LG 42LH90 Manual
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LG 42LH90 Manual

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Download this manual See also: Owner's Manual
1080P
Direct View LCD
42LH90
42LH90
Training
LED Backlights
Original February 09, 2010
Updated July 28, 2010

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Summary of Contents for LG 42LH90

  • Page 1 1080P Direct View LCD 42LH90 42LH90 Training LED Backlights Original February 09, 2010 Updated July 28, 2010...
  • Page 2 Board Operation Troubleshooting of : • Switch Mode Power Supply • Inverter Board (LED Backlight Driver) • T-CON (TFT Controller) Panel Driver board • Main Board • Ft Control Board • Side Keys • Speakers February 2010 LCD DV 42LH90...

  • Page 3: Overview Of Topics To Be Discussed

    Overview of Topics to be Discussed Overview of Topics to be Discussed 42LH90 LCD Direct View 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.

  • Page 4: Preliminary Matters (The Fine Print)

    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.

  • Page 5: Esd Notice

    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. February 2010 LCD DV 42LH90...

  • Page 6: Lg Contact Information

    Screen Marks LG CS Academy lgcsacademy.com http://136.166.4.200 LCD-DV: 32LG40, 32LH30, 37LH55, 42LG60, 42LG70, 42LH20, 42LH40, 42LH50, 42LH90, 42SL80, 47LG90, 47LH85, 47LE8500 PLASMA: 42PG20, 42PQ20, 42PQ30, 50PG20, 50PJ350, 50PK750, 50PS80, 50PS60, 60PK750, 60PS11, 60PS60, 60PS80 Also available on the Plasma Page:...

  • Page 7: Lcd Direct View Overview

    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… February 2010 LCD DV 42LH90...

  • Page 8: Basic Troubleshooting Steps

    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. February 2010 LCD DV 42LH90...

  • Page 9: 42Lh90 Product Information Section

    42LH90 PRODUCT INFORMATION SECTION 42LH90 PRODUCT INFORMATION SECTION This section of the manual will discuss the specifications of the 42LH90 LCD Direct View Display February 2010 LCD DV 42LH90...

  • Page 10: Basic Specifications

    • AV Mode II (Cinema, Sports, Game) • 1 Digital Audio Out • NTSC / ATSC / Clear QAM • USB 2.0 (JPEG, MP3, MP4, Divx) • PC Connectivity (D-Sub 15pin) • RF Antenna Input February 2010 LCD DV 42LH90...

  • Page 11: Basic Specifications (Logo Familiarization)

    Basic Specifications (LOGO Familiarization) Basic Specifications (LOGO Familiarization) Full HD 1080p Resolution Displays HDTV programs in full 1920 x 1080p resolution for a more detailed picture. February 2010 LCD DV 42LH90...

  • Page 12: Remote Control Familiarization

    Remote Control Familiarization Remote Control Familiarization p/n MKJ61841701 TOP PORTION BOTTOM PORTION February 2010 LCD DV 42LH90...

  • Page 13: Accessing The Service Menu

    Accessing the Service Menu To access the Service Menu. 1) You must have the Service Remote. p/n 105-201M 2) Press “In-Start” 3) A Password screen appears. Note: A Password is required to enter the Service Menu. Enter; 0000 February 2010 LCD DV 42LH90...

  • Page 14: Main Board

    TV Rear Input / Output Jacks TV Rear Input / Output Jacks Side In/Out USB Port Software Upgrades Music, Photos Rear In/Out Jacks MAIN BOARD Rear and Side Input/Output locations February 2010 LCD DV 42LH90...

  • Page 15: Software Download

    Do not remove AC power or the USB Flash Drive. restarted. Do not turn off Power, during the upgrade 8) When download is completed, you will see process. “COMPLETE”. 9) Your TV will be restarted automatically. February 2010 LCD DV 42LH90...
  • Page 16 42LH90 Product Dimensions 42LH90 Product Dimensions 42LH90 Dimensions There must be at least 4 inches of Clearance on all sides 3-11/16" Wattage 93.98mm 42" Average 210W 1066.8mm Stand By <1W 7-7/8" 200mm 9-5/8" 16-15/16" 244mm 430mm 14-1/8" 28-3/16" 357.98mm 716.28mm 7-7/8"...

