Jvc UXA 3 Service Manual

Page 1

UX7A3 A/C

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Contents - « a» »< ms we
Page
III Safety Precautions ..................... Main Adjustments . 44
IZI Safety Precautions about JX-A3 .. E} Block Diagram ...... 51
IE Freatures ....... Wiring Connections ................ 53
IE Specifications . IE Standard Schematic Diagram .. 54
E] Instructions (Extraci) ..... IE Elecfrical Parts List 66
IE Location of Main Parts . . IE Illustration of Packing and Parts List . 75
Removal of Main Parts and Parts List ................ 30 I Accessories ....................................... Back Cover
W

No. 1860
June 1992

Page 2

UX-A3 A/C/J/U

- 1 Safety Precautions

1. The 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. Service 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 manufacturer's warranty and will further
relieve the manufacturer or responsibility for personal injury or property damage resulting therefrom.

3. Many electrical and mechanical parts in the product 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 (A) on the schematic diagram and Parts List in Service Manual. The use
of a substitute replacement which does not have the same safety characteristics as the recommended replace-
ment part shown in the Parts List in 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

I that they have been returned to normal, after re-assembling.

1 5. Leakage current check (Electrical shock hazard testing)

i 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 pro-

duct 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.).

l 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 1,500 (I 10 W resistor paralleled by a 0.15 "F AC-type capacitor

between an exposed metal part and a known good earth ground.

. . A V TMETER

Measure the AC voltage across the reSIStor With the AC @ (Having; 1 000 ohms/v0
voltmeter. or more sensitivity.)
Move the resistor connection to each exposed metal 0 o

, .
part, partlcularly any exposed metal part haVIng a return 1
path to the chassis, and measure the AC voltage across 0' 5 "F AC TYPE
the resistor. Now, reverse the plug in the AC outlet and HA Place this robe
repeat each measurement, Any voltage measured must «M on each 959059,,
not exceed 0.75 V AC (r.m.s.). 1500 n 10 w metal pan.

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

The lightning flash with arrowhead symbol,

within an equilateral triangle, is intended to

CAUTION alert the user to the presence or uninsulated
lilSK lJF ELEURIE SHDDK "dangerous voltage" within the product's
nu Ilm OPEN enclosure that may be of suoicleni magni-

tude to constitute a risk of electric shock to
persons.

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CAUTlON: To REDUCE THE RISK OF ELEcTfiIc SHOCK
no NOT REMOVE covER (on BACK).
ND USER-SERVICEAELE PARTS INSIDE.
REFER SERVICING To DUALIFIED SERVICE PERSONNEL.

The exclamation point within an equilateral
triangle is intended to alert the user ID the
Dresenoe of important ouminn and main-
tenance (servicing) instructions in the litera-
lure accompanying the appliance.

2 (No. 1860)