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AV-28WFT1EPG
AV-28WFT1EPS
AV-32WFT1EPG
AV-32WFT1EPS
SAFETY PRECAUTIONS AV-28WFTIEPG / AV-32WFTIEPG
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 performed
by qualified personnel
only.
Alterations of the design or circuitry of the products 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.
Many
electrical
and
mechanical
parts in the products
have
special safety-related characteristics. These characteristics are
often not evident from visual inspection nor can the protection
afforded by them 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 shading
on the schematics and by (A\) on the parts list in Service
manual. The use of a substitute replacement which does not
have
the same
safety characteristics
as the recommended
replacement part shown in the parts list of Service manual may
cause shock, fire, or other hazards.
Don't short between the LIVE side ground and ISOLATED
(NEUTRAL)
side
ground
or EARTH
side
ground
when
repairing.
Some model's power circuit is partly different in the GND. The
difference of the GND is shown by the LIVE : (.L) side GND, the
ISOLATED(NEUTRAL) : (4,) side GND and EARTH : (@) side
GND.
Don't
short
between
the
LIVE
side
GND
and
ISOLATED(NEUTRAL)
side GND
or EARTH
side GND
and
never measure with a measuring apparatus (oscilloscope etc.)
the LIVE side GND and ISOLATED(NEUTRAL)
side GND or
EARTH side GND at the same time.
If above note will not be kept, a fuse or any parts will be broken.
If any repair has been made to the chassis, it is recommended
that the
B1
setting
should
be checked
or adjusted
(See
ADJUSTMENT OF B1 POWER SUPPLY).
The high voltage applied to the picture tube must conform with
that specified in Service manual.
Excessive high voltage can
cause
an
increase
in X-Ray
emission,
arcing
and
possible
component damage, therefore operation under excessive high
voltage conditions should be kept to a minimum, or should be
prevented.
If severe
arcing occurs,
remove
the AC
power
immediately
and
determine
the cause
by visual
inspection
(incorrect installation, cracked or melted high voltage harness,
poor soldering, etc.). To maintain the proper minimum level of
soft X-Ray emission, components in. the high voltage circuitry
including the picture tube must be the exact replacements or
alternatives
approved
by the manufacturer
of the complete
product.
Do not check high voltage by drawing an arc. Use a high voltage
meter or a high voltage probe with a VTVM.
Discharge the
picture tube before attempting meter connection, by connecting
a clip lead to the ground frame and connecting the other end of
the lead through a 10kQ 2W resistor to the anode button.
When service is required, observe the original lead dress. Extra
precaution should be given to assure correct lead dress in the
high voltage circuit area. Where
a short circuit has occurred,
those components that indicate evidence of overheating should
be
replaced.
Always
use
the
manufacturer's
replacement
components.
No.51694
9.
AV-28WFT1EPS / AV-32WFT1EPS
Isolation Check
(Safety for Electrical Shock Hazard)
After reassembling
the product, always
perform an isolation
check on
the exposed
metal
parts of the cabinet
(antenna
terminals, video/audio input and output terminals, Control knobs,
metal cabinet, screwheads, earphone jack, control shafts, etc.)
to be sure the product is safe to operate without danger of
electrical shock.
(1) Dielectric Strength Test
The isolation between the AC primary circuit and all metal parts
exposed to the user, particularly any exposed metal part having a
return path to the chassis should withstand a voltage of 3000V
AC (r.m.s.) for a period of one second.
(.... Withstand a voltage of 1100V AC (r.m.s.) to an appliance
rated up to 120V, and 3000V AC (r.m.s.) to an appliance rated
200V or more, for a period of one second.)
This method of test requires a test equipment not generally found
in the service trade.
(2) Leakage Current Check
Plug the AC line cord directly into the AC outlet (do not use a line
isolation
transformer
during this check.).
Using
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 exceed
0.5mA AC (r.m.s.).
However,
in tropical
area,
this must
not exceed
0.2mA
AC
(r.m.s.).
@ Alternate Check Method
Plug the AC line cord directly into the AC outlet (do not use a line
isolation transformer during this check.). Use an AC voltmeter
having 1000 ohms per volt or more sensitivity in the following
manner. Connect a 1500Q 10W resistor paralleled by a 0.15yF
AC-type capacitor 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 voltage across the resistor. Now, reverse the plug in the AC
outlet and repeat each measurement.
Any voltage measured
must not exceed 0.75V AC (r.m.s.).
This corresponds to 0.5mA
AC (r.m.s.).
However, in tropical area, this must not exceed 0.3V AC (r.m.S.).
This corresponds to 0.2mA AC (r.m.s.).
AC VOLTMETER
(HAVING 1000 Q/V,
OR MORE SENSITIVITY)
0.15uF AC-TYPE
PLACE THIS PROBE
ON EACH EXPOSED
1500 Q 10W
METAL PART
GOOD EARTH GROUND
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