LG 37LG3000, 37LG3000-ZA Service Manual

LCD TV

SERVICE MANUAL

CAUTION

BEFORE SERVICING THE CHASSIS, READ THE SAFETY PRECAUTIONS IN THIS MANUAL.

CHASSIS : LD84A

MODEL : 37LG3000

37LG3000-ZA

website:http://biz.LGservice.com

Internal Use Only

LGE Internal Use Only

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CONTENTS

CONTENTS .............................................................................................. 2

PRODUCT SAFETY ..................................................................................3

SPECIFICATION........................................................................................6

ADJUSTMENT INSTRUCTION ...............................................................13

TROUBLE SHOOTING............................................................................18

BLOCK DIAGRAM...................................................................................23

EXPLODED VIEW .................................................................................. 24

SVC. SHEET ...............................................................................................

LGE Internal Use Only

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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 Replacement Parts List. 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

LGE Internal Use Only

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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 wirebristle (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

LGE Internal Use Only

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IC Remove/Replacement

Some chassis circuit boards have slotted holes (oblong) through which the IC leads are inserted and then bent flat against the circuit foil. When holes are the slotted type, the following technique should be used to remove and replace the IC. When working with boards using the familiar round hole, use the standard technique as outlined in paragraphs 5 and 6 above.

Removal

1. Desolder and straighten each IC lead in one operation by gently prying up on the lead with the soldering iron tip as the solder melts.

2. Draw away the melted solder with an anti-static suction-type solder removal device (or with solder braid) before removing the IC.

Replacement

1. Carefully insert the replacement IC in the circuit board.

2. Carefully bend each IC lead against the circuit foil pad and solder it.

3. Clean the soldered areas with a small wire-bristle brush. (It is not necessary to reapply acrylic coating to the areas).

"Small-Signal" Discrete Transistor Removal/Replacement

1. Remove the defective transistor by clipping its leads as close as possible to the component body.

2. Bend into a "U" shape the end of each of three leads remaining on the circuit board.

3. Bend into a "U" shape the replacement transistor leads.

4. Connect the replacement transistor leads to the corresponding leads extending from the circuit board and crimp the "U" with long nose pliers to insure metal to metal contact then solder each connection.

Power Output, Transistor Device Removal/Replacement

1. Heat and remove all solder from around the transistor leads.

2. Remove the heat sink mounting screw (if so equipped).

3. Carefully remove the transistor from the heat sink of the circuit board.

4. Insert new transistor in the circuit board.

5. Solder each transistor lead, and clip off excess lead.

6. Replace heat sink.

Diode Removal/Replacement

1. Remove defective diode by clipping its leads as close as possible to diode body.

2. Bend the two remaining leads perpendicular y to the circuit board.

3. Observing diode polarity, wrap each lead of the new diode around the corresponding lead on the circuit board.

4. Securely crimp each connection and solder it.

5. Inspect (on the circuit board copper side) 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 replaced component and adjacent components and the circuit board to prevent excessive component temperatures.

Circuit Board Foil Repair

Excessive heat applied to the copper foil of any printed circuit board will weaken the adhesive that bonds the foil to the circuit board causing the foil to separate from or "lift-off" the board. The following guidelines and procedures should be followed whenever this condition is encountered.

At IC Connections

To repair a defective copper pattern at IC connections use the following procedure to install a jumper wire on the copper pattern side of the circuit board. (Use this technique only on IC connections).

1. Carefully remove the damaged copper pattern with a sharp knife. (Remove only as much copper as absolutely necessary).

2. carefully scratch away the solder resist and acrylic coating (if used) from the end of the remaining copper pattern.

3. Bend a small "U" in one end of a small gauge jumper wire and carefully crimp it around the IC pin. Solder the IC connection.

4. Route the jumper wire along the path of the out-away copper pattern and let it overlap the previously scraped end of the good copper pattern. Solder the overlapped area and clip off any excess jumper wire.

At Other Connections

Use the following technique to repair the defective copper pattern at connections other than IC Pins. This technique involves the installation of a jumper wire on the component side of the circuit board.

1. Remove the defective copper pattern with a sharp knife. Remove at least 1/4 inch of copper, to ensure that a hazardous condition will not exist if the jumper wire opens.

2. Trace along the copper pattern from both sides of the pattern break and locate the nearest component that is directly connected to the affected copper pattern.

3. Connect insulated 20-gauge jumper wire from the lead of the nearest component on one side of the pattern break to the lead of the nearest component on the other side. Carefully crimp and solder the connections. CAUTION: Be sure the insulated jumper wire is dressed so the it does not touch components or sharp edges.

