JVC UX-A70MD User manual

1-1
UX-A70MD
SERVICE MANUAL
MICRO COMPONENT MD SYSTEM
No.20901
Jan. 2001
COPYRIGHT 2001 VICTOR COMPANY OF JAPAN, LTD.
UX-A70MD
UX-A70MD
Contents
Safety precautions
Preventing static electricity
Important for laser products
Disassembly method
Main adjustment
Flow of functional operation
until TOC read (CD)
Flow of functional operation
until TOC read (MD)
Maintenance of laser pickup
Replacement of laser pickup
Maintenance of MD pickup
Procedures of changing
the MD pickup
Description of major ICs
1-2
1-3
1-5
1-6
1-28
1-32
1-33
1-34
1-34
1-35
1-35
1-36~56
This service manual is printed on 100% recycled paper.
Area Suffix
UB
US
UT
UF
UJ
Hong Kong
Singapore
Taiwan
China
U.S.Military
COMPACT
DIGITAL AUDIO
21 3
54 6
87
0 10 +10
ABCMARK
GHI JKL MNO
PQRS TUV WXYZ
DEF
9

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UX-A70MD
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 manufacturer`s
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 ( ) 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.
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 a return path to the chassis, to a known good earth ground. Any leakage
current 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 ohms
per volt or more sensitivity in the following manner. Connect a 1,500 10W resistor paralleled by
a 0.15 F AC-type capacitor between an exposed
metal part and a known good earth ground.
Measure the AC voltage across the resistor with the
AC voltmeter.
Move the resistor connection to eachexposed metal
part, particularly any exposed metal part having a
return path to the chassis, and meausre 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.).
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.
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
!
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 preforming repair of this system.

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UX-A70MD
Preventing static electricity
Electrostatic discharge (ESD), which occurs when static electricity stored in the body, fabric, etc.is discharged,
can destroy the laser diode in the traverse unit (optical pickup). Take care to prevent this when performing repairs.
1.1. Grounding to prevent damage by static electricity
Static electricity in the work area can destroy the optical pickup (laser diode) in devices such as DVD players.
Be careful to use proper grounding in the area where repairs are being performed.
1.1.1. Ground the workbench
1. Ground the workbench by laying conductive material (such as a conductive sheet) or an iron plate over
it before placing the traverse unit (optical pickup) on it.
1.1.2. Ground yourself
1. Use an anti-static wrist strap to release any static electricity built up in your body.
1.1.3. Handling the optical pickup
1. In order to maintain quality during transport and before installation, both sides of the laser diode on the
replacement optical pickup are shorted. After replacement, return the shorted parts to their original condition.
(Refer to the text.)
2. Do not use a tester to check the condition of the laser diode in the optical pickup.The tester's internal power
source can easily destroy the laser diode.
1.2. Handling the traverse unit (optical pickup)
1. Do not subject the traverse unit (optical pickup) to strong shocks, as it is a sensitive, complex unit.
2. Cut off the shorted part of the flexible cable using nippers, etc. after replacing the optical pickup. For specific
details, refer to the replacement procedure in the text.Remove the anti-static pin when replacing the traverse
unit. Be careful not to take too long a time when attaching it to the connector.
3. Handle the flexible cable carefully as it may break when subjected to strong force.
4. It is not possible to adjust the semi-fixed resistor that adjusts the laser power. Do not turn it
Conductive material
(conductive sheet) or iron plate
(caption)
Anti-static wrist strap

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UX-A70MD
1.3. Cautions on removing the CD traverse unit
* For removing the CD traverse unit in detail, refer to the "Adjustment Method" section of this manual.
1. Before disconnecting the flexible wire from the connector CN601 on the CD SERVO board, solder the part shown in
the figure below.
(Note:If the flexible wire is disconnected from the CN601 without presoldering, it may cause breakdown of the CD
pickup assembly.)
2. When reassembling the CD traverse unit, be sure to remove the solder from the soldered part after reconnecting the
flexible wire to the CN601.
CD SERVO board CD SERVO board
Soldering part
CN601
CN601
CN321
CN451
Pickup Soldering part b
MAIN board
CD SERVO board

