Lg 42pc5dc Training Manual [ET]

Plasma Display Panel Troubleshooting – Spring 2008 1

Advanced Single Scan Troubleshooting

42PC5DC Plasma Training Manual


Troubleshooting

•Y SUS Board

•Z SUS Board•Y Drive Boards

•Control Board•X Drive Boards

Circuit Board Operation, Troubleshooting and Alignment of :•Switch mode Power Supply

•Main Board

Section 1

Section 2

Contact Information, Preliminary Matters, Plasma Overview, General Troubleshooting Steps, Disassembly Instructions,Voltage and Signal Distribution

Overview of Topics to be Discussed


42PC5DC Plasma Display

Troubleshooting

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 generally not thought of , which can save time and money 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 remove and replace safely any Circuit Board or Assembly.

OUTLINE


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.

Troubleshooting

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.

Safety and Cautions


ESD NOTICE

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.

Troubleshooting

REGULATORY INFORMATIONThis 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 and Regulatory Information


Contact Information

Customer Service (and Part Sales) (800) 243-0000Technical Support (and Part Sales) (800) 847-7597

USA Website (GCSC) aic.lgservice.comCustomer Service Website us.lgservice.com

LG CS Academy lgcsacademy.com

Published March 2008 by LG Technical Support and Training

Troubleshooting

The responsible party for this device’s compliance is:

COMPLIANCE

LG Electronics Alabama, Inc. 201 James Record Road,

Huntsville, AL, 35824.


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: Y Board Failure, Mal-discharge on screen, etc.

1. Approximately 10 minute pre-run time is required before any adjustments are performed.

2. Refer to the Voltage Sticker inside the Panel when making adjustments on the Power Supply, Y SUS and Z SUS Boards.

Always adjust to the specified voltage level (+/- ½ volt).

3. Be cautious of electric shock from the PDP module since the PDP module uses high voltage, 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 used extensively for processing the Drive Signals and should be protected from static electricity.

5. The PDP Module must be carried by two people.

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

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

Checking Points to be Considered

TroubleshootingSafety and Handling Regulations


Troubleshooting

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.

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.

Basic Troubleshooting Steps


This section of the manual will discuss Disassembly, Layout and Circuit Board Identification, of the 42PC5DC Advanced Single Scan Plasma Display Panel.

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.

42PC5DC DISASSEMBLY SECTION


Troubleshooting42PC5DC

Remove the 33 screws as shown (the stand will not need to be removed).

Back Cover Removal

42PC5DC Removing the Back Cover


Troubleshooting

42PC5DC Back Cover Removed

Z SUS Board

SMPS Board

Y SUS Board

MAIN Board

LEFT X RIGHT X

Y

Drive

Board

42PC5DC Circuit Board Layout and Identification


Troubleshooting

Control

Right X BoardLeft X Board

Logic Signals to the Y SUS Board

Logic Signals to the Z SUS Board

5V, VS, VA to the Z SUS

5V, VS, VA to the Y SUS

Y/Z ER

42PC5DC Circuit Board Layout and Identification Continued


Software UpgradesMenu, Option, 7, (7 times)

Troubleshooting42PC5DC Circuit Board Layout and Identification Input Jacks


Troubleshooting

Notes: 1) All Plugs listed are from left to right Pin 1,2, 3, ETC.2) Remember to be cautious of ESD as semiconductors are CMOS and prone to static failure!

Switch Mode Power Supply Board Removal

Remove 8 screws securing the Power Supply and disconnect Connectors from Plugs CN1 ( AC Input ), P812 ( 5V, GND, VA, GND, GND, GND, NC, VS, VS ), P800 ( AC DET, RL ON, STB5V, GND, VS ON, 5V DET, M5V-ON, GND, NC, 6V, GND, 3.4V-ON ), P802 ( 19V, 19V, GND, GND, 6V, GND, 3.4V, GND,12V, GND ), and P803 (3.4V, 3.4V, GND, GND, 6V, 6V, GND, GND, 12V, 12V, GND ) after the board is replaced readjust RV901 ( VS ) andRV951 ( VA ) for DC voltage levels indicated by the Voltage Label in the upper left corner of the Panel.

Y SUS Board Removal

Remove 5 screws securing the Y SUS Board and disconnect Connectors from Plugs P1 ( Logic Signals from the Control Board ), P3 ( 5V, GND, VA, GND, GND, GND, NC, VS, VS ) P4 ( 5V, 5V, GND, GND, GND, NC, VA, VA, NC, VS, VS, VS ), P5, P6, ( Drive Signals to the Y Drive Board ), and P7 ( YER, YER, YER, YER ).

Y Drive Board Removal

Remove 3 screws securing the Y Drive Board and disconnect Connectors from Plugs P9 ( Logic and Drive Signals from the Y SUS Board for the Bottom Half of the Display ), P11 ( Logic and Drive Signals from the Y SUS Board for the Top Halfof the Display ) P1, P2,P3, P4, P5, P6, P7, and P8 ( Ribbon Cable to the Display Panel ) .

Z SUS Board Removal

Remove the 6 screws securing the Z Sus Board and disconnect connectors from Plugs P1 ( 5V, 5V, GND, GND, GND, NC, VA, VA, NC, VS, VS, VS ), P4 ( GND, GND, 5V, 15V, NC, VA, VA ), P5 ( Logic Signals from the Control Board ), P6( ZER, ZER, ZER, ZER ), P2 ( FPC to Display Panel ), P3 ( FPC to Display Panel).

