minutes Using no signal or full white pattern or the others check the back light on LGE Internal Use Only Copyright 2007 LG Electronics Inc All right reserved Only for training and service purposes CS 1000 CA 210 CH 9 CA 100 CH9 Cool x 0 276 0 002 0 276 0 002 0 276 0 002 y 0 283 0 002 0 283 0 002 0 2...

Page 13: ... Range of the Module In order to control white balance without the saturation of FULL DYNAMIC Range and DATA one of R Gain G Gain B Gain should be kept on 80 and other two is controlled lowering from 80 Color Temperature Cool Medium Warm 1 When R GAIN is set to 80 Control G GAIN and B GAIN by lowering from 80 2 When B GAIN is set to 80 Control R GAIN and G GAIN by lowering from 80 3 When G GAIN is...

Page 14: ...e power cord No Yes Is the power cord pluged in Connect the cable No Is the Line Filter and Power Board Cable connected Replace the fuse No Is the appropriate Fuse F101 on Power Board Connect the Cable After removing the cables connect them to the Power Board except the SC101 connection cable and change the AC voltage marking to manual When ST BY 5V does not operate replace the Power Board No Is t...

Page 15: ...eplace the connector After connecting each connector do they operate normally Yes No No Is the VSC Board normal If it operates normally after removing the P900 P901 Replace VSC Board Is the output voltage normal after removing P900 P901 of VSC Board No Yes 3 No Raster 1 Symptom 1 No OSD and image occur at screen 2 It maintains the condition where the front LED is green 2 Check following Does minut...

Page 16: ...lay the OSD 1 Symptom 1 LED is green 2 The minute discharge continuously accomplished from module 2 Check follow Is the LVDS cable normal Replace Power Board Is the LVDS cable connected Re insert the Cable Yes No No Replace the FIL8548 IC IC700 No Yes Is the VSC Board normal Replace the VSC B D Does the FIL8548 IC IC700 operate Yes No Yes Is the Ctrl Board of Module normal Replace the Ctrl B D No ...

Page 17: ...he Video Main Data Sub Video Main Video Sub have normal display from the PIP mode or DW mode Re Check it Swap 3 In case of becomes unusual display from RF mode Is the Tuner normal Is the Input voltage IIC Communication and CVBS output normal Replace the Tuner Is the Tuner Cable connected Re inserts the cable Yes No No No Yes Is the CXA2069Q normal Replace the IC Is the Input voltage IIC Communicat...

Page 18: ... voltage IIC Communication and HV sync normal Yes No No Replace the IC No Replace the IC No Is the CXA2069Q normal Yes Same as Block A 5 In the case of becomes unusual display from Component RGB mode Are the R G B input and H V Sync of the J1100 normal Yes Check the input source No Same as Block A 6 In the case of becomes unusual display from HDMI mode Is the HDMI002 IC1004 normal Yes Is the Input...

Page 19: ...ce purposes 7 In the case of becomes unusual display from SCART1 mode Is Video input of the A V jack J1200 normal Yes Check the input source No Same as Block A 8 In the case of becomes unusual display from SCART2 mode Is Video input of the A V jack J1201 normal Yes Check the input source No Same as Block A ...

Page 20: ... the IC1300 operating normally Replace IC1300 MSP4450 Is the IC1301 operation normally Replace IC1300 STA335BW Replace VSC B D Yes No Is there no sound only for HDMI Yes Download the EDID data No No No No No Only RF is no sound Yes Check the Tuner IN OUT No Check the signal before CXA2069 refer to circuit diagram Is there no sound only for AV Component PC input Yes Is there no sound only for speci...

Page 21: ... 3 V Buf f er 3 3 V 3 3 V ICL323 3 3 V 3 3 V 3 3 V V L R Y C V L R Y C Co mp o nent Y Pb Pr L R Co mp o nent Co mp o nent Y Pb Pr L R RF IN RF IN 1 8V 1 8V 3 3V 3 3V 5V 5V D A Tuner TDFC G107P S PDIF S PDIF 74LCX157 3 3 V 74LCX157 3 3 V 74LCX157 3 3 V FE_TS_Data TS_DATA CI_TS_Data 8Bit 656 27MHz CVBS DTV L R OUT I2S SPDIF_STI_OUT I2S I2S SPDIF_MSP_OUT SPDIF_MSP_OUT TMDS TMDS HDMI_CEC COMP Y Pb Pr ...

