Jvc UXF 72 MD Service Manual

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UX-F70MD/UX-F72M D

-Safety Precautions

1.This design of this product contains special hardware and 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. Services should be performed by qualified personnel only.

2. Alterations of the design or circuitry of the product should not be made. Any design alterations of

the product should not be made. Any design alterations or additions will void the manufacturers
warranty and will further relieve the manufacture 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 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 the Service Manual. The use of a
substitute replacement which does not have the same safety characteristics as the recommended
replacement parts shown in the Parts List of Service Manual may create shock, fire, or other
hazards.

4.The leads in the products are routed and dressed with ties, clamps, tubings, barriers and the

like to be separated from live parts, high temperature parts, moving parts and/or sharp edges
for the prevention of electric shock and fire hazard. When service is required, the original lead
routing and dress should be observed, and it should be confirmed that they have been returned
to normal, after re-assembling.

5. Leakage currnet check (Electrical shock hazard testing)

After re-assembling the product, always perform an isolation check on the exposed metal parts
of the product (antenna terminals, knobs, metal cabinet, screw heads, headphone jack, control
shafts, etc.) to be sure the product is safe to operate without danger of electrical shock.

Do not use a line isolation transformer during this check.

0 Plug the AC line cord directly into the AC outlet. Using a "Leakage Current Tester", measure
the leakage current from each exposed metal parts of the cabinet, particularly any exposed
metal part having areturn path to the chassis, to a known good earth ground. Any leakage
current must not exceed 0.5mA AC (r.m.s.)

0 Alternate check method
Plug the AC line cord directly into the AC outlet. Use an AC voltmeter having, 1,000 ohms
per volt or more sensitivity in the following manner. Connect a 1,5009 10W resistor paralleled by
a 0.15uF AC-type capacitor between an exposed

AC VOLTMETER
metal part and a known good earth ground. (Having 1000
Measure the AC voltage across the resistor with the ' 7 ohms/volts,
AC voltmeter. or more sensitivity)
Move the resistor connection to eachexposed metal ° °
part, particularly any exposed metal part having a Q15): AC TYPE
return path to the ch'ass1s, and meausre the AC _"_ Placethis
voltage across the reSIstor. Now, reverse the plug In probe on
the AC outlet and repeat each measurement. voltage 'W\, ' > each exposed
measured Any must not exceed 0.75 V AC (r.m.s.). 15009 10W metal part.

This corresponds to 0.5 mA AC (r.m.s.).
Good earth ground

-Warnlng
1.This equipment has been designed and manufactured to meet international safety standards.

2. It is the legal responsibility of the repairer to ensure that these safety standards are maintained.
3. Repairs must be made in accordance with the relevant safety standards.

4. It is essential that safety critical components are replaced by approved parts.

5.lf mains voltage selector is provided, check setting for local voltage.

A CAUTION Burrs formed during molding may be left over on some parts of the chassis. Therefore,

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pay attention to such burrs in the case of preforming repair of this system.