42PC5DC Removing the Circuit Boards (page 1)


Troubleshooting

Main Board Removal

Remove the Input Jack Faceplate by first removing 2 screws by the AC Input Filter, 4 screws at the HDMI Input Plugs,the nut and washer from the Antenna / Cable Input and the RS232 and PC Cable Securing Posts, the Faceplate can now be removed. After removing the Faceplate, remove the 2 screws holding the bottom of the Main Board to the support frame,and release the 2 Plastic Mounting Posts at the top of the board. Disconnect the connectors from Plugs P4004 ( AC DET,RL-ON, ST- 5V, GND, INV-ON/OFF, 5V-MNT, POD/INV, ST-5V, GND, PWM, 6V, GND, LIVE-ON ), P4005(3.3V,3.3V,GND, GND, 6V, 6V, GND, GND, 12V, 12V,GND, GND ), P4003 ( 19V, 19V, GND, GND, NC, GND, 3.3V, GND, 12V, GND ), P6001 ( LVDS ), P7002 ( Serial Data to the Control Board ), P7009 ( Right Speaker ), P7010 ( Left Speaker ), P5002 ( AV Input 2 ), P4007 ( Keyboard ).

42PC5DC

Control Board Removal

Remove 2 screws securing the Main Board Mounting Bracket Assy. and disconnect connector from Plug P3 ( LVDS ) on the Control Board, remove CN1 from the SMPS Board, and carefully place the Bracket Assy. off to the side. Remove 4Screws securing the Control Board and disconnect connectors from Plugs P2 ( Y SUS Logic Signals ), P1 ( Z SUS Logic Signals ), P7 ( Left X Board RGB Logic Signals ), P8 ( Right X Board RGB Logic Signals ) and P6 Serial Data to the Main Board.

X Board Removal

X Board Removal will require the most disassembly of all the boards. Remove 2 screws securing the Main Board Mounting Bracket Assy. and disconnect connector from Plug P3 ( LVDS ) on the Control Board, remove CN1 from the SMPS Board, and carefully place the Bracket off to the side. All the Brackets and Assemblies marked with an “A” will need to be removed including the Stand. Before an X Board can be removed the Heat Sink Assembly will also need Removal.



Troubleshooting

42PC5DC

A A

A

A

Main Board Mounting Bracket

Locking Tabs

LVDS Cable Connector

Left X Board Removal

Remove 20 Screws securing the X Board Heat Sink Assy. and 5 Screws securing the Left X Board. Disconnect connectors to Plug P107 ( RGB Logic Signals from the Control Board ), P108 ( GND, GND, 5V, 15V, NC, VA, VA ) carefully remove the FPC cables that supply the TCP IC’s.



Z SUS Board

5v, VA, VS

5V,VA, VS5v, VA

5v,15v, VA

Switch Mode Power Supply

Y SUS Board

ControlBoard

5v

5v, 15V, VA

Logic Signals

RGB Logic

Signals

RGBLogic

Signals

Logic Signals

Y Drive

Y Drive

Drive Signal

Troubleshooting

AC Input Filter

Logic Signals

Display Panel Display Panel

Main BoardLVDS

Left X Drive Board Right X Drive Board

Display Panel

Control/STB5V19, 12, 6, 3.4

Voltages

5V

Y/Z ERY/Z ER

5v, 15V, VA

5V

42PC5DC Signal and Voltage Distribution


Troubleshooting

++

KEY BOARD

CONTROL BOARD

MAIN BOARD

AV INPUT

POWER SUPPLY

Z SUS BOARDY SUS BOARD

LEFT X BOARD RIGHT X BOARD

Y

DRIVE

BOARD

AC

IPM

IPM

Z BIAS BLOCK

MCM

P812

P803

P802

P800

P6

P5

P1

P3

P4P7

P11

P9

P1

P6

P5

P4

P3

P2

P2

P6 P3

P1

P8P7

P109P114P108P107

Tuner IC1001

P4004 P4005 P4003 P7002 P6001

P4007 P5002

INPUT JACKS

SC101

42PC5DC Wiring and Cable Interconnect


Troubleshooting

At the end of this Section the technician should understand the operation of each circuit board and how to adjust the controls. The technician should be able with confidence to troubleshoot a circuit board failure, replace the defective circuit and perform all necessary adjustments.

This Section will cover Circuit Operation, Troubleshooting and Alignment of the Power Supply,Y SUS Board, Y Drive Board, Z SUS Board, Control Board, Main Board and the X Drive Boards.

42PC5DC TROUBLESHOOTING SECTION


Model : PDP 42 X 4A ### All Voltage : DC 5.0VVa : 60 Vs : 190N.A / 145 / N/A / N.A / 150Max Watt : 330 W ( Full White )

• DC Voltages developed on the SMPS• Adjustments VA and VS

• Always refer to the Voltage Sticker located in the upper left side of the PDP for the correct voltage levels for the VA, VS, Vscan, and Z Bias as they will vary from Panel to Panel.

Z_BIAS

Troubleshooting

-VY

This Section of the Presentation will cover troubleshooting the Switch Mode Power Supply for the Single Scan 42” Plasma Display. Upon completion of the section the technician will have a better understanding of the operation of the Power Supply circuit and will be able to locate voltage and test points needed for

troubleshooting and alignments.

42PC5DC SWITCH MODE POWER SUPPLY SECTION


Troubleshooting

There are 2 different Power Supply Boards used in the 42PC5DC Model Lines. One board ( EAY32927901 ) and the other ( EAY32808901 ).