  • Page 17: Disassembly Section

    Disassembly: This section of the manual will discuss Disassembly, Layout (Circuit Board Identification) of the 42LH90 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.

  • Page 18: Removing The Back Cover

    Putting in an improper screw when reassembling may Cause damage. Decorative Plastic Bottom two screws do Cap (if used) must not have to be be removed. removed. The Stand does not need to be removed before removing the back. February 2010 LCD DV 42LH90...

  • Page 19: Circuit Board Layout

    Main Board p/n EBR62151101 Side Keys Side Inputs Intelligent AC Input Rear Inputs Sensor / IR Tweeter R Moving Tweeter L Power Full Range Full Range Button p/n EAB58536001 p/n EAB58534501 Speaker R Speaker L February 2010 LCD DV 42LH90...
  • Page 20 42LH90 Connector Identification Diagram 42LH90 Connector Identification Diagram TFT PANEL T-CON CN305 CN306 CN307 INVERTER P3500 P3502 P203 P3501 P201 P700 POWER MAIN P101 SUPPLY BOARD P1200 P600 SK100 SK101 AC In P100 Main Speakers (Front Right) Speakers (Front Left)

  • Page 21: Power Supply Board Removal

    Power Supply Board Removal Board Removal Disconnect P201 P201, P203, AC In SK100 and SK101. Remove the 6 screws indicated Press in by the arrows. Two tabs to release lock AC In SK101 Power Switch February 2010 LCD DV 42LH90...

  • Page 22: T - Con Board Removal

    Remove the 3 Screws in the T-CON servicing the T-CON Board. shield and remove the shield Note: Chocolate (Heat Sink Material) Disconnect CN1, CN2, CN4 and CN5. STEP (2) See next slide for details about removing cables. February 2010 LCD DV 42LH90...
  • Page 23 To remove the LVDS cables CN1 and CN2; Press in on the two tabs and slowly rock the cable out of the connector. (Shown by the arrows in Figure above) Note: The tabs are fragile, use caution, they may break. February 2010 LCD DV 42LH90...
  • Page 24 Fig 1 Fig 2 CN5 or CN4 Locked Flip the lock up and back from the flex cable. Then the flex cable can be easily removed. Unlocked Fig 3 The locking tab is flipped down February 2010 LCD DV 42LH90...

  • Page 25: Removing The Main Board

    (See a and b) P600 NOTE: Always check on top and behind the Large ICs. And look for a piece Slide of Chocolate Right (Heat Transfer Material). Be sure to transfer to new Board if present. February 2010 LCD DV 42LH90...

  • Page 26: Removing The Inverter Board

    There should be 8 pieces on the DC to DC converter coils near the bottom right. NOTE: If Servicing the Board, return the screws into the board to provide stability Chocolate and grounding. February 2010 LCD DV 42LH90...
  • Page 27 Be sure to replace these on the New Inverter if the board is replaced. Chocolate Close Up Be sure they do not fall off if the Inverter is removed. Chocolate Chocolate Location White Box Outline February 2010 LCD DV 42LH90...

  • Page 28: Removing Front Boards (Ir Board And Moving Led Board)

    The Power Switch has p/n EBR61674001 Disconnect J1 or P100. Remove been removed for easier the LED board by lifting up on viewing of connectors and the two locking tabs and pull screws. backwards on the board. February 2010 LCD DV 42LH90...

  • Page 29: Removing Front Key Board

    Slots Push In Slots Disconnect Push In P100 and remove the Key Board Apply Pressure at point (B) on the Key Board itself while using an object to slightly pry out from the bottom. February 2010 LCD DV 42LH90...

  • Page 30: Troubleshooting Section

    TROUBLESHOOTING SECTION TROUBLESHOOTING SECTION 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. February 2010 LCD DV 42LH90...

