Service Manuals, User Guides, Schematic Diagrams or docs for : Samsung DVD DVD-HR755 DVD-HR755 DVD-HR755EUR precaution
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1. Precautions
1-1 Safety Precaution
1) Before returning an instrument to the customer,
always make a safety check of the entire instrument, Any measurements not within the limits specified
including, but not limited to, the following items: herein indicate a potential shock hazard that must
be eliminated before returning the instrument to
(1) Be sure that no built-in protective devices are
defective or have been defeated during servicing.
(READING SHOULD
(1)Protective shields are provided to protect both NOT BE ABOVE
the technician and the customer. Correctly replace 0.5mA)
LEAKAGE
all missing protective shields, including any DEVICE CURRENT
UNDER TESTER
removed for servicing convenience. TEST
(2)When reinstalling the chassis and/or other as- TEST ALL
sembly in the cabinet, be sure to put back in place EXPOSED METER
SURFACES
all protective devices, including, but not limited to,
nonmetallic control knobs, insulating fish papers, 2-WIRE CORD
adjustment and compartment covers/shields, and ALSO TEST WITH EARTH
isolation resistor/capacitor networks. Do not oper- PLUG REVERSED GROUND
(USING AC ADAPTER
ate this instrument or permit it to be operated with- PLUG AS REQUIRED)
out all protective devices correctly installed and
functioning. the customer.
Fig. 1-1 AC Leakage Test
(2) Be sure that there are no cabinet openings through
which adults or children might be able to insert (4) Insulation Resistance Test Cold Check-(1) Unplug
their fingers and contact a hazardous voltage. Such the power supply cord and connect a jumper wire
openings include, but are not limited to, excessive- between the two prongs of the plug. (2) Turn on the
ly wide cabinet ventilation slots, and an improper- power switch of the instrument. (3) Measure the
ly fitted and/or incorrectly secured cabinet back resistance with an ohmmeter between the
cover. jumpered AC plug and all exposed metallic cabinet
parts on the instrument, such as screwheads,
(3) Leakage Current Hot Check-With the instrument antenna, control shafts, handle brackets, etc. When
completely reassembled, plug the AC line cord an exposed metallic part has a return path to the
directly into a European model 230V(220V ~ 240V), chassis, the reading should be between 1 and 5.2
Asia and Austrailia model (110V ~240V) AC outlet. megohm. When there is no return path to the chas-
(Do not use an isolation transformer during this sis, the reading must be infinite. If the reading is
test.) Use a leakage current tester or a metering sys- not within the limits specified, there is the possibil-
tem that complies with American National ity of a shock hazard, and the instrument must be
Standards institute (ANSI) C101.1 Leakage Current repaired and rechecked before it is returned to the
for Appliances and Underwriters Laboratories
(UL) 1270 (40.7). With the instrument's AC switch
Antenna
first in the ON position and then in the OFF posi-
Terminal
tion, measure from a known earth ground (metal
water pipe, conduit, etc.) to all exposed metal parts
of the instrument (antennas, handle brackets, metal
Exposed
cabinets, screwheads, metallic overlays, control Metal Part
shafts, etc.), especially any exposed metal parts that
offer an electrical return path to the chassis.
Any current measured must not exceed 0.5mA. ohm
ohmmeter
Reverse the instrument power cord plug in the out-
let and repeat the test. See Fig. 1-1. customer. See Fig. 1-2.
Samsung Electronics 1-1
Precautions
2) Read and comply with all caution and safety re- 5) Components, parts, and/or wiring that appear to
lated notes on or inside the cabinet, or on the chas- have overheated or that are otherwise damaged
sis. should be replaced with components, parts and/ or
wiring that meet original specifications.
