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Precautions
1. Precautions
Follow these safety, servicing and ESD precautions to prevent damage and protect against potential
hazards such as electrical shock and X-rays.
1-1 Safety Precautions
1. Be sure that all of the built-in protective
devices are replaced. Restore any missing
(READING SHOULD
protective shields. LEAKAGE NOT BE ABOVE
DEVICE CURRENT 0.5mA)
UNDER TESTER
2. When reinstalling the chassis and its TEST
TEST ALL
assemblies, be sure to restore all protective EXPOSED METAL
devices, including: nonmetallic control knobs SURFACES
and compartment covers. 2-WIRE CORD
ALSO TEST WITH
3. Make sure that there are no cabinet openings PLUG REVERSED
(USING AC ADAPTER EARTH
through which people--particularly PLUG AS REQUIRED) GROUND
children--might insert fingers and contact
dangerous voltages. Such openings include
Fig. 1-1 AC Leakage Test
the spacing between fornt cabinet and back
cabinet, excessively wide cabinet
6. Antenna Cold Check:
ventilation slots, and improperly fitted back
With the unit's AC plug disconnected from the
covers.
AC source, connect an electrical jumper across
the two AC prongs. Connect one lead of the
4. Leakage Current Hot Check (Figure 1-1):
ohmmeter to an AC prong. Connect the other
Warning: Do not use an isolation
lead to the coaxial connector.
transformer during this test. Use a leakage-
current tester or a metering system that
7. High Voltage Limits:
complies with American National Standards
High voltage must be measured each time ser-
Institute (ANSI C101.1, Leakage Current for
vicing is done on the B+, horizontal deflection
Appliances), and Underwriters Laboratories
(UL Publication UL1950.5.2). or high voltage circuits.
5. With the unit completely reassembled, plug
the AC line cord directly into the power
outlet. With the unit's AC switch first in the
ON position and then OFF, measure the
current between a known earth ground (metal
water pipe, conduit, etc.) and all exposed
metal parts, including: antennas, handle
brackets, metal cabinets, screwheads and
control shafts. The current measured should
not exceed 3.5 milliamp. Reverse the power-
plug prongs in the AC outlet and repeat the
test.
Samsung Electronics 1-1
Precautions
1-2 Safety Precautions (Continued)
voltage power supplies. Always inspect for
8. High voltage is maintained within specified
pinched, out-of-place, or frayed wiring. Do
limits by close-tolerance, safety-related
not change the spacing between components
components and adjustments. If the high
and the printed circuit board. Check the AC
voltage exceeds the specified limits, check
power cord for damage. Make sure that leads
each of the special components.
and components do not touch thermally hot
9. Design Alteration Warning:
parts.
Never alter or add to the mechanical or
electrical design of this unit. Example: Do not
15. Product Safety Notice:
add auxiliary audio or video connectors. Such
Some electrical and mechanical parts have
alterations might create a safety hazard. Also,
special safety-related characteristics which
any design changes or additions will void the
might not be obvious from visual inspection.
manufacturer's warranty.
These safety features and the protection they
give might be lost if the replacement compo-
10. Hot Chassis Warning:
nent differs from the original--even if the
Some TV receiver chassis are electrically
replacement is rated for higher voltage,
connected directly to one conductor of the AC
wattage, etc.
power cord. If an isolation transformer is not
used, these units may be safely serviced only
Components that are critical for safety are
if the AC power plug is inserted so that the
indicated in the circuit diagram by shading,
chassis is connected to the ground side of the
( ) or ( ).
AC source.
Use replacement components that have the
same ratings, especially for flame resistance
To confirm that the AC power plug is inserted
and dielectric strength specifications.
correctly, do the following: Using an AC
A replacement part that does not have the
voltmeter, measure the voltage between the
same safety characteristics as the original
chassis and a known earth ground. If the
might create shock, fire or other hazards.
reading is greater than 1.0V, remove the AC
power plug, reverse its polarity and reinsert.
Re-measure the voltage between the chassis
and ground.
11. Some TV chassis are designed to operate with
85 volts AC between chassis and ground,
regardless of the AC plug polarity. These units
can be safely serviced only if an isolation
transformer inserted between the receiver and
the power source.
12. Some TV chassis have a secondary ground
system in addition to the main chassis ground.