Both Circuit Boards operate the same and substitute each other although care must be taken because of the differences, not only are the connectors marked differently but they are reversed top to bottom, except for the VA and VS Connector which although marked with a different connector number is pinned out the same.

Another difference is that the VA and VS Controls have circuit symbol numbers reversed between the boards. VR901 on one board is VS and on the other it will be VA!

42PC5DC SMPS Two Different Power Supply Used


Troubleshooting

The Switch Mode Power Supply Board Outputs to the :

VAY SUS Board

Main Board

VS

5V Vcc

Primarily responsible for Display Panel Vertical Grid

Drives the Display Panel Horizontal Grid

Used to develop Bias Voltages on the Y SUS, Z SUS,X Drive, and Control Boards

19V Audio B+ Supply

12V

6V

3.4V

Signal Processing Circuits

Signal Processing Circuits

Control Circuits

Adjustments There are 2 adjustments located on the Power Supply Board VA and VS. Both adjustments are made with relation to Chassis Ground.

VA

VS

RV951

RV901

42PC5DC SMPS Outputs


42PC5DC SMPS Layout EAY32927901 Troubleshooting

P12

P3

P2

P1

CN1

VR 901 (VS)

380V Source

AC Input

VS Source

VA Source

Standby 5V 19v, 12v,6v, 3.4v Source

EAY32927901

U702

VR 951 (VA)


Troubleshooting

EAY32808901

380V Source

AC Input

VS Source

VA Source

Standby 5V 19v, 12v,6v, 3.4v Source

U701

P800

P802

P803

P812

SC101

VA-ADJ VR901

VS-ADJ VR951

42PC5DC SMPS Layout EAY32808901


Troubleshooting

AC Voltage is supplied to the SMPS Board at Connector CN1 from the AC Input Filter. Standby 5V is developed from the Circuits of Transformer T201, RC401, RC402 and Q422. Standby 5V is then routed to 2 places, the Micro Processor IC4015 on the Main Board and to the Sub Micon U702 on the SMPS, where AC – ON / DETECT is developed and sent from Pin 1 of Connector P1 to IC4015. With the presence of both 5V STB and AC – ON/ DETECT, IC4015 is active.

When IC4015 receives an “ ON “ Command from either the Keyboard or the Remote IR Signal it outputs a high to RL-ON which enters the SMPS Board at Pin 2 of P1 and M5V-ON. The high RL-ON Voltage is sensed by the Sub Micon U702 which causes the Relay RL102 to close turning on the 380V Supply developing the 19V,12V and 6V Voltage Sources.

The M5V-ON Line located on the SMPS at Connector P1 (Pin 7) is sensed by U702 the Sub Micon IC turning on the 5V VCC line.

The last step to bring the supply to “Full Power” occurs when IC4015 brings the VS-ON line high at Pin 5 of Connector P1 the SMPS Board which when sensed by the U702 Sub Micon IC turns on the VA and VS Supplies.

The Operating Sequence discussed above can be confirmed by using the Oscilloscope in the XY Mode. Start by connecting Channel 1 of the Oscilloscope to 5V STB and Channel 2 to AC DET the delay between 5V STB and AC DET can be noted. Next Connect Channel 1 to RL ON and Channel 2 to VS ON again the delay between the 2 voltages can be noted. Connect Channel 1 to RL ON and Channel 2 to M5V-ON the 2 supplies come up at the same time proving the 5V VCC line becomes active before the VS ON line.

EAY32927901

The 3.4V line at P3 (Pins 1 and 2) also P2 (Pin 7) becomes active when Pin 13 the 3.4V-ON line of connector P1 goes high turning on the 3.4V Supply.

42PC5DC SMPS Operation and Troubleshooting PG 1 of 2


42PC5DC SMPS Operation and Troubleshooting Pg 2 of 2 Troubleshooting

Understanding the Power On Sequence when Troubleshooting a possible Power Supply Failure will simplify the process of isolating which circuit board failed to operate properly. In this Section we will investigate the Power on Sequence and examine ways to locate quickly where the failure occurred.

Check the Power On LED for Operation, a Red LED indicates a presence of 5V STB and AC-ON/DETECT.Failure of the Power ON LED to light is an indication of loss of 5V STB or AC ON/ Detect remember the 5V STBand AC-ON/DETECT are developed on the SMPS and sent to the Main Board.

Listen for Relay Click, the click of the Relay is an indication of RL-ON going high. RL-ON is sent from the Main Board to the SMPS and when present U702 controls the Relay Operation. RL-ON going High and no Relay is a failure of the SMPS, RL-ON staying low is a failure of the Main Board.

Relay Operation means that the SMPS if working properly will output 19V, 12V and 6V to the Main Board. If the Relay closed and these supplies failed suspect a problem with the SMPS.

The next step of operation calls for the M5V-ON line from the Main Board to the SMPS to go high. A high on the M5V-ON Line activates the 5V Vcc line. Loss of 5V Vcc results in no Raster, no Reset, no Y, Z, Control or X Boardoperation. Loss of 5V and M5V-ON going high could be caused by any of these boards or failure of the SMPS. M5V-ONstaying low indicates a problem on the Main Board.

Remember if a voltage is missing check for proper resistance before proceeding

VS-ON is the last step of the Power Sequence and is responsible for bringing the VS and VA Voltages up. The VS-ON signal is sent from the Main Board to the SMPS as a high, VS and VA and full operation of theDisplay Panel are now enabled. Loss of VS-ON results in loss of VA and VS and no Raster, no Resetbut Audio would be present. If VS-ON went high and VS and VA where missing the problem could be causedby a failure on the SMPS or a circuit using these voltages. A Resistance check should narrow the possiblefailures quickly.

