LG LN-15A10 Schematic
LCD TV
SERVICE MANUAL
CAUTION
BEFORE SERVICING THE CHASSIS,
READ THE SAFETY PRECAUTIONS IN THIS MANUAL.
CHASSIS : NF-99LA
MODEL : LN-15A10
- 2 -
CONTENTS
Contents .................................................................................................. 2
Safety Precautions ..................................................................................3
Servicing Precautions ............................................................................ 4
Adjustment Instruction ............................................................................6
Troubleshooting .......................................................................................8
Exploded View ...................................................................................... 10
Exploded View Parts List.......................................................................11
Replacement Parts List ........................................................................ 12
SVC. Sheet .................................................................................................
- 3 -
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
prevent X-RADIATION, Shock, Fire, or other Hazards.
Do not modify the original design without permission of manufacturer.
General Guidance
An lsolation 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 it's components from being
damaged by accidental shorts of the circuitary 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.
Due to high vacuum and large surface area of picture tube,
extreme care should be used in handling the Picture Tube.
Do not lift the Picture tube by it's Neck.
X-RAY Radiation
Warning:
To determine the presence of high voltage, use an accurate
high impedance HV meter.
Adjust brightness, color, contrast controls to minimum.
Measure the high voltage.
The meter reading should indicate
23.5
!1.5KV: 14-19 inch, 26!1.5KV: 19-21 inch,
29.0
!1.5KV: 25-29 inch, 30.0 ! 1.5KV: 32 inch
If the meter indication is out of tolerance, immediate service
and correction is required to prevent the possibility of
premature component failure.
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 positioin, 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 1MΩ and 5.2MΩ.
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 esposed 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 sepcified, 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
The source of X-RAY RADIATION in this TV receiver is the
High Voltage Section and the Picture Tube.
For continued X-RAY RADIATION protection, the
replacement tube must be the same type tube as specified in
the Replacement Parts List.
IMPORTANT SAFETY NOTICE
0.15uF
AC Volt-meter
To Instrument's
exposed
METALLIC PARTS
Good Earth Ground
such as WATER PIPE,
CONDUIT etc.
1.5 Kohm/10W
- 4 -
CAUTION: Before servicing receivers covered by this service
manual and its supplements and addenda, read and follow the
SAFETY PRECAUTIONS
on 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 board
module 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.
d. Discharging the picture tube anode.
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. Discharge the picture tube anode only by (a) first connecting
one end of an insulated clip lead to the degaussing or kine
aquadag grounding system shield at the point where the
picture tube socket ground lead is connected, and then (b)
touch the other end of the insulated clip lead to the picture
tube anode button, using an insulating handle to avoid
personal contact with high voltage.
4. Do not spray chemicals on or near this receiver or any of its
assemblies.
5. 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 nonabrasive 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.
6. Do not defeat any plug/socket B+ voltage interlocks with
which receivers covered by this service manual might be
equipped.
7. 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.
8. 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.
9.
Use with this receiver only the test fixtures specified in this
service manual.
CAUTION: Do not connect the test fixture ground strap to
any heatsink 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 fieldeffect
transistors and semicounductor "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
electostatic 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 sufficent to demage ES devices.
5. Do not use freon-propelled chemicals. These can generate
electrical charges sufficient to damage ES devices.
6. Do not remove a repalcement 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 ieads 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 bruching 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 maintan tip
temperature within the range or 500
cF to 600cF.
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. Thorohly clean the surfaces to be soldered. Use a mall
wirebristle (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.
(500cF to 600cF)
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
circuiboard printed foil.
6. Use the following soldering technique.
a. Allow the soldering iron tip to reach a normal
temperature (500cF to 600cF)
b. First, hold the soldering iron tip and solder the strand
against the component lead until the solder melts.
SERVICING PRECAUTIONS
- 5 -
c. Qulckly 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.
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 parapraphs 5 and 6 above.
Removal
1. Desolder and straighten each IC lead in one operation by
gently prying up on the lead with the soldering iron tip as the
solder melts.
2. Draw away the melted solder with an anti-static suctiontype solder removal device (or with solder braid) before
removing the IC.
Replacement
1. Carefully insert the replacement IC in the circuit boare.
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 heatsink 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 heatsink.
Diode Removal/Replacement
1. Remove defective diode by clipping its leads as close as
possible to diode body.
2. Bend the two remaining leads perpendicula 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
involoves 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.
- 6 -
1. Application Object
This instruction is for the application to the LCD TV.
2. Notes
(1) This set uses an adapter, so connect the adapter and the
set correctly before adjustment.
(2) The adjustment must be performed under the correct
sequence.
(3) The adjustment must be performed in the circumstance of
25!5cC of temperature and 65!10% of relative humidity if
there is no specific designation.
(4) The input voltage of the receiver must keep 220V, 60Hz in
adjusting.
(5) The set must be operated for 30 minutes preliminarily
before adjustment if there is no specific designation.
[ ‘Heat Run’ must be performed with the full white signal or TV
noise signal in the internal part of the set.
[ The time for ‘Heat Run’ can be changed owing to production
plan.
3. TV Mode Adjustment
Before entering into the adjustment mode set the TV up with
the MENU button as below.
Contrast 85
Brightness 100
Saturation 50
Tint 0
3-1. White Balance Adjustment
3-1-1. Required Test Equipment
(1) A Remote Control
(2) A Color Analyzer for LCD : CA-110
(3) A TV Signal Generator : Pattern of 64 (128) tones or Ch. 13
in the company.
3-1-2. Preparation for Adjustment
(1) This adjustment should be performed 30 minutes later
after ‘Heat Run’.
(2) This adjustment should be performed in a darkroom or in
the simmilar condition.
3-1-3. Low Light Adjustment
(1) Seletc Ch.13 in the company.
(2) Enter into the adjustment mode with the ADJ button.
(3) Select the Sub-bright and stop adjusting at the moment
when Gray 0 and 1 aren’t distinguished.
4. PC Input Mode Adjustment
4-1. Required Test Equipment
(1) A pattern generator being in proportion to VG819 ; Pattern
of 64 tones
(2) A remote control
4-2. Preparation for Adjustment
(1) Perform ‘Heat Run’ for more than 30 minutes in white
pattern.
(2) Connect the signal of pattern generator with LCD TV.
(3) Lean the set 45° backward. (Adjustment is easy.)
(4) Set the PC mode menu as below.
4-3. White Adjustment
(1) Approve the signal of 64 tones of XGA(1024 * 768).
(2) Select all the gain of R, B and G with using ADJ of remote
control.
(3) After making 62 tones, 63 tones and 64 tones not
distinguished with using each signal of R, G and B, finish
adjusting at the moment when the signal 62, 63 and 64 is
distinguished.
ADJUSTMENT INSTRUCTION
IC
VPC3230D
VPC3230D
VPC3230D
Name
BR
ACC_Sat
Tint
Default
0
2930
0
Unit-Decimal
Adj. Mode
No.304
No.236~237
No.248
IIC Type
IIC 0x52/7:0/
IIC 0x30/11:0/
Fp 0xDC
Low Light(Black)
3 x
3 y
Brightness:[cd/m^2]
Blue
0.14
0.10
Green
0.30
0.60
White
0.32
0.34
150[cd/m^2]
Red
0.63
0.34
45°
Initial Value
Contrast
70
Brightness
100
R
0.63 0.34
0x02
G
0.30 0.60
0x03
B
0.14 0.10
0x04
Error
! 0.03
Register
Color Coordinates(x,y)
AD9884
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