  • Page 31: Power Supply Section

    P201 Connector: (To Main Board) 12V is routed out P201 pins 5 and 6 and 24V is routed out P201 pins 1 and 2. P203 Connector: (To Inverter Board) 24V is routed out P203 pins 1 through 5. February 2010 LCD DV 42LH90...
  • Page 32 Power Supply (Main Power Switch Type 1) Location Power Supply (Main Power Switch Type 1) Location There are three types of Main Power switch used in LG televisions. Type 1: Shuts off AC to the Power Supply. Type 2: Opens ground to the front IR board. (Stand-By 5V Remains, the Main board stays alive).

  • Page 33: Power Supply (Smps) Board Layout

    Red Lead on Hot Ground 5A/250V Hazard AC IN The Left pin on SK101 goes to the Main Power Switch. AC IN The Right hand pin returns SK101 from the Main Power Switch. To Master Power Switch SK101 February 2010 LCD DV 42LH90...

  • Page 34: Power Supply (Smps)

    42LH90 Power Supply Turn On Sequence 42LH90 Power Supply Turn On Sequence Main (Master) POWER SUPPLY (SMPS) Power SW Power Supply will In Stand-By Inverter On not be on if Main Primary side is Inverter Starts the Inverter 160V Power Switch is off.
  • Page 35 42LH90 P700 on Main Board to SMPS Turn On Circuit 42LH90 P700 on Main Board to SMPS Turn On Circuit Q706 L728 L708 R739 47KΩ 12V_TCON (LVDS 12V) Q705 Q704 R740 47KΩ 0.6V L715 MAIN 5V_ST BOARD SMPS Q703 +5V_General...
  • Page 36 • P201 (24V pins 17 and 18) • P201 (12V pins 13 and 14) • P203 (24V pins 1 through 5) to the Inverter. Use P700 (2) Remove AC power. Side to insert resistors February 2010 LCD DV 42LH90...

  • Page 37: Remove Ac Power

    If the 24V was arriving at the Inverter in Test 1 (pins 1~5 of P203) and the Inverter On command (INV-ON pin 12 of P203) is arriving, then see Inverter Section for further testing. Use P700 Side to insert resistors February 2010 LCD DV 42LH90...

  • Page 38: Power Supply Connector P201 Voltage And Diode Check

    PDIM Pin 24 can vary according to type of signal being processed and the OSD Backlight setting. 0.33V 0% to 3.3V 100%. Output from the Video Processor IC100. Diode Mode values taken with all Connectors Removed February 2010 LCD DV 42LH90...

  • Page 39: Power Supply Connector P203 Voltage And Diode Check

    P-DIM Pin 24 can vary according to type of signal being processed and the OSD Backlight setting. *0.6V 0% to 3.3V 100%. Output from the Video Processor IC100. Diode Mode values taken with all Connectors Removed February 2010 LCD DV 42LH90...
  • Page 40 F100 F100 (Diode Check) 8A/250V Main Power Switch Closed AC IN Neutral Red Lead on Fuse (Open) Black Lead on Hot Ground Black Lead on Fuse (0.525V) Red Lead on Hot Ground Live SK101 SK100 February 2010 LCD DV 42LH90...

  • Page 41: Inverter (Led Backlights) Section

    The Left hand connector CN3 connects the 4 LED Boards (32 blocks) on the right side of the screen and the Right hand connector CN4 connects to the 4 LED Boards (32 blocks) on the left. February 2010 LCD DV 42LH90...
  • Page 42 42LH90 LED Backlight Controls (Block Diagram) 42LH90 LED Backlight Controls (Block Diagram) Drive Signals for CN3 and CN4/CN5 carry CN4 going to V1 through V64 CN3 Controls 4 Boards To Panel -5V, 3.3V, 16V, 26V and (LED Blocks) Each board controls 2 rows...

