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1. Precautions
1. Be sure that all of the built-in protective devices are
replaced. Restore any missing protective shields. (READING SHOULD
NOT BE ABOVE
0.5mA)
LEAKAGE
2. When reinstalling the chassis and its assemblies, be DEVICE CURRENT
UNDER TESTER
sure to restore all protective devices, including : TEST
control knobs and compartment covers.
TEST ALL
EXPOSED METER
3. Make sure that there are no cabinet openings SURFACES
through which people--particularly children 2-WIRE CORD
--might insert fingers and contact dangerous
voltages. Such openings include the spacing ALSO TEST WITH EARTH
PLUG REVERSED GROUND
between the picture tube and the cabinet mask, (USING AC ADAPTER
PLUG AS REQUIRED)
excessively wide cabinet ventilation slots, and
improperly fitted back covers.
Fig. 1-1 AC Leakage Test
If the measured resistance is less than 1.0 megohm
or greater than 5.2 megohms, an abnormality exists 7. Antenna Cold Check :
that must be corrected before the unit is returned With the unit's AC plug disconnected from the
to the customer. AC source, connect an electrical jumper across the
two AC prongs. Connect one lead of the ohmmeter
4. Leakage Current Hot Check (See Fig. 1-1) : to an AC prong.
Warning : Do not use an isolation transformer Connect the other lead to the coaxial connector.
during this test. Use a leakage current tester or a
metering system that complies with American 8. High Voltage Limit :
National Standards Institute (ANSI C101.1, High voltage must be measured each time
Leakage Current for Appliances), and Underwriters servicing is done on the B+, horizontal deflection
Laboratories (UL Publication UL1410, 59.7). or high voltage circuits.
5. With the unit completely reassembled, plug the AC Heed the high voltage limits. These include the
line cord directly the power outlet. With the unit's X-ray protection Specifications Label, and the
AC switch first in the ON position and then OFF, Product Safety and X-ray Warning Note on the
measure the current between a known earth service data schematic.
ground (metal water pipe, conduit, etc.) and all
exposed metal parts, including : antennas, handle 9. Some semiconductor ("solid state") devices are
brackets, metal cabinets, screwheads and control easily damaged by static electricity.
shafts. The current measured should not exceed Such components are called Electrostatically
0.5 milliamp. Reverse the power-plug prongs in the Sensitive Devices (ESDs); examples include
AC outlet and repeat the test. integrated circuits and some field-effect transistors.
The following techniques will reduce the
6. X-ray Limits : occurrence of component damage caused by static
The picture tube is designed to prohibit X-ray electricity.
emissions. To ensure continued X-ray protection,
replace the picture tube only with one that is the 10. Immediately before handling any semiconductor
same type as the original. components or assemblies, drain the electrostatic
charge from your body by touching a known
earth ground. Alternatively, wear a discharging
Wrist-strap device. (Be sure to remove it prior to
applying power--this is an electric shock
precaution.)
Samsung Electronics 1-1
Precautions
11. High voltage is maintained within specified limits 18. Picture Tube Implosion Warning :
by close-tolerance, safety-related components and The picture tube in this receiver employs
adjustments. If the high voltage exceeds the "integral implosion" protection. To ensure
specified limits, check each of the special continued implosion protection, make sure that
components. the replacement picture tube is the same as the
original.
12. Design Alteration Warning :
Never alter or add to the mechanical or electrical 19. Do not remove, install or handle the picture tube
design of this unit. Example : Do not add without first putting on shatterproof goggles
auxiliary audio or video connectors. equipped with side shields. Never handle the
Such alterations might create a safety hazard. picture tube by its neck. Some "in-line" picture
Also, any design changes or additions will void tubes are equipped with a permanently attached
the manufacturer's warranty. deflection yoke; do not try to remove such
"permanently attached" yokes from the picture
13. Hot Chassis Warning : tube.
Some TV receiver chassis are electrically
connected directly to one conductor of the AC 20. Product Safety Notice :
power cord. If an isolation transformer is not Some electrical and mechanical parts have special
used, these units may be safely serviced only if safety-related characteristics which might not be
the AC power plug is inserted so that the chassis obvious from visual inspection. These safety
is connected to the ground side of the AC source. features and the protection they give might be
lost if the replacement component differs from the
To confirm that the AC power plug is inserted original--even if the replacement is rated for
correctly, do the following : Using an AC higher voltage, wattage, etc.
voltmeter, measure the voltage between the
chassis and a known earth ground. If the reading Components that are critical for safety are
is greater than 1.0V, remove the AC power plug, indicated in the circuit diagram by shading,
reverse its polarity and reinsert. Re-measure the ( or ).
voltage between the chassis and ground. Use replacement components that have the same
ratings, especially for flame resistance and
14. Some TV chassis are designed to operate with 85 dielectric strength specifications. A replacement
volts AC between chassis and ground, regardless part that does not have the same safety
of the AC plug polarity. These units can be safely characteristics as the original might create shock,
serviced only if an isolation transformer inserted fire or other hazards.
between the receiver and the power source.
15. 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.
16. 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.
17. Observe the original lead dress, especially near
the following areas : Antenna wiring, sharp
edges, and especially the AC and high voltage
power supplies. Always inspect for pinched, out-
of-place, or frayed wiring. Do not change the
spacing between components and the printed
circuit board. Check the AC power cord for
damage. Make sure that leads and components
do not touch thermally hot parts.
1-2 Samsung Electronics