3) Design Alteration Warning-Do not alter or add to Additionally, determine the cause of overheating
the mechanical or electrical design of this instru- and/or damage and, if necessary, take corrective
ment. Design alterations and additions, including action to remove any potential safety hazard.
but not limited to, circuit modifications and the
addition of items such as auxiliary audio output 6) Product Safety Notice-Some electrical and mechani-
connections, might alter the safety characteristics of cal 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 spe-
cial safety characteristics are identified by shading,
4) Observe original lead dress. Take extra care to an ( )or a ( )on schematics and parts lists. Use
assure correct lead dress in the following areas: of a substitute replacement that does not have the
(1) near sharp edges, (2) near thermally hot parts (be same safety characteristics as the recommended
sure that leads and components do not touch ther- replacement part might create shock, fire and/or
mally hot parts), (3) the AC supply, (4) high voltage, other hazards. Product safety is under review con-
and (5) antenna wiring. Always inspect in all areas tinuously and new instructions are issued whenev-
for pinched, out-of-place, or frayed wiring, Do not er 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
sometimes clamped to prevent contact with heat-
Note : If unforseen circumstances create conflict ing components. Install such elements as they
between the following servicing precautions and any were.
of the safety precautions, always follow the safety pre-
cautions. Remember: Safety First. (5) After servicing, always check that the removed
screws, components, and wiring have been in-
1-2-1 General Servicing Precautions stalled correctly and that the portion around the
serviced part has not been damaged and so on.
(1) a. Always unplug the instrument's AC power cord Further, check the insulation between the blades of
from the AC power source before (1) re-moving the attachment plug and accessible conductive
or reinstalling any component, circuit board, parts.
module or any other instrument assembly, (2)
disconnecting any instrument electrical plug or 1-2-2 Insulation Checking Procedure
other electrical connection, (3) connecting a test
substitute in parallel with an electrolytic capaci- Disconnect the attachment plug from the AC outlet
tor in the instrument. and turn the power ON. Connect the insulation resi-
b. Do not defeat any plug/socket B+ voltage inter- stance meter (500V) to the blades of the attachment
locks with which instruments covered by this plug. The insulation resistance between each blade of
service manual might be equipped. 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 in- Note : Accessible conductive parts include metal pan-
stalled. els, input terminals, earphone jacks, etc.
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.
Samsung Electronics 1-3
Precautions
1-3 ESD Precautions
Electrostatically Sensitive Devices (ESD) (7) Immediately before removing the protective ma-
terials from the leads of a replacement ESD device,
Some semiconductor (solid state) devices can be dam- touch the protective material to the chassis or cir-
aged easily by static electricity. cuit assembly into which the device will be
Such components commonly are called Electrostati- installed.
cally Sensitive Devices(ESD). Examples of typical ESD
devices are integrated circuits and some field-effect CAUTION : Be sure no power is applied to the ch-
transistors and semiconductor chip components. The assis or circuit, and observe all other safety precau-
following techniques should be used to help reduce tions.
the incidence of component damage caused by static
electricity. (8) Minimize bodily motions when handling unpack-
aged replacement ESD devices. (Otherwise harm-
(1) Immediately before handling any semiconductor less motion such as the brushing together of your
component or semiconductor-equipped assembly, clothes fabric or the lifting of your foot from a car-
drain off any electrostatic charge on your body by peted floor can generate static electricity sufficient
touching a known earth ground. Alternatively, to damage an ESD device).
obtain and wear a commercially available dis-
charging wrist strap device, which should be
removed for potential shock reasons prior to apply-
ing power to the unit under test.
(2) After removing an electrical assembly equipped
with ESD devices, place the assembly on a conduc-
tive surface such as aluminum foil, to prevent elec-
trostatic charge buildup or exposure of the assem-
bly.
(3) Use only a grounded-tip soldering iron to solder or
unsolder ESD devices.
(4) Use only an anti-static solder removal devices.
Some solder removal devices not classified as
"anti-static" can generate electrical charges suffi-
cient to damage ESD devices.
(5) Do not use freon-propelled chemicals. These can
generate electrical charges sufficient to damage
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 short-
ed together by conductive foam, aluminum foil or
comparable conductive materials).
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 elec-
tricity 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
Fig.1-3
chassis is grounded to the sheet.
(6) Short the short terminal on the PCB, which is in-
(3) Place your hands on the conductive sheet(This
side 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 termi-
(5) Perform work on top of the conductive sheet. Be
nal 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
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