  • Page 43: Inverter Connector Identification

    Inverter Connector Identification Inverter Connector Identification CN305 n/c CN306 CN307 n/c Chocolate 27.5V Power Supplies February 2010 LCD DV 42LH90...
  • Page 44 General LED Backlight Board Information (As viewed from the Fron General LED Backlight Board Information (As viewed from the Fron There are 4 LED Boards per/side, 8 Total. There are 2 Rows of LED blocks per/board. There are 4 LED blocks per/row. February 2010 LCD DV 42LH90...

  • Page 45: General Led Backlight Block Information

    General LED Backlight Block Information General LED Backlight Block Information 9.4V p/p 120 Hz Connected to CN3 or CN4 There are 8 LEDs per/block. There are a total of 512 LEDs. February 2010 LCD DV 42LH90...
  • Page 46 This represents One Block. any pin on the left. There are 4 boards per/side. Each board contains 8 Blocks. Totaling 32 Blocks per/side. 64 Blocks over all. In the Diode Mode Check, the LED will light. (2.6V Reading) February 2010 LCD DV 42LH90...

  • Page 47: Led Backlight Basics (Local Dimming)

    Actual LED reaction capture To see a representation of the “Local Dimming” the TV has to be set to the “Store Mode”. Note: These graphics are from the 47LG90 which has more LEDs than the 42LH90, but the explanation remains the same.

  • Page 48: Inverter Component Identification

    Inverter Component Identification Inverter Component Identification February 2010 LCD DV 42LH90...

  • Page 49: Inverter 27V (M 1 - M4 Power Supplies) Information

    They are designated as “M1 through M4”. Each of the 4 have the same components. 27.5V Each of the 4 capacitors C12, C27, C212 and C227 have a TP just above the (+) leg of the cap. February 2010 LCD DV 42LH90...

  • Page 50: Inverter Component Top Half Identification

    Pins 31-32 (Out_M4) Pins 31-32 (Out_M1) Block of Backlight LEDs to turn on. Pins 43-44 (Out_M4) Pins 43-44 (Out_M1) (100mA to light one block) Pins 46-47 (Out_M4) Pins 46-47 (Out_M1) Pins 58-59 (Out_M4) Pins 58-59 (Out_M1) February 2010 LCD DV 42LH90...

  • Page 51: Inverter Led D302 Information

    Inverter. When it doesn’t blink, check the 24V arriving at the board on CN1 pins 1~5. Check the two fuses F1 and F2 for 24V. Check IC302 and IC303 regulator voltages (see page 56). February 2010 LCD DV 42LH90...

  • Page 52: Inverter Fuse F1 And F2 Check

    Inverter Fuse F1 and F2 Check Center of the Board 2A/125V Left of CN1 Connector 12A/65V F1 or F2 (Diode Mode Check) Open (Red Lead on Fuse) F1 or F2 0.46V (Black Lead on Fuse) Normal 24V in Run February 2010 LCD DV 42LH90...

  • Page 53: Inverter Crystal Y301 Information

    Inverter Crystal Y301 Information Inverter Crystal Y301 Information Crystal Y301 February 2010 LCD DV 42LH90...

  • Page 54: Inverter 27V (M 1 - M4 Power Supplies) Checks

    Q4, Q5, Q11, Q11, Q12, Q204, Q205, Q211, Q212 3.67V 23.9V D2, D3, D7, D8, D202, D203, D207, D208 26.4V 28.0V 3.74V 4.0V 3.73V 6.75V 4.0V Q2, Q10, Q3, Q09 Q202, Q210 Q203, Q209 February 2010 LCD DV 42LH90...

