Bedienungsanleitung JVC HD-52Z585 (Seite 3 von 37) (Englisch)

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(No.YA092B)1-3

SECTION 1

PRECAUTIONS

1.1 SAFETY PRECAUTIONS

(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

performed by qualified personnel only.

(2) 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.

(3) 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 that 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 ( ) 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.

(4) Use isolation transformer when hot chassis.

The chassis and any sub-chassis contained in some products are

connected to one side of the AC power line. An isolation transformer

of adequate capacity should be inserted between the product and the

AC power supply point while performing any service on some

products when the HOT chassis is exposed.

(5) 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 : ( ) side GND, the

ISOLATED(NEUTRAL) : ( ) 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.

(6) 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.

(7) 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).

(8) 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

10kΩ 2W resistor to the anode 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. Where a short circuit has occurred, those

components that indicate evidence of overheating should be

replaced. Always use the manufacturer's replacement components.

(10) Isolation Check

(Safety for Electrical Shock Hazard) After re-assembling 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.

a) 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 1100V 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 test equipment not generally

found in the service trade.

b) 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

Ω per volt or more sensitivity in the

following manner. Connect a 1500

Ω 10W resistor paralleled

by a 0.15µF 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.).

(11) High voltage hold down circuit check.

After repair of the high voltage hold down circuit, this circuit shall be

checked to operate correctly.

See item "How to check the high voltage hold down circuit".

AC VOLTMETER

(HAVING 1000 /V,

OR MORE SENSITIVITY)

PLACE THIS PROBE

ON EACH EXPOSED

METAL PART

1500 10W

0.15 F AC-TYPE

GOOD EARTH GROUND

PWB

White line side

WHT

POWER CORD

REPLACEMENT WARNING.

Connecting the white line side of power

cord to "WHT" character side.

A V

This mark shows a fast

operating fuse, the

letters indicated below

show the rating.

JVC HD-52Z585 Seite 3

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