JVC MXG-70 Service manual
SERVICE MANUAL
COMPACT COMPONENT SYSTEM
MX-G70
J
C
MX-G70
Area Suffix
U.S.A.
Canada
Contents
Safety precautions
Important for laser products
Warnings and Cautions
Preventing static electricity
Importance administering
point on the safety
Disassembly method
STANDBY/ON
CD-R/RW PLAYBACK
STANDBY
CA-MXG70SP-MXG70
1-2
1-3
1-3
1-4
1-5
1-6
PLAY & EXCHANGE
MX-G70
SP-MXG70
Adjustment method
1-26
Flow of functional operation
until TOC read
Maintenance of laser pickup
Replacement of laser pickup
Description of major ICs
1-30
1-31
1-31
1-32
COPYRIGHT 2001 VICTOR COMPANY OF JAPAN, LTD.
No.20920
Mar. 2001
MX-G70
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 proper ty
damage resulting therefrom.
3. Many electrical and mechanical par ts 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 or iginal 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.
AC VOLTMETER
(Having 1000
ohms/volts,
or more sensitivity)
Move the resistor connection to each exposed
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
0.15 F AC TYPE
1500 10W
Place this
probe on
each exposed
metal part.
exceed 0.75 V AC (r.m.s.). This corresponds to 0.5
mA AC (r.m.s.).
Good earth ground
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.
!
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.
1-2
Important for laser products
MX-G70
1.CLASS 1 LASER PRODUCT
2.DANGER : Invisible laser radiation when open and inter
lock failed or defeated. Avoid direct exposure to beam.
3.CAUTION : There are no serviceable parts inside the
Laser Unit. Do not disassemble the Laser Unit. Replace
the complete Laser Unit if it malfunctions.
4.CAUTION : The compact disc player uses invisible laser
radiation and is equipped with safety switches which
prevent emission of radiation when the drawer is open and
the safety interlocks have failed or are defeated. It is
dangerous to defeat the safety switches.
Warnings and Cautions
CAUTION
RISK OF ELECTRIC SHOCK
DO NOT OPEN
CAUTION: TO REDUCE THE RISK OF ELECTRIC SHOCK,
DO NOT REMOVE COVER (OR BACK).
NO USER SERVICEABLE PARTS INSIDE.
REFER SERVICING TO QUALIFIED SERVICE PERSONNEL.
5.CAUTION : If safety switches malfunction, the laser is able
to function.
6.CAUTION : Use of controls, adjustments or performance of
procedures other than those specified herein may result in
hazardous radiation exposure.
CAUTION
!
Please use enough caution not to
see the beam directly or touch it
in case of an adjustment or operation
check.
The lightning flash with arrowhead symbol,
within an equilateral triangle is intended to
alert the user to the presence of uninsulated
"dangerous voltage" within the product's
enclosure that may be of sufficient
magnitude to constitute a risk of electric
shock to persons.
The exclamation point within an equilateral
triangle is intended to alert the user to the
presence of important operating and
maintenance (servicing) instructions in the
literature accompanying the appliance.
WARNING: TO REDUCE THE RISK OF FIRE
OR ELECTRIC SHOCK, DO NOT EXPOSE
THIS APPLIANCE TO RAIN OR MOISTURE.
For Canada/pour le Canada
CAUTION: TO PREVENT ELECTRIC SHOCK, MATCH WIDE
BLADE OF PLUG TO WIDE SLOT, FULLY INSERT.
ATTENTION: POUR EVITER LES CHOCS ELECTRIQUES,
INTRODUIRE LA LAME LA PLUS LARGE DE LA FICHE DANS
LA BORNE CORRESPONDANTE DE LA PRISE ET POUSSER
JUSQUAU FOND.
1-3
MX-G70
Preventing static electricity
1. Grounding to prevent damage by 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.
2. About the earth processing for the destruction prevention by static electricity
In the equipment which uses optical pick-up (laser diode), optical pick-up is destroyed by the static electricity of
the work environment.
Be careful to use proper grounding in the area where repairs are being performed.
2-1 Ground the workbench
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.
2-2 Ground yourself
Use an anti-static wrist strap to release any static electricity built up in your body.
(caption)
Anti-static wrist strap
Conductive material
(conductive sheet) or iron plate
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.
4. 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
Attention when traverse unit is decomposed
*Please refer to "Disassembly method" in the text for pick-up and how to
detach the CD traverse mechanism.
1. Remove the disk stopper and T. bracket on the CD changer mechanism
assembly.
