LG 42LH40 Training Manual

42LH40 Direct View LCD

1080P

Direct View LCD

Updated Published July 2009

February 17, 2010

OUTLINE

Section 1

Section 2

Contact Information, Preliminary Matters, Specifications, LCD Overview, General Troubleshooting Steps, Signal Distribution, Disassembly Instructions and Voltages

Circuit Board Operation, Troubleshooting of :

• Switch mode Power Supply/Ballast Combination

• Main Board

• Ft Control Board

• Side Keys

July 2009 LCD DV 42LH40

Overview of Topics to be Discussed

42LH40 LCD Direct View Display

This Section will cover Contact Information and remind the Technician of Important Safety Precautions for the Customers Safety as well as the Technician and the Equipment.

Basic Troubleshooting Techniques which can save time and money sometimes can be overlooked. These techniques will also be presented.

Section 1

This Section will get the Technician familiar with the Disassembly, Identification and Layout of the LCD Display Panel.

At the end of this Section the Technician should be able to Identify the Circuit Boards and have the ability and knowledge necessary to safely remove and replace any Circuit Board or Assembly.

July 2009 LCD DV 42LH40

Preliminary Matters (The Fine Print)

IMPORTANT SAFETY NOTICE

The information in this training manual is intended for use by persons possessing an adequate background in electrical equipment, electronic devices, and mechanical systems. In any attempt to repair a major Product, personal injury and property damage can result. The manufacturer or seller maintains no liability for the interpretation of this information, nor can it assume any liability in conjunction with its use. When servicing this product, under no circumstances should the original design be modified or altered without permission from LG Electronics. Unauthorized modifications will not only void the warranty, but may lead to property damage or user injury. If wires, screws, clips, straps, nuts, or washers used to complete a ground path are removed for service, they must be returned to their original positions and properly fastened.

CAUTION

To avoid personal injury, disconnect the power before servicing this product. If electrical power is required for diagnosis or test purposes, disconnect the power immediately after performing the necessary checks. Also be aware that many household products present a weight hazard. At least two people should be involved in the installation or servicing of such devices. Failure to consider the weight of an product could result in physical injury.

July 2009 LCD DV 42LH40

(Electrostatic Static Discharge)

ESD

Today’s sophisticated electronics are electrostatic discharge (ESD) sensitive. ESD can weaken or damage the electronics in a manner that renders them inoperative or reduces the time until their next failure. Connect an ESD wrist strap to a ground connection point or unpainted metal in the product. Alternatively, you can touch your finger repeatedly to a ground connection point or unpainted metal in the product. Before removing a replacement part from its package, touch the anti-static bag to a ground connection point or unpainted metal in the product. Handle the electronic control repackaging a failed electronic control assembly in an anti-static bag, observe these same precautions.

Regulatory Information

This equipment has been tested and found to comply with the limits for a Class B digital device, pursuant to Part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference when the equipment is operated in a residential installation. This equipment generates, uses, and can radiate radio frequency energy, and, if not installed and used in accordance with the instruction manual, may cause harmful interference to radio communications. However, there is no guarantee that interference will not occur in a particular installation. If this equipment does cause harmful interference to radio or television reception, which can be determined by turning the equipment off and on, the user is encouraged to try to correct the interference by one or more of the following measures: Reorient or relocate the receiving antenna; Increase the separation between the equipment and the receiver; Connect the equipment to an outlet on a different circuit than that to which the receiver is connected; or consult the dealer or an experienced radio/TV technician for help.

Notice

(Electrostatic Static Discharge)

assembly by its edges only. When

July 2009 LCD DV 42LH40

LG CONTACT INFORMATION

Customer Service (and Part Sales) (800) 243-0000 Technical Support (and Part Sales) (800) 847-7597 USA Website (GCSC) aic.lgservice.com Customer Service Website us.lgservice.com LG Web Training lge.webex.com

LG CS Academy lgcsacademy.com

LCD-DV:

PLASMA:

Also available on

the Plasma page

32LG40, 32LH30, 37LH55, 42LG60, 42LG70, 42LH20, 42LH40, 42LH50, 47LG90, 47LH85 42PG20, 42PQ20, 50PQ30, 50PG20, 50PS80, 50PS60

Plasma Panel

Alignment Handbook

New Training Materials on

the Learning Academy site

Published July 2009 by LG Technical Support and Training

LG Electronics Alabama, Inc.

