Jvc RX 777 VBK Service Manual

Page 2

RX-771VBK
RX-777VSBK
RX-777VLBK

-Safety Precautions

1. The design of this product contains special hardware and many circuits a'nd components specially for safety purposes.

For continued protection, no changes should be made to the original design unless auth_orized in writing by the
manufacturer. Replacement parts must be identical to those used in the originarc'irTfiTits. Service should be per-

: formed 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 manufacturer of responsibility for personal injury or property damage resulting therefrom.

3. Many electrical and mechanical parts in the product have special safety 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 sub-
stitute replacement which does not have the same safety characteristics as the recommended replacement part shown

5 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.

Leakage current 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 iack, 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 part of the cabinet, particularly any exposed metal part having a return path to the
chassis, to a known good earth ground. Any leakage current must not exceed 0.5 mA AC (r.m.s.).

0 Alternate check method
Plug the AC line cord directly into the AC ontlet. Use an AC voltmeter having 1,000 ohms par volt or more sensi="
tivity in the following manner. Connect a 1,500 9 10 W resistor paralleled by a 0.15 pF AC-type capacitor be-
tween an exposed metal part and a known good earth ground.

Measure the AC voltage across the resistor with the AC VOLTMETER
AC voltmeter. E (Having 1000 ohms/volt,

. _ or more sensitivityJ
Move the resistor connection to each exposed metal
part, particularly any exposed metal part having a Lj-
return path to the chassis, and measure the AC volt- 5" AC "PE
age across the resistor. Now, reverse the plug in the Place this probe
AC outlet and repeat each measurement.'Any voltage 41w» . on each exposed
measured must not exceed 0.75 VAC (r.m.s.i. This isoon low metal part.
corresponds to 0.5 mA AC lr.m.s.l.

S"

r

Good earth ground

-Warning

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.

5.

It is essential that safety critical components are replaced by approved parts.
If mains voltage selector is provided, check setting for local voltage.

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