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LG 42PG20 Training Manual
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LG 42PG20 Training Manual

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LG TRAINING MANUAL
LG TRAINING MANUAL
Fall 2008 PDP Training
42PG20

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Summary of Contents for LG 42PG20

  • Page 1 LG TRAINING MANUAL LG TRAINING MANUAL Fall 2008 PDP Training 42PG20...
  • Page 3 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.

  • Page 4: Table Of Contents

    Switch Mode Power Supply removal ..13 42PG20 :: waveforms ........ 112 y-Sus board removal ........13 42PG20 :: Main Board :: video & BCM ..113 y-Drive board removal ....... 13 42PG20 :: Main Board :: Control ....114 Z-Sus board removal ........

  • Page 5: Overview

    USB flash memory drives loaded with media or firmware for the TV. SimpLink allows for control of other LG SimpLink products via the HDMI connection. All PDP TV models are covered by a one year parts and labor warranty. Refer to the last page of the owner’s manual for more warranty information.

  • Page 6: Model Number Structure

    60 = Full HD & THX L = LCD Z= Zenith D = DLP RPTV Blank = LG J = Projector SeRIAL NUMBeR STRUCTURe 4 0 3 M X X Q 0 5 1 0 6 Sequential Number (5-7 Numbers)

  • Page 7: Remote Control

    OveRvIeW ReMOTe CONTROL POWER 2008 models feature a newly designed, easier to use remote. The remote has fewer buttons than previous designs which was accomplished by INPUT Q. MENU MENU moving many functions to an on-screen Quick Menu. The “Q. MENU” button on the remote opens the Quick Menu and the user can choose between options like aspect ratio, closed captions, sleep timer, etc.

  • Page 8: Service Remote

    OveRvIeW SeRvICe ReMOTe NUM KEY FUNCTION POWER To turn the TV on or off POWER ON To turn the TV on automatically if the power is supplied to the TV. Use the POWER key to deactivate; It should be deactivated when delivered. MUTE To activate the mute function.

  • Page 9: Check Firmware Version

    OveRvIeW CHeCk FIRMWARe veRSION LP81A LP81A LPL L42FHD LPL L42FHD You can check the firmware version by Main Main V1.62 USB V2.14 V1.62 USB V2.14 opening the service menu. It is located 00 HDCP 0 00 HDCP 0 near the top of the menu. UPDATe FIRMWARe Tool Option1 Tool Option1...

  • Page 10: 42Pg20 Dimensions

    DISASSeMBLy 42PG20 DIMeNSIONS 40.9" 3.4" 1038.9mm 86.4mm 15.8" 400mm 4.72" 120mm 12.4" 315mm 15.8" 6.6" 400mm 168.78mm 28.8" 26.7" Center 731.5mm 678.2mm 17.48" 15.55" 443.95mm 394.95mm Model No. Remove 4 screws to 6.2" Serial No. remove stand for 158mm Label wall mount 1.93"...
  • Page 11 The Adjust and Instart menu can be accessed 42LB50C-UA 240W using the service remote (Service remotes are 42LB5DC-UA 240W available from LG parts). They can also be 42LC4D-UA 230 240W accesed by holding down the menu button on 42LC50C-UA 240W...

  • Page 12: Disassembly

    42PG20 INTRODUCTION This section of the manual will discuss disassembly of the 42PG20 PDP 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.

  • Page 13: Switch Mode Power Supply Removal

    DISASSeMBLy SWITCH MODe POWeR SUPPLy ReMOvAL Disconnect the following connectors: P812, P813, CN101. Remove the 8 screws holding the board in place. Remove the board. When replacing, be sure to readjust the Va/Vs voltages in accordance with the Panel Label. Confirm VSC, -Vy and Zbias as well. y-SUS BOARD ReMOvAL Disconnect the following connectors: P201, P801, P101, P202.
  • Page 14 DISASSeMBLy A) Remove the sStand mounting support Power Supply Y-Drive plastic piece. Y-sus & Z-Sus Drive B) Remove the stand Z-Sus m e t a l s u p p o r t bracket, unplug AC ground lug. Control (Logic) C) Remove the 2 screws Main (Digital) from the decorative...