  • Page 55: Inverter Ic2, Ic4 And Ic15 Checks

    Inverter IC2, IC4 and IC15 Checks Inverter IC2, IC4 and IC15 Checks Center of the Board 3.29V 6.99V IC15 1.0V 0.46V 4.6V GND 1.71V 6.95V February 2010 LCD DV 42LH90...
  • Page 56 Inverter IC303 and IC302 Checks (Controller IC301 B+) Inverter IC303 and IC302 Checks (Controller IC301 B+) Top of the Board 3.3V 7.0V IC303 IC302 7.0V 1.8V February 2010 LCD DV 42LH90...
  • Page 57 OPEN 13~14 Out_M3 Silk 27.0V OPEN OPEN Screening OPEN 49~52 V56~V53 0.7-1.2V OPEN 8~11 V52~V49 on Board. 0.7-1.2V OPEN 53~56 V61~V64 0.7-1.2V OPEN V57~60 0.7-1.2V OPEN OPEN OPEN 58~59 Out_M4 27.0V OPEN Out_M3 OPEN OPEN February 2010 LCD DV 42LH90...
  • Page 58 OSD Backlight setting. 0.33V 0% to 3.3V 100%. 24.0V 2.9V Output from the 24.0V 2.9V Video Processor 24.0V 2.9V IC100. 24.0V 2.9V 24.0V 2.9V Diode Mode values taken with all Connectors Removed February 2010 LCD DV 42LH90...
  • Page 59 CN306 Connector “Inverter” to P3501 “Main” Label STBY Resistance OPEN Dclk OPEN OPEN *Din 0.7 TO 3.0V* OPEN OPEN OPEN Scel 0.02V OPEN * Local Dimming Off 0.85V Diode Mode values taken with all Connectors Removed February 2010 LCD DV 42LH90...

  • Page 60: T - Con (Tft Drive) Board Section

    U5 is a DC to DC converter IC which develops the Panels driver voltages. 16V, 3.3V, -5V and 26V. These voltages can be read at the ribbon connector or at test points on the board which will be identified later. February 2010 LCD DV 42LH90...

  • Page 61: T - Con (Tft Drive) Board (Shield Removed)

    CON (TFT Drive) Board (Shield Removed) CON (TFT Drive) Board (Shield Removed) To TFT Panel To TFT Panel T-CON p/n: EAT60665101 Remember to replace screws for ground purposes if testing the Board. Main Board February 2010 LCD DV 42LH90...
  • Page 62 42LH90 T-CON (TFT Drive) Board Drawing (Components and Voltages Identified) 42LH90 T-CON (TFT Drive) Board Drawing (Components and Voltages Identified) Pin 56,57,58 Pin 2 -4.9V Pin 59 Pin 3,4,5 -4.9V TO TFT MODULE Pin 53,54 Pin 4 3.3V Pin 57 Pin 7,8 3.3V...

  • Page 63: T - Con (Tft Drive) Board Checks

    Transfer if board is replaced. Check Fuse F1 for 12V from CN1 Pins 48~51 1.8V 3.3V Check the Regulator U11 for Correct Voltage F1 (Diode Mode Check) Open (Red Lead on Fuse) 0.46V (Black Lead on Fuse) February 2010 LCD DV 42LH90...
  • Page 64 3.3V TP Source D9 Anode Pin 25,26 Chip B+ Source 3.3V Source Cathode Pin 8 Pin 23, 24 3.3V Pin 37,38 Chip B+ 16V (VDD) Pin 42 16V (D6) Cathode Not for Panel T-CON Board 16.9V February 2010 LCD DV 42LH90...

  • Page 65: T - Con (Tft Driver) Board Cn4 And Cn5 (Voltage Check)

    CON (TFT Driver) Board CN4 and CN5 (Voltage Check) CON (TFT Driver) Board CN4 and CN5 (Voltage Check) 3.3V 3.3V Pin 7,8 Pin 53,54 Pin 59 Pin 3,4,5 Pin 56,57,58 Pin 2 Pin 57 Pin 4 T-CON Board February 2010 LCD DV 42LH90...
  • Page 66 1.22V Open URSA-A1P 1.3V Open URSA-A1M 1.2V Open URSA-BCKP 1.21V Open URSA-A2P 1.4V Open URSA-BCKM 1.22V Open URSA-A2M 1.4V Open URSA-B3P 1.2V Open URSA-ACKP 1.25V Open URSA-B3M 1.21V Open URSA-ACKM 1.26V Open URSA-B4P 1.44V Open February 2010 LCD DV 42LH90...
  • Page 67 1.2V Open URSA-DCKP 1.23V Open URSA-C2P 1.3V Open URSA-DCKM 1.29V Open URSA-C2M 1.2V Open URSA-D3P 1.3V Open URSA-C2P 1.23V Open URSA-D3M 1.25V Open URSA-C2M 1.23V Open URSA-D4P 1.4V Open URSA-D4M 1.15V Open URSA-C3P 1.3V Open February 2010 LCD DV 42LH90...

