Precautions; Safety Precautions; Precautions 1-1 - Samsung VP-MX10 Service Manual

1. Precautions

1-1 Safety Precautions

1) Before returning an instrument to the customer,
always make a safety check of the entire instrument,
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
removed 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 fish papers,
adjustment and compartment covers/shields, and
isolation resistor/capacitor networks. Do not operate
this instrument or permit it to be operated without
all protective devices correctly installed and
functioning.
(2) Be sure that there are no cabinet openings through
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.
(3) Leakage Current Hot Check-With the instrument
completely reassembled, plug the AC line cord
directly into a 230V(220V ~ 240V) AC outlet. (Do
not use an isolation transformer during this test.)
Use a leakage current tester or a metering system
that complies with American National Standardsp
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 water pipe,
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 0.5mA.
Reverse the instrument power cord plug in the outlet
and repeat the test. See Fig. 1-1.
Samsung electronics
Any measurements not within the limits specified
herein indicate a potential shock hazard that must
be eliminated before returning the instrument to
the customer.
Fig. 1-1 AC Leakage Test
(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
repaired and rechecked before it is returned to the
customer. See Fig. 1-2.
Fig. 1-2 Insulation Resistance Test
1-1