  • Page 15: Tcp Connector Removal

    DISASSeMBLy TCP CONNeCTOR ReMOvAL Lift up the lock as shown by arrows. (The Lock can be easily broken. It needs to be handled carefully.) Pull TCP apart as shown by the arrows. The TCP Film can be easily damaged, handle with care. P232 &...

  • Page 16: Control Button Board Removal

    DISASSeMBLy CONTROL BUTTON BOARD ReMOvAL The control button board and power switch board are located in the lower left hand section (as viewed from the rear). To remove, unplug the connector P101 and remove the 2 screws. Under each screw there is a black tab.

  • Page 17: 42Pg20 Exploded View

    DISASSeMBLy 42PG20 eXPLODeD vIeW Part numbers subject to change. Check GCSC (aic.lgservice.com) for the current part numbers. Location Part Num Description Location Part Num Description Full Range Speaker Right Filter Support EAB42609901 AJJ35122602 EAJ41970710 PDP Panel (PDP Module) MDJ42350902 Glass Filter...

  • Page 18: Block Diagram

    CIRCUIT DeSCRIPTIONS BLOCk DIAGRAM PDP Training - Fall 2008...

  • Page 19: Signal And Voltage Block Diagram

    DISASSeMBLy SIGNAL AND vOLTAGe BLOCk DIAGRAM Y Drive PWB PDP Training - Fall 2008...

  • Page 20: Circuit Descriptions

    (1 1) UL Approval No. (4) Adjusting Voltage DC, Va, Vs (12) Model Name (5) Adjusting Voltage (Set Up/-Vy/Vsc/Ve/Vzb) (13) Max. Watt (Full White) (6) Trade name of LG Electronics (14) Max. Volts (7) Manufactured date (Year/Month) (15) Max. Amps (8) Warning...

  • Page 21: Power Supply (Smps)

    CIRCUIT DeSCRIPTIONS POWeR SUPPLy (SMPS) P812 To Y/Z-Sus VS Source 380V Source Circuit VA Source VA VR901 Standby Source F801 340V Fuse VS VR951 10Amp/230V F101 16V, 12V, 5V, 3.2V 340V Fuse Source 10Amp/230V P813 CN 101 To Main AC Input IC701 Sub Micon Hot Ground Symbol represents a SHOCK Hazard...
  • Page 22 CIRCUIT DeSCRIPTIONS SMPS Outputs Adjustments Board Voltage Description Drives the display panel Horizontal Grid Voltage Location Responsible for display panel Vertical Grid RV901 Y-Sus Used to develop Bias Voltages on the Y-Sus, RV951 M5V VCC X-Drive, and Control boards M5V VCC Fixed Audio B+ Supply Main Control Circuits...
  • Page 23 CIRCUIT DeSCRIPTIONS 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.
  • Page 24 CIRCUIT DeSCRIPTIONS could be caused by a failure on the SMPS or a circuit using these voltages. A resistance check should narrow the possible failures quickly. POWER SUPPlY STATIC TEST This test can confirm the proper operation of the SMPS 5VSTB 5VSTB 5VSTB...
  • Page 25 CIRCUIT DeSCRIPTIONS MICRO POWER SUPPlY CONTROl 42PG20 Power Supply Controls from Micro Side P701 Level Shifter Q706 9 10 11 12 +5V-General +5V-ST R763 RL-ON 1.6V 1.8V RL-ON R718 LD703 R723 Green RL-ON R715 Q703 LD703 Set Off +5VST Red...
  • Page 26 CIRCUIT DeSCRIPTIONS MICRO POWER SUPPlY CONTROl - STEP1 PDP Training - Fall 2008...
  • Page 27 CIRCUIT DeSCRIPTIONS MICRO POWER SUPPlY CONTROl - STEP2 PDP Training - Fall 2008...
  • Page 28 CIRCUIT DeSCRIPTIONS PIN vOlTAGES P701 “Main” to P813 “SMPS” Label STBY Run No Load Diode Pin Label STBY Run No Load Diode 16.5V 16.5V 3.8V 16.5V 16.5V 2.82V Open Open 0.75V 0.75V 0.75V 0.75V 17 5_V Det .15V 3.25V 18 AC Det Open RL_On 3.73V...

