Samsung DVD-R150, Service Manual

Page: 7 / 124

Precautions
Samsung Electronics 1-3
1-2 Servicing Precautions
CAUTION : Before servicing units covered by this
service manual and its supplements, read and follow
the Safety Precautions section of this manual.
Note : If unforseen circumstances create conflict
between the following servicing precautions and any
of the safety precautions, always follow the safety pre-
cautions. Remember: Safety First.
1-2-1 General Servicing Precautions
(1) a. Always unplug the instrument’s AC power cord
from the AC power source before (1) re-moving
or reinstalling any component, circuit board,
module or any other instrument assembly, (2)
disconnecting any instrument electrical plug or
other electrical connection, (3) connecting a test
substitute in parallel with an electrolytic capaci-
tor in the instrument.
b. Do not defeat any plug/socket B+ voltage inter-
locks with which instruments covered by this
service manual might be equipped.
c. Do not apply AC power to this instrument and
/or any of its electrical assemblies unless all
solid-state device heat sinks are correctly in-
stalled.
d. Always connect a test instrument’s ground lead
to the instrument chassis ground before connect-
ing the test instrument positive lead. Always
remove the test instrument ground lead last.
Note : Refer to the Safety Precautions section ground
lead last.
(2) The service precautions are indicated or printed on
the cabinet, chassis or components. When servic-
ing, follow the printed or indicated service precau-
tions and service materials.
(3) The components used in the unit have a specified
flame resistance and dielectric strength.
When replacing components, use components
which have the same ratings. Components identi-
fied by shading, by( ) or by ( ) in the circuit dia-
gram are important for safety or for the characteris-
tics of the unit. Always replace them with the exact
replacement components.
(4) An insulation tube or tape is sometimes used and
some components are raised above the printed
wiring board for safety. The internal wiring is
sometimes clamped to prevent contact with heat-
ing components. Install such elements as they
were.
(5) After servicing, always check that the removed
screws, components, and wiring have been in-
stalled correctly and that the portion around the
serviced part has not been damaged and so on.
Further, check the insulation between the blades of
the attachment plug and accessible conductive
parts.
1-2-2 Insulation Checking Procedure
Disconnect the attachment plug from the AC outlet
and turn the power ON. Connect the insulation resi-
stance meter (500V) to the blades of the attachment
plug. The insulation resistance between each blade of
the attachment plug and accessible conductive
parts(see note) should be more than 1 Megohm.
Note : Accessible conductive parts include metal pan-
els, input terminals, earphone jacks, etc.