Samsung SWA-4000, Руководство по обслуживанию

Страница: 16 / 24

Samsung Electronics 1-1
Precaution
1. Precaution
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.
2. When reinstalling the chassis and its assemblies, be sure to restore all protective devices, including control
knobs and compartment covers.
3. Make sure that there are no cabinet openings through which people--particularly children--might insert fingers
and contact dangerous voltages. Such openings include the spacing between the picture tube and the cabinet
mask, excessively wide cabinet ventilation slots, and improperly fitted back covers.
4. 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.
5. 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 line
cord directly into a 120V AC 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, etc.) and all exposed metal parts. Examples:
Handle brackets, metal cabinets, screwheads and control shafts. The current measured should not exceed 0.5
milliamp. Reverse the powerplug prongs in the AC outlet and repeat.
6. 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, antenna, control shafts or handle
brackets.
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
DEVICE
UNDER
TEST
LEAKAGE
CURRENT
TESTER
TEST ALL
EXPOSED METAL
SURFACES
2-WIRE CORD
ALSO TEST WITH
PLUG REVERSED
(USING AC
ADAPTER PLUG
AS REQUIRED)
EARTH
GROUND
(READING
SHOULD NOT BE
ABOVE 0.5mA)
<Fig. 1-1 AC Leakage Test>
Antenna
Terminal
ohm
<Fig. 1-2 Insulation Resistance Test>
Exposed
Metal Part
Ohmmeter