201 James Record Road, Huntsville, AL, 35813.

July 2009 LCD DV 42LH40

http://136.166.4.200

LG Learning Academy

SECTION 1: LCD DIRECT VIEW OVERVIEW

Safety and Handling Regulations

1. Approximately 20 minute pre-run time is required before any adjustments are performed.

2. Refer to the Voltage Sticker on the Switch Mode Power Supply silk screening. (+/- ½ volt).

3. Be cautious of electric shock from the Backlight section, it uses high voltage AC. Check that the Power Supply and Drive Circuits are completely discharged because of residual current stored before Circuit Board removal.

4. C-MOS circuits are sensitive to static electricity. Use caution when dealing with these IC and circuits.

5. Exercise care when making voltage and waveform checks to prevent costly short circuits from damaging the unit.

6. Be cautious of lost screws and other metal objects to prevent a possible short in the circuitry.

Checking Points to be Considered

1. Check the appearance of the Replacement Panel and Circuit Boards for both physical damage and part number accuracy.

2. Check the model label. Verify model names and board model matches.

3. Check details of defective condition and history. Example: Oscillator failure dead set, etc…

July 2009 LCD DV 42LH40

Basic Troubleshooting Steps

Define, Localize, Isolate and Correct

•Define the failure. Use your senses Sight, Smell, Touch and Hearing. Look for burned parts and check for possible overheated components. Capacitors will sometimes leak dielectric material and give off a distinct odor. Frequency of power supplies will change with the load, or listen for relay closing etc. Observation of the front Power LED may give some clues.

•Localize checked and after giving a thorough examination using your senses the first check should always be the DC Supply Voltages to those circuits under test. Always confirm the supplies are not only the proper level but be sure they are noise free. If the supplies are missing check the resistance for possible short circuits.

•Isolate Oscilloscope to make a final determination of the failure. Look for correct Amplitude Phasing and Timing of the signals also check for the proper Duty Cycle of the signals. Sometimes “glitches” or “road bumps” will be an indication of an imminent failure.

Look at the symptom carefully and determine what circuits could be causing

After carefully checking the symptom and determining the circuits to be

To further isolate the failure, check for the proper waveforms with the

•Correct check the DC Supplies for proper levels. Make all necessary adjustments and lastly always perform a Safety AC Leakage Test before returning the product back to the Customer.

The final step is to correct the problem. Be careful of ESD and make sure to

July 2009 LCD DV 42LH40

42LH40 Product Information

This section of the manual will discuss the specifications of the 42LH40

LCD Direct View Display Panel.

July 2009 LCD DV 42LH40

Basic Specifications

Key Features

• Full HD 1080p HD Resolution

• 70,000:1 Dynamic Contrast Ratio

• TruMotion 120Hz

• Intelligent Sensor Mode

• 2.7ms Response Time (GTG)

• 500 cd/m2 Brightness

• Wide Color Gamut

• Super IPS Panel

• Wide Viewing Angle

• XD Engine®

• 24p Real Cinema

• ISFccc® Ready

• Picture Wizard

• AV Mode II (Cinema, Sports, Game)

• 60,000 Hour Panel Life (typical)

• NTSC/ATSC Tuners with Clear QAM

July 2009 LCD DV 42LH40

Basic Specifications (LOGO Familiarization)

Full HD 1080p Resolution

Displays HDTV programs in full 1920 x 1080p resolution for a more detailed picture.

July 2009 LCD DV 42LH40

Pixel Count to Resolution Comparisons

FULL HD 1080p HD Resolution Pixels: 1920 (H) × 1080 (V) High definition television is the highest performance segment of the DTV system used in the US. It’s a wide screen, high-resolution video image, coupled with multi-channel, compact-disc quality sound.

1080P

FORMATS

NTSC

HD HD

480I 480P

1080I 720P

1080P

Possible Frame Rates: 24FPS 30FPS 60FPS

Interlaced Progressive

Progressive

240 Lines 480 Lines

540 Lines 720 Lines

1080 Lines

Interlaced 2 Fields to make a Frame

Progressive Each Field is a Frame

BASIC

PIXEL COUNTS

720P Panel

1365 (H) × 768 (V)

1080P Panel

1920 (H) x 1080 (V)

Think of sync as the Panels “Refresh Rate”

July 2009 LCD DV 42LH40

Remote Control Familiarization

TOP PORTION

BOTTOM PORTION

July 2009 LCD DV 42LH40

Accessing the Service Menu

REMOTE

BOTTOM PORTION

To access the Service Menu.

1) Turn the Set On

2) Simultaneously, Press and “Hold” the Menu Key on the Side Key pad and Press and “Hold” the Menu Key on the Remote approximately 5 seconds.

3) If Customer’s Menu appears, continue to hold until it disappears.

