JVC MXJ-50 Service manual

Power T ransformer Section

Parts are safety assurance parts.
When replacing those parts make
sure to use the specified one.

Power Amplifier & Regulator Section

Parts are safety assurance parts.
When replacing those parts make
sure to use the specified one.

MAIN SIGNAL

Function & Main Amplifier Section

CD / MAIN SIGNAL
TUNER SIGNAL
TAPE P.B. SIGNAL

TUNER Section (For Ver.J,C,A,U,DOM)

FM/TUNER MAIN SIGNAL
AM SIGNAL

FL Display & System controller Section

RECL
RECR

PBL

PBR

MIC

KCMND

MS TAT

KCLK

DATA

RDS-DATA

RDS-CLK

MRDY

FVOLDA

VOLCK

SPI-A
SPI-B
SPI-C

SPICSB

CK
RESET
SPIDTI

INH
PROSADA
PROSACK

POUT
TUCE

SMUTE

RVOLDA

TAPE P.B. SIGNAL

MIC & Headphone Section

CD Servo & CD Mechanism control section

CD SIGNAL

Head amplifier & Mechanism control section

TAPE P.B. SIGNAL

MX-J50

Removal of Main Parts

< Main body >

Removing the Metal Cover (See Fig.1 to 3)

Remove the six A screws attaching the metal cover on

1.
the back of the body.

Remove the two B screws attaching the metal cover on

2.
both sides of the body.

Lift the metal cover on the back of the body and remove it

3.
from the body.

A

A

Metal cover

A

CAUTION: DO NOT break the front panel tab fitted to the

metal cover.

Metal cover

B

Fig.1

Fig.2

2-16

Fig.3

Metal cover

B

MX-J50

Removing the CD Changer Mechanism Assembly

(See Fig.4 to 6)

Prior to performing the following procedure, remove the
metal cover.

Disconnect the connector CN410 of the card wire

1.
connecting the CD changer mechanism board to the
main board.

Remove the two C screws on the upper side of the CD

2.
changer assembly and the two D screws on the back of
the rear panel.

Remove the plastic rivet attaching the main board.

3.
Lift and remove the CD changer mechanism assembly on

4.
the back of the body while pulling the rear panel and the
front panel assembly.

* To prevent damage to the CD fitting, be sure to pull the

rear panel and the front panel assembly enough to
remove the CD changer mechanism.

CN410

Main board

Fig.4

D

C

CD changer
assembly

Rear panel

Rear panel

Front panel assembly

Plastic rivet

Fig.5

Main board

Main board

Fig.6

2-17

MX-J50

< Front Assembly >

Removing the Front Panel Assembly

(See Fig.7 to 9)

Prior to performing the following procedure, remove the
metal cover and CD changer mechanism assembly.

Disconnect the card wires from connector CN411, CN412

1.
and CN413 on the main board.

Disconnect the flat wire from connector CN703 on the

2.
amplifier board.

Remove the four E screws attaching the front panel

3.
assembly on the bottom of the body.

Release the two joints(a) and (b) on the lower left and

4.
right sides of the body using a screwdriver, and remove
the front panel assembly toward the front.

Main board

Amplifier board

CN413

CN703

CN411

Front panel assembly

CN412

Fig.7

E

2-18

Fig.9a

Joint(a)

Fig.8

Joint(b)

Fig.9b

MX-J50

Removing the Rolling panel Panel assembly

(See Fig.10 and 11)

Disconnect the card wires from connector CN817,CN812,

1.
CN951 and CN816 on the upper system control & FL
board and on the rolling panel assembly on the reverse
side of the front panel assembly

Disconnect the card wire from connector CN859 on the

2.
relay board on the back of the rolling panel assembly.

Disconnect the flat wire from connector CN858 on the

3.
relay board. (Only Ver.U type)

Remove the six F screws attaching the stay bracket.

4.
Remove the four G screws attaching the rolling panel

5.
assembly.

Disconnect the flat wire extending from the phones

*

board through the slit of the rolling panel assembly.

