Precautions - Samsung SVR-527 Service Manual

1. Precautions

1. Be sure that all of the built-in protective devices are
replaced. Restore any missing protective shields.
2. When reinstalling the chassis and its assemblies, be
sure to restore all pretective 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.
If the measured resistance is less than 1.0 megohm
or greater than 5.2 megohms, an abnormality exists
that must be corrected before the unit is returned
to the customer.
4. Leakage Current Hot Check (See 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).
DEVICE
UNDER
TEST
TEST ALL
EXPOSED METER
SURFACES
2-WIRE CORD
ALSO TEST WITH
PLUG REVERSED
(USING AC ADAPTER
PLUG AS REQUIRED)
Fig. 1-1 AC Leakage Test
Samsung Electronics
(READING SHOULD
NOT BE ABOVE
0.5mA)
LEAKAGE
CURRENT
TESTER
EARTH
GROUND
5. With the unit completely reassembled, plug the AC
line cord directly the power outlet. With the unitÕs
AC switch first in the ON position and then OFF,
measure the current between a known erath
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
0.5 milliamp. Reverse the power-plug prongs in the
AC outlet and repeat the test.
6. Antenna Cold Check :
With the unitÕs AC plug disconnected from the
AC source, connect an electrical jumper across the
two AC prongs. Connect one lead of the ohmmeter
to an AC prong.
Connect the other lead to the coaxial connector.
7. Some semiconductor (Òsolid stateÓ) devices are
easily damaged by static electricity.
Such components are called Electrostatically
Sensitive Devices (ESDs); examples include
integrated circuits and some field-effect transistors.
The following techniques will reduce the
occurrence of component damage caused by static
electricity.
8. Immediately before handling sny semiconductor
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.)
9. Design Alteration Warning :
Never alter or add to the mechanical or electrical
design of this 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 manufacturerÕs warranty.
10. 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.
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