LG 32lc42 Service Manual

							
R

LCD TV
SERVICE MANUAL
CAUTION
BEFORE SERVICING THE CHASSIS,
READ THE SAFETY PRECAUTIONS IN THIS MANUAL.
CHASSIS : LP78A
MODEL : 32LC41/4R32LC41/4R-ZA
MODEL : 32LC4232LC42-ZC
MODEL : 32LC4332LC43-ZA/ZE
MODEL : 32LC4432LC43-ZB
website:http://biz.LGservice.com
 
						

							
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CONTENTS
CONTENTS ...............................................................\
............................... 2
SAFETY PRECAUTIONS ........................................................................\
..3
SPECIFICATION ........................................................................\
................6
ADJUSTMENT INSTRUCTION .................................................................9
TROUBLE SHOOTING ........................................................................\
....17
BLOCK DIAGRAM........................................................................\
...........25
EXPLODED VIEW ........................................................................\
.......... 26
EXPLODED VIEW PARTS LIST ..............................................................27
REPLACEMENT PARTS LIST ............................................................... 28
SVC. SHEET  ........................................................................\
.......................
 
						

							
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SAFETY PRECAUTIONS
Many electrical and mechanical parts in this chassis have special safety\
-related characteristics. These parts are identified by      in the
Schematic Diagram and Replacement Parts List. 
It is essential that these special safety parts should be replaced with \
the same components as recommended in this manual to pr event
Shock, Fire, or other Hazards. 
Do not modify the original design without permission of manufacturer.

General Guidance
An  isolation Transformer should always be used during the
servicing of a receiver whose chassis is not isolated from the AC
power line. Use a transformer of adequate power rating as this
protects the technician from accidents resulting in personal injury
from electrical shocks.
It will also protect the receiver and its components from being
damaged by accidental shorts of the circuitry that may be
inadvertently introduced during the service operation.
If any fuse (or Fusible Resistor) in this TV receiver is blown,
replace it with the specified.
When replacing a high wattage resistor (Oxide Metal Film Resistor,
over 1W), keep the resistor 10mm away from PCB.
Keep wires away from high voltage or high temperature parts.
Before returning the receiver to the customer,
always perform an  AC leakage current check on the exposed
metallic parts of the cabinet, such as antennas, terminals, etc., to
be sure the set is safe to operate without damage of electrical
shock. 
Leakage Current Cold Check(Antenna Cold Check)
With the instrument AC plug removed from AC source, connect an
electrical jumper across the two AC plug prongs. Place the AC
switch in the on position, connect one lead of ohm-meter to the AC
plug prongs tied together and touch other ohm-meter lead in turn to
each exposed metallic parts such as antenna terminals, phone
jacks, etc. 
If the exposed metallic part has a return path to the chassis, the
measured resistance should be between 1M Ωand 5.2M Ω. 
When the exposed metal has no return path to the chassis the
reading must be infinite.
An other abnormality exists that must be corrected before the
receiver is returned to the customer.
Leakage Current Hot Check(See below Figure) 
Plug the AC cord directly into the AC outlet.
Do not use a line Isolation Transformer during this check.
Connect 1.5K/10watt resistor in parallel with a 0.15uF capacitor
between a known good earth ground (Water Pipe, Conduit, etc.)
and the exposed metallic parts.
Measure the AC voltage across the resistor using AC voltmeter
with 1000 ohms/volt or more sensitivity.
Reverse plug the AC cord into the AC outlet and repeat AC voltage
measurements for each exposed metallic part. Any voltage
measured must not exceed 0.75 volt RMS which is corresponds to
0.5mA.
In case any measurement is out of the limits specified, there is
possibility of shock hazard and the set must be checked and
repaired before it is returned to the customer.
Leakage Current Hot Check circuit

1.5 Kohm/10W
To Instrument’s
exposed 
METALLIC PARTS Good Earth Ground
such as WATER PIPE,
CONDUIT etc.
AC Volt-meter

IMPORTANT SAFETY NOTICE
0.15uF
 
						

