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1. Precautions
1-1 Safety Precautions
1) Before returning an instrument to the customer, Any measurements not within the limits specified
always make a safety check of the entire instrument, herein indicate a potential shock hazard that must
including, but not limited to, the following items: be eliminated before returning the instrument to
the customer.
(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.
Fig. 1-1 AC Leakage Test
(2) Be sure that there are no cabinet openings through (4) Insulation Resistance Test Cold Check-(1) Unplug
which adults or children might be able to insert the power supply cord and connect a jumper wire
their fingers and contact a hazardous voltage. Such between the two prongs of the plug. (2) Turn on the
openings include, but are not limited to, excessively power switch of the instrument. (3) Measure the
wide cabinet ventilation slots, and an improperly resistance with an ohmmeter between the
fitted and/or incorrectly secured cabinet back jumpered AC plug and all exposed metallic cabinet
cover. parts on the instrument, such as screwheads,
antenna, control shafts, handle brackets, etc. When
(3) Leakage Current Hot Check-With the instrument an exposed metallic part has a return path to the
completely reassembled, plug the AC line cord chassis, the reading should be between 1 and 5.2
directly into a 230V(220V ~ 240V) AC outlet. (Do megohm. When there is no return path to the chassis,
not use an isolation transformer during this test.) the reading must be infinite. If the reading is
Use a leakage current tester or a metering system not within the limits specified, there is the possibility
that complies with American National Standardsp of a shock hazard, and the instrument must be
institute (ANSI) C101.1 Leakage Current for repaired and rechecked before it is returned to the
Appliances and Underwriters Laboratories (UL) customer. See Fig. 1-2.
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.
Fig. 1-2 Insulation Resistance Test
Samsung electronics 1-1
Precautions
2) Read and comply with all caution and safety related 5) Components, parts, and/or wiring that appear to
notes on or inside the cabinet, or on the chassis. have overheated or that are otherwise damaged
should be replaced with components, parts and/ or
3) Design Alteration Warning-Do not alter or add to wiringthatmeetoriginalspecifications.
the mechanical or electrical design of this Additionally, determine the cause of overheating
instrument. and/or damage and, if necessary, take corrective
Design alterations and additions, including action to remove any potential safety hazard.
butnotlimitedto,circuitmodificationsandthe
addition of items such as auxiliary audio output 6) Product Safety Notice-Some electrical and mechanical
connections, might alter the safety characteristics of parts have special safety-related characteristics
this instrument and create a hazard to the user. Any which are often not evident from visual inspection,
design alterations or additions will make you, the nor can the protection they give necessarily be
servicer, responsible for personal injury or property obtained by replacing them with components rated
damage resulting therefrom. for higher voltage, wattage, etc. Parts that have
specialsafetycharacteristicsareidentifiedby
4) Observe original lead dress. Take extra care to shading,
assure correct lead dress in the following areas: an ( )or a ( )on schematics and parts lists. Use
(1) near sharp edges, (2) near thermally hot parts (be of a substitute replacement that does not have the
sure that leads and components do not touch same safety characteristics as the recommended
thermally replacementpartmightcreateshock,fireand/or
hot parts), (3) the AC supply, (4) high voltage, other hazards. Product safety is under review
and (5) antenna wiring. Always inspect in all areas continuously and new instructions are issued
for pinched, out-of-place, or frayed wiring, Do not whenever appropriate.
change spacing between a component and the
printed-circuit board. Check the AC power cord for
damage.
1-2 Samsung Electronics
Precautions
1-2 Servicing Precautions
CAUTION : Before servicing units covered by this (4) An insulation tube or tape is sometimes used and
service manual and its supplements, read and follow some components are raised above the printed
the Safety Precautions section of this manual. wiring board for safety. The internal wiring is
Note:Ifunforseencircumstancescreateconflict sometimes clamped to prevent contact with heating
between the following servicing precautions and any components. Install such elements as they
of the safety precautions, always follow the safety pre- were.
cautions.
Remember: Safety First. (5) After servicing, always check that the removed
screws, components, and wiring have been installed
1-2-1 General Servicing Precautions correctly and that the portion around the
(1) a. Always unplug the instrument's AC powercord serviced part has not been damaged and so on.
from the AC power source before (1) re-moving Further, check the insulation between the blades of
or reinstalling any component, circuit board, the attachment plug and accessible conductive
module or any other instrument assembly, (2) parts.
disconnecting any instrument electrical plug or
other electrical connection, (3) connecting a test
substitute in parallel with an electrolytic ca 1-2-2 Insulation Checking Procedure
pacitor in the instrument.
