Sam4s ER-900 Series Operation & Programming Manual page 4

1-2 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 power cord 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.
1-3 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 wrist-strap
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
aluminum 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
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
megohm.
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.
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,
aluminum 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.