hit counter script
LG 42LH40 Manual
  1. Manuals
  2. Brands
  3. LG Manuals
  4. LCD TV
  5. 42LH40 Series
  6. Manual

LG 42LH40 Manual

1080p direct view lcd
Hide thumbs Also See for 42LH40:
Table of Contents

Advertisement

Quick Links

Download this manual
42LH40 Direct View LCD
42LH40 Direct View LCD
1080P
Direct View LCD
Updated February 17, 2010
Published July 2009

Advertisement

Table of Contents
loading

Related Manuals for LG 42LH40

Summary of Contents for LG 42LH40

  • Page 1 42LH40 Direct View LCD 42LH40 Direct View LCD 1080P Direct View LCD Updated February 17, 2010 Published July 2009...
  • Page 2 LCD Overview, General Troubleshooting Steps, Signal Distribution, Disassembly Instructions and Voltages Section 2 Circuit Board Operation, Troubleshooting of : • Switch mode Power Supply/Ballast Combination • Main Board • Ft Control Board • Side Keys July 2009 LCD DV 42LH40...

  • Page 3: Overview Of Topics To Be Discussed

    Overview of Topics to be Discussed Overview of Topics to be Discussed 42LH40 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. July 2009 LCD DV 42LH40...

  • Page 6: Lg Contact Information

    LG CS Academy lgcsacademy.com LG Learning Academy LCD-DV: 32LG40, 32LH30, 37LH55, 42LG60, 42LG70, 42LH20, 42LH40, 42LH50, 47LG90, 47LH85 PLASMA: 42PG20, 42PQ20, 50PQ30, 50PG20, 50PS80, 50PS60 Plasma Panel New Training Materials on New Training Materials on Also available on...
  • Page 7 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… July 2009 LCD DV 42LH40...

  • 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. July 2009 LCD DV 42LH40...
  • Page 9 42LH40 Product Information 42LH40 Product Information This section of the manual will discuss the specifications of the 42LH40 LCD Direct View Display Panel. July 2009 LCD DV 42LH40...

  • Page 10: Key Features

    • Wide Viewing Angle • XD Engine® • 24p Real Cinema • ISFccc® Ready • Picture Wizard • AV Mode II (Cinema, Sports, Game) • 60,000 Hour Panel Life (typical) • NTSC/ATSC Tuners with Clear QAM July 2009 LCD DV 42LH40...

  • 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. July 2009 LCD DV 42LH40...
  • Page 12 1365 (H) × 768 (V) Possible Frame Interlaced Rates: 2 Fields to make a Frame 24FPS 1080P Panel 1920 (H) x 1080 (V) 30FPS Progressive 60FPS Each Field is a Frame Think of sync as the Panels “Refresh Rate” July 2009 LCD DV 42LH40...

  • Page 13: Remote Control Familiarization

    Remote Control Familiarization Remote Control Familiarization BOTTOM PORTION TOP PORTION July 2009 LCD DV 42LH40...

  • Page 14: Side Keys

    “Hold” the Menu Key on the Remote approximately 5 seconds. 3) If Customer’s Menu appears, continue to hold until it disappears. 4) The Service Menu appears Note: If a Password is required to enter the Service Menu. Enter; 0000 July 2009 LCD DV 42LH40...
  • Page 15 Rear and Side Input Jacks Rear and Side Input Jacks Side In/Out USB Port Software Upgrades Music, Photos Rear In/Out Jacks Rear MAIN PWB Rear and Side Side Input/Output locations July 2009 LCD DV 42LH40...

  • Page 16: Usb 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. July 2009 LCD DV 42LH40...
  • Page 17 42LH40 Product Dimensions 42LH40 Product Dimensions Wattage Average: 143W There must be at least 4 inches of Clearance on all sides 3-1/2" Stand By: less than 1W 88.9mm 40-13/16" 1036.3mm 7-7/8" 200mm 9-1/16" 16-1/8" 12-15/16" 230mm 25-13/16" 410mm 327.8mm 655.3mm 3-7/8"...

  • Page 18: Disassembly And Troubleshooting Section

    Disassembly: This section of the manual will discuss Disassembly, Layout and Circuit Board Identification, of the 42LH40 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 19 Pay attention to the size and type of screw as there are many different types. Putting in an improper screw when reassembling may Cause damage. The Stand does not need to be removed before removing the back. July 2009 LCD DV 42LH40...

  • Page 20: Circuit Board Layout

    Circuit Board Layout Circuit Board Layout No T-CON or Ballast board LVDS Cable LVDS Cable POWER SUPPLY Main PWB Side Keys Backlight Connections Input Rear Input Inputs Speaker L Speaker R Master Ft IR/LED Control Power Switch July 2009 LCD DV 42LH40...