  • Page 29: Y-Sus Board

    CIRCUIT DeSCRIPTIONS y-SUS BOARD VR602 VR601 FS202 (Vs) V-Set Up V-Set Down 4A 250V P204 To Y-Drive C221 Drive TP R210 P201 -VY TP Vs & Va From SMPS FS201 P200 To Y-Drive P801 Z-Drive to -VY ADJ VR502 Z output Z-Bias ADJ VR905 VSC ADJ VR501 Z-Bias TP R496...
  • Page 30 CIRCUIT DeSCRIPTIONS vSC AND -vY ADJUSTMENTS Set should run for 15 minutes, this is the “Heat Run” mode. Set screen to White Wash mode or 100IRE White input. Adjust –Vy to 190V (+/- 1V). Adjust VSC to 140 (+/- 1V). Lower Left Side of Y-Sus R210...
  • Page 31 CIRCUIT DeSCRIPTIONS v-SET UP AND v-SET DOWN ADJUSTMENTS VSC and –VY Must have already been completed. Observe the Picture while making these adjustments. Normally, they do not have to be done. 2.00ms 100V per division 1.00ms 100V per division A) Observe the Ramp Up portion Y Setup Ramp VR602 Pulse...
  • Page 32 CIRCUIT DeSCRIPTIONS v-SET UP AND v-SET DOWN ADJUSTMENTS Fig1 top shows the Y-Drive Waveform signal locked in at 4ms per/div. The signal for Vsetup Outlined Area is outlined within the Waveform. FIG1 Area to At 400uSec per/division, the Fig1 lower be adjusted waveform shows Vsetup isolated.
  • Page 33 CIRCUIT DeSCRIPTIONS v-SET UP TOO hIGh OR lOW The center begins to wash out and arc due to Vset UP peeking too late and alters the start of the Vset DN V-Set Up Too High phase. Very little alteration to the picture, the wave form V-Set Up Too Low indicates a distorted Vset UP.
  • Page 34 CIRCUIT DeSCRIPTIONS Y-SUS blOCk DIAGRAM Power Supply Board - SMPS Z SUS Section on the Same PWB Distributes 5V VS Receive 5V VCC, Va, Vs Distributes 5V Control Board from SMPS Distributes 16V VA Logic signals needed to generate drive waveform Circuits generate Generates Vsc, -Vy and V Set Up...
  • Page 35 CIRCUIT DeSCRIPTIONS PDP Training - Fall 2008...
  • Page 36 CIRCUIT DeSCRIPTIONS Y-SUS CONNECTIONS “Y-Sus” P801 to “Z-Drive” P1 Label Standby Diode Mode *194V Open P204 To Y-Drive ZSUS 70.46V Open P201 Vs & Va From SMPS ZSUS 70.46V Open P801 ZSUS 70.46V Open Z-Drive to Z output ZSUS 70.46V Open P200 P101...

