LG 42PQ20 Series Installation guide

Advanced Single Scan Troubleshooting
Training Manual
42PQ20 Plasma Display
42PQ20 Plasma Display
720p
720p
NOTICE:
ALL INFORMATION CONTAINED WITHIN THIS PACKAGE IS BASED ON PRE-
SALES MODEL. INFORMATION SUBJECT TO CHANGE AT FINAL PRODUCTION
Updated: September 23
rd
, 2009

2January 2009 Plasma 42PQ20
Overview of Topics to be Discussed
• Y SUS Board
• Z SUS Output Board (Connects directly with FPC to Panel)
• Y Drive Boards (Receives Y Drive signals from Y-SUS PWB)
• Control Board
• X Drive Boards (2)
Circuit Board Operation, Troubleshooting and Alignment of :
• Switch mode Power Supply
• Main Board
Section 1
Section 2
Contact Information, Preliminary Matters, Specifications,
Plasma Overview, General Troubleshooting Steps,
Disassembly Instructions, Voltage and Signal Distribution
OUTLINE
OUTLINE
NEW
•Main Power Switch, deactivates all inputs from IR or Keys
NEW

3January 2009 Plasma 42PQ20
42PQ20 Plasma Display
Section 1
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.
This Section will get the Technician familiar with the Disassembly, Identification and
Layout of the Plasma 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.
Overview of Topics to be Discussed
Overview of Topics to be Discussed

4January 2009 Plasma 42PQ20
IMPORTANT SAFETY NOTICE
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
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.
Preliminary Matters (The Fine Print)
Preliminary Matters (The Fine Print)

5January 2009 Plasma 42PQ20
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 assembly by its edges only. When
repackaging a failed electronic control assembly in an anti-static bag, observe these same precautions.
REGULATORY INFORMATION
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.
ESD Notice
ESD Notice (Electrostatic Discharge)
(Electrostatic Discharge)

6January 2009 Plasma 42PQ20
Also available on the
Also available on the
Plasma page
Plasma page New Training Materials on
New Training Materials on
the Learning Academy site
the Learning Academy site
Contact Information
Contact Information
Customer Service (and Part Sales) [phone]
Technical Support (and Part Sales) [phone]
USA Website (GCSC) aic.lgservice.com
Customer Service Website us.lgservice.com
LG Web Training lge.webex.com
LG CS Academy lgcsacademy.com
LG Electronics Alabama, Inc. 201
James Record Road, Huntsville,
AL, 35813.
http://136.166.4.200
Published January 2009 by LG Technical Support and Training
32LG40, 32LH30, 42LG60, 42LG70, 42LH20, 42LH40, 42LH50, 47LG90
42PG20, 42PQ20, 42PQ30, 50PG20, 50PS80, 50PS60
LCD-DV:
PLASMA:
Plasma Panel
Alignment Handbook

7January 2009 Plasma 42PQ20
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.
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…
Checking Points to be Considered
OVERVIEW
OVERVIEW

8January 2009 Plasma 42PQ20
Basic Troubleshooting Steps
Basic Troubleshooting Steps
Define, Localize, Isolate and Correct
•Define Look at the symptom carefully and determine what circuits could be causing
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 After carefully checking the symptom and determining the circuits to be
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 To further isolate the failure, check for the proper waveforms with the
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.
•Correct The final step is to correct the problem. Be careful of ESD and make sure to
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.

9January 2009 Plasma 42PQ20
This section of the manual will discuss the specifications of the
42PQ20 Advanced Single Scan Plasma Display Panel.
42PQ20 Product Information
42PQ20 Product Information

10 January 2009 Plasma 42PQ20
42PQ20 Specifications
42PQ20 Specifications
• 720p HD Resolution
• Dual XD Engine™
• 20,000:1 Contrast Ratio
• Fluid Motion
• 3x HDMI™ V.1.3 with Deep Color
• AV Mode (Cinema, Sports, Game)
• Clear Voice
• LG SimpLink™ Connectivity
• Invisible Speaker System
• 100,000 Hours to Half Brightness (Typical)
• PC Input
720P PLASMA HDTV
42” Class (41.5” diagonal)

11 January 2009 Plasma 42PQ20
Grid to Pixel to Resolution Relationship
Grid to Pixel to Resolution Relationship
Y-Drive
“Buffers”
Horizontal Grids
Z-SUS
Horizontal Grids are on “Front” of the Cells as
viewed from the front.
Layout below as viewed from the rear.
Where the 3 Grids Intersect is
a single Colored Cell
Red, Green and Blue
Cells make a “Pixel”
Green
Blue
Vertical Grids are in “Back” of the Cells as
viewed from the front.
X-Boards
Same as (A-BUS)
Initialize the Cell
Deliver Color information
Y-SUS
Cell Clean up (Y-Drive Edge)
Deliver Luminance Fire
Firing the Cell via Wall Charge
Line by Line
Z-SUS
Firing the Cell via Wall Charge
All Lines fire at once
Horizontal Grids
Determine Vertical Resolution
Vertical Grids
Determine Horizontal
Resolution
Red
X-Boards
“TCPs”
Vertical Grids