  • Page 68: Main Board Section

    • 9V which is used to make 5V TU Mstar IC100 Video and Micro Processors • 5V TU • 1.2V • 3.3V IC3502 Tru-Motion and Dimming IC. • 1.2V • 1.26V_MEMC, 1.8V_MEMC, 1.8V_DDR, and 3.3V February 2010 LCD DV 42LH90...

  • Page 69: Mainboard Layout

    IC100 and Tru-Motion IC3502 runs Hot. X3500 This is normal. P700 IC100 to SMPS Micro/Video Processor IC801 X800 SW100 Reset P1200 to IR Board P600 HDMI to Speakers Selector X100 IC600 Audio Tuner TU1001 Rear Inputs February 2010 LCD DV 42LH90...
  • Page 70 P3500 P3502 12V LVDS 42LH90 42LH90 Pins 1~4 Main Board Main Board 42LH90 IC3504 IC3502 (Front Side) (Front Side) SW3500 MAIN Tru- IC3503 P3501 Not Used Motion/ BOARD Component Layout Component Layout Dimming IC3500 IC3502 Operates at high temperature X3500...
  • Page 71 42LH90 Main (Front Side) Component Voltages Serial Flash +1.26V_VDDC +1.26V_PVSB +1.8V Reg +5V/12VLVDS IC101 IC705 IC1000 IC3503 Q706 Memory Regulator Regulator Dimming Switch [1] 0.05V [1] 0.8V [1] 0V [1] 0.58 [1] 5.1V [2] 3.2V [2] Gnd [2] 3.39V [2] 1.8V [2] 0.29V...

  • Page 72: Main Board

    42LH90 42LH90 Main Board Main Board (Back Side) (Back Side) 42LH90 MAIN BOARD Component Layout Component Layout (Back View) IC3505 Q705 Q704 IC107 Q703 IC800 IC102 IC104 IC1202 IC702 Q105 D500 IC103 Q1000 D102 Q1001 IC1201 Q600 IC501 19 Video...
  • Page 73 42LH90 Main (Back Side) Component Voltages Reset Gen 9V Reg Reset Gen Tuner Video IC103 IC1003 IC3505 Q1001 Mstar IC100 to IC1002 for IC3502 Buffer [1] Gnd [1] 12V [1] 3.3V B 3.09V [2] 0V [2] Gnd [2] Gnd C 0V [3] 3.3V...
  • Page 74 Main Board X100 and X800 Crystal Checks X100 1.58V IC100 Microprocessor Crystal 2.56Vp/p 12Mhz Set on or off. Use bottom leg. 1.51V 1.59V IC800 XD Engine Crystal 2.25Vp/p 12Mhz Set on. Use bottom leg. 1.54V MAIN Board X800 February 2010 LCD DV 42LH90...
  • Page 75 Right Leg IC3502 Dimming IC Crystal 1.54V 1.57V 3.94Vp/p 25Mhz Set on. Use Left leg. IC1005 Tuner Control IC Crystal X1005 1.54V 3.54Vp/p 25Mhz Set on. Use Top leg. 5.67Vp/p 25Mhz 1.64V MAIN Board Bottom February 2010 LCD DV 42LH90...