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UX-A70MD

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UX-A70MD
Remove the nine screws Aattaching the rear cover
on the back of the body.
Remove the two screws Battaching the rear cover
on the bottom of the body.
Unlock the speaker terminal and the antenna
terminal, then remove the rear cover backward with
releasing the hooks.
1.
2.
3.
Disassembly method
Removing the rear cover
(See Fig.1 and 2)
Prior to performing the following procedure, remove
the rear cover.
Remove each side panel backward while releasing
the joints a.
1.
Removing the side panels
(See Fig.3 and 4)
<Main body>
Fig.1
Fig.2
A
B
B
A
Fig.3
Speaker
terminal
Antenna terminal
Side panel (Right) Joints a
Joints a
Fig.4
Joints a
Joints a
Side panel (Left)
A
Rear cover
Rear cover

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UX-A70MD
Prior to performing the following procedure, remove
the rear cover and the side panels.
Remove the two screws Con each side of the body.
Release the joint bon each side of the body and
remove the top cover backward and upward.
1.
2.
Removing the top cover (See Fig.5 and 6)
Prior to performing the following procedure, remove
the rear cover, the side panels, the top cover and the
fan assembly.
Disconnect the card wire from connector CN721 on
the tuner & function board.
Remove the four screws Dand the MD mechanism
assembly backward and upward while pulling the
front panel assembly forward.
1.
2.
Removing the MD mechanism assembly
unit (See Fig.7)
*Prior to performing the following procedure, remove
the rear cover, the right and left side panels.
Remove the two screws Don the right side of the
body and pull out the fan assembly sideward.
Disconnect the wire from connector CN807 on the
main board.
1.
2.
Removing the fan assembly (See Fig.6)
Fig.5
Fig.6
Joint b
C
Tuner & function board
Top cover
Joint b
Fig.7
D
D
D
MD mechanism assembly
Front panel assembly
C
Top cover
Fan assembly
D
D
CN807
CN721

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UX-A70MD
Removing the tuner & function board
(See Fig.8)
Removing the AC jack board (See Fig.9)
For the card wire connected to CN707,
disconnect it after performing the following
procedure 2 and 3.
CAUTION:
Prior to performing the following procedure, remove
the rear cover, the side panels and the top cover.
Disconnect the card wire from connector CN701,
CN705, CN707, CN708 and CN721 on the tuner &
function board on the right side of the body.
Similarly, disconnect the harness from CN706.
1.
2.
3.
Disconnect connector CN711 and CN712 on the
tuner & function board from CN801 and CN802 on
the main board by pulling them outward.
Disconnect connector CN703 and CN704 on the
tuner & function board from CN603 and CN604 on
the CD servo board by pulling them upward.
Prior to performing the following procedure, remove
the rear cover and the right side panel.
Remove the screw Eon the right side of the body
and release the AC jack board from the two joints c.
Disconnect the harness from connector CN805 on
the AC jack board.
1.
2.
Removing the antenna terminal board
(See Fig.10)
Prior to performing the following procedure, remove
the rear cover and the left side panel.
Disconnect the card wire from connector CN1 on the
left side of the body.
Remove the screw Fand release the antenna
terminal board from the joint dupward.
1.
2.
CN703
CN705
Fig.8
CN708
CN706
CN721
CN701
CN707
CN712 CN704 CN711
Joints c
E
AC jack board
CN1 FJoint d
Antenna terminal board
Fig.9
Fig.10
AC jack board

1-9
UX-A70MD
Removing the front panel assembly unit
(See Fig.11 to 15)
Prior to performing the following procedure, remove
the rear cover, the side panels, thetop cover, the MD
mechanism assembly and the tuner & function
board.
Disconnect the wire from connector CN804 and
CN806 on the main board. Disconnectthe wire from
W802 pin terminal.
Remove the two screws Gon the bottom of the
body.
Remove the lower screw Hon each side of the body.
Release the lower joint eon each side of the body.
Pull out the front panel assemblytoward the front.
1.
2.
3.
4.
Fig.11
Fig.12
G
CN804
CN806
Front panel assembly
Main board
Joint e Joint e
Front panel assembly
Fig.15
Fig.13
Fig.14
Front panel assembly
Front panel assembly
W802
Front panel assembly
W802
Main board
H
H