  • Page 21: Power Supply Section

    FETs (on the far left hand heat sink) which in turn switch the primary sides of the two ballast transformers T703 and T704. They output 1.2Kv (48Khz) pulses to the backlights via P401 and P402. July 2009 LCD DV 42LH40...
  • Page 22 Supply PWB Supply PWB Removal Removal P201 Disconnect P201 P201, P401, P402, AC In SK101 and SK102. Remove the 6 screws indicated by the arrows Press in w/screw. Two tabs to release lock P402 P401 SK102 July 2009 LCD DV 42LH40...
  • Page 23 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. This set utilizes Type 1. Type 1: Shuts off AC to the Power Supply.
  • Page 24 FETs (on the far left hand heat sink) which in turn switch the primary sides of the two ballast transformers T703 and T704. They output 1.2Kv (48Khz) pulses to the backlights via P401 and P402. July 2009 LCD DV 42LH40...

  • Page 25: Power Supply (Smps)

    42LH40 Power Supply Start Up Sequence 42LH40 Power Supply Start Up Sequence Master (Main) Power Sw BALLAST SECTION POWER SUPPLY (SMPS) Power Supply will 1.2Kv not be on if Main Ballast 380V Power Switch is off. Driver FETs Regulator Drive Sig 1.2Kv...
  • Page 26 42LH40 P700 on Main Board to SMPS P201 Turn On Circuit Diagram 42LH40 P700 on Main Board to SMPS P201 Turn On Circuit Diagram L708 Q706 L728 R739 47KΩ R732 LVDS 12V Panel Power Q704 Q705 22KΩ 0.6V R740 47KΩ...

  • Page 27: Test 1 Power Supply Pwb Low Voltage Test

    Check that the 24V and 12V power supplies are turned on, P201 (24V pins 17 and 18) • P201 (12V pins 13 and 14) • (2) Remove AC power. Use P700 Side to insert resistors July 2009 LCD DV 42LH40...

  • Page 28: Remove Ac Power

    Check the connections to the Backlights. DO NOT check these when AC is applied as they carry 1.2Kv each. Note, either of the connections are unplugged, the backlights will not light. Use P700 Side to insert resistors July 2009 LCD DV 42LH40...
  • Page 29 General Backlight Information To Backlights Over 1.2KV Ballast Section of SMPS To Backlights Over 1.2KV Currently, number of lamps “Unknown” EEFL (External Electrode Fluorescent Lamp) LOW COST Large number of lamps driven by a single inverter July 2009 LCD DV 42LH40...
  • Page 30 Introducing EEFL Simple structure, Low price Simple structure Low Cost Complicated structure Lamp manufacturing process Large number of Lamp Lamp assembly structure Drive by single inverter July 2009 LCD DV 42LH40...
  • Page 31 Introducing EEFL Contacts (Bulb Design) Key: Long Life Time • For CCFL, Hg gas is consumed mainly near the internal electrode • For EEFL, longer life time is expected because there is no internal electrode consuming Hg gas July 2009 LCD DV 42LH40...
  • Page 32 Ballast Section of SMPS Layout Ballast Section of SMPS Layout SMPS PWB Viewed from rear Backlights Test Point Bottom of R406 or R403 38V P/P 48Khz To Backlights T703 Left Side 1.2Kv To Backlights Right Side T704 July 2009 LCD DV 42LH40...
  • Page 33 42LH40 Ballast Control Signals Circuit Diagram 42LH40 Ballast Control Signals Circuit Diagram MAIN PWB POWER SUPPLY BALLAST P201 P700 R717 SECTION IC100 3.3KΩ Mstar +5V General Stand By 5V STBY5V R714 R719 R759 R244 To Backlights 100Ω 1KΩ 0Ω 100Ω...

  • Page 34: Power Supply Backlight Drive Signal Effects

    IC. After 4 attempts, if ADIM also the Error Out line manipulates returns to 5V, this tells the Micro to the Burst turn the set off. Triangle Oscillator But it is not used. July 2009 LCD DV 42LH40...
  • Page 35 PDIM 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 July 2009 LCD DV 42LH40...
  • Page 36 2 in STBY and RUN with one lead on Neutral of SK100. Bottom With the Master Power Switch Right of Closed (On) AC flows. SMPS F100 When Open (Off) AC open and does not flow. F100 6.3A/250V AC IN Neutral Live SK101 SK100 July 2009 LCD DV 42LH40...

  • Page 37: Main Pwb Section

    • VGH+24V • VGHM+24V Mstar IC100 (Video) / MICROPROCESSOR • VGL-5V • 1.2V, 1.26V, 1.8V, and 3.3V TUNER and VSB CIRCUIT • 9V which is used to make 5V TU • 5V • 3.3V • 1.2V July 2009 LCD DV 42LH40...

