Precaution; Safety Precautions - Samsung HW-C450 Service Manual

1. Precaution

Follow these safety instructions while servicing the ESD to prevent damage and to protect against potential
hazards such as electrical shock and X-rays.
1-1 Safety Precautions
1. When reinstalling the chassis and its assemblies, be sure to restore all of the protective devices, including the
control knobs and the compartment covers.
2. Make sure that there are no cabinet openings through which people (particularly children) can make contact
with dangerous internal components.
3. Design Alteration Warning:
Never alter or add to the mechanical or electrical design of the unit.
Example: Do not add auxiliary audio or video connectors. Such alterations might create a safety hazard.
Also, any design changes or additions will void the manufacturer's warranty.
4. Leakage Current Hot Check (Fig. 1-1):
Warning: Do not use an isolation transformer during this
test. Use a leakage-current tester or a metering system
that complies with American National Standards Institute
(ANSI C101.1, Leakage Current for Appliances), and
Underwriters Laboratories (UL Publication UL1410,
59.7).
With the unit completely reassembled, plug the AC cord
directly into a 120V AC outlet. With the unit's power
switched from the ON to the OFF position, measure the
current between a known ground and all exposed metal
parts.
Known Grounds - Earth
Known Metal parts - screwheads, metal cabinets, etc.
5. Insulation Resistance Cold Check:
(1) With the unit's AC plug disconnected from the AC
source, connect an electrical jumper across the two AC
prongs. (2) Set the power switch to ON. (3) Measure
the resistance between the shorted AC plug and any
exposed metallic parts.
Example: screwheads, metal cabinets, antenna port
If any of the exposed metallic parts has a return path
to the chassis, the measured resistance should be
between 1 and 5.2 megohms. If there is no return path,
the measured resistance should be "infinite." If the resistance is outside these limits, a shock hazard might
exist. See Fig. 1-2
Samsung Electronics
LEAKAGE
DEVICE
CURRENT
UNDER
TESTER
TEST
TEST ALL
EXPOSED METAL
SURFACES
2-WIRE CORD
ALSO TEST WITH
PLUG REVERSED
(USING AC
ADAPTER PLUG
AS REQUIRED)
<Fig. 1-1 AC Leakage Test>
Antenna
Terminal
Exposed
Metal Part
ohm
<Fig. 1-2 Insulation Resistance Test>
Precaution
(READING
SHOULD NOT BE
ABOVE 0.5mA)
EARTH
GROUND
Ohmmeter
1-1