3.4V-ON will activate the 3.4V Supply to the Main Board, at this time Audio should be present as the Tuner and Signal Processing circuits are operational.


Troubleshooting

The Operation of the Power Supply can be Confirmed by removing the SMPS Board and placing it in theService Position. Place two 60Watt lamps in series across pin 9 ( VS ) and 5 ( Ground ) of P812.

Apply AC Power and check for 5V STB and AC-ON / DETECT at P800, if present remove AC Power and install a 100Ω ¼ watt resistor from 5V STB to RL-ON on Connector P800. Apply AC PowerThe AC Relays should close and 19V, 12V and 6V should be Present. If ok remove AC Power.

Install a 100Ω ¼ watt resistor from 5V STB to M5V-ON on Connector P800, 5V Vcc should now become active, If present remove AC Power.

Install a 100Ω 1/4 Watt resistor from 5V STB to VS-ON on Connector P800, VS and VA should now be present. This test will confirm the normal operation of the SMPS.

This test can confirm the proper operation of the SMPS without the need to exchange the board.

EAY32808901

Solder a 100Ω ¼ watt resistor from 5V STB to 3.4V-ON at P800. Apply AC Power the 3.4V Supply should now be present. If ok remove AC Power.

42PC5DC SMPS How to Turn On EAY32808901


Troubleshooting

Resistors 100 Ohms ¼ Watt

AC - ON

RL-ON

STB 5V

GND

VS-ON

5V _ MT

M5V-ON

P1

STB 5V

GND

NC

6V

NC

3.4V_ON

Switch ModePower Supply

P12

CN1

EAY32927901

5V VCC

P3

P2

P1

+

+

VS-ADJ VR901

VA-ADJ VR951

VSVSNC

GNDGND

GND

VAGND


( 2 ) 60WLight Bulbs

AC IN

42PC5DC SMPS Light Bulb Test EAY32927901


Troubleshooting

Switch ModePower Supply

SC101

EAY32808901VSVSNC

GNDGND

GND

VAGND5V VCC

P803

P802

P800

+

+

VS-ADJ VR951

VA-ADJ VR901

Resistors 100 Ohms ¼ Watt

AC - ON

RL-ON

STB 5V

GND

VS-ON

5V _ MT

M5V-ON

P800

STB 5V

GND

NC

6V

NC

3.4V_ON

( 2 ) 60WLight Bulbs


P812

42PC5DC SMPS Light Bulb Test EAY32808901


Operating Voltages

Troubleshooting

This Section of the Presentation will cover troubleshooting the Y SUS Board for the SingleScan Plasma. Upon completion of the Section the technician will have a betterunderstanding of the operation of the circuit and will be able to locate voltage andresistance test points needed for troubleshooting and alignments.

SMPS Supplied VA VS VCC 5V

Y SUS Developed -VY V SET DNRamp UPY ER

VA supplies the Panel Vertical Grid VS Supplies the Panel Horizontal Grid5V Supplies Bias to Y SUS, Z SUS, Control, and X Boards

-VY Sets the Negative excursion of the Y SUS Drive Waveform V Set Down sets the Pitch of the Bottom Ramp of the Drive WaveformRamp UP sets Pitch of the Top Ramp of the Drive WaveformY ER is being used to Monitor IPM Currents

AdjustmentsDC Voltage and Waveform ChecksResistance Measurements

42PC5DC Y-SUS SECTION


Troubleshooting

V SET Down

RAMP UP

-VY

P3 P1

P4

P7

P6 P5

IC13

Output to Y Drive Output to Y Drive


-VY TP R65

42PC5DC Y-SUS Layout with Panel Label


Troubleshooting

FS1

FS2

FS3

FS4

Logic Signals from the Control Board

VS, VA, 5V VCC from the SMPS

VS, VA, 5V VCC to the Z SUSY/Z ER

VR3Ramp up

VR2V SET DOWN

VR4 -VY

FS5

FS1 VA Fuse

FS2 VS Fuse

FS3 5V

FS4 GND ReturnFS5 5V

IC13

Cathode D34 18V

-VY TP R65

42PC5DC Y-SUS Layout


Troubleshooting

VS

FL1

FS2

YER

SUS_OUT

P5

P6

YER

FS3

P1

P3

IC8

IC4

IC5

VS

VA

5V

IC14IC20

IC21

IC22

P8

IC7

18VIPM IC29

GRD

IPM

IC13

FS4

IPM 18V (Measured at Cathode 0f D34)

ToPDP

ToPDP

Logic fromControl PCB

42PC5DC Y-SUS Block Diagram with IPM


Normal Waveform

Panel Waveform Adjustment

RAMP UP

-VY

V SET DOWN

Oscilloscope TP Y Drive Board

-VY TP

120 +/- 5µs

305 +/- 1VFlat Section 0µs

42PC5DC Y-SUS Waveform Adjust


The center begins to wash out and arc due to -VYrunning to long and clipping.

Colors and the image will bloom slightly and the unitwill have difficulty with clean frame changes in a quicklyaltering image.

-VY Normal -145

Rotated Fully CCW -138V

Rotated Fully CW -166

42PC5DC Y-SUS -Vy Too High or Low


All of the center washes out due to increased Vset_DN time.

The center begins to wash out and arc due to decreased Vset DN time.