LGE Internal Use Only

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SPECIFICATION

NOTE : Specifications and others are subject to change without notice for improvement

4. General Specification

No Item Specification Remark

1 Display Screen Device 37”/42” wide Color Display Module LCD 2 Aspect Ratio 16:9 3 LCD Module 37" TFT LCD HD MAKER : 37"- LPL

42" TFT LCD HD 42"- AUO

4 Operating Environment Temp. : 0 ~ 40 deg

Humidity : 0 ~ 85% LGE SPEC

5 Storage Environment Temp. : -20 ~ 60 deg

Humidity : 0 ~ 85 % 6 Input Voltage AC100 ~ 240V, 50/60Hz 7 Power Consumption Power on (Green)

37" ≤ 125, Max:TBD LG3000

42" ≤ 183, Max:192.5 LCD + Backlight

8 Type Size 37" 877(H) x 516.8(V) x 55.5(D) LG3000

42" 983.0(H) x 576.0(V) x 52.7(D) With inverter

9 Pixel Pitch 37" 200 x 600 x RGB LG3000

42" 0.227 x 0.681 x RGB

10 Back Light 37" 16 Lamp EEFL LG3000

42" 18pcs, Straight type

11 Display Colors 16.7M (16,777,216) 12 Coating 3H, AG

1. Application Range.

This spec sheet is applied to the 37"/42" LCD TV used LD84A chassis.

2. Specification

Each part is tested as below without special appointment

2.1 Temperature : 25±5°C(77±9°F), CST : 40±5°C

2.2 Relative Humidity : 65±10%

2.3 Power Voltage : Standard input voltage

(100~240V@ 50/60Hz)

• Standard Voltage of each products is marked by models

2.4 Specification and performance of each parts are followed

each drawing and specification by part number in accordance with BOM .

2.5 The receiver must be operated for about 5 minutes prior to

the adjustment.

3. Test method

3.1 Performance : LGE TV test method followed.

3.2 Demanded other specification Safety : CE, IEC specification EMC : CE, IEC

5. MODEL General Specification

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LGE Internal Use Only

No Item Specification Remarks

1 Broadcasting system 1) PAL-BG

2) PAL-DK

3) PAL-I/I’

4) SECAM L/L’

5) DVB-T (ID TV)

2 Receiving system Analog : Upper Heterodyne

Digital : COFDM

3 Scart Jack (2EA) PAL, SECAM Scart 1 Jack is Full scart and support

RF-OUT(analog) Scart 2 jack is Half scart and support MNT/DTV-OUT.

4 Video Input RCA(1EA) PAL, SECAM, NTSC 4 System :

PAL, SECAM, NTSC, PAL60

5 S-Video Input (1EA) PAL, SECAM, NTSC 4 System :

PAL, SECAM, NTSC, PAL60

6 Component Input (1EA) Y/Cb/Cr

Y/Pb/Pr 7 RGB Input RGB-PC Analog(D-SUB 15PIN) 8 HDMI Input (3EA) HDMI1-DTV/DVI PC(HDMI version 1.3)

HDMI2-DTV Support HDCP

HDMI3-DTV 9 Audio Input (3EA) RGB/DVI Audio L/R Input

Component

10 SDPIF out (1EA) SPDIF out 11 Earphone out (1EA) Antenna, AV1, AV2, AV3, Component,

RGB, HDMI1, HDMI2, HDMI3

12 USB (1EA) For service only

LGE Internal Use Only

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6. Chroma & Brightness

6.1 37"LCD Module

1) Standard Test Condition (The unit has been ‘ON’)

2) Stable for approximately 30 minutes in a dark environment at 25±2°C

3) The values specified are at approximate distance 50Cm from the LCD surface

4) Ta= 25±2°C, VLCD=12.0V, fV=60Hz, Dclk=148.5MHz VBR_A=1.6V, ExtVBR_B=100%

5) Measurement condition : Set the value of VBRT to maximum luminance of white.

6.2 42"LCD Module

1) Standard Test Condition (The unit has been ‘ON’)

2) Stable for approximately 30 minutes in a dark environment at 25±2°C

3) The values specified are at approximate distance 40Cm from the LCD surface

4) Ta= 25°C, Vcc=12.0V, VIVN=24.0Hz, VBRT=3.3V, Timing:60Hz(typ.value)

5) Measurement condition : Set the value of VBRT to maximum luminance of white.

