Precautions - Samsung DVD-907 Service Manual

1. Precautions

1-1 Safety Precautions
1. Before returning an instrument to the customer,
always make a safety check of the entire instru-
ment, including, but not limited to, the following
items:
(1) Be sure that no built-in protective devices are
defective or have been defeated during servicing.
(1)Protective shields are provided to protect both
the technician and the customer. Correctly replace
all missing protective shields, including any remove
for servicing convenience. (2) When reinstalling the
chassis and/or other assembly in the cabinet, be
sure to put back in place all protective devices,
including, but not limited to, nonmetallic control
knobs, insulating fishpapers, adjustment and
compartment covers/shields, and isolation resis-
tor/capacitor networks. Do not operate this instru-
ment or permit it to be operated without all protec-
tive devices correctly installed and functioning.
(2) Be sure that there are no cabinet openings
throught which adults or children might be able to
insert their fingers and contact a hazardous volt-
age. Such openings include, but are not limited to,
excessively wide cabinet ventilation slots, and an
improperly fitted and/or incorrectly secured cabinet
back cover.
(3) Leakage Current Hot Check-With the instrument
completely reassembled, plug the AC line cord
directly into a 120V AC outlet. (Do not use a isola-
tion 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) 1270 (40.7). With
the instrument's AC switch first in the ON position
and then in the OFF position, measure from a
known earth ground (metal waterpipe, conduit, etc.)
to all exposed metal parts of the instrument (anten-
nas, handle brackets, metal cabinets, screwheads,
metallic overlays, control shafts, etc.), especially
any exposed metal parts that offer an electrical
return path to the chassis.
Samsung Electronics
Any current measured must not exceed 0.5 mil-
lamp. Reverse the instrument power cord plug in
the outlet and repeat the test. See Figure 1-1.
Device
Under
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
Any measurements not within the limits specified
herein indicate a potential shock hazard that must
be ellminated before returning the instrument to the
customer.
(4) Insulation Resistance Test Cold Check-(1) Unplug
the power supply cord and connect a jumper wire
between the two prongs of the plug. (2) Turn on
the power switch of the instrument. (3) Measure
the resistance with an ohmmeter between the
jumpered AC plug and all exposed metallic cabinet
parts on the instrument, such as screwheads,
antenna, control shafts, handle brackets, etc. When
an exposed metallic part has a return path to the
chassis, the reading should be between 1 and 5.2
megohm. When there is no return path to the chas-
sis, the reading must be infinite. If the reading is not
within the limits specified, there is the possibility of
a shock hazard, and the instrument must be
repared and rechecked before it is returned to the
customer. See figure 1-2.
(Reading should
not be above
0.5mA)
Leakage
Current
Tester
Earth
Ground
1-1