Disconnect the attachment plug from the AC outlet
b. Do not defeat any plug/socket B+ voltage and turn the power ON. Connect the insulation resist-
interlocks with which instruments covered by ance meter (500V) to the blades of the attachment
this service manual might be equipped. plug. The insulation resistance between each blade of
the attachment plug and accessible conductive
c. Do not apply AC power to this instrument and parts(see note) should be more than 1 Megohm.
/or any of its electrical assemblies unless all
solid-state device heat sinks are correctly installed. Note : Accessible conductive parts include metal panels,
input terminals, earphone jacks, etc.
d. Always connect a test instrument's ground lead
to the instrument chassis ground before connecting
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 servicing,
follow the printed or indicated service precautions
and service materials.
(3)Thecomponentsusedintheunithaveaspecified
flameresistanceanddielectricstrength.
When replacing components, use components
whichhavethesameratings.Componentsidentified
by shading, by( ) or by ( ) in the circuit diagram
are important for safety or for the characteristics
of the unit. Always replace them with the exact
replacement components.
Samsung Electronics 1-3
Precautions
1-3 ESD Precautions
Electrostatically Sensitive Devices (ESD)
CAUTION : Be sure no power is applied to the chassis
Some semiconductor (solid state) devices can be dam- or circuit, and observe all other safety precautions.
agedeasily by static electricity.
Such components commonly are called Electrostati- (8) Minimize bodily motions when handling
cally Sensitive Devices(ESD). Examples of typical ESD unpackaged replacement ESD devices.
devicesareintegratedcircuitsandsomefield-effect (Otherwise harmless
transistors and semiconductor chip components. The motion such as the brushing together of your
following techniques should be used to help reduce clothes fabric or the lifting of your foot from a
the incidence of component damage caused by static carpetedfloorcangeneratestaticelectricity
electricity. sufficienttodamageanESDdevice).
(1) Immediately before handling any semiconductor
component or semiconductor-equipped assembly,
drain off any electrostatic charge on your body by
touching a known earth ground. Alternatively,
obtain and wear a commercially available
discharging wrist strap device, which should be
removed for potential shock reasons prior to
applying power to the unit under test.
(2) After removing an electrical assembly equipped
with ESD devices, place the assembly on a
conductive surface such as aluminum foil, to
prevent electrostatic
charge buildup or exposure of the assembly.
(3) Use only a grounded-tip soldering iron to solder or
unsolder ESD devices.
(4) Use only an anti-static solder removal devices.
Somesolderremovaldevicesnotclassifiedas
"anti-static"cangenerateelectricalchargessufficient
to damage ESD devices.
(5) Do not use freon-propelled chemicals. These can
generateelectricalchargessufficienttodamage
ESD devices.
(6) Do not remove a replacement ESD device from its
protective package until immediately before your
are ready to install it.(Most replacement ESD
devices are packaged with leads electrically shorted
together by conductive foam, aluminum foil or
comparable conductive materials).
(7) Immediately before removing the protective
materials from the leads of a replacement ESD
device, touch the protective material to the
chassis or circuit assembly into which the device
will be installed.
1-4 Samsung Electronics
Precautions
1-4 Handling the optical pick-up
The laser diode in the optical pick up may suffer elec-
trostatic breakdown because of potential static electric-
ity from clothing and your body.
The following method is recommended.
(1) Place a conductive sheet on the work bench (The
black sheet used for wrapping repair parts.)
(2) Place the set on the conductive sheet so that the
chassis is grounded to the sheet. Fig.1-3
(6) Short the short terminal on the PCB, which is inside
(3) Place your hands on the conductive sheet(This
the Pick-Up ASS'Y, before replacing the Pick-
gives them the same ground as the sheet.)
Up. (The short terminal is shorted when the Pick-
Up Ass'y is being lifted or moved.)
(4) Remove the optical pick up block
(7) After replacing the Pick-up, open the short terminal
(5) Perform work on top of the conductive sheet. Be
on the PCB.
careful not to let your clothes or any other static
sources to touch the unit.
Be sure to put on a wrist strap grounded to the sheet.
Be sure to lay a conductive sheet made of copper
etc. Which is grounded to the table.
Samsung Electronics 1-5
Precautions
MEMO
1-6 Samsung Electronics