Hitachi HTD-K210 Service Manual page 23

SERVICING PRECAUTIONS
CAUTION : Before servicing the DVD covered by this
service data and its supplements and ADDENDUMS, read
and follow the SAFETY PRECAUTIONS NOTE : if
unforeseen circumstances create conflict between the
following servicing precautions and any of the safety
precautions in this publications, always follow the safety
precautions.
Remember Safety First:
General Servicing Precautions
1. Always unplug the DVD AC power cord from the AC
power source before:
(1) Removing or reinstalling any component, circuit board,
module, or any other assembly.
(2) Disconnection or reconnecting any internal electrical
plug or other electrical connection.
(3) Connecting a test substitute in parallel with an
electrolytic capacitor
A wrong part substitution or incorrect
Caution :
polarity installation of electrolytic capacitors may
result in an explosion hazard.
2. Do not spray chemicals on or near this DVD or any of its
assemblies.
3. Unless specified otherwise in this service data, clean
electrical contacts by applying an appropriate contact
cleaning solution to the contacts with a pipe cleaner,
cotton-tipped swab, or comparable soft applicator.
Unless specified otherwise in this service data,
lubrication of contacts is not required.
4. Do not defeat any plug/socket B+ voltage interlocks with
witch instruments covered by this service manual might
be equipped.
5. Do not apply AC power to this DVD and/or any of its
electrical assemblies unless all solid-state device heat
sinks are correctly installed.
6. Always connect test instrument ground lead to the
appropriate ground before connection the test
instrument positive lead. Always remove the test
instrument ground lead last.
Insulation Checking Procedure
Disconnect the attachment plug trom the AC outlet and turn
the power on. Connect an insulation resistance meter(500V)
to the blades of the attachment plug. The insulation
resistance between each blade of the attachment plug and
accessible conductive parts (Note 1) should be more than
1M ohm.
Accessible Conductive Parts including Metal
Note 1 :
panels, input terminals, Earphone jacks, etc.
Electrostatically Sensitive (ES) Devices
Some semiconductor (solid state) devices can be damaged
easily by static electricity. Such components commonly are
called Electrostatically Sensitive (ES) Devices. Examples of
typical ES devices are integrated circuits and some field
effect transistors and semiconductor chip components.
The following techniques should be used to help reduce the
incidence of component damage caused by static electricity.
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 ES
devices, place the assembly on a conductive surface
such as aluminum toil, to prevent electrostatic charge
buildup or exposure of the assembly.
3. Use only a GROUNDED-tip soldering iron to solder or
unsolder ES devices.
4. Use only an anti-static solder removal device. Some
solder removal devices not classified a "anti-static" can
generate electrical charges sufficient to damage ES
devices.
5. Do not use freon-propelled chemicals. These can
generate electrical charge sufficient to damage ES
devices.
6. Do not remove a replacement ES device from its
protective package until immediately before you are
ready to install it. (Most replacement ES devices are
packaged with leads electrically shorted together by
conductive foam, aluminum foil, or comparable
conductive material.)
7. Immediately before removing the protective material
from the leads of a replacement ES device, touch the
protective material to the chassis or circuit assembly
into which the device will be installed.
Caution : Be sure no power is applied to the chassis or
circuit, and observe all other safety precautions.
8. Minimize bodily motions when handling unpackaged
replacement ES devices. (Normally harmless motion
such as the brushing together of your clothes fabric or the
lifting of your foot from a carpeted floor can generate
static electricity sufficient to damage an ES device.)
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