							
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CAUTION: Before servicing receivers covered by this service
manual and its supplements and addenda, read and follow the
SAFETY PRECAUTIONSon page 3 of this publication.
NOTE: If unforeseen circumstances create conflict between the
following servicing precautions and any of the safety precautions on
page 3 of this publication, always follow the safety precautions.
Remember: Safety First.
General Servicing Precautions
1.  Always unplug the receiver AC power cord from the AC power source before;
a.  Removing or reinstalling any component, circuit boardmodule or any other receiver assembly.
b.  Disconnecting or reconnecting any receiver electrical plug or other electrical connection.
c. Connecting a test substitute in parallel with an electrolytic capacitor in the receiver.
CAUTION: A wrong part substitution or incorrect polarity
installation of electrolytic capacitors may result in an
explosion hazard.
2.  Test high voltage only by measuring it with an appropriate high voltage meter or other voltage measuring device (DVM,
FETVOM, etc) equipped with a suitable high voltage probe.
Do not test high voltage by drawing an arc.
3.  Do not spray chemicals on or near this receiver or any of its assemblies.
4. Unless specified otherwise in this service manual, clean electrical contacts only by applying the following mixture to the
contacts with a pipe cleaner, cotton-tipped stick or comparable
non-abrasive applicator; 10% (by volume) Acetone and 90% (by
volume) isopropyl alcohol (90%-99% strength)
CAUTION: This is a flammable mixture.
Unless specified otherwise in this service manual, lubrication of
contacts in not required.
5.  Do not defeat any plug/socket B+ voltage interlocks with which receivers covered by this service manual might be equipped.
6.  Do not apply AC power to this instrument and/or any of its electrical assemblies unless all solid-state device heat sinks are
correctly installed.
7.  Always connect the test receiver ground lead to the receiver chassis ground before connecting the test receiver positive
lead.
Always remove the test receiver ground lead last.
8.  Use with this receiver only the test fixtures specified in this
service manual.
CAUTION: Do not connect the test fixture ground strap to any
heat sink in this receiver.
Electrostatically Sensitive (ES) Devices
Some semiconductor (solid-state) devices can be damaged easily
by static electricity. Such components commonly are called
Electrostatically Sensitive (ES) Devices. Examples of typical ES
devices are integrated circuits and some field-effect transistors and
semiconductor chip components. The following techniques
should be used to help reduce the incidence of component
damage caused by static by static electricity.
1.  Immediately before handling any semiconductor component or semiconductor-equipped assembly, drain off any electrostatic
charge on your body by touching a known earth ground.
Alternatively, obtain and wear a commercially available
discharging wrist strap device, which should be removed to
prevent potential shock reasons prior to applying power to the unit under test.
2.  After removing an electrical assembly equipped with ES devices, place the assembly on a conductive surface such as
aluminum foil, to prevent electrostatic charge buildup or
exposure of the assembly.
3.  Use only a grounded-tip soldering iron to solder or unsolder ES devices.
4. Use only an anti-static type solder removal device. Some solder removal devices not classified as anti-static can generate
electrical charges sufficient to damage ES devices.
5.  Do not use freon-propelled chemicals. These can generate
electrical charges sufficient to damage ES devices.
6.  Do not remove a replacement ES device from its protective package until immediately before you are ready to install it.
(Most replacement ES devices are packaged with leads
electrically shorted together by conductive foam, aluminum foil
or comparable conductive material).
7.  Immediately before removing the protective material from the leads of a replacement ES device, touch the protective material
to the chassis or circuit assembly into which the device will be
installed.
CAUTION:  Be sure no power is applied to the chassis or circuit,
and observe all other safety precautions.
8. Minimize bodily motions when handling unpackaged replacement ES devices. (Otherwise harmless motion such as
the brushing together of your clothes fabric or the lifting  of your
foot from a carpeted floor can generate static electricity
sufficient to damage an ES device.)
General Soldering Guidelines
1.  Use a grounded-tip, low-wattage soldering iron and appropriate tip size and shape that will maintain tip temperature within the
range or 500°F to 600°F.
2.  Use an appropriate gauge of RMA resin-core solder composed of 60 parts tin/40 parts lead.
3.  Keep the soldering iron tip clean and well tinned.
4.  Thoroughly clean the surfaces to be soldered. Use a mall wire- bristle (0.5 inch, or 1.25cm) brush with a metal handle.
Do not use freon-propelled spray-on cleaners.
5.  Use the following unsoldering technique a.  Allow the soldering iron tip to reach normal temperature.(500°F to 600°F)
b.  Heat the component lead until the solder melts.
c.  Quickly draw the melted solder with an anti-static, suction- type solder removal device or with solder braid.
CAUTION: Work quickly to avoid overheating the circuit
board printed foil.
6.  Use the following soldering technique. a.  Allow the soldering iron tip to reach a normal temperature(500°F to 600°F)
b.  First, hold the soldering iron tip and solder the strand against the component lead until the solder melts.
c. Quickly move the soldering iron tip to the junction of the component lead and the printed circuit foil, and hold it there
only until the solder flows onto and around both the
component lead and the foil.
CAUTION: Work quickly to avoid overheating the circuit
board printed foil.
d. Closely inspect the solder area and remove any excess or splashed solder with a small wire-bristle brush.
SERVICING PRECAUTIONS
 
