Panasonic AG-5700 - Safety Precautions; General Safety Guidelines; Electrostatically Sensitive Device Handling

SAFETY PRECAUTIONS
GENERAL GUIDELINES
1.
When
servicing,
observe
the
origina!
lead
dress.
If
a
short
circuit
is
found,
replace
all
parts
which
have
been
overheated
or
damaged
by
the
short
circuit.
2.
After
servicing,
see
to
it
that
all
the
protective
devices
such
as
insulation
barriers,
insulation
papers
shields
are
properly
installed.
3.
After
servicing,
make
the
following
leakage
current
checks
to
prevent
the
customer
from
being
exposed
to
shock
hazards.
LEAKAGE CURRENT COLD CHECK
1. Unplug the AC cord and connect a jumper between the
two prongs on the plug.
2. Measure the resistance value, with an ohm meter, be-
tween the jumpered AC plug and each exposed metallic
cabinet part on the equipment such as screwheads con-
nectors, control shafts,etc. When the exposed metallic
part has a return path to the chassis, the reading should
be between 1M ohm and 5.2 M ohm.
When the exposed meta! does not have a return path to
the chassis, the reading must be ©o.
LEAKAGE CURRENT HOT CHECK
ee Figure 1)
1. Plug the AC cord directly Into the AC outlet. Do not use
an \solation transformer for this check.
2. Connect a 1.5k ohm, 10 watts resistor, in parallel with a
0.15uF capacitor, between each exposed metallic part
on the set and a good earth ground such as a water pipe,
as shown in Figure 1.
3. Use an AC voltmeter, with 1000 ohms/voit or more sen-
Sitivity, to measure the potential across the resistor.
4. Check each exposed metallic part, and measure the
voltage at each point.
5. Reverse the AC plug in the AC outlet repeat each of the
above measurements.
6. The potential at any point should not exceed 0.75 volts
RMS. A leakage current tester (Simpson Model 229
equivalent) may be used to make the hot checks, leak-
age Current must not exceed 1/2 milliamp. In case a
measurement is outside of the limits specified, there is a
possibility of a shock hazard, and the equipment should
be
repaired
and
rechecked
before
it
is
returned
to
the
customer.
AC VOLTMETER
Hot-Check Circuit
TO
APPLIANCES { COLD
EXPOSED WATER PIPE
METAL PARTS 15002 10W
Figure 1
(EARTH GROUND)
ELECTROSTATICALLY
SENSITIVE (ES) DEVICES
Some semiconductor (solid state) devices can be dam-
aged
easily
by
static
electricity.
Such
components
com-
monly 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 com-
ponent or semiconductor-equipped assembly, drain off
any electrostatic charge on your body by touching a
known earth ground.
Alternatively, obtain and wear a commercialy available
discharging wrist strap device, which should be re-
moved for potential shock reasons prior tio applying
power to the unit under test.
. After ramoving an electrical assembly equipped with ES
devices, place the assembly on a conductive surface
such as aluminum foil, to prevent electrostatic charge
buildup or exposure of the assembly.
. Use only a grounded-tip soldering iron to solder or un-
solder ES devices.
. Use only an anti-static solder removal device classified
as anti-static can generate electrical charges sufficient
to damage ES devices.
. Do not use freon-propelled chemicals. These can gener-
ate electrical charges sufficient to damage ES devices.
. Do not remove a replacement ES device from .its protec-
tive package untilimmediately before you aie ready to
install it. (Most replacementES devices are packaged
with leads eletcrically shorted together by conductive
foam, aluminum foil or comparable conductive mate-
rial).
. Immediately before removing the protective material
from the leads of 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 otner asfety precautons.
. Minimize bodily motions when handling unpackaged
replacement ES devices. (Otherwise harmbss motion
such as the brushing together of your cloths fabric or
the
lifting
of
your
foot
from
a
carpeted
floor
cam
generate
Static electricity sufficient to damage an ES clevice).