This secondary ground system is not
isolated from the AC power line. The two
ground systems are electrically separated by
insulating material that must not be defeated
or altered.
13. Components, parts and wiring that appear to
have overheated or that are otherwise
damaged should be replaced with parts that
meet the original specifications. Always
determine the cause of damage or overheat-
ing, and correct any potential hazards.
14. Observe the original lead dress, especially
near the following areas: Antenna wiring,
sharp edges, and especially the AC and high
1-2 Samsung Electronics
Precautions
1-3 Servicing Precautions
Warning 1 : First read the "Safety Precautions" section of this manual. If some unforeseen circumstance creates a
conflict between the servicing and safety precautions, always follow the safety precautions.
Warning 2 : An electrolytic capacitor installed with the wrong polarity might explode.
8. Plasma display panels have partial afterim-
1. Servicing precautions are printed on the
ages when a same picture continues to be dis-
cabinet. Follow them.
played for a certain time. This happens due to
the degradation of brightness caused by a
2. Always unplug the unit's AC power cord from
scale-down effect.
the AC power source before attempting to: (a)
To prevent such afterimages when displaying
Remove or reinstall any component or
a same picture for a certain time, be sure to
assembly, (b) Disconnect an electrical plug or
reduce the level of brightness and contrast.
connector, (c) Connect a test component in
ex) Contrast : 50 or 75, Brightness : 25
parallel with an electrolytic capacitor.
9. Plasma display is an array of pixels(cells).
3. Some components are raised above the printed
Therefore, if at least 99.9% pixels keep normal,
circuit board for safety. An insulation tube or
the appropriate panel is judged as `approved
tape is sometimes used. The internal wiring is
product.' Even though some of pixels keep
sometimes clamped to prevent contact with
luminescent or always light off, do not worry
thermally hot components. Reinstall all such
because the panel is approved.
elements to their original position.
4. After servicing, always check that the screws,
components and wiring have been correctly
reinstalled. Make sure that the portion around
the serviced part has not been damaged.
5. Check the insulation between the blades of the
AC plug and accessible conductive parts
(examples: metal panels, input terminals and
earphone jacks).
6. Never defeat any of the B+ voltage interlocks.
Do not apply AC power to the unit (or any of
its assemblies) unless all solid-state heat sinks
are correctly installed.
7. Always connect a test instrument's ground
lead to the instrument chassis ground before
connecting the positive lead; always remove
the instrument's ground lead last.
Samsung Electronics 1-3
Precautions
1-4 Precautions for Electrostatically Sensitive Devices (ESDs)
1. Some semiconductor ("solid state") devices 5. Use only a grounded-tip soldering iron when
are easily damaged by static electricity. Such soldering or unsoldering ESDs.
components are called Electrostatically
Sensitive Devices (ESDs); examples include 6. Use only an anti-static solder removal device.
integrated circuits and some field-effect Many solder removal devices are not rated as
transistors. The following techniques will "anti-static"; these can accumulate sufficient
reduce the occurrence of component damage electrical charge to damage ESDs.
caused by static electricity.
7. Do not remove a replacement ESD from its
2. Immediately before handling any semicon protective package until you are ready to
ductor components or assemblies, drain the install it. Most replacement ESDs are
electrostatic charge from your body by packaged with leads that are electrically
touching a known earth ground. Alternatively, shorted together by conductive foam,
wear a discharging wrist-strap device. (Be aluminum foil or other conductive materials.
sure to remove it prior to applying power--
this is an electric shock precaution.) 8. Immediately before removing the protective
material from the leads of a replacement ESD,
3. After removing an ESD-equipped assembly, touch the protective material to the chassis or
place it on a conductive surface such as circuit assembly into which the device will be
aluminum foil to prevent accumulation of installed.
electrostatic charge.
9. Minimize body motions when handling
4. Do not use freon-propelled chemicals. These unpackaged replacement ESDs. Motions such
can generate electrical charges that damage as brushing clothes together, or lifting a foot
ESDs. from a carpeted floor can generate enough
static electricity to damage an ESD.
CAUTION
These servicing instructions are for use by
qualified service personnel only.
To reduce the risk of electric shock do not
perform any servicing other than that contained
in the operating instructions unless you are
qualified to do so.
1-4 Samsung Electronics