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Servicing Precautions
WARNING: First read the-Safety Precautions-section of this manual. If some unforeseen circumstance creates
a conflict between the servicing and safety precautions, always follow the safety precautions.
WARNING: An electrolytic capacitor installed with the wrong polarity might explode.
1. Servicing precautions are printed on the cabinet.
Follow them.
2. Always unplug the units AC/DC Adaptor from the
AC power source before attempting to:
(a) Remove or reinstall any component or
assembly
(b) Disconnect an electrical plug or connector
(c) Connect a test component in parallel with an
electrolytic capacitor
3. Some components are raised above the printed
circuit board for safety. An insulation tube or
tape is sometimes used. The internal wiring is
sometimes clamped to prevent contact with
thermally hot components. Reinstall all such
elements to their original position.
4. After servicing, always check that the screws,
components and wiring have been correctly
reinstalled. Make sure that the portion around the
serviced part has not been damaged.
5. Check the insulation between the blades of the
AC plug and accessible conductive parts
(examples: metal panels and input terminals).
6. Insulation Checking Procedure:
Disconnect the power cord from the AC source
and turn the power switch ON. Connect an
insulation resistance meter (500V) to the blades
of AC plug.
The insulation resistance between each blade of
the AC plug and accessible conductive parts (see
above) should be greater than 1 mega ohm.
7. 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.
8. Always connect an instrument’s ground lead to
the instrument chassis ground before connecting
the positive lead ;
Always remove the instrument’s ground lead last.
Precautions for Electrostatically Sensitive Devices (ESDs)
1. Some semiconductor (solid state) devices are
easily damaged by static electricity. Such
components are called Electrostatically Sensitive
Devices (ESDs); examples include integrated
circuits and some field-effect transistors. The
following techniques will reduce the occurrence
of component damage caused by static
electricity.
2. Immediately before handling any semiconductor
components or assemblies, drain the electrostatic
charge from your body by touching a known earth
ground. Alternatively, wear a discharging wriststrap device. (Be sure to remove it prior to
applying power - this is an electric shock
precaution.)
3. After removing an ESD-equipped assembly,
place it on a conductive surface such as
aluminium foil to prevent accumulation of
electrostatic charge.
4. Do not use freon-propelled chemicals. These
can generate electrical charges that damage
ESDs.
5. Use only a grounded-tip soldering iron when
soldering or unsoldering ESDs.
6. Use only an anti-static solder removal device.
Many solder removal devices are not rated as
anti-static; these can accumulate sufficient
electrical charge to damage ESDs.
7. 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, aluminium foil or other
conductive materials.
8. Immediately before removing the protective
material from the leads of a replacement ESD,
touch the protective material to the chassis or
circuit assembly into which the device will be
installed.
9. Minimize body motions when handling
unpackaged replacement ESDs. Motions such
as brushing clothes together or lifting a foot
from a carpeted floor can generate enough
static electricity to damage an ESD.