  • Page 37: Y-Drive Board

    Y-Drive board works as a path supplying the Sustain and Reset waveforms which are made in the Y-Sustain board and sent to the panel through scan driver IC’s. The Y-Drive boards supply a waveform which selects the horizontal electrodes sequentially. The 42PG20 uses 8 driver ICs on 1 Y-Drive board.
  • Page 38 CIRCUIT DeSCRIPTIONS REMOvING RIbbON CAblES To remove the Ribbon Cable from the connector, first carefully lift the Locking Tab from the back and tilt it forward (lift from under the tab as shown in Fig 1). The locking tab must be standing straight up as shown in Fig 2. Lift up the entire Ribbon Cable gently to release the Tabs on each end.
  • Page 39 CIRCUIT DeSCRIPTIONS Y-DRIvE bUFFER TROUblEShOOTING Using the “Diode Test” on the DVM, check the pins for shorts or abnormal loads. You can check all 8 buffer ICs using this procedure. Using the “Diode Test” on a digital volt meter, check the pins for shorts or abnormal loads. Any of the output lugs can be tested. Look for shorts indicating a defective Buffer IC.
  • Page 40 CIRCUIT DeSCRIPTIONS P200 ON ThE Y-DRIvE Voltages taken with unit running and snow as a picture. TOP (Front View) P200 52.3V -87.9V -87.9V -87.9V -85.2V -90.8V -83V -87.9V -88V DATA -83V PDP Training - Fall 2008...
  • Page 41 CIRCUIT DeSCRIPTIONS Z-bIAS ADJUSTMENT The Z-Sus Drive section is now located on the Y-Sus board. Set should run for 15 minutes in “Heat Run” mode prior to any adjustments. Set screen to white wash mode or 100IRE White input. Adjust VZ (Z-Bias) to 100V (+/- 1V). FS202 (Vs) 4A 250V Read the Label on the back of the...

  • Page 42: Z-Sus Board

    CIRCUIT DeSCRIPTIONS Z-SUS BOARD Provides the SUSTAIN PULSE and ERASE PULSE for generating SUSTAIN discharge in the panel by receiving Drive signals from the Y/Z-Sus board. This waveform is supplied to the panel through FPC (Flexible Printed Circuit (Z). Z-Bias is a “DC” adjustment. The effects of this adjustment can be observed on the scope looking at the Z-Sus output.
  • Page 43 CIRCUIT DeSCRIPTIONS Z-SUS blOCk DIAGRAM Distributes 5V VCC, VA, VS Y-SUS Board Z-SUS Section of the Y- SUS PWB Receives NO IPMs Distributes Logic Signals VS M5V Control Board Circuits generate erase, Generates Z Bias 100V sustain waveforms Z-SUS PWB Display Panel FET Makes Drive waveform Z-SUS FETs...

  • Page 44: Control Board

    CIRCUIT DeSCRIPTIONS CONTROL BOARD P131 Download P164 Crystal Connection Temperature P121 IC121 LEDs IC101 IC212 IC133 IC201 P160 VS_DA IC211 3V ~3.3V To Y/Z-Sus IC213 Auto Gen Test Pattern IC122 Control board Inputs IC171 IC171 Board Input Pin1 = 3.29V Pin2 = 1.20V Main LVDS...
  • Page 45 CIRCUIT DeSCRIPTIONS If there is a picture of cycling colors, the Y-Sus, Y-Drive, Z-Sus, Power Supply, Control boards and Panel are all OK. Same test to tell if No Video is caused by the Main board. Quick observation Of Temperature LEDs will tell if the Control board is running. With the unit on.
  • Page 46 CIRCUIT DeSCRIPTIONS CRYSTAl ClOCk C h e c k t h e o u t p u t o f the Oscillator package. The frequency of the sine wave is 50 MHZ. Missing this clock signal 50 Mhz can halt operation of the unit.
  • Page 47 CIRCUIT DeSCRIPTIONS CONTROl bOARD SIGNAl blOCk The Control board supplies Video Signals to IC201 the TCP (Tape Carrier Package) ICs. If there is a bar defect on the screen, it could be a Control CONTROL PWB board problem. This Picture shows Signal Flow Distribution to help determine the failure depending on where the it shows on the screen.
  • Page 48 CIRCUIT DeSCRIPTIONS CONTROl TO Y-SUS P160 is show below. These pins are very close together, so use caution when taking voltage measurements. This connector is a little confusing in its labeling. It is actually a 60 pin connector. This shows the Pin Labeling that is shown on the silk screening. Remember, this connector has many more pins than the labels indicate.
  • Page 49 CIRCUIT DeSCRIPTIONS PDP Training - Fall 2008...
  • Page 50 CIRCUIT DeSCRIPTIONS CONTROl TO X-DRIvE Connector P161 on the Control board connects to P232 on the left X-Drive. Connector P162 on the Control board connects to P331 on the right X-Drive. These pins are covered in silicon, so no measurement can be made. CONTROl TO X-bOARD Signal Cable Power Cables...