V SET DOWN Rotated Fully CCW

V SET DOWN Rotated Fully CW

42PC5DC Y-SUS Ramp Down Too High or Low


Noticeable low level color distortion with the Ramp_up too high.

Noticeable low level color distortion with the Ramp_up too low.

RAMP UP Rotated Fully CCW

RAMP UP Rotated Fully CW

42PC5DC Y-SUS Ramp Up Too High or Low


Generates -Vy from Vs by transformer

Control Board

Diagram of Y Sustain Board

IPM Generates Sustain Waveform

Troubleshooting

Distributes 5v VA VS Distributes 5v

Logic signals needed to

generate drive waveform

Y/Z ER IPM Current Monitor Receive 5V,Va, Vs

from SMPS

Transfer Waveformto Y Drive Board

Z SUS Board

Display Panel

Power Supply Board - SMPS

FETs amplify Sustain Waveform

42PC5DC Y-SUS Block Diagram


There is one IPM ( Intelligent Power Module) on the Y Sustain Board both the SUS and ER Functions are all controlled by IC13

SUS_DNSUS_DN

SUS_UP

ER_UP ER_DN

Troubleshooting

IPM Intelligent Power Module

42PC5DC Y-SUS IPM Explained


Y_SUS Z_SUS

GND

CP

Panel

Vzb

ER_COM

SUS_OUT

SUS_UP

Vs

-Vy

ER_UP

ER_DN

SUS_UP

SUS_DN

Ramp

PASS_TOP

SET_DN

SUS_DN

SUS_OUT

ER_UP

ER_DN

SUS_UP

SUS_DNZBIAS

Vs

Vzb

SCAN

GND

GND GND

ER_COM

GND

Vsc

Troubleshooting

IPMs control both Y and Z Board ER Up Down and SUS Up Down functions used to Drive the Display Panel

42PC5DC Y-SUS and Z-SUS Panel Drive Output Circuits


Troubleshooting

How to Check IPMs “ Diode Check”, Board Removed from Set

Test Points referenced from the silk screenfound on the bottom of the PC Board.

SUS_OUT VS .804

VS SUS_OUT ∞

SUS_OUT YER .395

YER SUS_OUT ∞

YER VS .410

YERVS ∞

GND VS .539

VS GND ∞

SUS_OUT GND ∞

GND SUS_OUT ∞

IC13

42PC5DC Y-SUS Testing IPMs


Y-Drive Board works as a path supplying the Sustain and Reset waveforms which are made in the Y SUSTAIN B/D and sent to the Panel through SCAN DRIVER IC’s.

The Y Drive Board supplies a waveform which selects the horizontal electrodes sequentially.

* 42PC5DC uses 10 DRIVER ICs on 1 Board.

Troubleshooting

Y DRIVE WAVEFORM

42PC5DC Y-DRIVE SECTION


Troubleshooting

To remove the Ribbon Cable from the connector first carefully lift the Locking Tab from the back and tilt it forward ( lift from the outside edge as shown in Fig 1). Gently slide the Ribbon Cable free from the connector.

Fig 1

To reinstall the Ribbon Cable carefully slide it back into the slot see ( Fig 2 ), be sure it is seated securely and press the Locking Tab back to the locked position see ( Fig 3).

Fig 2 Fig 3

P11 P9

P1 P2 P3 P4 P5 P6 P7 P8

42PC5DC Y-Drive Connectors to the Panel


Troubleshooting

Use Diode test as shown below to test Connector P11 Y-DRIVE Board.

12

3

45

6

1

2

3

4

5

6

∞

∞

∞∞

∞

∞

42PC5DC Testing The Y-Drive Buffer Inputs P11 Using Red Lead


Troubleshooting

Use Diode test as shown below to test Connector P11 Y-DRIVE Board.

12

3

45

6

1

2

3

4

5

6

.485

1.01

∞∞

.406

.661

42PC5DC Testing The Y-Drive Buffer Inputs P11 Using Black Lead


42PC5DC Testing The Y-Drive Buffer Inputs Red Lead Troubleshooting

.41 2

3

4

5

6

78

9

10

Use Diode test as shown below to test P9 Connector on the Y-DRIVE Board.

1

2

3

4

5

7

8

9

10

6

.402

.616

.498

.493

.498

.498

∞

∞

∞11

11 .482


Troubleshooting

1 23

4

5

6

78

9

10

Use Diode test as shown below to test the Y-DRIVE Board.Reverse Bias test method is shown below

1

2

3

4

5

7

8

9

10

6

∞

∞

∞

2.36

∞

∞

∞

∞

∞

∞

11 .08

42PC5DC Testing The Y-Drive Buffer Inputs Black Lead


Y-DRIVE Scan IC Testing

Horizontal ElectrodeScan IC Test Points (-)

Scan IC's can be tested to identify a defectiveScan IC. Use forward reverse bias diode test to checkeach IC to confirm the board is defective.

Troubleshooting

Horizontal ElectrodeScan IC Test Points (+)

.759

42PC5DC Testing The Y-Drive Buffer Outputs


• DC Voltage and Waveform Test Points• Z BIAS Alignment• Resistance Test Points

Operating Voltages

Y SUS Supplied VA VS 5v VCC

Developed on Z SUS Z Bias IPM 18v

Troubleshooting

This Section of the Presentation will cover troubleshooting the Z-SUS Board Assembly. Upon completion of this section the Technician will have a better

understanding of the circuit and be able to locate voltage and resistance test points needed for troubleshooting and alignment.

