LG 50PY2DR Service Manual

LG TRAINING MANUAL

50PY2DR Training Manual Addendum - Fall 2007

Published August 2007 by LG USA Training Center Customer Service (and Part Sales): 1-800-243-0000 Technical Support (and Part Sales): 1-800-847-7597 USA Website: www.lgusa.com Customer Service Website: us.lgservice.com B2B Service Website: aic.lgservice.com Training Website: www.LGCSAcademy.com

IMPORTANT SAFETY NOTICE

This manual was prepared for use only by properly trained audio-visual service technicians. 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. All components should be replaced only with types identical to those in the original circuit and their physical location, wiring, and lead dress must conform to original layout upon completion of repairs. If any fuse (or Fusible Resistor) in this TV receiver is blown, replace it only with the factory speciﬁed fuse type and rating. When replacing a high wattage resistor (Oxide Metal Film Resistor, over 1W), keep the resistor 10mm away from PCB. Always keep wires away from high voltage or high temperature parts. Do not attempt to modify this product in any way.

Special components are also used to prevent shock and ﬁre hazard and are required to maintain safe performance. No deviations are allowed without prior approval by LG Electronics. Service work should be performed only after you are thoroughly familiar with these safety checks and servicing guidelines. Circuit diagrams may occasionally differ from the actual circuit used. This way, implementation of the latest safety and performance improvement changes into the set is not delayed until the new service literature is printed.

GENERAl SAFETY GuIdANCE

An lsolation 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 to protect against personal injury from electrical shocks. It will also protect the receiver and its components from being damaged by accidental shorts of the circuitry that may be inadvertently introduced during the service operation. 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.

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. Any other abnormality that exists must be corrected before the receiver is returned to the customer.

ElECTROSTATICAllY SENSITIvE 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 electricity.

Immediately before handling any semiconductor component or semiconductor-equipped assembly, drain off any electrostatic charge on the body by touching a known earth ground. Alternatively, obtain and wear a commercially available discharging wrist strap device, which should be removed for potential shock reasons prior to applying power to the unit under test. After removing an electrical assembly equipped with ES devices, place the assembly on a conductive surface such as an ESD mat, to prevent electrostatic charge buildup or exposure of the assembly. Use only a grounded-tip soldering iron to solder or unsolder ES devices. Use only an anti-static solder removal device. Some solder removal devices not classiﬁed as “antistatic” can generate electrical charges sufﬁcient to damage ES devices. Do not use freon-propelled chemicals which can generate electrical charge sufﬁcient to damage ES devices. Do not remove a replacement ES device from its protective package until immediately before you are ready to install it. Minimize bodily motions when handling unpackaged replacement ES devices (Otherwise, seemingly harmless motion, such as the brushing together of your clothing or the lifting of your foot from a carpeted ﬂoor, can generate static electricity sufﬁcient to damage an ES device).

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 receiver; Connect the equipment into an outlet on a circuit different from that to which the receiver is connected; Consult the dealer or an experienced radio/TV technician for help.

The responsible party for this device’s compliance is:

LG Electronics of Alabama, Inc. 201 James Record Road Huntsville, AL 35813, USA

Table of ConTenTs

INTRODUCTION .............................................................................................5

PCB LAYOUT .................................................................................................5

SIGNAL AND VOLTAGE DISTRIBUTION ................................................................6

SIGNAL AND VOLTAGE DISTRIBUTION (CONT.) .....................................................7

SWITCH MODE POWER SUPPLY ..........................................................................8

Y-SUSTAIN BOARD ........................................................................................9

DUAL SCAN Y-SUSTAIN DISTRIBUTION ............................................................. 10

Y-SUSTAIN TEST POINTS ................................................................................ 11

WAVEFORMS ................................................................................................ 12

Y-DRIVE BOARDS ......................................................................................... 19

50PY2DR Training Addendum 3 Contents

- 4 -

INTROduCTION

HDD

SMPS

Analog

Digital

Control

Y SUS

Z SUS

Top X Drive

Bottom X Drive

Y Drive

This addendum to the 50PY2DR Dual Scan Plasma Display Panel manual will discuss Layout, Circuit Board Identiﬁcation, and Troubleshooting. 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.

PCB lAYOuT

TRoUblesHooTInG

50PY2DR Training Addendum 5 Troubleshooting

TRoUblesHooTInG

Z SUS

Board

Top X Drive Boards

5v, VA, VS

VA, VS

5v, VA

Switch Mode

Power Supply

Y SUS

Board

Control

Board

5v, VA

Logic Signals

RGB Logic Signals

RGB

Logic Signals

RGB

Logic Signals

5v, VA

Y Drive Top

5V, VA

Y Drive Bottom

Drive Signal

5V, VA 5V, VA

5v, VA

RGB

Logic Signals

SIGNAl ANd vOlTAGE dISTRIBuTION

50PY2DR Training Addendum 6 Troubleshooting

TRoUblesHooTInG

Control Board

LVDS Cable

Digital Board

Analog Board

Antenna Input

Cable Input

Power Supply

Digital Video Signal

(includes OSD)

P801 P803 P802

CN1700

P402

P201

For voltages see interconnect Diagram

Clock, Data,

Analog Audio and Video signals

SIGNAl ANd vOlTAGE dISTRIBuTION (CONT.)

50PY2DR Training Addendum 7 Troubleshooting

TRoUblesHooTInG

VCC

Standby

SwITCh MOdE POwER SuPPlY

50PY2DR Training Addendum 8 Troubleshooting

+ 18 hidden pages