  • Page 51: X-Drive Boards

    CIRCUIT DeSCRIPTIONS X-DRIve BOARDS Warning: DO NOT attempt to run the set with the heat sinks removed from the TCPs. After a very short time, these ICs will begin to self destruct due to overheating. TCP IC’s shown are part of the Ribbon Cable. Left X-Board P232 P211...

  • Page 52: Tcp Connector Removal

    CIRCUIT DeSCRIPTIONS TCP CONNECTOR REMOvAl Lift up the lock as shown by arrows. The Lock can be easily broken. It needs to be handled carefully. Pull TCP apart as shown by arrow. TCP Film can be easily damaged., handle with care. TCP ICs supply RGB 16 bit signal to the PDP by connecting the PAD Electrode of the panel with the X-Board.
  • Page 53 CIRCUIT DeSCRIPTIONS TCP TESTING Typical Reading 0.65V Opposite reads open. Look for any TCPs being discolored. Ribbon Damage. Cracks, folds Pinches, scratches, etc. On any Gnd 10,11,12,13,14,27,28,2 9,30,37,38,39,40,41 On any Va 4,5,6,7,44,45,46,47 DAMAGED TCP Warning: DO NOT attempt to run the set with the heat sinks over the TCPs removed. After a very short time, these ICs will begin to self destruct due to overheating.
  • Page 54 CIRCUIT DeSCRIPTIONS P211 “X-Drive Left” to “Y-Sus” P202 P311 “X-Drive Right” to “Y-Sus” P202 Pin Label Stby Diode Check Label Stby Run Diode Check 15.4V Open Open *61.4V Open *61.4V Open *61.4V Open *61.4V Open *64.9V Open *64.9V Open P232 & P331 CONNECTORS Voltage and resistance measurements for the X-Drive board.

  • Page 55: Left And Right X-Drive Removal

    CIRCUIT DeSCRIPTIONS LeFT AND RIGHT X-DRIve ReMOvAL After the back cover is removed, the Main board is lifted out of the way, the 15 screws are removed from the heat sinks covering the TCPs, the X-Drive boards can be removed. Gently lift the locking mechanism upward on all TCP connectors P201-206 or P301-306.

  • Page 56: Main (Digital) Board

    CIRCUIT DeSCRIPTIONS MAIN (DIGITAL) BOARD Main Input Voltages Board Voltage SMPS 3.3V Main 2.5V 1.8V IC702 LVDS IC709 P701 IC702 5) .29V 1) 3.29V Reset 4) 5V 2) 1.26V IC705 IC709 IC101 3) 0V 3) 0V P302 **LD400 2) 0V Pin 16 IC501 1) 0V...

  • Page 57: Circuit Descriptions

    CIRCUIT DeSCRIPTIONS MAIN bOARD bOTTOM Be sure to prevent the board from touching the frame while the board is turned over. Use a piece of cardboard or towel to insulate. Main ICs Chip Pin Voltage 1 5V IC705 2 3.29V IC709 IC101 3 0V...
  • Page 58 CIRCUIT DeSCRIPTIONS MAIN bOARD TUNER TEST POINTS Refer to the image below with the shield off and pins exposed on the tuner. LD400 Tuner Osc. Lock On Unlocked VIF Pin 16 Video Test Point O Locked SIF Pin 14 Audio Test point IC400 Tuner Controller...
  • Page 59 CIRCUIT DeSCRIPTIONS MAIN bOARD CONNECTORS P701 To Power Supply SW100 Reset IC702 P302 LVDS To Control X400 25 Mhz IC1001 X100 HDMI 3 12 Mhz RS-232 RGB/PC Remote P303 AV 3 To Front Controls Optical JK501 Audio Speaker Out A/V Composite Component Audio HDMI Inputs...
  • Page 60 CIRCUIT DeSCRIPTIONS P701 “Main” to P813 “SMPS” Label STBY Diode Check Label STBY Diode Check 16.5V 3.8V 16.5V 2.82V Open Open 0.75V 0.75V 0.75V 0.75V 5_V Det .15V 3.25V AC Det Open RL_On 3.73V Open Vs_On 3.2V 1.22V M5V_ 3.27V 3.24V 1.22V AUTO CN701 “Main”...
  • Page 62 Spring 2008 PDP Training...