						

							
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IC Remove/Replacement
Some chassis circuit boards have slotted holes (oblong) through
which the IC leads are inserted and then bent flat against the
circuit foil. When holes are the slotted type, the following technique
should be used to remove and replace the IC. When working with
boards using the familiar round hole, use the standard technique
as outlined in paragraphs 5 and 6 above.
Removal
1.  Desolder and straighten each IC lead in one operation by gentlyprying up on the lead with the soldering iron tip as the solder
melts.
2.  Draw away the melted solder with an anti-static suction-type solder removal device (or with solder braid) before removing the
IC.
Replacement
1.  Carefully insert the replacement IC in the circuit board.
2.  Carefully bend each IC lead against the circuit foil pad and solder it.
3.  Clean the soldered areas with a small wire-bristle brush. (It is not necessary to reapply acrylic coating to the areas).
Small-Signal Discrete Transistor
Removal/Replacement
1.  Remove the defective transistor by clipping its leads as close as possible to the component body.
2.  Bend into a U shape the end of each of three leads remaining on the circuit board.
3.  Bend into a U shape the replacement transistor leads.
4.  Connect the replacement transistor leads to the corresponding leads extending from the circuit board and crimp the U with
long nose pliers to insure metal to metal contact then solder
each connection.
Power Output, Transistor Device
Removal/Replacement
1.  Heat and remove all solder from around the transistor leads.
2. Remove the heat sink mounting screw (if so equipped).
3.  Carefully remove the transistor from the heat sink of the circuit board.
4.  Insert new transistor in the circuit board.
5. Solder each transistor lead, and clip off excess lead.
6.  Replace heat sink.
Diode Removal/Replacement
1.  Remove defective diode by clipping its leads as close as possible to diode body.
2.  Bend the two remaining leads perpendicular y to the circuit board.
3.  Observing diode polarity, wrap each lead of the new diode around the corresponding lead on the circuit board.
4.  Securely crimp each connection and solder it.
5. Inspect (on the circuit board copper side) the solder joints of the two original leads. If they are not shiny, reheat them and if
necessary, apply additional solder.
Fuse and Conventional Resistor
Removal/Replacement
1.  Clip each fuse or resistor lead at top of the circuit board hollow stake.
2.  Securely crimp the leads of replacement component around notch at stake top.
3.  Solder the connections. CAUTION: Maintain original spacing between the replaced
component and adjacent components and the circuit board to
prevent excessive component temperatures. Circuit Board Foil Repair
Excessive heat applied to the copper foil of any printed circuit
board will weaken the adhesive that bonds the foil to the circuit
board causing the foil to separate from or lift-off the board. The
following guidelines and procedures should be followed whenever
this condition is encountered.
At IC Connections
To repair a defective copper pattern at IC connections use the
following procedure to install a jumper wire on the copper pattern
side of the circuit board. (Use this technique only on IC
connections).
1.  Carefully remove the damaged copper pattern with a sharp
knife. (Remove only as much copper as absolutely necessary).
2.  carefully scratch away the solder resist and acrylic coating (if used) from the end of the remaining copper pattern.
3.  Bend a small U in one end of a small gauge jumper wire and carefully crimp it around the IC pin. Solder the IC connection.
4.  Route the jumper wire along the path of the out-away copper pattern and let it overlap the previously scraped end of the good
copper pattern. Solder the overlapped area and clip off any
excess jumper wire.
At Other Connections
Use the following technique to repair the defective copper pattern
at connections other than IC Pins. This technique involves the
installation of a jumper wire on the component side of the circuit
board.
1.  Remove the defective copper pattern with a sharp knife. Remove at least 1/4 inch of copper, to ensure that a hazardous
condition will not exist if the jumper wire opens.
2.  Trace along the copper pattern from both sides of the pattern break and locate the nearest component that is directly
connected to the affected copper pattern.
3.  Connect insulated 20-gauge jumper wire from the lead of the nearest component on one side of the pattern break to the lead
of the nearest component on the other side.
Carefully crimp and solder the connections.
CAUTION: Be sure the insulated jumper wire is dressed so the
it does not touch components or sharp edges.
 