42PC5DC Z-SUSTAIN SECTION


Troubleshooting

Z BIAS Adjustment

P3 P2

P4

P5 P6 P1

IC9

Z BIASTest Point

42PC5DC Z-SUS Board Identification


Z Sustain Board provides the SUSTAIN and ERASE PULSES for generating SUSTAIN discharge in the panel by receiving LOGIC signals from the CONTROL B/D.

The Drive Waveform is supplied to the panel through Z FPC (Flexible Printed Circuit) (Z).

Troubleshooting

Z DRIVE WAVEFORM

Vzb Voltage

42PC5DC Z-SUS Board Waveform TP


Z Bias Adjust

Z Bias Test Points

Scope Test Point

Troubleshooting


42PC5DC Z-SUS Board Layout


Troubleshooting

To PDP

IPM18V

P12

P6

P5

P4

P2

FL7

P3

IPM

IC9VS

VA

5V

To PDP

ZER

L1

VS

ZER

FS1Logic from

Control PCB

5 V

SUS OUT

Z Bias

Block

Q1Q2

18V

42PC5DC Z-SUS Board Block Diagram


Troubleshooting

Y Drive Waveform Y Drive Waveform

Z Drive Waveform Z Drive Waveform

Troubleshooting a no picture (no raster) symptom can sometimes be made easier by checking the Y and Z Drive Waveforms. The illustration above shows both waveforms at 100 and 400μs time durations. Since both waveforms are developed independently of each other, checking them will reveal which circuit has failed. Make note of the wave shapes and phase relationship of the signals, distortion or loss of the signals when recognized will speed up the troubleshooting process and prevent the need to replace circuit boards which are working normally.

42PC5DC Y-SUS and Z-SUS Drive Waveform Summary


• DC Voltage and Waveform Test Points• Resistance Test Points

Operating Voltages

Y SUS Supplied 5V VCC

Developed on the 1.8V

Control board (2) 3.3V

Troubleshooting

Main Board Supplied LVDS Signal

Logic Signals

This Section of the Presentation will cover troubleshooting the Control Board Assembly. Upon completion of this section the Technician will have a better understanding of the circuit and be able to

locate voltage and resistance test points needed for troubleshooting.

42PC5DC CONTROL BOARD SECTION


Troubleshooting

MCM IC

50Mhz

P2

P7 P8

P3

Check the output of the Oscillator package. The frequency of the sine wave is 50 MHZ.Missing this clock signal can halt operation of the unit

AUTO GENInternal Pattern Generator

Panel Test: Remove the LVDS Cable. Short the Auto Generator.

Patterns should appear on the Screen.

The Panel Test is a good way to tell if the Panel or the Main board is the problem.Don’t forget to also investigate the LVDS cable as a source of Video problems.

42PC5DC Control Board Layout and Auto Gen. Panel Test


Troubleshooting

IC13LGDP4006

MCM

P7 P8

P1

LVDS

P3

P2

IC4

IC5

Temp Diodes

Logic Signals to the

Y SUS Board

Logic Signals to the

Z SUS Board

RGB Logic Signals to the

Left X Board

RGB Logic Signals to the

Right X Board

IC25

D4D3D2D1

Download

P6

X1

3.3V3.3V

1.8V

Look for activity at the Temp Diodes if not lit check supplies. Supplies present replace the Control Board

42PC5DC Control Board Drawing


Troubleshooting

LVDSVideo Signals from the Main Board to the Control Board are referred to as Low Voltage Differential Signals or LVDS. Their presence can be confirmed with the Oscilloscope by monitoring the LVDS signals with no input signal selected while pressing the Menu Button “on” and “off” with the Remote Control or Keypad. Loss of these Signals would confirm the failure is on the Main Board!

Example of Normal Signals measured at 200mv/cm at 5µs/cm.

Menu Off Menu ON

LVDS Cable

42PC5DC Control Board LVDS Signal Information


MCM

TCP TCPTCP

16 line

Resistor Array

192 Lines output

Diagram of Control Board Control Board to X Board Address Signal Flow

16 line

LGDP4006This Picture shows Signal Flow Distribution to help determine the failure depending on where the it shows on the screen.

The Control Board supplies Video Signals to the X Boards, which then drive the TCP ICs. A bar defect on the screen, could be a Control Board problem.

Troubleshooting42PC5DC Control Board to X-Board Signal Information


Troubleshooting

Right X Drive Board

P107

P108 P114

P109

Right X Board

TCP IC

Left X Board

There are 2 X Drive Boards used in the 42PC5DC. Each board drives 6 TCP IC’s which are used for developing the Vertical Grid.

42PC5DC X-DRIVE BOARD SECTION


TCP IC

Front side

TCP ICs supply RGB 16 bit signal to the PDP by connecting the PAD Electrode of the PANEL with the X Board.

TCP

Connector

Fram

e X_B/D

Front panel

Rear panel

Troubleshooting42PC5DC TCP (Tape Carrier Package)


1 50

VA (7,8,9) 15 Thru 2526-29

Grnd

30 Thru 36

45,46

NC

VA (42,43,44)

37 Thru 39 GrndRGB Logic Signals RGB Logic Signals

VA

2,3,4Ground

5,6NC

10,11NC

12,13,14Ground

40, 41NC

47,48,49 Ground

VA

NC NC

42PC5DC FPC Output to TCP IC

TCP (Taped Carrier Package) Connector Information


Operating Voltages SMPS Supplied

Troubleshooting

This Section of the Presentation will cover troubleshooting the Main Board. Upon completion of the Section the technician will have a better understanding of the operation of the circuit and will be able to locate voltage and resistance test points needed for troubleshooting and alignments.