1-10
UX-A70MD
Removing the main board / heat sink
(See Fig.16 to 18)
Prior to performing the following procedure, remove
the rear cover, the side panels, thetop cover, the MD
mechanism assembly and the tuner & function
board.
Disconnect the wire from connector CN803, CN804
and CN806 on the main boardrespectively.
Disconnect the wire from W802 pin terminal.
Remove the screw Iattaching the main board and
the screw Jattaching the wireterminal.
1.
2.
Remove the three screws Kon the heat sink bracket.
Remove the two screws Lon the back of the main
board.
3.
4.
When reasse mbling, fit the slots of the
main board to the two bosses.
CAUTION:
When removing the heat sink bracket,
disengage the two joints don theback of
the main board.
CAUTION:
CN806
CN804
I
CN803
Fig.16
Main board
Fig.17
Fig.18
L
Heat sink
K
Heat sink bracket
Main board
Main borad
Heat sink
L
J
Joint d
Bosse
Bosse W802

1-11
UX-A70MD
Removing the CD mechanism assembly
and the CD servo board(See Fig.19 to 24)
Prior to performing the following procedure, remove
the rear cover, the side panels, the top cover, the
MD mechanism assembly, the tuner & function
board, the AC jack board, the antenna terminal
board, the front panel assembly and the main board.
Cut off the two tie band on the back of the CD
mechanism assembly top cover.
Remove the screw Mand the top cover.
Move the lever f in the direction of the arrow to draw
the loading tray manually.
Remove the screw Non the CD tray and pull out the
CD tray from the CD mechanism assembly.
Remove the two screws Oattaching the clamper
base on top of the CD mechanism assembly.
Release the two joints gwith the CD mechanism
assembly and remove the clamper base upward.
Remove the three screws Pattaching the CD
mechanism assembly.
Remove the three screws Qattaching the CD servo
board on the back of the CD mechanism assembly.
Disconnect the harness from connector P031 on the
CD mechanism assembly. Disconnect the harness
and the card wire from connector CN602 and CN601
on the CD servo control board respectively.
1.
2.
3.
4.
5.
6.
7.
8.
MTie band
CD mechanism assembly
Fig.19
Lever f
CD mechanism assembly
Fig.21
N
Clamper base
Loading tray
Fig.20
Fig.22
Joint g
Joint g
OO
CD mechanism assembly
Loading tray
Clamper base
Fig.23
CD mechanism assembly
P
P

1-12
UX-A70MD
Removing the transformer assembly
(See Fig.19 and 25)
Prior to performing the following procedure, remove
the rear cover, the side panels, the top cover, the
MD mechanism assembly, the tuner & function
board, the AC jack board, the antenna terminal
board, the front panel assembly and the main board.
Cut off the two wire clamp on the back of the CD
mechanism assembly upper cover.
Remove the screw Mand the CD mechanism
assembly upper cover.
Remove the four screws Rattaching the transformer
assembly.
1.
2.
3.
R
P031
CN602
CN601
Q
Q
CD servo board
CD mechanism board
Fig.24
R
Transformer assembly
Fig.25

1-13
UX-A70MD
Remove the four screws Sattaching the bracket (a)
and (b) on both sides of the MD mechanism
assembly unit.
Disconnect the card wire from connector CN521 on
the MD mechanism board. Remove the MD
mechanism assembly bottom cover downward.
1.
2.
Removing the MD mechanism assembly
(See Fig.26 to 28)
<MD mechanism assembly unit>
Prior to performing the following procedure, remove
the rear cover, the side panels, the top cover unit
and the MD mechanism assembly unit.
S
MD mechanism assembly
Bracket (a)
Fig.26
S
MD mechanism assembly
bottom cover
CN521
Fig.27
Fig.28
MD mechanism assembly
Bracket (b)
MD mechanism assembly

1-14
UX-A70MD
Disconnect the card wire from connector CN908 on
the relay board respectively.
Remove the screw Tattaching the relay board.
1.
2.
Removing the relay board (See Fig.29)
<Front panel assembly unit>
Prior to performing the following procedure,remove
the rear cover,the side panels, the top cover, the MD
mechanism assembly unit,the tuner & function board
and the front panel assembly unit.
Remove the four screws Uattaching the drive motor
assembly.
Remove the belt and the screw Vattaching the drive
motor.
1.
2.
Removing the drive motor assembly
(See Fig.29 and 30)
Remove the six screws Wattaching the bracket (c),
and detach the headphone jack board.
1.
Removing the headphone jack board
(See Fig.31)
Fig.29
Fig.30
Relay board
Drive motor assembly
U
U
Drive motor
Belt
V
W
W
Headphone jack board
Bracket (c)
Fig.31
T