						

							
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1. Application range
This specification is applied to LP78A chassis.
2. Requirement for Test
Testing for standard of each part must be followed in below
condition.
(1) Temperature : 25 ± 5°C(77 ± 9°F), CST : 40 ± 5°C
(2) Humidity : 65% ± 10%
(3) Power : Standard input voltage (100-240V~, 50/60Hz)
*Standard Voltage of each products is marked by models (4) Specification and performance of each parts are followed
each drawing and specification by part number in
accordance with BOM.
(5) The receiver must be operated for about 20 minutes prior to the adjustment.
3. Test method
3.1 Performance : LGE TV test method followed
3.2 Demanded other specificationSafety : CE, IEC Specification
EMC : CE, IEC
SPECIFICATION
NOTE : Specifications and others are subject to change without notice fo\
r improvement.
4. General Specification(LCD Module)
Remark
LCD
MAKER : AUO/CMO/LPL/CPT
LGE SPEC
Volume: 1/8 volume of sound distortion point 
(H) x (V) x (D)  [with inverter]
(H) x (W)
(H) x (V) x (D)  [with inverter]
(H) x (V)
(H) x (V) x (D)  [with inverter]
(H) x (V)
(LC260WX2-SLB3)
(LPL 26”)
Specification
26/27/32/37/42” wide Color Display Module
16:9
26/27/32/37/42” TFT WXGA LCD
Temp. : 0 ~ 40 deg, Humidity : 0 ~ 85%
Temp. : -20 ~ 60 deg, Humidity : 0 ~ 85 %
100-240V~, 50/60Hz
Power on (Green) ≤TBD (42”)
≤ max (26”, 27”, 32”, 37”) 
St-By (Red) : 1.0 W
AUO Outline Dimension 26” 32”
37”
Pixel Pitch 26” 32”
37”
Back Light 26”,32” 37”
CMO Outline Dimension 27” 32”
Pixel Pitch 27” 32”
Back Light 27” 32”
LPL Outline Dimension 26” 32”
37”
42”
Pixel Pitch 26” 32”
37”
42”
Back Light 26” 32”
37”
42”
Display Colors
Coating Measurement
626.0 x 373.0 x 47.5
760.0 x 450.0 x 45
877.0 x 514.6 x 54.7
0.4215
0.51075
0.6 x 0.6
8 U-lamp
10 U-lamp
637.55 x 379.8 x 40.7
760 x 450 x 47.53
0.1455 x 0.4365
0.1730 x 0.5190
14 CCFL
16 CCFL
626 x 373 x 44.1
760.0 x 450.0 x 48.0
877.0 x 516.8 x 55.5
1006 x 610 x 56
0.1405 x 0.4215
0.17025 x 0.51075
0.200 x 0.600
0.227 x 0.681
18 EEFL (17 EEFL)
18 EEFL
20 EEFL
20 CCFL
16.7M (16,777,216)
3H, AG Result
mm
mm
mm
mm
mm
mm
mm
mm
Item
Display Screen Device
Aspect Ratio
LCD Module
Operating Environment
Storage Environment
Input Voltage
Power Consumption
LCD Module
 
						

							
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5. Model Specification(EU)
Remark
Full Scart 1EA, Harf 1EA
Side AV
Side AV S-Video Priority
L/R Input(PC 1EA,SCART 2EA, SIDE AV 1EA, Component 1EA)
Specification
EU
PAL BG/DK, PAL I/II, SECAM L/L’ BAND PAL
VHF/UHF C1_C69 CATV S1_S47
Upper Heterodyne
PAL, SECAM, NTSC
PAL, SECAM, NTSC
PAL, SECAM, NTSC
Y/Cb/Cr, Y/ Pb/Pr
RGB-PC
HDMI-DTV
PC Audio, AV (3A), Component (1EA)
Item
Market
Broadcasting system
Available Channel
Receiving system
SCART Input(2EA)
Video Input (1EA)
S-Video Input (1EA)
Component Input (1EA)
RGB Input (1EA)
HDMI Input (2EA)
Audio Input (4EA)
Variable Audio out(1EA)
6. Component Video Input (Y, PB, PR)
V-freq(kHz) 59.94
60.00
50.00
59.94
60.00
50.00
59.94
60.00
50.00
59.94
60.00
50.00 Proposed
SDTV, DVD 480I(525I)
SDTV, DVD 480I(525I)
SDTV, DVD 576I(625I) 50Hz
SDTV 480P
SDTV 480P
SDTV 576P 50Hz
HDTV 720P
HDTV 720P
HDTV 720P 50Hz
HDTV 1080I
HDTV 1080I
HDTV 1080I 50Hz
H-freq(kHz)
15.73
15.75
15.625 31.47
31.50
31.25
44.96
45.00
37.50
33.72
33.75
28.125
Resolution
720*480
720*480
720*576
720*480
720*480
720*576
1280*720
1280*720
1280*720
1920*1080
1920*1080
1920*1080Pixel clock(MHz) 13.500
13.514
13.500
27.000
27.027
27.000
74.176
74.25074.25
74.176
74.250
74.250
7. RGB Input (Analog PC)
V-freq(kHz) 70.80
70.80
59.94
60.31
60.00
59.87
59.799
59.799 Proposed
EGA
DOS
VESA(VGA)
VESA(SVGA) VESA(XGA) WXGA
WXGA
WXGA Remark
XGA only
XGA only
XGA only
H-freq(kHz)
31.468
31.469
31.469
37.879
48.363
47.776
47.720
47.720
Resolution
640*350
720*400
640*480
800*600
1024*768
1280*768
1360*768
1366*768Pixel clock(MHz) 25.17
28.321 25.17
40.00
65.00
79.50
84.75
84.75
 