9V

2.5V

19V12V6V3.4V

Developed on the Main Board 3.3V (2)

5V

42PC5DC MAIN BOARD SECTION

DC Voltage and Waveform ChecksResistance Measurements


Troubleshooting

Tuner IC1001

A/V Component Inputs

A/V Composite inputs

RS 232HDMI

Cable/ Antenna

Speakers P7009 P7010

No Fan in 42”

LVDS P6001

PC

P4004 P4005 P4003

USB

Audio Output IC7017

IC4015 Micro Controller

AV2 Input

Keyboard InputP4007

P5002

42PC5DC Main Board Layout


Troubleshooting

Tuner

IC4003

IC401612V0V9V

0V3.3V

5V

IC4013IC4008

P4007P5002

Input Jacks

IC4008

3.4V Input

3.3V Control

0V

1.1V

2.5V Output

IC4013

6V Input

3.2V Control

5V Output

0V

0VAudio Output

IC7017

IC4011

4.9V 3.3V

P4004 P4005 P4003 P6001

LVDS

IC1001

BCM3550

MST3361

IC7004

D4006

P7009

P7010

MTV416GMFIC4015

IC5003 CXA2069Q

P7002

RF INPUT

42PC5DC Main Board Drawing


42PC5DC BLOCK DIAGRAM SECTION

See the following pages for Block Diagrams


MST3361

Side AV V,LR

Rear AV V, LRRear S YC, LR

Side S YC, LRMNT_V_Out

IN1

OUT1IN4IN1

IN4

IN5

OUT3

Comp_1YCbCrComp_2YCbCr

IN3IN4

CV

BS

CVBS

ATSC/NTSC Tuner

CableANT.

64-Bit I/F

BCM3550IC1001

12LVDSTransVDEC_CVBS/S_Y

VSB/QAM/NTSC/SIF

SPDIF Out

R/L Output

SPDIF_OUT

Flash Memory16MByte

HDMI/DVI

RS-232C

SDRAM256Mbit X-tal

54MHz

Reset IC

D-class AMP

Sub Micom(MTV416)

Sub Micom(MTV416)

EEPROM

HDMI & ComponentRGB-PC

Audio 부

Tuner부

Comp_1 LRComp_2 LRRGB(Phone) LR AUDIO

ADCAudio R/L I2S

I2S Audio Input

R/G/BH/V Sync

DVI Input

Digital Output.

SDRAM256Mbit x2

DDS

Data [24] Hsync/Vsync/DE/Clk2X1

S/W

2X1S/W

HDCP

IIC

TMDS

DDS

SPDIF

Y,C

IF P/N for DTVSIF for NTSC

SIF for NTSC

USB for upgrade S/W

LRMNT_OutAUDIO DAC

IIS

TMDS

CXA2069(AV S/W)

Troubleshooting

IC6004

IC7004

THC63LVD

IC4015

42PC5DC Block diagram Analog and Digital Inputs


42PC5DC Video signal path for Composite/S-video/IF

MNT_V_Out

SD_CVBSCXA2069

IC5003

OUT3

Side AV V,LR

Rear AV V, LR

Rear S YC, LR

Side S YC, LR

IN1

IN4

IN1

IN4

IN3

IN4

Comp_1 LR

Comp_2 LR

RGB(Phone) LR

BCM3550

SD_Y

SD_C

ANT/ Cable

TV IN

CVBS from TUNER

FMS6400

Y/CVBS

C

OUT1/Y

OUT1/C

M_CVBS/Y

C

M_CVBS

C

Y

LPF for CVBS

SD_CVBS

TUNER

IF_P

IF_N

IF_P from TUNER for DTV

IF_N from TUNER for DTV

Troubleshooting


IC7004BCM3550

GPIOGPIO for Interrupt

HD-DVIData [0: 23]

H sync/V sync/DE/Clock H,V Sync/Clock

GPIO

GPIO for Power detectionGPIO

GPIO for Hot plug detection

IC1001

MST3361

TMDS1 RX0+/-TMDS1 RX1+/-TMDS1 RX2+/-TMDS1 RX3+/-

DDC SDA1

DDC SCL1EEPROMFor EDID

DDC SDA1

DDC SCL1

TMDS1INPUT

DDC1INPUT

TMDS2 RX0+/-TMDS2 RX1+/-TMDS2 RX2+/-TMDS2 RX3+/-

DDC SDA2

DDC SCL2EEPROMFor EDID

DDC SDA2

DDC SCL2

TMDS2INPUT

DDC2INPUT

HDCP SDA

HDCP SCLEEPROMFor HDCP

NDA

NCL

INT

DATA_OUT

H,V Sync/DE/Clock

HDMI 1

HDMI 2

Troubleshooting42PC5DC Video signal path for HDMI Inputs


SIF from TUNER

CXA2069

Side AV V,LR

Rear AV V, LRRear S YC, LR

Side S YC, LR

IN1

IN4IN1

IN4

IN3

IN4Comp_1 LR

Comp_2 LRRGB(Phone) LR

OUT1/R

OUT1/L

ANT/ Cable

TUNER

AUDIO ADC(CS5331)

Audio R I2S_SCK_IN

Audio L

BCM3550

SIF

I2S_LRCH_IN

I2S_LRCK_IN

I2S_SCK_IN

I2S_LRCH_IN

I2S_LRCK_IN

SPDIF_IN_P SPDIF from MST3361

_RMNT_OutAUDIO DAC

(CS4344)

