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TD-W20A/B/C/E/G/J/U
Safety precaution
1. The design
of this product contains special hardware.
Many
circuits
and
components
specially
for
safety
purposes.
.
For continued protection, no changes should be made to
the original design unless authorized
in writing by the
manufacturer.
Replacement
parts must be identical to
those used in the original circuits. Service should be per-
formed by qualified personnel only.
2. Alterations
of the design or circuitry
of the product
should not be made. Any design alterations or additions
will void the manufacturer's warranty and will further
relieve the manufacturer
of responsibility for personal
injury or property damage resulting therefrom.
3. Many
electrical
and
mechanical
parts
in the product
have special safety-related characteristics. These charac-
teristics
are
often
not evident
from
visual
inspection
nor can
the protection
afforded
by then necessarily be
obtained
by using replacement
components
rated
for
higher voltage, wattage,
etc. Replacement
parts which
have these special safety characteristics are identified in
the parts list of Service manual. Electrical components
having
such
features
are
identified
by
( Z\) on the
schematics and parts list in Service manual. The use of
a substitutue replacement which does not have the same
safety characterisitics as the recommended
replacement
part
shown
in the
parts
list in Service
manual
may
create shock, fire, or other hazards.
4. The leads in the products are routed and dressed with
ties, clamps,
tubings
barriers
and/or
the
like to be
separated from live parts, high temperature
part, mov-
ing parts and/or sharp edges for the prevention of elec-
tric shock and fire hazard.
When
service is required, the original lead routing and
dress should be observed, and they should be confirmed
to be returned to normal, after re-assembling.
2 (No. 4256)
5, Leakage current check
(Safety for electrical shock hazard)
After
re-assembling
the
product,
always
perform
an
isolation check on the exposed
metal parts of the Pro-
ducts
(antenna
terminals,
knobs,
metal cabinet, screw
heads, earphone jack, contro! shafts, etc.) to be sure the
product is safe to operate without danger of electrical
shock.
Do not use a line isolation transformer during this check.
e Plug the AC line cord directly into the AC outlet. Us-
ing a 'Leakage Current Tester', measure the leakage
current from each exposed metal part of the cabinet,
particularly
any
exposed
metal
part having a return
path to the chassis, to a known
good earth ground
(water pipe, etc,). Any leakage current must not ex-
ceed 0.5 mA AC (r.m.s.).
e
Alternate check method.
Plug the AC line cord directly into the AC outlet. Use
an AC voltmeter
having 1,000 ohms per volt or mroe
sesitivity in the following manner. Connect a 1500 2
10.W
resistor paralleled by a 0.15 uF AC-type capaci-
tor between an exposed metal part and a known good
earth ground (water pipe, etc.).
Measure the AC voltage across the resistor with the
AC voltmeter.
Move the resistor connection to each exposed metal
part,
particularly
any
exposed
metal
part
having a
return path to the chassis, and measure the AC volt-
age across the resistor. Now, reverse the plug in the
AC outlet and repeat each measurement. Any voltage
measured musy not exceed 0.75 V AC (r.m.s.).
This corresponds to 0.5 mA AC (r.m.s.).
AC VOLTMETER
(HAVING
1000 2/V OR
MORE
SENSITIVITY)
O.1SpF AC- TYPE
GOOO
EARTH
GROUND
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