						

							
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8. HDMI input (DTV)
V-freq(kHz)
60.00
59.94
50.00
59.94
60.00
50.00
59.94
60.00
50.00
59.94
60.00
50.00
59.9460
50 Proposed
SDTV, DVD 480I(525I)
SDTV, DVD 480I(525I)
SDTV, DVD 576I(625I) 50Hz
SDTV 480P
SDTV 480P
SDTV 576P 50Hz
HDTV 720P
HDTV 720P
HDTV 720P 50Hz
HDTV 1080I
HDTV 1080I
HDTV 1080I 50Hz
HDTV 1080P
HDTV 1080P
HDTV 1080P 50Hz
H-freq(kHz)
15.75
15.73
15.625 31.47
31.50
31.25
44.96
45.00
37.50
33.72
33.75
28.125
67.432 67.5
56.250
Resolution
720*480
720*480
720*576
720*480
720*480
720*576
1280*720
1280*720
1280*720
1920*1080
1920*1080
1920*1080
1920*1080
1920*1080
1920*1080Pixel clock(MHz) 13.514
13.500
13.500
27.000
27.027
27.000
74.176
74.25074.25
74.176
74.250
74.250
148.350 148.5
148.5
 
						

							
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ADJUSTMENT INSTRUCTION
1. Application Range
This spec sheet is applied all of the 26/32/37/42” LCD
TV(LP78A) by manufacturing LG TV Plant all over the world.  
2. Specification
1) Because this is not a hot chassis, it is not necessary to usean isolation transformer. However, the use of isolation
transformer will help protect test instrument.
2) Adjustment must be done in the correct order.
3) The adjustment must be performed in the circumstance of 25±5°C of temperature and 65±10% of relative humidity if
there is no specific designation.
4) The input voltage of the receiver must keep 100~220V, 50/60Hz.
5) Before adjustment, execute Heat-Run for 30 minutes at RF no signal.
3. Adjustment items
3.1. PCB assembly adjustment items
1) Download the VCTP main software (IC500,VCT_Pro)
2) Channel memory (IC501,EEPROM)
3) Color carrier Adjustment
3.2. SET assembly adjustment items
1) DDC Data input.
2) Adjustment of White Balance.
3) Factoring Option Data input.
4. PCB assembly adjustment method
(Using VCTP Download program)
4.1. Download program installation
(1) Extract a Zip file
(2) Visual I2C & LPT Driver Installation LPT Port  Driver (LptDrv) Setups : 
Program Files > Micronas >
Visual I2C > Port_Driver
*Use for Windows 95/98 : Setup_LptDrv_v0104_9x.exe
*Use for Windows 2000/XP : Setup_LptDrv_v0202_XP_2000.exe
*Use for Windows NT : Setup_LptDrv_v0104_NT.exe
(3) Verification (Start > Programs > Micronas > Visual I2C or LptDrv)
(4) LPT delay setting(File > Preference > LPT preferences)
(5) Exchange the bootloader.bat file.

Install the LPT Driver
Install the Visual I2C
*LPT SETTING - Delay => 1
- Time out => 500 ms
 
						

							
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=> Select the Bootloader.bat file(install > VCTP_download >Bootloader)
=> Push OK
=> Finish the program, after saving the file download_cs.vi2c (if you click     ,  the massage appears automatically)
4.2. S/W program download
(1) Download method 1 (PCB Ass’y)
1) Connect the download jig to D-sub jack
2) Execute ‘Download.vi2c’ program in PC, then a mainwindow will be opened 3) Double click the blue box and confirm Bootloader
Version as 42.
4) Click the Erase Flash button
5) Double click the download file low, then edit window will be opened
6) Click the choice button in the “edit window”, then “file choice window” will be opened.
7) Choose the Hex file in folder and execute downloading with click  open button.

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