CN817

Stay bracket

CN951CN812

CN816

System control & FL board

Fig.10

F

Phones board

Removing the Cassette Mechanism Assembly

(See Fig.12)

1.Prior to performing the following procedure, remove the
rolling panel assembly.

Remove the four H screws and four H1 screws attaching
the cassette mechanism assembly.

H

G

Relay board

G

CN858

G

CN859

Fig.11

H

H1

Fig.12

Cassette mechanism

H1

assembly

2-19

MX-J50

Removing the System Control & FL Board

(See Fig.13 and 14)

1.

Disconnect the card wires and flat wires from connector
CN812, CN817, CN816, CN951, CN813, CN810 and
CN811 on the system control & FL board respectively.

Disconnect the flat wire from connector D851 on the relay

2.
board.

Remove the six F screws attaching the stay bracket.

3.
Remove the two I screws attaching the system control &

4.
FL board.

CN817

I

CN812

Stay bracket

System control & FL board

CN810

CN813

Fig.13

CN951

I

CN816

CN811

F

Removing the Relay Board (See Fig.15)

Disconnect the card wires, the 2P harness and the flat

1.
wires from connector CN856, CN857, CN859, CN863,
CN858 (Only Ver.U type) and D851 on the relay board
respectively.

2.

Remove the one screw J attaching the relay board.

3.

Release the five c tabs fitted to the relay board.

J

Relay board

D851

Fig.14

Tab cCN856Tab c

CN859
CN857

CN858

2-20

Tab c

Relay board

D851

Tab c CN863 Tab c

Fig.15

MX-J50

Removing Each Board of the Front Panel
Assembly (See Fig.16 and 17)

Disconnect the flat wire from connector CN816 on the

1.
system control & FL board on top of the rolling panel
assembly.

Remove the three K screws attaching the power switch

2.
board.

Remove the two L screws attaching the phones board

3.
together with bracket.

Remove the flat wire extending from the phones

*

board through the slit of the rolling panel assembly.
The flat wire connected with CN858 is removed for U

*

version.
The screw H1 is removed and the earth wire is

*

removed for U version.

Remove the four M screws attaching the CD eject board

4.
and unsolder the flat wire.

Remove the rolling panel assembly.

Pull out the volume knob and nut toward the front.

5.
Remove the two N screws attaching the volume board

6.
and unsolder the flat wire.

CD eject board

M

Unsolder

Unsolder Volume board

Fig.16

Power switch

KM

board

Phones board

CN858

H1

K

L

CN816

L

Remove the three O screws attaching the function board

7.
1 and unsolder the flat wire.

Remove the four P screws attaching the function board 2.

8.

N

Unsolder

O

Function board 1

O

PP

Function
board 2

PP

Fig.17

2-21

MX-J50

< Rear Panel Assembly >

Prior to performing the following procedure, remove the
metal cover and the CD changer mechanism assembly.

The following procedure can be performed even if the
front panel assembly is attached.

Removing the Rear Cover (See Fig.18)

1. Remove the two Q screws attaching the rear cover on the
back of the body.

Removing the Rear Panel (See Fig.18 to 21)

Prior to performing the following procedure, remove the
rear cover.

Remove the four R screws attaching the heat sink and

1.
the rear panel.

S

Q
S

S

Rear cover

Rear panel

T

Q

S

S

Fig.18

Rear panel

Remove the ten S screws attaching the rear panel.

2.
Remove the two T screws attaching the voltage selector

3.
and the rear panel. (Only Ver.U type)

Release the two joints(d) and (e) on the lower part of the

4.
rear panel using a screwdriver, and remove the rear
panel toward the rear side.

R

R

Heat sink

Fig.19

2-22

Joint(d)

Joint(e)

Fig.21Fig.20

MX-J50

Removing the Main Board (See Fig.22 and 23)

Prior to performing the following procedure, remove the
metal cover, the CD changer mechanism assembly and
the rear panel.