1-15
UX-A70MD
Removing the key switch board / (d)
board (See Fig.32 and 33)
Prior to performing the following procedure, remove
the bracket (c).
Remove the three screws Xattaching the key switch
board.
Remove the spring g and the screw Yattaching the
(d) board.
1.
2.
Fig.32
Fig.33
XX
Y
Relay board
CN908
Key switch board
(d) board
Spring g
Y
(d) board

1-16
UX-A70MD
Removing the LCD board / sub board
(See Fig.32 and 34 to 37)
Disconnect the card wire from connector CN908 on
the relay board on the back of thefront panel
assembly.
Remove the four screws A’ attaching the CD / MD
door cover on the front side of the frontpanel
assembly. Remove the CD / MD door cover, then the
LCD board unit.
Pull out the LCD lens from the four bosses on the
LCD board unit.
Remove the LCD board and the lens cover in the
direction of the arrow (The lens cover isattached with
a double-sided tape).
Disconnect the sub board from connector CN913 on
the LCD board.
1.
2.
3.
4.
5.
CD / MD door cover A'
Fig.34
LCD board unit
Fig.35
Slot h
Slot h
Slot h
Lens cover LCD board
LCD lens
Fig.36
Sub board
LCD board
CN913
Fig.37
A'

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UX-A70MD
Removing the CD / MD door board
(See Fig.38 and 39)
Prior to performing the following procedure,remove
the LCD board unit.
Remove the four screws B' attaching the two
brackets (e). Remove the CD / MD door base and
the two brackets (e).
Remove the screw C' attaching the CD / MD door
board.
1.
2.
Fig.38
Fig.39
B'
B'
Brackets (e)
CD / MD door base
C'
CD / MD door board

1-18
UX-A70MD
Turn over the body and disconnect the card wire
from connector CN408 and the flexible wire from
CN407 on the main board.
Remove the two screws A attaching the main board.
Slide the main board in the direction of the arrow to
release the two joints a with the single flame.
Solder part b on the pickup in the body. Disconnect
the flexible harness from connector CN321 and
CN451 on the underside of the main board. Then
remove the main board.
1.
2.
3.
Disassembly method
Removing the main board
(See Fig.1 and 2)
Remove the four screws B on both sides of the
body.
Move the mechanism cover toward the front to
disengage the front hook of the mechanism cover
from the internal loading assembly (Joint c). Then
remove the mechanism cover upward.
1.
2.
Removing the mechanism cover
(See Fig.3)
<Main body>
Fig.1
Fig.2
Fig.3
AA
Main board
(Bottom)
CN408
CN321
CN451
Pickup
Joint c
Fook
Joint c
Mechanism cover
Solder part b
CN407
Joint b Joint b
Main board
B
B

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UX-A70MD
Move the head lifter on top of the body in the
direction of the arrow and turn around.
Detach the spring from the hook of the body.
Remove the head lifter with the spring.
If necessary, remove the spring from the head lifter.
1.
2.
3.
Removing the head lifter (See Fig.4 to 6)
Remove the screw C on the upper side of the body.
Remove the head assembly while pulling the flexible
harness from the body.
1.
Removing the head assembly (See Fig.7)
Fig.4
Fig.5
Fig.6
Fig.7
C
Head lifter
Spring
Spring
Head lifter
Head assembly
Head lifter

1-20
UX-A70MD
Prior to performing the following procedure, remove
the main board, the mechanism cover, the head lifter
and the head assembly.
Remove the three screws D on the upper side of the
body.
Move the loading assembly forward to disengage it
from the traverse mechanism assembly (Joint d).
Then remove it upward.
Remove the traverse mechanism assembly from the
single flame.
1.
2.
3.
Removing the Loading assembly
(See Fig.8 and 9)
The loading assembly, the traverse mechanism
assembly and the single flame will be
removable after removing the loading assembly
from the body.
Ref:
Fig.8
Fig.9
D
Loading assembly
Joint d
D
D
Loading assembly
Traverse mechanism
assembly
Single flame