Samsung MAX-485 - Page 3

1-6.
Before
returning
an
instrument
to
the
customer,
Any
measurements
not
within
the
limits
specified
always
make
a
safety
check
of
the
entire
herein
indicate
a
potential
shock
hazard
that
must
be
instrument,
including,
but
not
limited
to,
the
ellminated
before
returning
the
instrument
to
the
following
items:
customer.
(1) Be sure that no built-in protective devices are
defective or have been defeated during
servicing. (1) Protective shields are provided to
(Reading should
not be above
protect both the technician and the customer. 0.5mA)
Correctly replace all missing protective shields, isanage
including any remove for servicing Current
convenience. (2) When reinstalling the chassis Tester
and/or other assembly in the cabinet, be sure to Test all
. : 7 exposed metal
put back in place all protective devices, SiraeEs
including, but not limited to, nonmetallic
control knobs, insulating fishpapers,
adjustment and compartment covers/shields,
and isolation resistor/capacitor networks. Do bene as
not
operate
this
instrument
or
permit
it
to
be
plug
as
required)
operated without all protective devices correctly
installed and functioning.
2-Wire Cord
Also test with
Earth
Ground
FIG. 1 AC Leakage Test
(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
voltage. Such openings include, but are not
limited to, excessively wide cabinet ventilation
slots, and an improperly fitted and/or
incorrectly secured cabinet back cover.
(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 chassis, 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 2.
(3) Leakage Current Hot Check-With the instrume-
nt completely reassembled, plug the AC line
cord directly into a 120V AC outlet. (Do not use
a 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)
1270 (40.7). With the instrument's AC switch
first in the ON positin and then in the OFF
position, measure from a known earth ground
(metal waterpipe, conduit, etc.) to all exposed
metal parts of the instrument (antennas, handle
brackets, metal cabinets, screwheads, metallic
overlays, control shafts, etc.), especially any
exposed metal parts that offer an electrical
return path to the chassis.
Any current measured must not exceed 0.5
millamp. Reverse the instrument power cord
plug in the outlet and repeat the test.
See Figure 1.