Page 22: ... Copyright 2007 LG Electronics Inc All right reserved Only for training and service purposes 300 121 800 800 120 500 510 700 520 200 812 813 810 811 814 815 816 530 817 900 910 610 600 820 400 821 552 551 550 553 EXPLODED VIEW ...

Page 23: ...2 J3 LD_D 8 002 C2 002 J3 LD_D 0 002 G3 002 J2 LD_D 12 002 H3 002 J3 LD_D 13 002 C2 002 J3 LD_D 4 002 C1 002 J2 LD_D 5 002 G3 002 J3 LD_D 2 002 C1 002 J2 LD_D 14 002 H3 002 J3 LD_D 5 002 C1 002 J3 LD_D 10 002 H3 002 J3 LD_D 6 002 C2 002 J3 LD_A 1 002 G4 002 J1 LD_A 4 002 H5 002 J2 LD_A 1 002 C2 002 J1 LD_A 7 002 H4 002 J1 LD_CS 002 G4 002 J4 LD_A 0 002 C2 002 J1 LD_A 8 002 H4 002 J2 LD_BA0 002 G4 ...

Page 24: ..._4 AB4 ADC_1 8_1 AC4 ADC_1 8_2 AC5 ADC_1 8_3 A14 VDD18_DLL C25 RPLL_1 8 D26 RPLL3 3 AD3 ADC_3 3 AD4 ADCA_3 3 AD5 ADCB_3 3 AD6 ADCC_3 3 AD7 ADCSC_3 3 FLI8532_ Right B4 FSDATA0 A4 FSDATA1 B5 FSDATA2 A5 FSDATA3 B7 FSDATA4 A7 FSDATA5 B8 FSDATA6 A8 FSDATA7 B9 FSDATA8 A9 FSDATA9 B10 FSDATA10 A10 FSDATA11 B12 FSDATA12 A12 FSDATA13 B13 FSDATA14 A13 FSDATA15 B15 FSDATA16 A15 FSDATA17 B16 FSDATA18 A16 FSDAT...

Page 25: ...DMI2 HDMI1 JP1212 330pF C1215 SCART_RGB_FILTER 220K R1207 3 3uH L1220 SCART_RGB_FILTER JP1208 75 R1219 JP1211 75 R1230 0 R1201 1K R1237 220pF C1210 SCART_RGB_FILTER 3 3uH L1217 JP1200 1000pF C1206 JP1201 3 3uH L1216 10uF 25V C1237 JP1204 JP1213 220K R1212 3 3uH L1219 SCART_RGB_FILTER 1000pF C1208 3 3uH L1214 47K R1204 220K R1210 OPT C1214 470K R1236 220pF C1204 SCART_RGB_FILTER 330pF C1211 SCART_R...

Page 26: ... 51 SC3_IN_R 52 SC2_IN_L 53 SC2_IN_R 54 SC1_IN_L 55 SC1_IN_R 56 VREFTOP 57 SC5_IN_L MONO_IN 58 SC5_IN_R 59 AVSS_1 60 AVSS_2 61 AVSUP_1 62 AVSUP_2 63 ANA_IN1 64 ANA_IN 65 ANA_IN2 66 TESTEN 67 XTAL_IN 68 XTAL_OUT 69 TP 70 AUD_CL_OUT 71 NC_6 72 NC_7 73 NC_8 74 NC_9 75 NC_10 76 SPDIF_OUT 77 DCTRI O_1 78 DCTRI O_0 79 ADR_SEL 80 STANDBYQ 5V_MSP4450 0 1uF C1342 RLZ8 2B TE11 ZD1300 56pF C1318 500 ohm HH 1...

Page 27: ......

Page 28: ...Sep 2007 Printed in Korea P NO MFL39970803 ...

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