  • Page 76: Main Board Ld1000 Function

    Use LD1000 as a visual aid. This lets you know the PLL (Phase Lock Loop) circuit is working correctly in IC1004. This indicates the Tuner Crystal is Locked to the Reference frequency in IC1004. Main Board LD1000 Location LD1000 February 2010 LCD DV 42LH90...
  • Page 77 It is an Open connection on the Inverter Board. being processed, OSD Backlight setting. 0.6V 0% to 3.3V 100% and the Intelligent Sensor. Output from the Video Processor IC100. Diode Mode values taken with all Connectors Removed February 2010 LCD DV 42LH90...
  • Page 78 Main Board. 1.44V 1.23V LVDS_CH2_D- 1.4V 0.88V LVDS_CH1_C+ LVDS_CH1_C- 1.4V 1.22V LVDS_CH2_CLK+ 1.22V 1.14V LVDS_CH1_B+ 1.2V 1.11V 1.21V 1.25V LVDS_CH2_CLK- LVDS_CH1_B- 1.3V 1.23V P3500 LVDS_CH1_A+ 1.2V 1.18V LVDS_CH2_C+ 1.13V 1.23V 1.3V 1.05V LVDS_CH1_A- 1.4V 0.87V LVDS_CH2_C- February 2010 LCD DV 42LH90...
  • Page 79 LVDS_CH4_CLK- LVDS_CH3_B+ 1.3V 1.23V LVDS_CH3_B- 1.2V 0.87V 1.2V 1.20V LVDS_CH4_C+ LVDS_CH3_A+ 1.3V 0.87V 1.28V 0.87V LVDS_CH4_C- LVDS_CH3_A- LVDS_CH4_B+ 1.3V 1.23V LVDS_CH4_B- 1.29V 0.87V LVDS_CH4_A+ 1.25V 1.23V LVDS_CH4_A- 1.29V 0.87V 1.18V 1.08V LVDS_CH3_E+ 1.13V 1.07V LVDS_CH3_E- February 2010 LCD DV 42LH90...
  • Page 80 3.2V 1.6V Key1 3.2V 3.2V 1.0V Key2 3.2V 3.2V 1.0V 5V_ST 5.1V 5.1V 1.1V WARM_ST 3.5V 3.5V Open Open 3.3V_ST 3.2V 3.2V 0.67V PWR On 3.2V Open Diode Mode values taken with all Connectors Removed February 2010 LCD DV 42LH90...

  • Page 81: Main Board Connector P600 To Speakers Voltage And Diode Check

    Use speaker out to test for defective Audio Amp IC600 Note: (Normal, ½ Audio B+) P400 CONNECTOR "Main" to "Speakers" LABEL Diode Check SPK-R(-) 2.63V SPK-R(+) 2.63V SPK-L(-) 2.63V SPK-L(+) 2.63V Diode Mode values taken with all Connectors Removed February 2010 LCD DV 42LH90...

  • Page 82: Front (Ir, Intelligent Sensor And Moving Led) Section

    The Key board is routed to the IR board via P100 to P102 on the Key 1 and Key 2 lines, (Key 1 pin 1 and Key 2 pin 3). Then out P101 pins 4 and 5 to P1200 on the Main Board. Then to the Microprocessor A4 and B4 lines. February 2010 LCD DV 42LH90...

  • Page 83: Front Boards (Connections Identified)

    Front Boards (Connections Identified) Front Boards (Connections Identified) p/n EBR62127501 Key board p/n EBR62128101 Intelligent Sensor / IR board P101 P100 P102 P100 Moving LED board (Power LEDs) p/n EBR61674001 February 2010 LCD DV 42LH90...

  • Page 84: Front Moving Led Board Identified

    Front Moving LED Board Identified The Front LED Board (located on the bottom left as viewed from the rear) Contains the front Power LEDs. Power LEDs J1 Connector To Intelligent Sensor and IR Pin 1 Board LED Driver February 2010 LCD DV 42LH90...

  • Page 85: Front Board Connectors P101 And P2 Voltage And Diode Check

    Open Key2 3.2V 3.2V Open Key 2 3.2V 3.2V Open ST_5V 5.1V 5.1V Open Warm_ST Open 3.5V 3.5V Open 3.3V 3.2V 3.2V Open LED On 3.2V Open Diode Mode values taken with all Connectors Removed February 2010 LCD DV 42LH90...

