1 Precautions
1-2 Servicing Precautions
WARNING1: First read the OSafety Precautions� section of this manual. If unforeseen circumstances
create conflict between the servicing precautions and safety precautions, always
follow the safety precautions.
WARNING2: A high voltage VR replaced in the wrong direction may cause excessive X-ray
emissions.
WARNING3: An electrolytic capacitor installed with the wrong polarity might explode.
1. Servicing precautions are printed on the cabinet,5. Check the insulation between the blades of the AC
and should be followed closely.plug and accessible conductive parts (examples:
2. Always unplug the unitOs AC power cord from themetal panels, input terminals and earphone jacks).
AC power source before attempting to: (a) remove6. Insulation Checking Procedure: Disconnect the
or reinstall any component or assembly, (b)power cord from the AC source and turn the power
disconnect PCB plugs or connectors, (c) connect allswitch ON. Connect an insulation resistance meter
test components in parallel with an electrolytic(500 V) to the blades of the AC plug.
capacitor.The insulation resistance between each blade of the
3. Some components are raised above the printedAC plug and accessible conductive parts (see
circuit board for safety. An insulation tube or tapeabove) should be greater than 1 megohm.
is sometimes used. The internal wiring is
7. Never defeat any of the +B voltage interlocks. Do
sometimes clamped to prevent contact withnot apply AC power to the unit (or any of its
thermally hot components. Reinstall all such
assemblies) unless all solid-state heat sinks are
elements to their original position.correctly installed.
4. After servicing, always check that the screws,
8. Always connect a test instrumentOs ground lead to
components and wiring have been correctlythe instrument chassis ground beforeconnecting the
reinstalled. Make sure that the area around the
positive lead; always remove the instrumentOs
serviced part has not been damaged.ground lead last.
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 devices are integrated circuits and some field-
effect transistors. The following techniques will reduce the incidence of component damage caused by static electricity.
1. Immediately before handling any semiconductor6. Do not remove a replacement ESD from its
components or assemblies, drain the electrostaticprotective package until you are ready to install it.
charge from your body by touching a known earthMost replacement ESDs are packaged with leads
ground. Alternatively, wear a discharging wrist-that are electrically shorted together by conductive
strap device. To avoid a shock hazard, be sure tofoam, aluminum foil or other conductive materials.
remove the wrist strap before applying power to7. Immediately before removing the protective
the monitor.material from the leads of a replacement ESD,
2. After removing an ESD-equipped assembly, place ittouch the protective material to the chassis or
on a conductive surface such as aluminum foil tocircuit assembly into which the device will be
prevent accumulation of an electrostatic charge.installed.
3. Do not use freon-propelled chemicals. These canCaution: Be sure no power is applied to the
generate electrical charges sufficient to damagechassis or circuit and observe all
ESDs.other safety precautions.
4. Use only a grounded-tip soldering iron to solder or
desolder ESDs.8. Minimize body motions when handling
unpackaged replacement ESDs. Motions such as
5. Use only an anti-static solder removal device. Somebrushing clothes together, or lifting your foot from
solder removal devices not classified as Oanti-static�
a carpeted floor can generate enough static
can generate electrical charges sufficient to damageelectricity to damage an ESD.
ESDs.
9.Indicates ESDs on the Schematic Diagram in
this manual.
1-2CHB5**7L/6**7L/7**7L |
ACEC
SAMSUNG