Disconnect the card wires from connector CN411, CN412

1.
and CN413 on the main board and the flat wire from
connector CN415.

Remove the screw U attaching the main board on the

2.
right side of the body.

Disconnect connector CN416 and CN417 under the main

3.
board, and remove the main board upward.

Removing the Rated Voltage Board and Power
Amplifier Board (See Fig.22, 24 and 25)

Prior to performing the following procedure, remove the
metal cover, the CD changer mechanism assembly and
the rear panel.

The following procedure can be performed even if the
front panel assembly is attached.

Disconnect the flat wire from connector CN703 on the

1.
power amplifier board.

CN415

Main board

CN703

CN413

CN411

CN412

Fig.22

Disconnect the flat wire from connector CN415 on the

2.
main board.

Pull out the rated voltage board and the power amplifier

3.
board upward from connector CN102 and CN103 on the
power board respectively.

Remove the two V screws and two W screws attaching

4.
the heat sink together with the heat sink bracket.

Power board

CN105

V

Heat sink

Main boardMain board

CN416
Fig.23

CN417

U

Power amplifier board

Rated voltage board

W

CN102

Rated voltage board

Power amplifier board

CN103

Speaker board

Heat sink bracket

Fig.25Fig.24

2-23

MX-J50

Removing the Speaker Board (See Fig.24)

Prior to performing the following procedure, remove the
metal cover, the CD changer mechanism assembly and
the rear panel.

The following procedure can be performed even if the
front panel assembly is attached.

Pull out the speaker board upward from connector

1.
CN105 on the power board.

Power board

CN102

Rated voltage board

Power amplifier board

Fig.24

CN103

CN105

Speaker board

Removing the Power Transformer Board

(See Fig.26)

Prior to performing the following procedure, remove the
metal cover, the CD changer mechanism assembly and
the rear panel.

Disconnect the 5P harness and the flat wire from

1.
connector CN109 and CN111 on the power board.

Remove the four X screws attaching the power

2.
transformer assembly.

Push the cord stopper upward to remove it.

3.

CN111

CN109

Power transformer board

Fig.26

X

X

Cord stopper

2-24

Removing the rolling Panel Assembly

(See Fig.27)

1.2.Remove the two Y screws attaching the rolling panel
assembly.

Remove the rolling panel assembly while pulling outward
the left and right hooks attaching the rolling panel
assembly.

MX-J50

Removing the operation switch Board

(See Fig.28 and 29)

Remove the six Z screws attaching the cover and the

1.
bracket.

Release the two f tabs fitted to the bracket, and pull out

2.
the left and right panel holders.

Remove the two A screws attaching the operation switch

3.
board.

Removing the Drive Motor (See Fig.30 and 31)

1.

Remove the two B screws and the two C screw attaching

2.

Pull out the gear shaft A upward.

3.

Remove the motor belt.

Panel holder

Tab f

Rolling panel assembly

Fig.27

Z

Fig.28

Hook

Y

Bracket

Panel holder

Tab f

Cover

operation switch Board

Joint bracket

B C

Fig.30

Joint bracket

Gear shaft A

Fig.29

Fig.31

A

Motor belt

Drive motor

2-25

MX-J30/MX-J330/MX-J35R

CD Changer Mechanism Type:VC3 Section

Removing the CD Servo control board
(See Fig.1)

1.Remove the metal cover.

2.Remove the CD changer mechanism assembly.

3.From bottom side the CD changer mechanism assembly,
remove the two screws 1 retaining the CD servo control
board.

4.Absorb the four soldered positions "M" of the right and
left motors with a soldering absorber.

5.Pull out the earth wire on the CD changer mechanism
assembly.

6.The two screws A is removed and C.B.holder is detached.

7.Disconnect the connector CN854 on the CD servo
control board.

8.Disconnect the card wire CN601 and the connector
CN801 on the CD servo control board.

Removing the CD tray assembly
(See Fig.2

Remove the front panel assembly.

