AV-28X37SUE AV-28X37HKE
AV-28X35HKE AV-28X37HIE
AV-28H35SUE AV-28H35BUE
AV-28X35HUE
SECTION 1
PRECAUTIONS
1.1 SAFETY PRECAUTIONS [EXCEPT FOR UK]and connecting the other end of the lead through a 10k
2W resistor to the anode button.
(1) The design of this product contains special hardware,
(8) When service is required, observe the original lead dress.
many circuits and components specially for safety
Extra precaution should be given to assure correct lead
purposes. For continued protection, no changes should be
dress in the high voltage circuit area. Where a short circuit
made to the original design unless authorized in writing by
has occurred, those components that indicate evidence of
the manufacturer. Replacement parts must be identical to
overheating should be replaced.
those used in the original circuits. Service should be
Always use the manufacturer?s replacement components.
performed by qualified personnel only.
(9) Isolation Check
(2) Alterations of the design or circuitry of the products should
(Safety for Electrical Shock Hazard)
not be made. Any design alterations or additions will void
After re-assembling the product, always perform an
the manufacturer?s warranty and will further relieve the
isolation check on the exposed metal parts of the cabinet
manufacturer of responsibility for personal injury or
(antenna terminals, video/ audio input and output
property damage resulting therefrom.
terminals, Control knobs, metal cabinet, screw heads,
(3) Many electrical and mechanical parts in the products have
earphone jack, control shafts, etc.) to be sure the product
special safety-related characteristics. These
is safe to operate without danger of electrical shock.
characteristics are often not evident from visual inspection
a) Dielectric Strength Test
nor can the protection afforded by them necessarily be
The isolation between the AC primary circuit and all metal
obtained by using replacement components rated for
parts exposed to the user, particularly any exposed metal
higher voltage, wattage, etc. Replacement parts which
part having a return path to the chassis should withstand a
have these special safety characteristics are identified in
voltage of 3000V AC (r.m.s.) for a period of one second. (.
the parts list of Service manual. Electrical components
. . . Withstand a voltage of 1100V AC (r.m.s.) to an
having such features are identified by shading on the
appliance rated up to 120V, and 3000V AC (r.m.s.) to an
schematics and by ( ) on the parts list in Service
appliance rated 200V or more, for a period of one second.)
manual. The use of a substitute replacement which does
This method of test requires a test equipment not generally
not have the same safety characteristics as the
found in the service trade.
recommended replacement part shown in the parts list of
b) Leakage Current Check
Service manual may cause shock, fire, or other hazards.
Plug the AC line cord directly into the AC outlet (do not use
(4) Don?t short between the LIVE side ground and
a line isolation transformer during this check.). Using a
ISOLATED (NEUTRAL) side ground or EARTH side
?Leakage Current Tester?, measure the leakage current
ground when repairing.
from each exposed metal part of the cabinet, particularly
Some model?s power circuit is partly different in the GND.
any exposed metal part having a return path to the chassis,
The difference of the GND is shown by the LIVE : ( ) side
to a known good earth ground (water pipe, etc.). Any
GND, the ISOLATED (NEUTRAL) : ( ) side GND and
leakage current must not exceed 0.5mA AC (r.m.s.).
EARTH : ( ) side GND.
However, in tropical area, this must not exceed 0.2mA AC
Don't short between the LIVE side GND and ISOLATED
(r.m.s.).
(NEUTRAL) side GND or EARTH side GND and never
measure the LIVE side GND and ISOLATED (NEUTRAL)Alternate Check Method
side GND or EARTH side GND at the same time with aPlug the AC line cord directly into the AC outlet (do not
measuring apparatus (oscilloscope etc.). use a line isolation transformer during this check.). Use an
If above note will not be kept, a fuse or any parts will beAC voltmeter having 1000 ohms per volt or more
broken.sensitivity in the following manner. Connect a 1500 ohm
(5) If any repair has been made to the chassis, it is10W resistor paralleled by a 0.15?F AC-type capacitor
recommended that the B1 setting should be checked orbetween an exposed metal part and a known good earth
adjusted (See ADJUSTMENT OF B1 POWER SUPPLY).ground (water pipe, etc.). Measure the AC voltage across
(6) The high voltage applied to the picture tube must conformthe resistor with the AC voltmeter. Move the resistor
with that specified in Service manual. Excessive highconnection to each exposed metal part, particularly any
voltage can cause an increase in X-Ray emission, arcingexposed metal part having a return path to the chassis,
and possible component damage, therefore operationand measure the AC voltage across the resistor. Now,
under excessive high voltage conditions should be kept toreverse the plug in the AC outlet and repeat each
a minimum, or should be prevented. If severe arcingmeasurement. Any voltage measured must not exceed
occurs, remove the AC power immediately and determine0.75V AC (r.m.s.). This corresponds to 0.5mA AC (r.m.s.).
the cause by visual inspection (incorrect installation,However, in tropical area, this must not exceed 0.3V AC
cracked or melted high voltage harness, poor soldering,(r.m.s.). This corresponds to 0.2mA AC (r.m.s.).
etc.). To maintain the proper minimum level of soft X-RayAC VOLTMETER
(HAVING 1000 /V,
emission, components in the high voltage circuitry
OR MORE SENSITIVITY)
including the picture tube must be the exact replacements
or alternatives approved by the manufacturer of the
complete product.
(7) Do not check high voltage by drawing an arc. Use a high0.15 F AC-TYPE
voltage meter or a high voltage probe with a VTVM.
PLACE THIS PROBE
Discharge the picture tube before attempting meterON EACH EXPOSED1500 10W
METAL PART
connection, by connecting a clip lead to the ground frameGOOD EARTH GROUND
1-4 (No.52106) |
ACEC