  • Page 63: Power Supply

    Y-SUS DRIVE WAVEFORM 42PG20 CIRCUIT INTERCONNECT DIAGRAM Z-SUS RAMP 150V To Peak See next page for Y-SUS TP waveforms VZ Bias P302 Remove all input signals State Ref# Z-SUS TP from the unit so the Menu Off P812 P813 menu will be the only...
  • Page 64 Time per division Trigger offset Volts per division Pin 22 - Menu off P302 P302 Pin 16 - Menu off Pin 12 - Menu off Pin 13 - Menu off Pin 19 - Menu off State State Ref # Ref # Menu Off Menu Off Menu On...

  • Page 65: 42Pg20 :: Main Board :: Video & Bcm

    42PG20 :: maIn Board :: vIdeo Processor & Bcm 1 13 PDP Training - Fall 2008 Schematics...

  • Page 66: 42Pg20 :: Main Board :: Control

    42PG20 :: maIn Board :: control LVDS Key Pad 1 14 PDP Training - Fall 2008 Schematics...

  • Page 67: 42Pg20 :: Main Board :: Ddr Memory

    42PG20 :: maIn Board :: ddr memory 1 15 PDP Training - Fall 2008 Schematics...

  • Page 68: 42Pg20 :: Main Board :: Tuner

    42PG20 :: maIn Board :: tuner 1 16 PDP Training - Fall 2008 Schematics...

  • Page 69: 42Pg20 :: Main Board :: Audio Processor

    42PG20 :: maIn Board :: audIo Processor 1 17 PDP Training - Fall 2008 Schematics...

  • Page 70: 42Pg20 :: Main Board :: Power Regulator

    42PG20 :: maIn Board :: PoWer reGulator 1 18 PDP Training - Fall 2008 Schematics...

  • Page 71: 42Pg20 :: Main Board :: Inputs

    42PG20 :: maIn Board :: InPuts 1 19 PDP Training - Fall 2008 Schematics...

  • Page 72: 42Pg20 :: Main Board :: Hdmi & Usb

    42PG20 :: maIn Board :: HdmI & usB PDP Training - Fall 2008 Schematics...

  • Page 73: 42Pg20 :: Power Supply :: Pfc & Mcu

    42PG20 :: PoWer suPPly :: Pfc & mcu PDP Training - Fall 2008 Schematics...
  • Page 74 42PG20 :: PoWer suPPly :: multI & stand-By PDP Training - Fall 2008 Schematics...

  • Page 75: 42Pg20 :: Power Supply :: Va & Va

    42PG20 :: PoWer suPPly :: va & va PDP Training - Fall 2008 Schematics...

  • Page 76: 42Pg20 :: Main Board :: Pcb Layout

    42PG20 :: maIn Board :: PcB layout PDP Training - Fall 2008 Schematics...

  • Page 77: 42Pg20 :: Main Board :: Bottom Pcb

    42PG20 :: maIn Board :: Bottom PcB layout PDP Training - Fall 2008 Schematics...

  • Page 78: 42Pg20 :: Sub Boards :: Pcb Layout

    42PG20 :: suB Boards :: PcB layout PRE AMP(TOP) CONTROL(TOP) PRE AMP(BOTTOM) CONTROL(BOTTOM) PDP Training - Fall 2008 Schematics...

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