1.
Remove the CD changer mechanism assembly.

2.
Remove the CD Servo control board.

3.
From the T.bracket section

4.
section
rod(See Fig.2 and 3).
Remove the screw 2 retaining the Disc stopper

5.
(See Fig.3).
Remove the three screws 3 retaining the T.bracket

6.
(See Fig.3).
Remove the screws 4 retaining the clamper assembly

7.
(See Fig.3).
From the left side face of the chassis assembly, remove

8.
the one screw 5 retaining both of the return spring and
lock lever(See Fig. 4).
By removing the pawl at the section

9.
return spring, dismount the return spring(See Fig.4).

10.

Remove the three lock levers(See Fig.4).

T.Braket

C , remove both of the edges fixing the

B and clamper base

D fixing the

Disc stopper

4)

B

1

M

M

CN854

1

CN651

CD servo control board

CN801

CN601

Earth

wire

A

A

C.B.Holder

Fig.1

Clamper base

Rod

C

T.Braket

Fig.2

3

B

C

Clamper ass'y

Fig.3

2

3

Lod stopper
(C/J version only)

3

4

Lock lever

Fig.4

D

Return spring

5

2-17

MX-J30/MX-J330/MX-J35R

11.

Check whether the lifter unit stopper has been caught
into the hole at the section
as shown in Fig.5.

12.

Make sure that the driver unit elevator is positioned as
shown in Fig.6 from to the second or fifth hole on the
left side face of the CD changer mechanism assembly.

[Caution]

13.

14.

15.

Chassis assembly

In case the driver unit elevator is not at above
position, set the elevator to the position as
shown in Fig.7 by manually turning the pulley
gear as shown in Fig.8.

Manually turn the motor pulley in the clockwise
direction until the lifter unit stopper is lowered from the
section
Pull out all of the three stages of CD tray assembly in
the arrow direction
(See Fig.6).
At the position where the CD tray assembly has
stopped, pull out the CD tray assembly while pressing
the two pawls
assembly(See Fig.9). In this case, it is easy to pull out
the assembly when it is pulled out first from the stage
CD tray assembly.

E of CD tray assembly(See Fig.8).

G and G on the back side of CD tray

E of CD tray assembly

F until these stages stop

Fig.5

Stopper

E

CD tray
assembly

Refer to Fig.7

Pawl

CD tray assembly

G

F

Drive unit of elevator

Fig.7Fig.6

CD tray assembly

2-18

Pulley gear

Motor pulley

Fig.8

Pawl ,

G

Fig.9

G'

MX-J30/MX-J330/MX-J35R

Removing the CD loading mechanism
assembly(See Fig.10)

1.2.While turning the cams R1 and R2 assembly in the
arrow direction
loading mechanism assembly to the position shown in
Fig.10.
Remove the four screws 6 retaining the CD loading
mechanism assembly.

H align the shaft I of the CD

Removing the CD traverse mechanism
(See Fig.11 and 12 )

For dismounting only the CD traverse mechanism

1.
without removing the CD loading mechanism assembly,
align the shaft
assembly to the position shown Fig.11 while turning the
cam R1 and R2 assembly in the arrow direction
By raising the CD loading mechanism assembly in the

2.
arrow direction
lifter unit

Cam R1, R2 assembly

J of the CD loading mechanism

K .

L , remove the assembly from the

Cams R1, R2 assembly

Arrow

H

I

6

6

CD loading mechanism assembly

Fig.10

6

6

CD traverse mechanism

Arrow

K

J

Fig.11

Removing the CD pick unit
(See Fig.13 )

Move the cam gear in the arrow direction a . Then, the

1.
CD pickup unit will be moved in the arrow direction b .
According to the above step, shift the CD pickup unit to

2.
the center position.
While pressing the stopper retaining the shaft in the

3.
arrow direction c , pull out the shaft in the arrow
direction d .
After dismounting the shaft from the CD pickup unit,

4.
remove the CD pickup unit

Lifter unit

c

Shaft

Fig.12

CD Pickup unit

b

a

Shaft

d

Arrow

CD loading

mechanism

Shaft

Cam gear

L

Stopper

Fig.13

Stopper

2-19

MX-J30/MX-J330/MX-J35R

Removing the cam unit
(See Fig.14

1.