No. Item Specification Min. Typ. Max. Remark

1. Viewing Angle<CR>10> Right/Left/Up/Down 89

2. Luminance Luminance (cd/m2) 400 500 Variation - 1.3 MAX / MIN

3. Contrast Ratio CR 1000 1500

4. CIE Color Coordinates White WX Typ 0.280 Typ AUO(42")

WY -0.03 0.290 +0.03

RED Xr 0.640

Yr 0.330

Green Xg 0.290

Yg 0.600

Blue Xb 0.150

Yb 0.060

No. Item Specification Min. Typ. Max. Remark

1. Viewing Angle<CR>10> Right/Left/Up/Down 89

2. Luminance Luminance (cd/m2) 400 500 Variation - 1.3 MAX / MIN

3. Contrast Ratio CR 800 1200

4. CIE Color Coordinates White WX Typ 0.279 Typ LPL(37")

WY -0.03 0.292 +0.03

RED Xr 0.641

Yr 0.334

Green Xg 0.291

Yg 0.614

Blue Xb 0.145

Yb 0.062

LGE Internal Use Only

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8. Component Video Input (Y, PB, PR)

9. RGB PC

No Resolution H-freq(kHz) V-freq.(Hz) Pixel clock(MHz) Proposed Remarks

1. 720*400 31.468 70.08 28.321

2. 640*480 31.469 59.94 25.17 VESA

Input 848x480 60Hz, 852x480 60Hz

37.684 75.00 31.50 => 640x480 60Hz Display

3 800*600 37.879 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 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 1920*1080 66.647 59.988 138.625 WUXGA FHD Model only

7. SET Optical Feature

(Measurement Condition: Full white/ Dynamic) -> Measure the black luminance after 30 seconds.

No Item module

Luminance (min) C/R(min)

Remark

AV, COMPONENT, HDMI AV, COMPONENT, HDMI

1 37 inch LPL 400cd/m

1000 LG3000

2 42 inch AUO 400cd/m

1000

C/R is excepted for PC mode.

No.

Specification

Remark

Resolution H-freq(kHz) V-freq(Hz)

1. 720x480 15.73 60.00 SDTV, DVD 480i

2. 720x480 15.63 59.94 SDTV, DVD 480i

3. 720x480 31.47 59.94 SDTV, 480p

4. 720x480 31.50 60.00 SDTV, 480p

5. 720x576 15.625 50.00 SDTV, DVD 625 Line

6. 720x576 31.25 50.00 HDTV 576p

7. 1280x720 45.00 60.00 HDTV 720p

8. 1280x720 44.96 59.94 HDTV 720p

9. 1280x720 37.50 50 HDTV 720p 50Hz

10. 1920x1080 31.25 50.00 HDTV 1080i

11. 1920x1080 33.75 60.00 HDTV 1080i

12. 1920x1080 33.72 59.94 HDTV 1080i

13. 1920x1080 56.25 50.00 HDTV 1080P

14. 1920x1080 67.433 59.94 HDTV 1080P

15. 1920x1080 67.50 60 HDTV 1080P

LGE Internal Use Only

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10. HDMI Input (DTV)

11. HDMI Input (PC)

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)

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 31.25 50.00 27.000 SDTV 576P

8. 1280*720 37.50 50.00 74.176 HDTV 720P HDCP

9. 1280*720 44.96 59.94 74.176 HDTV 720P HDCP

10. 1280*720 45.00 60.00 74.250 HDTV 720P HDCP 11 1920*1080 33.72 59.94 74.176 HDTV 1080I HDCP 12 1920*1080 33.75 60.00 74.250 HDTV 1080I HDCP 13 1920*1080 28.125 50.00 74.250 HDTV 1080I 50Hz HDCP 14 1920*1080 27.000 24.00 74.250 HDTV 1080P 24Hz HDCP 15 1920*1080 56.250 50 148.500 HDTV 1080P 50Hz HDCP 16 1920*1080 67.433 59.94 148.352 HDTV 1080P HDCP 17 1920*1080 67.500 60 148.500 HDTV 1080P HDCP

No Resolution H-freq(kHz) V-freq.(Hz) Pixel clock(MHz) Proposed Remarks

1. 720*400 31.468 70.08 28.321 HDCP

2. 640*480 31.469 59.94 25.17 VESA HDCP

37.684 75.00 31.50

3 800*600 37.879 60.31 40.00 VESA HDCP

46.875 75.00 49.50

4. 832*624 49.725 74.55 57.283 Macintosh HDCP 5 1024*768 48.363 60.00 65.00 VESA(XGA) HDCP

56.470 70.00 75.00

60.123 75.029 78.75 6 1280*768 47.78 59.87 79.5 WXGA HDCP 7 1360*768 47.72 59.8 84.75 WXGA HDCP 8 1366*768 47.56 59.6 84.75 WXGA HDCP 9 1280*1024 63.595 60.0 108.875 SXGA FHD Model only, HDCP

10 1920*1080 66.647 59.988 138.625 WUXGA FHD Model only, HDCP

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