Service Manuals, User Guides, Schematic Diagrams or docs for : Samsung LCD TV LA20S51BP 02_Precaution
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1 Precautions
1 Precautions
Follow these safety, servicing and ESD precautions to prevent damage and to protect against potential hazards such as electrical shock.
1-1 Safety Precautions
1-1-1 Warnings
1. For continued safety, do not attempt to modify the
circuit board.
2. Disconnect the AC power and DC Power Jack before
servicing.
1-1-2 Servicing the LCD Monitor
1. When servicing the LCD Monitor Disconnect the AC
line cord from the AC outlet.
2. It is essential that service technicians have an accurate
voltage meter available at all times. Check the
calibration of this meter periodically.
1-1-3 Fire and Shock Hazard
Before returning the monitor to the user, perform the Figure 1-1. Leakage Current Test Circuit
following safety checks:
1. Inspect each lead dress to make certain that the leads 4. With the unit completely reassembled, plug the AC
are not pinched or that hardware is not lodged between line cord directly into a 120V AC outlet. With the
the chassis and other metal parts in the monitor. unit s AC switch first in the ON position and then
2. Inspect all protective devices such as nonmetallic OFF, measure the current between a known earth
control knobs, insulating materials, cabinet backs, ground (metal water pipe, conduit, etc.) and all
adjustment and compartment covers or shields, exposed metal parts, including: metal cabinets,
isolation resistor-capacitor networks, mechanical screwheads and control shafts. The current measured
insulators, etc. should not exceed 0.5 milliamp. Reverse the power-
3. Leakage Current Hot Check (Figure 1-1): plug prongs in the AC outlet and repeat the test.
WARNING: Do not use an isolation
transformer during 1-1-4 Product Safety Notices
this test.
Some electrical and mechanical parts have special
Use a leakage current tester or a metering system that
safety-related characteristics which are often not evident
complies with American National Standards Institute from visual inspection. The protection they give may not
(ANSI C101.1, Leakage Current for Appliances), and be obtained by replacing them with components rated for
Underwriters Laboratories (UL Publication UL1410, higher voltage, wattage, etc. Parts that have special safety
59.7). characteristics are identified by on schematics and parts
lists. A substitute replacement that does not have the same
safety characteristics as the recommended replacement part
might create shock, fire and/or other hazards. Product
safety is under review continuously and new instructions
are issued whenever appropriate.
1-1
1 Precautions
1-2 Servicing Precautions
WARNING: An electrolytic capacitor installed with the wrong polarity might explode.
Caution: Before servicing units covered by this service manual, read and follow the Safety
Precautions section of this manual.
Note: If unforeseen circumstances create conflict between the following servicing precautions and any of the safety
precautions, always follow the safety precautions.
1-2-1 General Servicing 4. Check the insulation between the blades of the AC
Precautions plug and accessible conductive parts (examples: metal
panels, input terminals and earphone jacks).
1. Always unplug the unit s AC power cord from the AC 5. Insulation Checking Procedure: Disconnect the power
power source and disconnect the DC Power Jack cord from the AC source and turn the power switch
before attempting to: ON. Connect an insulation resistance meter (500 V) to
(a) remove or reinstall any component or assembly, (b) the blades of the AC plug.
disconnect PCB plugs or connectors, (c) connect a test The insulation resistance between each blade of the
component in parallel with an electrolytic capacitor. AC plug and accessible conductive parts (see above)
2. Some components are raised above the printed circuit should be greater than 1 megohm.
board for safety. An insulation tube or tape is 6. Always connect a test instrument s ground lead to the
sometimes used. The internal wiring is sometimes instrument chassis ground before connecting the
clamped to prevent contact with thermally hot positive lead; always remove the instrument s ground
components. Reinstall all such elements to their lead last.
original position.
3. After servicing, always check that the screws,
components and wiring have been correctly
reinstalled. Make sure that the area around the
serviced part has not been damaged.
1-3 Static Electricity Precautions
Some semiconductor (solid state) devices can be easily damaged by static electricity. Such components are commonly called
Electrostatically Sensitive Devices (ESD). Examples of typical ESD are integrated circuits and some field-effect transistors.
The following techniques will reduce the incidence of component damage caused by static electricity.
1. Immediately before handling any semiconductor
6. Do not remove a replacement ESD from its protective
components or assemblies, drain the electrostatic
package until you are ready to install it. Most
charge from your body by touching a known earth
replacement ESDs are packaged with leads that are
ground. Alternatively, wear a discharging wrist-strap
electrically shorted together by conductive foam,
device. To avoid a shock hazard, be sure to remove the
aluminum foil or other conductive materials.
wrist strap before applying power to the monitor.
7. Immediately before removing the protective material
2. After removing an ESD-equipped assembly, place it
from the leads of a replacement ESD, touch the
on a conductive surface such as aluminum foil to
protective material to the chassis or circuit assembly
prevent accumulation of an electrostatic charge.
into which the device will be installed.
3. Do not use freon-propelled chemicals. These can
Caution: Be sure no power is applied to
generate electrical charges sufficient to damage ESDs.
the chassis or circuit and
4. Use only a grounded-tip soldering iron to solder or observe all other safety
desolder ESDs. precautions.
5. Use only an anti-static solder removal device. Some
solder removal devices not classified as anti-static 8. Minimize body motions when handling unpackaged
can generate electrical charges sufficient to damage replacement ESDs. Motions such as brushing clothes
ESDs. together, or lifting your foot from a carpeted floor can
generate enough static electricity to damage an ESD.
1-2
1 Precautions
1-4 Installation Precautions
1. For safety reasons, more than two people are required 6. Keep the antenna far away from any high-voltage
for carrying the product. cables and install it firmly. Contact with the high-
voltage cable or the antenna falling over may cause fire
2. Keep the power cord away from any heat emitting or electric shock.
devices, as a melted covering may cause fire or
electric shock. 7. When installing the product, leave enough space(10cm)
between the product and the wall for ventilation
3. Do not place the product in areas with poor ventilation purposes.
such as a bookshelf or closet. The increased internal A rise in temperature within the product may cause
temperature may cause fire. fire.
4. Bend the external antenna cable when connecting it to
the product. This is a measure to protect it from being
exposed to moisture. Otherwise, it may cause a fire or
electric shock.
5. Make sure to turn the power off and unplug the power
cord from the outlet before repositioning the product.
Also check the antenna cable or the external connectors
if they are fully unplugged.
Damage to the cord may cause fire or electric shock.
1-3
1 Precautions
Memo
1-4
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