SECTION 1
PRECAUTION
1.1 SAFETY PRECAUTIONS
(1) The design of this product contains special hardware, many(10) Isolation Check (Safety for Electrical Shock Hazard)
circuits and components specially for safety purposes. ForAfter re-assembling the product, always perform an isolation
continued protection, no changes should be made to the originalcheck on the exposed metal parts of the cabinet (antenna
design unless authorized in writing by the manufacturer.terminals, video/audio input and output terminals, Control knobs,
Replacement parts must be identical to those used in the originalmetal cabinet, screw heads, earphone jack, control shafts, etc.) to
circuits. Service should be performed by qualified personnel only.be sure the product is safe to operate without danger of electrical
(2) Alterations of the design or circuitry of the products should not beshock.
made. Any design alterations or additions will void thea) Dielectric Strength Test
manufacturer's warranty and will further relieve the manufacturerThe isolation between the AC primary circuit and all metal parts
of responsibility for personal injury or property damage resultingexposed to the user, particularly any exposed metal part having a
therefrom.return path to the chassis should withstand a voltage of 1100V AC
(3) Many electrical and mechanical parts in the products have special(r.m.s.) for a period of one second.
safety-related characteristics. These characteristics are often not(. . . . Withstand a voltage of 1100V AC (r.m.s.) to an appliance rat-
evident from visual inspection nor can the protection afforded by themed up to 120V, and 3000V AC (r.m.s.) to an appliance rated 200V
necessarily be obtained by using replacement components rated foror more, for a period of one second.) This method of test requires
higher voltage, wattage, etc. Replacement parts which have thesea test equipment not generally found in the service trade.
special safety characteristics are identified in the parts list of Serviceb) Leakage Current Check
manual. Electrical components having such features arePlug the AC line cord directly into the AC outlet (do not use a line
identified by shading on the schematics and by ( ) on theisolation transformer during this check.). Using a "Leakage
parts list in Service manual. The use of a substitute replacementCurrent Tester", measure the leakage current from each exposed
which does not have the same safety characteristics as themetal part of the cabinet, particularly any exposed metal part
recommended replacement part shown in the parts list of Servicehaving a return path to the chassis, to a known good earth ground
manual may cause shock, fire, or other hazards.(water pipe, etc.). Any leakage current must not exceed 0.5mA AC
(4) Use isolation transformer when hot chassis.(r.m.s.).
The chassis and any sub-chassis contained in some products areHowever, in tropical area, this must not exceed 0.2mA AC (r.m.s.).
connected to one side of the AC power line. An isolationAlternate Check Method
transformer of adequate capacity should be inserted between thePlug the AC line cord directly into the AC outlet (do not use a
product and the AC power supply point while performing anyline isolation transformer during this check.). Use an AC
service on some products when the HOT chassis is exposed.voltmeter having 1000& per volt or more sensitivity in the
(5) Don't short between the LIVE side ground and ISOLATED (NEU-following manner. Connect a 1500& 10W resistor paralleled by
TRAL) side ground or EARTH side ground when repairing. a 0.15?F AC-type capacitor between an exposed metal part
Some model's power circuit is partly different in the GND. The differ-and a known good earth ground (water pipe, etc.). Measure the
ence of the GND is shown by the LIVE : ( ) side GND, the ISOLAT-AC voltage across the resistor with the AC voltmeter. Move the
ED (NEUTRAL) : ( ) side GND and EARTH : ( ) side GND. resistor connection to each exposed metal part, particularly any
Don't short between the LIVE side GND and ISOLATED (NEUTRAL)exposed metal part having a return path to the chassis, and
side GND or EARTH side GND and never measure the LIVE sidemeasure the AC voltage across the resistor. Now, reverse the
GND and ISOLATED (NEUTRAL) side GND or EARTH side GND atplug in the AC outlet and repeat each measurement. Any
the same time with a measuring apparatus (oscilloscope etc.). Ifvoltage measured must not exceed 0.75V AC (r.m.s.). This
above note will not be kept, a fuse or any parts will be broken.corresponds to 0.5mA AC (r.m.s.).
(6) If any repair has been made to the chassis, it is recommended thatHowever, in tropical area, this must not exceed 0.3V AC
the B1 setting should be checked or adjusted (See B1 POWER(r.m.s.). This corresponds to 0.2mA AC (r.m.s.).
SUPPLY check).
AC VOLTMETER
(7) The high voltage applied to the picture tube must conform with that(HAVING 1000 /V,
OR MORE SENSITIVITY)
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.
0.15 F AC-TYPE
If severe arcing occurs, remove the AC power immediately and
determine the cause by visual inspection (incorrect installation,PLACE THIS PROBE
ON EACH EXPOSED
cracked or melted high voltage harness, poor soldering, etc.). To1500 10WMETAL PART
maintain the proper minimum level of soft X-Ray emission,GOOD EARTH GROUND
(11) High voltage hold down circuit check.
components in the high voltage circuitry including the picture tube
After repair of the high voltage hold down circuit, this circuit shall
must be the exact replacements or alternatives approved by the
manufacturer of the complete product.be checked to operate correctly.See item "How to check the high
(8) Do not check high voltage by drawing an arc. Use a high voltagevoltage hold down circuit".
meter or a high voltage probe with a VTVM. Discharge the picture
tube before attempting meter connection, by connecting a clip leadThis mark shows a fast POWER CORD
operating fuse, the REPLACEMENT WARNING.
to the ground frame and connecting the other end of the leadletters indicated belowConnecting the white line side of power
through a 10k& 2W resistor to the anode button. show the rating.cord to "WHT" character side.
(9) When service is required, observe the original lead dress. ExtraPWB
White line side
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 beA VPW
WHT
replaced. Always use the manufacturer's replacement
components.
(No.YA166)1-3 |
ACEC
