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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
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
cotton-tipped
stick
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.
SERVICING PRECAUTIONS
reconnecting
any
with
a
pipe
or
comparable
non-abrasive
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
semiconductor
techniques should be used to help reduce the incidence
of component dam- age caused by static by static
receiver
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. Alter- natively, 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 expo- sure 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 sol- der removal devices not classified as
cleaner,
"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
conductive material).
7.
Immediately
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
4
some
field-effect
"chip"
components.
foam,
aluminum
foil
before
removing
Copyright ⓒ 2017 LG Electronics. Inc. All right reserved.
Only for training and service purposes
transistors
and
The
following
or
comparable
the
protective
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