JVC KD-AVX55A, Service Manual

(No.MA454<Rev.001>)1-5

SECTION 1

PRECAUTION

1.1

Safety Precautions

(1) This design of this product contains special hardware and

many circuits and components specially for safety  purpos-
es. 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 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
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 characteris-
tics are often not evident from visual inspection nor can the
protection afforded by them necessarily be obtained by us-
ing replacement components rated for higher voltage, watt-
age, etc. Replacement parts which  have these special
safety characteristics are identified in the Parts List of Ser-
vice Manual. Electrical components having such features
are identified by shading on the schematics and by (   ) on
the Parts List in the Service Manual. The use of a substitute
replacement which does not have the same safety charac-
teristics 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 reassem-
bling.

(5) Leakage shock hazard testing

After reassembling the product, always perform an isola-
tion check on the exposed metal parts of the product (an-
tenna 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.
• 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, particular-
ly any exposed metal part having a return path to the
chassis, to a known good earth ground. Any leakage cur-
rent must not exceed 0.5mA AC (r.m.s.).

• Alternate check method

Plug the AC line cord directly into the AC outlet. Use an
AC voltmeter having, 1,000

Ω

 per volt or more sensitivity

in the following manner. Connect a 1,500

Ω

 10W resistor

paralleled by a 0.15

µ

F AC-type capacitor between an ex-

posed metal part and a known good earth ground.
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. Voltage measured any must
not exceed 0.75 V AC (r.m.s.). This corresponds to  0.5
mA AC (r.m.s.). 

1.2

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) It is essential that safety critical components are replaced

by approved parts.

(5) If mains voltage selector is provided, check setting for local

voltage.

1.3

Caution

Burrs formed during molding may be left over on some parts
of the chassis. 
Therefore, pay attention to such burrs in the case of pre-
forming repair of this system.

1.4

Critical parts for safety

In regard with component parts appearing on the silk-screen
printed side (parts side) of the PWB diagrams, the parts that are
printed over with black such as the resistor ( 

 ), diode ( 

 )

and ICP ( 

 ) or identified by the "   " mark nearby are critical

for safety.  When replacing them, be sure to use the parts of the
same type and rating as specified by the manufacturer. 
(This regulation dose not Except the J and C version)

Good earth ground

Place this 
probe on 
each exposed
metal part.

AC VOLTMETER
(Having 1000 
ohms/volts,
or more sensitivity)

1500     10W

0.15   F  AC TYPE