12 January 2009 Plasma 42PQ20
HD RESOLUTION 720p HD Resolution Pixels: 1365 (H) × 768 (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.
Pixel Count to Resolution Comparisons
Pixel Count to Resolution Comparisons
FORMATS
480I
480P
1080I
720P
1080P
Interlaced
Progressive
Interlaced
Progressive
Progressive
Interlaced
2 Fields to make a Frame
Progressive
Each Field is a Frame
Think of sync as the Panels “Refresh Rate”
240 Lines
480 Lines
540 Lines
720 Lines
1080 Lines
NTSC
SD
HD
HD
HD
Possible Frame
Rates:
24FPS
30FPS
60FPS
768
720P Panel
720P Logo
BASIC
PIXEL COUNTS
720P Panel
1365 (H) ×768 (V)
1080P Panel
1920 (H) x 1080 (V)

13 January 2009 Plasma 42PQ20
42PQ20 Specifications Logo Familiarization
42PQ20 Specifications Logo Familiarization
Invisible Speaker
Personally tuned by Mr. Mark Levinson for LG
TAKE IT TO THE EDGE newly introduces ‘Invisible Speaker’ system,
guaranteeing first class audio quality personally tuned by Mr. Mark
Levinson, world renowned as an audio authority. It provides Full Sweet
Spot and realistic sound equal to that of theaters with its Invisible
Speaker.
HDMI (1.3 Deep Color) Digital multi-connectivity
HDMI (1.3 Deep color) provides a wider bandwidth (340MHz,
10.2Gbps) than that of HDMI 1.2, delivering a broader range of colors,
and also drastically improves the data-transmission speed.
Dual XD Engine
Realizing optimal quality for all images
One XD Engine optimizes the images from RF signals as another XD
Engine optimizes them from External inputs. Dual XD Engine presents
images with optimal quality two times higher than those of previous
models.

14 January 2009 Plasma 42PQ20
42PQ20 Specifications Logo Familiarization
42PQ20 Specifications Logo Familiarization
AV Mode "One click" - Cinema, Sports, Game mode.
TAKE IT TO THE EDGE is a true multimedia TV with an AV Mode
which allows you to choose from 3 different modes of Cinema, Sports
and Game by a single click of a remote control.
Clear Voice Clearer dialogue sound
Automatically enhances and amplifies the sound of the human voice
frequency range to provide high-quality dialogue when background
noise swells.
Save Energy, Save Money
Home electronic products use energy when they're off to power features like clock
displays and remote controls. Those that have earned the ENERGY STAR use as much
as 60% less energy to perform these functions, while providing the same performance at
the same price as less-efficient models. Less energy means you pay less on your energy
bill. Draws less than 1 Watt in stand by.
Save Energy, Save Money
It reduces the plasma display’s power consumption.
The default factory setting complies with the Energy Star requirements
and is adjusted to the comfortable level to be viewed at home.

15 January 2009 Plasma 42PQ20
42PQ20 Specifications Logo Familiarization
42PQ20 Specifications Logo Familiarization
LG SIMPLINK™ MULTI-DEVICE CONTROL
Allows for convenient control of other LG SimpLink products using the
existing HDMI connection.
Tru-Surround is a sound-scheme that has the ability to take multi-
channel encoded sources, such as Dolby Digital, and reproduce the
multi-channel surround effect by just using two-speakers. The result is
not as impressive as true Dolby Digital 5.1 (the front and side surround
effects are impressive, but the rear surround effects fall a little short,
with the sense they are coming from just to rear of your head rather
than from the back of the room).
Dolby® Digital
In thousands of cinemas and millions of homes worldwide, Dolby
Digital is the reigning standard for surround sound technology in
general and 5.1-channel surround sound in particular.
FluidMotion (180 Hz Effect)
Enjoy smoother, clearer motion with all types of programming such as sports and
action movies.
The moving picture resolution give the impression of performance of up to 3x the
Panels actual refresh rate.

16 January 2009 Plasma 42PQ20
PDP
180Hz
LCD
60Hz
Moving Picture Response Time
is 16.5 milliseconds
(120Hz takes MPRT to 8.25ms)
Panel Response Time
is 4 to 8 milliseconds
Moving Picture Response Time
is 5.44 milliseconds
Panel Response Time
is less than 1 millisecond
FluidMotion (180 Hz Effect)
Enjoy smoother, clearer motion with all types of programming such as sports and action movies.
The moving picture resolution give the impression of performance of up to 3x the panels actual refresh rate.
42PQ20 Specifications FluidMotion Familiarization
42PQ20 Specifications FluidMotion Familiarization

17 January 2009 Plasma 42PQ20
42PQ20 Remote Control
42PQ20 Remote Control
TOP PORTION
BOTTOM PORTION

18 January 2009 Plasma 42PQ20
Rear and Side Input Jacks
Rear and Side Input Jacks
AC In
USB
Software
Upgrades

25.5/8"
650mm
40.5/8"
1031mm
15.3/4"
400mm
Remove 4 screws to
remove stand for
wall mount
Model No.
Serial No.
Label
12.3/16"
310mm
23.5\8"
600mm
3.1/8"
78.7mm
12.1/8"
307.3mm
4.1/16"
104mm
5.13/16"
148mm
2.3/4"
69.85mm
Center
There must be at least 4 inches of Clearance on all sides
Weight without Stand: 53.1 lb
Weight with Stand: 48.5 lb
42PQ20 Product Dimensions
42PQ20 Product Dimensions
28.3/8"
721mm
Wattage
Average: 181W
Stby: 0.13W
12.13/16"
325mm
15.3/4"
400mm
15.3/4"
400mm
19

20 January 2009 Plasma 42PQ20
This section of the manual will discuss Disassembly, Layout and Circuit
Board Identification, of the 42PQ20 Advanced Single Scan Plasma Display Panel.
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.
DISASSEMBLY SECTION
DISASSEMBLY SECTION