I2S_SCK_OUT

I2S_LRCH_OUT

I2S_LRCK_OUT

I2S_SCK_OUT

I2S_LRCH_OUT

I2S_LRCK_OUT

_LMNT_Out

Analog L_OUTAudioAMP

(TPA3100)

SPDIF Out SPDIF_OUT_P

AUD_LEFT_P

AUD_LEFT_N

AUD_RIGHT_N

AUD_RIGHT_P

SPK_L_P

SPK_L_N

SPK_R_N

SPK_R_P

Analog R_OUT

MC3307(OP-AMP)

IF_P from TUNER for DTV

IF_N from TUNER for DTVIF_PIF_N

Troubleshooting42PC5DC Audio signal path Block Diagram


42PC5DC FLOWCHART SECTION

(1) Check and see if LED’s are lit on the CTRL B/D. Missing check for 5VDC No Reset Occurs and no waveformspresent to drive the display panel! Check M5V_ON going high on the SMPS Board.

(5) Check LVDS cable from Main to CTRL B/D, Use the oscilloscope check for LVDS waveforms while pressing the menu button on and off.

(2) Check for VS, VA from SMPS. Missing check Resistances, look for possible shorts on the Y and Z SUS Boards. Check VS ON, going high on the SMPS Board from the Main Board. No Reset Occurs.

(3) Check Waveforms at TP Y Driver, and FL2 Z SUS, if missing or distorted check on the Power Supply for VS, Y SUS BD for V Set Down, -VY and Ramp Up, Z SUS BD Z Bias, 18V IPM’s Both Y&Z Boards No Reset

(6) Check VA to the X Boards Reset Occurs

(4) Examine Scan IC’s on Y Drive Boards use Diode Check No Reset

Flowchart No Picture Sound OK Look for Reset

“No raster” in details

- 72 -

TROUBLESHOOTING GUIDE

TV/CATV doesn’t display

Check TU4001 Pin9(Video output)Can you see the normal signal?

Check the input(Pin63) of AV switch(IC5003).Can you see the normal waveform?

Check the output(Pin56) of AV switch(IC5003).Can you see the normal waveform?

Check the input(Pin1) of LPF(IC4006).Can you see the normal waveform?

YES

YES

YES

NO Could you measure voltage of TU4001 & IIClines?

Are they all normal?

Check the output(Pin8) of LPF(IC4006).Can you see the normal waveform?

YES

Check the input(PinH26) of BCM3550(IC4006).Measure waveform at C1010 because it s more

easy to check.Can you see the normal waveform?

YES

YES

NO You should check power line& IIC lines.

YES

You should replace TUNER.

NO After checking the Power of AV switch you shoulddecide to replace AV switch or not.


NO After checking the Power of LPF you should decide toreplace LPF or not.


This board has big problem because Mainchip(BCM3550) have some troubles.

After checking thoroughly all path once again, Youshould decide to replace BCM3550 or not.

- 73 -


Video doesn’t display

Check J5007 Pin3CCan you see the normal waveform?

Check the input(Pin1 or Pin8) of AVswitch(IC5003). Pin1 is for video1,Pin8 is for

video 2.Can you see the normal waveform?

Check the output(Pin56) of AV switch(IC5003).Can you see the normal waveform?

Check the input(Pin1) of LPF(IC4006).Can you see the normal waveform?

YES

YES

YES

NOJ5007 may have problem. Replace this Jack.

Check the output(Pin8) of LPF(IC4006).Can you see the normal waveform?

YES

Check the input(PinH26) of BCM3550(IC4006).Measure waveform at C1010 because it s more

easy to check.Can you see the normal waveform?

YES

YES







- 74 -


Component doesn’t display

Check J5004,J5005.Can you see the normal waveform?

Check the input of Componentswitch(IC5001,IC5002).

Can you see the normal waveform?

Check the output of Componentswitch(IC5001,IC5002).


Check the input of MST3361(IC7004Pin41,44,46).


YES

YES

YES

NOJ5004,J5005 may have problem. Replace this Jack.

Check the output of MST3361(IC7004 ).Can you see the normal waveform?

YES

Check the input and output ofBCM3550(IC4006). Especially you should check

The H,V sync and clock.Can you see the normal waveform?

YES

YES

NO After checking the input TR of component, you shoulddecide to replace component switch or not.

NO

NO After checking the Power of MST3361 you shoulddecide to replace MST3361 or not.

NO



After checking the Power of component switch youshould decide to replace component switch or not.

After checking the Power of MST3361 you shoulddecide to replace MST3361 or not.

- 75 -


RGB_PC doesn’t display

Check input connect P7004.Can you see the normal waveform?

Check the input of Component switch(IC5002).Can you see the normal waveform?

Check the output of Component switch(IC5002).Can you see the normal waveform?

Check the input of MST3361(IC7004Pin41,44,46).


YES

YES

YES

NOP7004 may have problem. Replace this Jack.

Check the output of MST3361(IC7004 ).Can you see the normal waveform?

YES

Check the input and output ofBCM3550(IC4006). Especially you should check

The H,V sync and clock.Can you see the normal waveform?

YES

YES

NO After checking the input TR of RGBHV, you shoulddecide to replace these components or not.

NO

NO After checking the Power of MST3361 you shoulddecide to replace MST3361 or not.

NO



After checking the Power of RGB switch you shoulddecide to replace component switch or not.

After checking the Power of MST3361 you shoulddecide to replace MST3361 or not.


Troubleshooting

The EndThank You

42PC5DC Conclusion Page

Documents

Lg 42pc5dc Training Manual [ET]