  • Page 38: Removing The Main Pwb

    P700. P1200 P600 NOTE: Be sure to check on top and behind the Video Processor ICs. Look for a piece of Chocolate (Heat Transfer Material). Be sure to transfer to new PWB if present. July 2009 LCD DV 42LH40...
  • Page 39 Hot. This is normal. Video Processor To SMPS P1401 P1400 P700 To SMPS IC1100 X1100 IC100 To Ft Control PWB P1200 LD1000 LD1000 X100 Tuner OK P600 when Green To Speakers X1005 SW100 Reset Tuner TU1001 July 2009 LCD DV 42LH40...
  • Page 40 Main PWB (Front Side) Component Locations Main PWB (Front Side) Component Locations July 2009 LCD DV 42LH40...
  • Page 41 42LH40 Front Side Component Voltages 42LH40 MAIN (FRONT SIDE) SIMICONDUCTORS IC701 1.8V DDR IC705 3.3V / 1.26V IC101 Flash Boot IC103 Reset IC707 5V EXT IC1001 3.3V FE Memory Pin 1.8V MEMC [1] n/c [1] 0.8V [1] 0V [1] Gnd [1] 0.8V...
  • Page 42 Main PWB Main PWB (Back View) (Back View) July 2009 LCD DV 42LH40...
  • Page 43 42LH40 Front Side Component Voltages 42LH40 MAIN (BACK SIDE) SIMICONDUCTORS Q1000 Tuner SIF IC1200 HDMI Q1202 Moving LED Q703 Turns on 5V IC104 EEPROM D1403 LVDS 16V Driver Pin General Q706 Pin Source E 2.4V [1] Gnd E 0.1V E 0V [1] Gnd A 12.2V...
  • Page 44 Set on. Use bottom leg. IC100 Microprocessor Crystal X1100 2.4Vp/p 12Mhz 3.2Vp/p 12Mhz Set on or off. Use bottom leg. Tuner Control X1005 IC1005 X100 Crystal MAIN PWB 4.95Vp/p 25Mhz Set on. Use top leg. July 2009 LCD DV 42LH40...
  • Page 45 LD1000 Use LD1000 as a visual aid. This lets you know if the tuner internal PLL (Phase Locked Loop) system is locked. Illuminated PLL is normal. Off is abnormal tuner lock. Main PWB LD1000 Location July 2009 LCD DV 42LH40...

  • Page 46: Main Pwb Tuner With Shield Off (Pin Id)

    Main PWB Tuner with Shield Off (Pin ID) Main PWB Tuner with Shield Off (Pin ID) July 2009 LCD DV 42LH40...
  • Page 47 Channel. MAIN PWB Tuner Location Pin 19 “Video” Signal 2.24Vp/p Pin 16 “SIF” Signal Pin 12 and Pin 13 “Dig IF” Signal 450mVp/p Note: “Dig IF” Signal only when 700mVp/p receiving a Digital Channel. July 2009 LCD DV 42LH40...

  • Page 48: Main Pwb Tuner Clock And Data Lines

    Main PWB Tuner Clock and Data Lines Main PWB Tuner Clock and Data Lines Note: Pin 9 SCL SCL and SDA only active during an actual Channel Change. 1V per/div 100uS 5V p/p Pin 8 SDA 1V per/div 100uS 5V p/p July 2009 LCD DV 42LH40...
  • Page 49 Main Board LVDS Power Supply Voltage Generation Circuit Main Board LVDS Power Supply Voltage Generation Circuit 3.3V VGHM July 2009 LCD DV 42LH40...
  • Page 50 PDIM Pin 24 can vary according to type of signal 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 July 2009 LCD DV 42LH40...
  • Page 51 LMLV3P 1.23V 0.89V LMLV2N 1.3V 1.29V 2.0V 0.6V 1.3V LMLV2P 1.2V 1.29V GSP_R 0.6V 1.3V 2.0V LMLV1N 1.3V 1.29V 1.63V 1.3V 2.0V LMLV1P 1.2V 1.29V H_CONV Open LTD_L 8.2V Open LMLV0N 1.28V 1.29V GSP_R 1.3V July 2009 LCD DV 42LH40...
  • Page 52 VCOM_R 2.0V GMA6 11.2V 1.4V RMLV3N 1.21V 1.3V GMA7 10.4V 2.0V Open RMLV3P 1.26V 1.3V GMA9 8.45V 2.0V RMLV2N 1.19V 1.3V 0.6V 1.3V RMLV2P 1.26V 1.3V (-5V) 0.925V GSP_Rev 1.3V RMLV1N 1.22V 1.3V 1.6V 1.3V July 2009 LCD DV 42LH40...