Remove the CD loading mechanism assembly.

2.

While turning the cam gear L, align the pawl
position of the drive unit to the notch position(Fig.16) on
the cam gear L.
Pull out the drive unit and cylinder gear(See Fig.17).

3.
While turning the cam gear L, align the pawl

4.
position of the select lever to the notch position(Fig.18)
on the cam gear L.
Remove the four screws 9 retaining the cam unit(cam

5.
gear L and cams R1/R2 assembly)(See Fig.18).

17 )

N

O

Chassis assembly

CN801

CN802

Fig.14

Drive unit

Cylinder gear

Tray select
switch board

CN804

Drive unit

N

8

Cam gear L

Cam gear L

Fig.15

Cams R1, R2 assembly

9

Cam unit

2-20

Fig.16

9

9

O

Select lever

Fig.17

MX-J30/MX-J330/MX-J35R

Removing the actuator motor and belt
(See Fig.18

1.

Remove the two screws 10 retaining the gear bracket
(See Fig.19).

2.

While pressing the pawl
the arrow direction, remove the gear bracket
(See Fig.19).
From the notch

3.
fixing the edge of gear bracket, remove and take out the
gear bracket(See Fig. 20).

4.

Remove the belts respectively from the right and left
actuator motor pulleys and pulley gears(See Fig. 19).

5.

After turning over the chassis assembly, remove the
actuator motor while spreading the four pawls
fixing the right and left actuator motors in the arrow
direction(See Fig. 21).

[Note]

When the chassis assembly is turned over under
the conditions wherein the gear bracket and belt
have been removed, then the pulley gear as well
as the gear, etc. constituting the gear unit can
possibly be separated to pieces. In such a case,
assemble these parts by referring to the assembly
and configuration diagram in Fig. 22.

Q section on the chassis assembly

P fixing the gear bracket in

21)

R

Pulley gear

Gear bracket

Belt

Motor pulley

10

Fig.18

Actuator motor

Pulley gear
Belt
Motor pulley

10

Pawl

P

Chassis assembly

Q

Gear bracket

Fig.19

Assembly and Configuration Diagram

Pulley gear

R

R

Fig.20

Pulley gear

Gear B

Cylinder gear

Gear B

Gear C

Select gear

Gross gear L

Fig.21

Gross gear U

Gear C

2-21

MX-J30/MX-J330/MX-J35R

Removing the cams R1/R2 assembly
and cam gear L(See Fig.22)

Remove the slit washer fixing the cams R1 and R2

1.
assembly.
By removing the two pawls

2.
separate R2 from R1.

3.

Remove the slit washer fixing the cam gear L.

4.

Pull out the cam gear L from the C.G. base assembly.

S fixing the cam R1,

Removing the C.G. base assembly
(See Fig.22 and 23)

Remove the three screws 11 retaining the C.G. base
assembly.

[Caution]

To reassemble the cylinder gear, etc.with the
cam unit (cam gear and cans R1/R2 assembly),
gear unit and drive unit, align the position of the
pawl

N on the drive unit to that o f the notch
on the cam gear L. Then, make sure that the
gear unit is engaged by turning the cam gear L
(See Fig. 24).

Slit washer

Cam gear L

11

Slit washer
Cam R2

Pawl

S

Cam R1

Cam switch board

C.G. base assembly

Pawl

S

Notch

Pawl

N

Cylinder
gear

Drive unit

Fig.22

Cam gear L

Cam R1, R2 assembly

Gear unit

Gear bracket

Fig.23

2-22

MX-J30/MX-J330/MX-J35R

< Cassette Mechanism Section >

Removing the Playback,Recording and Eraser

Heads

1. While shifting the trigger arms seen on the right
side of the head mount in the arrow direction,turn
the flywheel R in counterclockwise direction until
the head mount has gone out with a click
(See Fig 1).

