- 4 - LGE Internal Use OnlyCopyright©2007 LG Electronics. Inc. All right reserved.
Only or training and service purposes
CAUTION: Be ore servicing receivers covered by this service
manual and its supplements and addenda, read and ollow the
SAFETY PRECAUTIONS on page 3 o this publication.
NOTE: I un oreseen circumstances create con lict between the
ollowing servicing precautions and any o the sa ety precautions on
page 3 o this publication, always ollow the sa ety precautions.
Remember: Sa ety First.
General Servicing Precautions
1. Always unplug the receiver AC power cord rom the AC power
source be ore;
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 o 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 o its
assemblies.
4. Unless speci ied otherwise in this service manual, clean
electrical contacts only by applying the ollowing 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 lammable mixture.
Unless speci ied otherwise in this service manual, lubrication o
contacts in not required.
5. Do not de eat 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 o 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 be ore connecting the test receiver positive
lead.
Always remove the test receiver ground lead last.
8. Use with this receiver only the test fixtures s ecified in this
service manual.
CAUTION: Do not connect the test ixture 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 o typical ES
devices are integrated circuits and some ield-e ect transistors and
semiconductor "chip" components. The ollowing techniques
should be used to help reduce the incidence o component
damage caused by static by static electricity.
1. Immediately be ore handling any semiconductor component or
semiconductor-equipped assembly, drain o 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. A ter removing an electrical assembly equipped with ES
devices, place the assembly on a conductive sur ace such as
aluminum oil, to prevent electrostatic charge buildup or
exposure o 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 classi ied as "anti-static" can generate
electrical charges su icient to damage ES devices.
5. Do not use reon-propelled chemicals. These can generate
electrical charges su icient to damage ES devices.
6. Do not remove a replacement ES device rom its protective
package until immediately be ore you are ready to install it.
(Most replacement ES devices are packaged with leads
electrically shorted together by conductive oam, aluminum oil
or comparable conductive material).
7. Immediately be ore removing the protective material rom the
leads o 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 sa ety precautions.
8. Minimize bodily motions when handling unpackaged
replacement ES devices. (Otherwise harmless motion such as
the brushing together o your clothes abric or the li ting o your
oot rom a carpeted loor can generate static electricity
su icient 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 500ºF to 600ºF.
2. Use an appropriate gauge o RMA resin-core solder composed
o 60 parts tin/40 parts lead.
3. Keep the soldering iron tip clean and well tinned.
4. Thoroughly clean the sur aces to be soldered. Use a mall wire-
bristle (0.5 inch, or 1.25cm) brush with a metal handle.
Do not use reon-propelled spray-on cleaners.
5. Use the ollowing unsoldering technique
a. Allow the soldering iron tip to reach normal temperature.
(500ºF to 600ºF)
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
circuitboard printed oil.
6. Use the ollowing soldering technique.
a. Allow the soldering iron tip to reach a normal temperature
(500ºF to 600ºF)
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 o the
component lead and the printed circuit oil, and hold it there
only until the solder lows onto and around both the
component lead and the oil.
CAUTION: Work quickly to avoid overheating the circuit
board printed oil.
d. Closely inspect the solder area and remove any excess or
splashed solder with a small wire-bristle brush.
SER ICING PRECAUTIONS