  • Page 86: Front Board Connector P100 And J1 Voltage And Diode Check

    *Pin 7: From Pin 12 of P101 IR board Pin 7: From Pin 7 of P100 From Pin 12 of P1200 Main board From R196 Main board From Pin GPIO96 of Micro IC100 Diode Mode values taken with all Connectors Removed February 2010 LCD DV 42LH90...
  • Page 87 SIDE KEY BOARD SECTION p/n EBR62127501 SIDE KEY BOARD SECTION p/n EBR62127501 SW101 SW103 SW105 SW107 SW100 SW102 SW104 SW106 To Ft Control P100 P100 February 2010 LCD DV 42LH90...
  • Page 88 Volume (+) 0.906V Menu 1.65V CH (Dn) 1.65V Enter 2.24V CH (Up) 2.24V P100 P100 Connector “Side Key" to “IR/Intelligent Sensor Board“ P2 Label STBY Diode Check Key1 3.3V 3.3V Open Key2 3.3V 3.3V Open February 2010 LCD DV 42LH90...

  • Page 89: Invisible Speaker Section

    INVISIBLE SPEAKER SECTION INVISIBLE SPEAKER SECTION The 42LH90 contains the Invisible Speaker system. The Full Range Speakers point downward, so there is no front viewable speaker grill or air ports. Main Speaker Tweeter (Full Range Frequencies) (High Frequencies) Full Range...

  • Page 90: Invisible Speaker System Overview (Tweeters)

    Speaker Attachment post Invisible Speaker Tweeter shown separately. The Front (down) has an adhesive surface which Cabinet works as Outlined adheres to front bezel. Note, there is a diaphragm. Circle no diaphragm, only voice coil. February 2010 LCD DV 42LH90...

  • Page 91: Invisible Speaker System Overview

    (to left) has an adhesive Terminals surface which adheres to front bezel. Note, there is no Cone (Diaphragm), only Spider voice coil. Speaker Wires Dust Cap with Magnet adhesive Voice Coil Inside Frequency Pass Capacitor Mount February 2010 LCD DV 42LH90...

  • Page 92: Interconnect Diagram (11 X 17 Foldout) Section

    This Power Point shows a graphical representation of the 11 X 17 This Power Point shows a graphical representation of the 11 X 17 foldout page so clarity is limited. foldout page so clarity is limited. February 2010 LCD DV 42LH90...
  • Page 93 42LH90 INTERCONNECT DIAGRAM P700 "Main" to P201 “SMPS" P201 “SMPS" to P700 "Main" Diode Pin 2 -4.9V Diode Check Label STBY Pin 59 -4.9V Pin 3,4,5 56,57,58 TO TFT MODULE 3.3V Pin 4 Check 3.3V Pin 57 Pin 7,8 Pin 53,54...
  • Page 94 42LH90 MAIN (FRONT SIDE) SIMICONDUCTORS Serial Flash +3.3V_FE +1.8V_MEMC +3.3V_PVSB +3.3V_Dimming W/P IC101 +5V/12VLVDS IC101 IC704 IC707 IC1001 IC3500 Q100 Q706 Memory Regulator Regulator +3.3V_FE Regulator Switch [1] 0.05V [1] 0.8V [1] 0.8V [1] 4.94V [1] Gnd B 0V [1] 5.1V [2] 3.2V...
  • Page 95 Pin 28 Pin 30 Pin 33 Pin 35 Pin 32 Pin 36 42LH90 P3500 LVDS CABLE WAVEFORMS: Waveforms taken using SMTP Color Bar input. All readings give the Scale 10mV and Time Base related to scope settings. Pin 37 Pin 38...
  • Page 96 Pin 15 Pin 22 Pin 24 Pin 25 Pin 27 Pin 28 42LH90 P3502 LVDS CABLE WAVEFORMS: Waveforms taken using SMTP Color Bar input. All readings give the Scale 10mV and Time Base related to scope settings. Pin 29 Pin 30...
  • Page 97 42LH90 42LH90 Direct View LCD Direct View LCD This concludes the 42LH90 training session.

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