  • Page 53: Power On/Off

    3.3V 3.3V 1.14V Key1 3.3V 3.3V 1.08V Key2 3.3V 3.3V 1.08V 5V ST 5.1V 5.1V 1.13V 4.8V 4.8V Open 3.3V_ST 3.29V 3.29V 0.6V POWER On/Off 3.29V 2.17V Diode Mode values taken with all Connectors Removed July 2009 LCD DV 42LH40...
  • Page 54 P600 CONNECTOR "Main" to "Speakers" Diode LABEL Check SPK-R(-) 10.7V 1.5V SPK-R(+) 10.7V 1.5V SPK-L(-) 10.7V 1.5V SPK-L(+) 10.7V 1.5V Use speaker out to test for defective Audio Amp IC600 Diode Mode values taken with all Connectors Removed July 2009 LCD DV 42LH40...

  • Page 55: Front Control (Ir And Intelligent Sensor) Section

    The Key board connector P3000 is routed to the Ft control board via P2. Then through the front Control board and out P2 to the Microprocessor via P1200 pins 4 and 5. Finally, the front Power LEDs are controlled by pin 12 and pin 8. July 2009 LCD DV 42LH40...

  • Page 56: Front Control Board Connections Identified

    FRONT CONTROL BOARD CONNECTIONS IDENTIFIED FRONT CONTROL BOARD CONNECTIONS IDENTIFIED The below picture shows the connections to the Front Control board. p/n EBR59216901 Side P3000 Main Power Switch July 2009 LCD DV 42LH40...

  • Page 57: Front Control (Ir And Intelligent Sensor) Identified

    The Front Control PWB (located on the bottom left as viewed from the rear) contains the IR (Infrared Remote Sensor) and the Intelligent Sensor plus the front Power LEDs. Power LEDs Light Diffuser Intelligent Sensor Infrared Sensor July 2009 LCD DV 42LH40...
  • Page 58 3.3V Open Key2 3.3V 3.3V Open Key 2 3.3V 3.3V Open 5V ST 5.1V 5.1V 1.13V 4.8V 4.8V Open 3.3V_ST 3.29V 3.29V Open POWER 3.29V Open On/Off Diode Mode values taken with all Connectors Removed July 2009 LCD DV 42LH40...

  • Page 59: Side Key Assembly

    Side Key Assembly Side Key Assembly SW3001 SW3002 SW3003 SW3004 SW3005 SW3006 SW3007 SW3008 P3000 P3000 To Ft Control July 2009 LCD DV 42LH40...

  • Page 60: Side Key Assembly P3000 Voltage And Diode Check

    Volume (+) 0.906V Menu 1.65V CH (Dn) 1.65V Enter 2.24V CH (Up) 2.24V P3000 Connector “Side Key" to “IR/LED Control PWB“ P1 Label STBY Diode Check Key1 3.3V 3.3V Open P3000 Key2 3.3V 3.3V Open July 2009 LCD DV 42LH40...
  • Page 61 Invisible Speaker System Overview (Full Range Speakers) Invisible Speaker System Overview (Full Range Speakers) The 42LH40 contains the full progression of the Invisible Speaker system. First: The woofer layout is the basic system. The Full Range Speakers point downward, so there is no front viewable speaker grill or air ports.

  • Page 62: Invisible Speaker System Overview (Tweeters)

    Speaker Attachment post Invisible Speaker Tweeter shown separately. The Front (down) has sticky surface which adheres to Cabinet works as Outlined front bezel. Note, there is no a diaphragm. Circle diaphragm, only voice coil. July 2009 LCD DV 42LH40...

  • Page 63: Invisible Speaker System Overview

    (to left) has sticky surface Terminals 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 July 2009 LCD DV 42LH40...
  • Page 64 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. July 2009 LCD DV 42LH40...
  • Page 65 42LH40 INTERCONNECT DIAGRAM TO TFT MODULE SMPS TEST 1: To Force Power Supply On. Disconnect P700 on Main PWB. Jump pin 7,8,9 or 10 (5V) to pin 2 using a 100Ω resistor. (Test Voltage Outputs 12V, and 24V). SMPS TEST 2: Jump pin 2 to pin 20 (INV-ON).
  • Page 66 42LH40 MAIN (BACK SIDE) SIMICONDUCTORS Q1000 Tuner SIF IC1200 HDMI Q1202 Moving LED Q703 Turns on 5V IC104 EEPROM D1403 LVDS 16V D1100 LD1100 (Q1100) D1223 B+ Routing Driver Pin General Q706 Pin Source Pin Gate Pin RGB E 2.4V [1] Gnd E 0.1V...
  • Page 67 42LH40 42LH40 Direct View LCD This concludes the 42LH40 training session.

Table of Contents