AV-27320
AV-27330
AV-27S33
SAFETY PRECAUTIONS
1. The design of this product contains special hardware, many10. Isolation Check
circuits and components specially for safety purposes. For(Safety for Electrical Shock Hazard)
continued protection, no changes should be made to theAfter re-assembling the product, always perform an isolation
original design unless authorized in writing by the manufacturer.check on the exposed metal parts of the cabinet (antenna
Replacement parts must be identical to those used in theterminals, video/audio input and output terminals, Control
original circuits. Service should be performed by qualifiedknobs, metal cabinet, screwheads, earphone jack, control
personnel only.shafts, etc.) to be sure the product is safe to operate without
2. Alterations of the design or circuitry of the products should notdanger of electrical shock.
be made. Any design alterations or additions will void the(1) Dielectric Strength Test
manufacturer's warranty and will further relieve theThe isolation between the AC primary circuit and all metal parts
manufacturer of responsibility for personal injury or propertyexposed to the user, particularly any exposed metal part having
damage resulting therefrom.a return path to the chassis should withstand a voltage of
3. Many electrical and mechanical parts in the products have1100V AC (r.m.s.) for a period of one second.
special safety-related characteristics. These characteristics are(. . . . Withstand a voltage of 1100V AC (r.m.s.) to an appliance
often not evident from visual inspection nor can the protectionrated up to 120V, and 3000V AC (r.m.s.) to an appliance rated
afforded by them necessarily be obtained by using200V or more, for a period of one second.)
replacement components rated for higher voltage, wattage, etc.This method of test requires a test equipment not generally
Replacement parts which have these special safetyfound in the service trade.
characteristics are identified in the parts list of Service manual.(2) Leakage Current Check
Electrical components having such features are identifiedPlug the AC line cord directly into the AC outlet (do not use a
by shading on the schematics and by (!!!!) on the parts listline isolation transformer during this check.). Using a "Leakage
in Service manual. The use of a substitute replacement whichCurrent Tester", measure the leakage current from each
does not have the same safety characteristics as theexposed metal part of the cabinet, particularly any exposed
recommended replacement part shown in the parts list ofmetal part having a return path to the chassis, to a known good
Service manual may cause shock, fire, or other hazards.earth ground (water pipe, etc.). Any leakage current must not
4. Use isolation transformer when hot chassis.exceed 0.5mA AC (r.m.s.).
The chassis and any sub-chassis contained in some productsHowever, in tropical area, this must not exceed 0.2mA AC
are connected to one side of the AC power line. An isolation(r.m.s.).
transformer of adequate capacity should be inserted between"""" Alternate Check Method
the product and the AC power supply point while performingPlug the AC line cord directly into the AC outlet (do not use a
any service on some products when the HOT chassis isline isolation transformer during this check.). Use an AC
exposed.voltmeter having 1000 ohms per volt or more sensitivity in the
5. Don't short between the LIVE side ground and ISOLATEDfollowing manner. Connect a 1500? 10W resistor paralleled
(NEUTRAL) side ground or EARTH side ground whenby a 0.151F AC-type capacitor between an exposed metal
repairing.
part and a known good earth ground (water pipe, etc.).
Some model's power circuit is partly different in the GND. TheMeasure the AC voltage across the resistor with the AC
difference of the GND is shown by the LIVE : (") side GND,voltmeter. Move the resistor connection to each exposed metal
the ISOLATED(NEUTRAL) : (#) side GND and EARTH : ($)part, particularly any exposed metal part having a return path to
side GND. Don't short between the LIVE side GND and
the chassis, and measure the AC voltage across the resistor.
ISOLATED(NEUTRAL) side GND or EARTH side GND and
Now, reverse the plug in the AC outlet and repeat each
never measure with a measuring apparatus (oscilloscope etc.)
measurement. Any voltage measured must not exceed 0.75V
the LIVE side GND and ISOLATED(NEUTRAL) side GND orAC (r.m.s.). This corresponds to 0.5mA AC (r.m.s.).
EARTH side GND at the same time.However, in tropical area, this must not exceed 0.3V AC
If above note will not be kept, a fuse or any parts will be broken.(r.m.s.). This corresponds to 0.2mA AC (r.m.s.).
6. If any repair has been made to the chassis, it is recommended
that the B1 setting should be checked or adjusted (See
AC VOLTMETER
ADJUSTMENT OF B1 POWER SUPPLY).
(HAVING 1000?/V,
7. The high voltage applied to the picture tube must conform withOR MORE SENSITIVITY)
that specified in Service manual. Excessive high voltage canGOOD
EARTH
cause an increase in X-Ray emission, arcing and possible
GROUND
component damage, therefore operation under excessive high0.151F AC-TYPE
voltage conditions should be kept to a minimum, or should bePLACE THIS PROBE
prevented. If severe arcing occurs, remove the AC powerON EACH EXPOSED
immediately and determine the cause by visual inspectionMETAL PART
1500? 10W
(incorrect installation, cracked or melted high voltage harness,
poor soldering, etc.). To maintain the proper minimum level of
11. High voltage hold down circuit check.
soft X-Ray emission, components in the high voltage circuitry
After repair of the high voltage hold down circuit, this circuit
including the picture tube must be the exact replacements or
shall be checked to operate correctly.
alternatives approved by the manufacturer of the complete
See item "How to check the high voltage hold down
product.
circuit".
8. Do not check high voltage by drawing an arc. Use a high
voltage meter or a high voltage probe with a VTVM. Discharge
This mark shows a fast
the picture tube before attempting meter connection, by
connecting a clip lead to the ground frame and connecting theoperating fuse, the
letters indicated below
other end of the lead through a 10k? 2W resistor to the anode
show the rating.
button.
9. 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. W here a short circuit has
occurred, those components that indicate evidence of
overheating should be replaced. Always use theA V
manufacturer's replacement components.
No. 519373 |
ACEC
JVC
