Samsung DVD-HR755 Service Manual Download

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Samsung Electronics

1-1

1. Precautions

1-1 Safety Precaution

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 as-
sembly 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 oper-
ate this instrument or permit it to be operated with-
out 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, excessive-
ly wide cabinet ventilation slots, and an improper-
ly 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 European model 230V(220V ~ 240V),
Asia and Austrailia model (110V ~240V) AC outlet.
(Do not use an isolation transformer during this
test.) Use a leakage current tester or a metering sys-
tem 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 posi-
tion, 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 out-
let and repeat the test. See Fig. 1-1.

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 chas-
sis, the reading must be infinite. If the reading is
not within the limits specified, there is the possibil-
ity of a shock hazard, and the instrument must be
repaired and rechecked before it is returned to the

customer. See Fig. 1-2.

DEVICE
UNDER

TEST

(READING SHOULD

NOT BE ABOVE

0.5mA)

LEAKAGE

CURRENT

TESTER

EARTH

GROUND

TEST ALL