DOWNLOAD LG 47LW6500-SA (CHASSIS:LJ12C) Service Manual ↓ Size: 22.72 MB | Pages: 108 in PDF or view online for FREE

BEFORE SERVICING THE CHASSIS,
READ THE SAFETY PRECAUTIONS IN THIS MANUAL.

P/NO : MFL66981621 (1108-REV00)

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

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 it's 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.

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. 

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

Ω

and 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.

(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.

1.5 Kohm/10W

To Instrument's
exposed 
METALLIC PARTS

Good Earth Ground
such as WATER PIPE,
CONDUIT etc.

AC Volt-meter

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 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.

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.