2. When the flywheel R is rotated in counterclockwise
direction, the playback head will be turned in
counterclockwise direction from the position in
Fig 2 to that in Fig 3.

3. At this position, disconnect the flexible P.C.board
(outgoing from the playback head) from the
connector CN301 on the head amp. and mechanism
control P.C. board.

4. After dismounting the FPC holder,remove the
flexible P.C.board.

5. Remove the flexible P.C.board from the chassis
base.

6. Remove the spring "a" from behind the playback
head.

7. Loosen the reversing azimuth screw retaining the
playback head.

8. Take out the playback head from the front of the
head mount.

9. The recording and eraser heads should also be
removed similarly according to Steps 1~8 above.

Reassembling the Playback, Recording and

Eraser Heads

Cassette mechanism

Playback/Recording &

eraser head
Flexible
board

CN31

Head amplifier & mechanism
control P.C. board

Flywheel R

Trigger armHead mount

(Mechanism A side)

Spring "a"

Trigger arm

Flywheel R

(Mechanism A side)

1. Reassemble the playback head from the front of
the head mount to the position as shown in Fig 3.

2. Fix the reversing azimuth screw.

3. Set the spring a from behind the playback head.

4. Attach the flexible P.C.board to the chassis base,
and fix it with the FPC holder as shown in Fig 3.

5. The recording and eraser heads should also be
reassembled similarly according to Steps 1~4
above.

Playback head

Spring "a"

FPC holder

Reversing azimuth
screw

Head
mount

Flexible
board

CN301

Head amplifier &
mechanism control
P.C. board

(Mechanism B side)

2-23

MX-J30/MX-J330/MX-J35R

Removing the head Amp.and Mechanism

Control P.C.Board (See Fig 4)

1.Remove the cassette mechanism assembly.

2.After turning over the cassette mechanism
assembly,remove the five screws "A" retaining
the head amp. and mechanism control P.C.
board

3.Disconnect the connectors CN303 and CN304
on the P.C.Board and the connectors CN1 on
both the right and left side reel pulse
P.C.Boards.

4.When necessary, remove the 4pin parallel
wire soldered to the main motor

Removing the Capstan Motor Assembly

1.Remove the six screws "B" retaining capstan
motor assembly (See Fig 5).

2.While raising the capstan motor, remove the
capstan belts A and B respectively from the
motor pulley (See Fig 6).

A

Flexible
board

Head amplifier &
mechanism control board

AA

CN304

CN302 CN301

Flexible
board

BB

CN303

Capstan motor
assembly

AA

Caution 1: Be sure to handle the capstan
belts so carefully that these belts
will not be stained by grease and
other foreign matter. Moreover,
these belts should be hand while
referring to the capstan belt
hanging method.

Capstan
belt A

Capstan
belt B

Capstan
belt A

BBBB

Capstan motor

Capstan
belt B

Motor pulley

2-24

MX-J30/MX-J330/MX-J35R

Removing the Capstan Motor (See Fig 8)

From the joint bracket, remove the two screws "C"
retaining the capstan motor.

Removing the Flywheel (See Fig 9.10)

1.Remove the head amp. and mechanism control
P.C.Board.

2.Remove the capstan motor assembly.

3.After turning over the cassette mechanism, remove
the slit washers "a" and "b" fixing the capstan shafts
R and L, and pull out the flywheels R and L respectively
from behind the cassette mechanism.

C

Capstan motor

Joint
bracket

C

Flywheel R Flywheel L

Flywheel R Flywheel L

Removing the Reel Pulse P.C.Board and Solenoid
(See Fig 11)

1.Remove the five pawls (c,d,e,f,g) retaining
the reel pulse P.C.Board.

2.From the surface of the reel pulse P.C.Board parts,
remove the two pawls "h" and "i" retaining the solenoid.

hi

Solenoid

c

a

Slit
washer "a"

d

b

Slit
washer "b"

g

f

e

Reel pulse board

Solenoid

2-25