SIDE KEYS

4) The Service Menu appears

Note: If a Password is required to enter the

Service Menu. Enter;

0000

July 2009 LCD DV 42LH40

Rear and Side Input Jacks

Rear In/Out Jacks

USB Port

Software Upgrades

Music, Photos

Side In/Out

MAIN PWB

Rear and Side

Input/Output locations

Rear

Side

July 2009 LCD DV 42LH40

USB DOWNLOAD

1) Create an LG_DTV folder on the USB Flash Drive

Shows the

Currently

Installed

Version

2) Copy new software (xxx.epk) to "LG_DTV" folder. Make sure to have correct software file.

3) With TV turned on, insert USB flash drive.

4) You can see the message “TV Software Upgrade” (See figure to right)

5) Cursor left and highlight "START" Button and push “Enter” button using the remote control.

6) You can see the download progress Bar.

7) Do not unplug until unit has automatically restarted.

8) When download is completed, you will see “COMPLETE”.

9) Your TV will be restarted automatically.

Shows the

Software

Version

found on the

USB Flash

Drive

Shows the

Software file found

on the USB Flash

Drive

* CAUTION: Do not remove AC power or the USB Flash Drive. Do not turn off Power, during the upgrade process.

July 2009 LCD DV 42LH40

42LH40 Product Dimensions

Wattage Average: 143W Stand By: less than 1W

There must be at least 4 inches of Clearance on all sides

40-13/16"

1036.3mm 7-7/8"

200mm

3-1/2"

88.9mm

25-13/16"

655.3mm

28-3/8"

721.4mm

2-9/16"

65.7mm

16-1/8"

410mm

3-7/8"

97.8mm

12-15/16"

327.8mm

20-7/16"

518mm

8-7/8"

225.3mm

12-15/16"

327.8mm

Center

7-7/8"

200mm

9-1/16"

230mm

Model No.

Serial No.

Label

Remove 4 screws to

remove stand for

wall mount

Weight without Stand: 36.4 lb Weight with Stand: 40.3 lb

22-13/16"

580mm

11-9/16"

294mm

DISASSEMBLY AND TROUBLESHOOTING SECTION

Disassembly:

This section of the manual will discuss Disassembly, Layout and Circuit Board Identification, of the 42LH40 LCD Direct View Television.

Upon completion of this section the Technician will have a better understanding of the disassembly procedures, the layout of the printed circuit boards and be able to identify each board.

Troubleshooting:

This section of the manual will also discuss troubleshooting. Upon completion of this section the Technician will have a better understanding of

how to diagnosis and resolve problems.

July 2009 LCD DV 42LH40

Removing the Back Cover

Remove the 21 screws indicated.

Pay attention to the size and type of screw

as there are many different types.

Putting in an improper screw when

reassembling may Cause damage.

The Stand does not need to be removed before removing the back.

July 2009 LCD DV 42LH40

Circuit Board Layout

No T-CON or Ballast board

POWER SUPPLY

Side Keys

LVDS Cable

Main PWB

Master

Power

Switch

Backlight

Connections

Ft IR/LED Control

Input

Speaker R

Input

Rear

Inputs

Speaker L

July 2009 LCD DV 42LH40

POWER SUPPLY SECTION

This switch mode power supply has the ballast section built in. The power supply develops Stand By 5V, 12V and 24V for the Main board.

This power supply draws a little less that 1 watt during stand by mode. The fuse F501 reads 157V (from hot ground) during this time. When the controller chip (on the back) receives the PWR-ON command via P201 Pin 19, the primary section increases its current supplying ability. The Primary fuse F501 now reads 380V. 12V is routed out P201 pins 5 and 6 and 24V is routed out P201 pins 1 and 2. Internally, the power supply also sends B+ (390V) voltage to the Ballast section but it is not turned on at this time. When the power supply receives the INV-ON command via P201 pin 20, it is routed to the driver for the ballast (on the back of the board). The driver now starts to deliver drive information to the output FETs (on the far left hand heat sink) which in turn switch the primary sides of the two ballast transformers T703 and T704. They output 1.2Kv (48Khz) pulses to the backlights via P401 and P402.

July 2009 LCD DV 42LH40

+ 46 hidden pages

LG 42LH40 Training Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

OUTLINE

Overview of Topics to be Discussed

Preliminary Matters (The Fine Print)

SECTION 1: LCD DIRECT VIEW OVERVIEW

Basic Troubleshooting Steps

42LH40 Product Information

Basic Specifications

Basic Specifications (LOGO Familiarization)

Remote Control Familiarization

Accessing the Service Menu

Rear and Side Input Jacks

USB DOWNLOAD

42LH40 Product Dimensions

DISASSEMBLY AND TROUBLESHOOTING SECTION

Removing the Back Cover

Circuit Board Layout

POWER SUPPLY SECTION