Samsung AN17HS - Page 2

1
Precautions
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1-1 Safety Precautions
WARNINGS
1. For continued safety, do not attempt to modify the
circuit board.
2. Disconnect the AC power before servicing.
3. When the chassis is operating, semiconductor
heatsinks are potential! shock hazards.
1-1-1 Servicing the High Voltage and CRT:
1. When servicing the high voltage system, remove
the static charge by connecting a 10 kohm resistor
in series with an insulated wire (such as a test
probe) between the chassis and the anade lead.
i)
When troubleshooting a monitor with excessively
RY, avoid being unnecessarily close to the monitor.
Do not operate the monitor for longer than is
necessary to locate the cause of excessive voltage.
3. High voltage should always be kept at the rated
value, no higher. Only when high voltage is
excessive are X-rays capable of penetrating the shell
of the CRT, including the lead in glass material.
Operation at high voltages may also cause failure of
the CRT or high voltage circuitry.
4. When the HV regulator is operating properly, there
is no possibility of an X-ray problem. Make sure the
HV does not exceed its specified value and that it is
regulating correctly.
5. The CRT is especially designed to prohibit
X-ray emissions. To ensure continued X-ray
protection, replace the CRT only with one that is
the same or equivalent type as the original.
6. Handle the CRT only when wearing shatterproof
goggles and after completely discharging the high
voltage anode.
7. Do not lift the CRT by the neck.
1-1-2 Fire and Shock Hazard :
Before returning, the monitor to the user, perform the
following safety checks:
1. Inspect each lead dress to make certain that the
Jeads are net pinched or that hardware is not
lodged between the chassis and other metal parts in
the monitor,
2. Inspect all protective devices such as nonmetallic
control knobs, insulating materials, cabinet backs,
adjustment and compartment covers or shields,
ischation resistor-capacitar networks, mechanical
insuistars, ete
ANI7HS/AN171S/
ANISMS/ANTSIS/ANTSMT
3. Leakage Current Hot Check (Figure 1-1}:
WARNING: Do not use an isolation transformer during
this test.
Use a leakage current tester or a metering system
that complies with American * ational Standards
Institute (ANS) C101.1, Leakage Current for
Appliances), and Underwriters Laboratories (LIL
Publication ULT419, 59.7).
4. With the unit completely reassembled, plug the AC
line cord directly into a 120V AC outlet. With the
unit's AC switch first in the ON position and then
OFF, measure the current between a known earth
ground (meta! water pipe, conduit, etc.) and all
exposed metal! parts, including: metal cabinets,
screwheads and contro} shafts. The current
measured should not exceed 0.5 milliamp. Reverse
the power-plug prongs in the AC outlet and repeat
the test.
——
(READING SHOULD
NOT BE AROVE O.5mAi
LEAKAGE
poviCe CURRENT
we TESTER
TEST ALL
EXPOSED METAL
SURFACES
2-WIRE CORD.
ALSO TEST WITH
PLUG REVERSED
(USING AC ADAPTER
PLUG AS REQUIRED)
EARTH
ROUND
Figure 1-1. Leakage Current Test Circuit
1-1-3 Product Safety Notices
Some electrical and mechanical parts have special
safety-related characteristics which are often not
evident from visual inspection. The protection they give
may not be obtained by replacing them with
components rated for higher voltage, wattage, etc. Parts
that have special safety characteristics are identified by
ZX on schematics and parts lists. A substitute :
replacement that does not hay e the same safety
characteristics as the recommended rept
might create shock. fire andor other ha
hasment part
ards. Product
sdiety is under review continuously and nein
instructions are issued when e: eppropricte,
Components identitied by ive) on schematics and parts
lists must be sealed by a solctering iron after
yeplacement and adjustment.
1 Precautions
1-2 Servicing Precautions
WARNING 1: First read the “Safety Precautions” section of this manual. If unforeseen
circumstances create conflict between the servicing precautions and safety
precautions, always follow the safety precautions.
WARNING 2: A high voitage VR replaced in the wrong direction may cause excessive X-ray
emissions.
WARNING 3 : An electrolytic capacitor installed with the wrong polarity might explode.
1.
i)
w
Servicing precautions are printed on the cabinet, 5
and should be followed closely.
Always unplug the unit’s AC power cord from the
AC power source before attempting to: (a) remove 6.
or reinstall any component or assembly, (b)
disconnect PCB plugs or connectors, (c) connect all
test components in parallel with an electrolytic
capacitor.
Some components are raised above the printed
circuit board for safety. An insulation tube or tape
is sometimes used. The interna! wiring is 7
sometimes clamped to prevent contact with
thermally hot components. Reinstall all such
elements to their origina! position.
After servicing, always check that the screws, 8,
components and wiring have been correctly
reinstalled. Make sure that the area around the
serviced part has not been damaged.
Check the insulation between the blades af the AC
plug and accessible conductive parts (examples:
metal panels, input terminals and earphone jacks).
Insulation Checking Procedure: Disconnect the
power cord from the AC source and turn the power
switch ON. Connect an insulation resistance meter
(300 V) to the blades of the AC plug.
The insulation resistance between each blade of the
AC plug and accessible conductive parts (see
above) should be greater than 1 megohm.
Never defeat any of the +B voltage interlocks. Do
not apply AC power to the unit (or any of its
assemblies) unless all solid-state heat sinks are
correctly installed.
Always connect a test instrument's ground lead to
the instrument chassis ground before connecting
the positive lead; always remove the instrument's
ground lead Jast.
1-3 Electrostatically Sensitive Devices (ESD) Precautions
Some semiconductor (solid state) devices can be easily damaged by static electricity. Such components are commonly
called Electrostatically Sensitive Devices (ESD). Examples of typical ESD are integrated circuits and some field-effect
transistors. The following techniques will reduce the inciderice of component damage caused by static electr:
bo
a)
wn
12
Immediately before handling any semiconductor 6.
components or assemblies, drain the electrostatic
charge from your body by touching a known earth
ground. Alternatively, wear a discharging wrist-
strap device. To avoid a shock hazard, be sure to
remove the wrist strap before applying power to
the monitor,
Atler removing an ESD-equigyped assembly, place it
ena conductive surface s uminum foil to
prevent accumulation ef ane
Do not use treon-propelled cher
generate electrical charges suiticic
Ess.
Use only a grounded-tip soldering iron fo sulder or
yay
:
8
desolder ESDs.
Use only an anti-static solder removal device. Some
solder removal devices not classified as “anti-static”
can generate electrical charges sufficient to damage
ESDs. -
9.
NI
Do not remove a replacement ESD from its
protective package until you are ready to install it.
Most replacement ESDs are packaged with leads
that are electrically shorted together by conductive
foam, aluminum foil or other conductive materials.
Immediately before removing the protective
material from the leads of a replacement ESD,
Jtitasis OF
touch the protective riaterial to tl
cirenit assembly into which the device will be
installed
Caution: Be sure no power is anplicd to the
chassis or circuit and observe al
other safety precautions
Minimize budy motions when handling
umpackaged replacement ESDs. Motions such as
brushing clothes together, or lifting your foot from
a carpeted floor can generate enough static
electricity to damage an ESD.
A\ Indicates ESDs on the Schematic Diagram in
this manual.
ANI7HS/ANT7iS/
ANISMS/AN1SIS/ANTSMT