Jvc UXT 3 Service Manual

Page 1

UX -- T3 A/US/U

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DIGITAL AUDlO

Area Suffix

A...
us
U .............................. (her/335

Australia

~- Sigapore

Contents

1. Safety Precautions~ 10. Block Diagram

2. Safety Precaution about UX - T3 11. Wiring Connections ----------------- 56
3. Main Features ..................................................... 6 12. IC Block Diagram ............................................. 57
4. Specifications ...................................................... 5 13. Standard Schematic Diagram ............................ 63
5. Instructions -------------------------------- 7 14. Location of P.C. Board Parts ~-~68
6. Location of Main Parts -33 15. Electrical Parts List~~~~

7. Removal of Main Parts ~ --------------------- 36 16. Analytic Drawing and Parts List---- "~34
8. Main Adjustment ................................................ 45 17. Illustration 01' Packing and Parts List ................... 90
9. Troub|eshoofing ( CDPan) ................................. 50 18. Accessories .................................... t ............... 91

No. 1928

February 1995

Page 2

UX , T3 A/US/U

1. Safety Precautions

.The design of this product contains special hardware and many circuits and components specialty 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.

.vAlterationsof 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 manufacture's warranty and will further relieve the manufacture of responsibility for personal

injury or property damage resulting therefrom

. 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
Svarvioe Manual. Electrical components having such features are identified by shading on the schematic 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 part shown in the Parts List of Service Manual may create shock. fire. or other hazards.

. 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
on'ginal lead routing and dress should be observed, and it should be confirmed that they have been returned to normal. after
reassembling.

. Leakage current check (Electrical shock hazard testing)

After reassembling 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.

' 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. paniculary any exposed metal part having a return path to the chassis. to a known good saith ground. Any
leakage current must not exceed 0.5mA AC(r.m.s.).

AC VOLTMETER
- Alternate check method @ (Having 1000 ohms/volt,
Plug the AC line cord directly into the AC outlet. Use an Ac voltmeter or mon "RMYJ
having. 1.000 ohms per volt or more sensitivity in the following manner. _'LJ
. 0.15 uF Ac TYPE

Connect a 1.500 ohms 10W resistor paralleled by a 0.15 i F AC type
capacitor between an exposed metal part and a known good earth place this probe

' ' on each lxposad
ground. Measure the AC voltage across the resistor With the AC 1500 a 10 W metal part.

voltmeter. Move the resistor connection to each exposed metal part.
particularly any exposed metal part having a return path to the chassis. G°°d earth 9'0
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 D.75V AC(r.rn.s.).This corresponds to 0.5mA AC(r.m.s.).

Warning

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

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

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

If mains voltage selector is provided, check setting for local voltage.

2 (No.1928)

Page 42

UX - T3 A/US/U

I How to Remove the Dolby NR P.C.
Board (Refer to Figs. 7-22 and 7723)

1. Remove the upper cover (Refer to How to Remove the
Upper Cover").

2. Remove the CD player ass'y (Refer to How to Remove
the CD Player Assy).

3. Remove the cassette mechanism assy (Refer to How
to Remove the Cassette Mechanism Assy").

4. Remove the two screws (22) retaining the Dolby NR
P.C. board.

5. While shifting the Dolby NR P.C. board toward the front
side, disconnect the connection between the connector
CN322 on the equalizer amplifier P.C. board and
connector CN342 on the Dolby NR P.C. board as well as
that between the connector CN343 on the Dolby NR
PC. board and connector CN851 on the mechanism
control P.C. board.

I How to Remove the Mechanism Control
P.C. Board (Refe to Figs. 7-22 and 7:23)

1. Remove the two screws (23) retaining the mechanism
control P.C. board.

2. Disconnect the connections between the connectors
CN853 and CN852 on the mechansim control PC.
board and connectors CN1 and 0N2 on the mechanism
P.C.board.

3. Disconnect the connection between the connector
CN302 on the equalizer amplifier PC. board and
connector CN855 on the mechanism control P.C. board.

I How to Remove the Ecbualizer amplifier
P.C. Board and Bias P. . Board
(Refer to Figs. 7-22 and 7* 23)

1. From the connector CN301 on the equalizer amplifier
PC. board, remove the flexible P.C. board outgoing from
the recording and playback head.

2. Remove the one screw (24) retaining the equalizer
amplifier P.C. board.

3. Remove the two protrusions (E) on the cassette mechaa
nism retaining the equalizer amplifier P.C. board.

4 From the P.C. board bracket. remove the two screws
(25) retaining the equalizer amplifier P.C. board.

5. Disconnect the connection between the connector
CN303 on the equalizer amplifier P.C. board and
connector CN321 on the bias P.C. board.

6. From the PC. board bracket, remove the one screw (26)
retaining the bias P.C. board.

lHow to Remove the Cassette Holder
(Refer to Fig. 7a 24)

1. Remove the cassette door spring from the cassette
holder.

2. While pressing the cassette holder arm to inside, remove
the arm from the mechanism bracket (Then the cassette
holder and door damper will be removed simulta ,
neously).

Reference: For dismounting the mechanism bracket,

remove the three screws [(27) x 2 and (28) x 1]
retaining the cassette mechanism bracket.

42 (No.1928)

Mechanism control 3
PC. board assy

E0 amp. P.C.
board assy

Dolby NR PC.
board assy

@ Fig. 7-22
EQ amp. P.C. board assy

5,, Bias P.C.
board ass'y /
. 2 \)

Door spring
assembly view

L Cass ttedoor
, . - spring
. ». [\\\

5.
:fi Cassette holder
arm section

Mechanism bracket

Mechanism easy
@ Fig. 7-24

Page 62

UX - T3 AlUS/U

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62 (No.1928)