2. Disconnect the harness from connector on the CD motor board.
3. CD traverse unit is put up as shown in Fig.1.
4. Solder is put up before the card wire is removed from connector CN601
on the CD servo control board as shown in Fig. 2.
(When the wire is removed without putting up solder, the CD pick-up
assembly might destroy.)
5. Please remove solder after connecting the card wire with CN601 when
you install picking up in the substrate.
CD changer
mechanism
assembly
CD traverse
unit
Flexible cable
Fig.1
Soldering
Fig.2
1-4
Importance administering point on the safety
F102
F101
F001
MX-G70
Caution: For continued protection against risk of
fire, replace only with same type 5A/125V for
F001, 6A/125V for F101 and F102. This symbol
specifies type of fast operating fuse.
Precaution: Pour eviter risques de feux, remplacez
le fusible de surete de F001 comme le meme type
que 5A/125V, et 6A/125V pour F101 et F102.
Ce sont des fusibles suretes qui functionnes rapide.
^
1-5
MX-G70
Disassembly method
<Main body>
Removing the metal cover
(See Fig.1 to 3)
Remove the six screws A on the back of the body.
1.
Remove the two screws B on both sides of the
2.
body.
Remove the metal cover from the body by lifting the
3.
rear part of the cover.
CAUTION:
Do not break the front panel tab fitted to
the metal cover.
A
Metal cover
Metal cover
AA
Fig.1
B
Fig.2
Metal cover
B
Fig.3
1-6
MX-G70
Removing the CD changer mechanism
assembly (See Fig.4 and 5)
Prior to performing the following procedure, remove
the metal cover.
Disconnect the card wire from connector CN661 on
1.
the Main board.
Remove the two screws C on the upper side of the
2.
body and the two screws D on the back of the rear
panel.
Remove the plastic rivet attaching the main board.
3.
Remove the fan connector CN705.
4.
Pull both the rear panel and the front panel assembly
5.
to the outside, then remove the CD changer
mechanism assembly by lifting the rear part of the
assembly.
CAUTION:
To prevent damage to the CD fitting, be
sure to pull both the rear panel and the
front panel assembly enough to remove
the CD changer mechanism assembly.
Front panel assembly
C
Main board
CN661
Fig.4
CD changer mechanism assembly
Main board
CN661
Plastic rivet
Front panel assembly
Fig.5
C
CD changer
mechanism assembly
Rear panel
Rear panel
D
Removing the front panel assembly
(See Fig.6 to 10)
Prior to performing the following procedure, remove
the metal cover and CD changer mechanism
assembly.
Disconnect the card wires from connector CN870,
1.
CN871 and CN315 on the main board respectively.
Remove the tie band and disconnect the wire from
2.
connector CN703 on the amplifier board.
Disconnect the wire from connector CN220 on the
3.
transformer board.
Amplifier board
CN703
Tie band
Fig.6
Main board
CN870
CN871
CN315
Front panel
assembly
Transformer board
CN220
Front panel assembly
Fig.7
Main board
1-7
MX-G70
Remove the four screws E on the bottom of the
4.
body.
Release the two joints a on the lower right and left
5.
sides of the body using a screwdriver, and remove
the front panel assembly toward the front.
Front panel assembly
E
(Bottom)
Fig.8
Front panel assembly
Joint a
Joint a
Fig.9
Front panel assembly
Fig.10
1-8
MX-G70
Removing the tuner board
(See Fig.11 and 12)
Prior to performing the following procedure, remove
the metal cover and the CD changer mechanism
assembly.
1.
Disconnect the card wire from connector CN1 on the
tuner board on the right side of the body.
2.
Remove the plastic rivet fixing the tuner board.
3.
Remove the two screws F on the back of the body.
Removing the rear cover / rear panel
(See Fig.12 to 15)
Prior to performing the following procedure, remove
the metal cover and the CD changer mechanism
assembly.
F
Joint b
CN1
Plastic rivet
Fig.11
G
Tuner board
Rear panel
Rear panel
Joint b
Remove the screw G attaching the rear cover on the
1.
back of the body.
Push each tab of the four joints b in the direction of
2.
the arrow and release.
Remove the eleven screws F attaching the rear
3.
panel.
Release the joints c on each lower side of the rear
4.
panel using a screwdriver and remove the rear panel
backward.
Note : Remove the tuner board in case of necessity.
(Refer to Fig.21)
F
F
F
Rear cover
Fig.12
Rear panel
F
Fig.13
Joint c
Fig.15
Rear panel
Rear panel
Fig.14
Joint c
1-9
MX-G70
Removing the main board
(See Fig.16 and 17)
Prior to performing the following procedure, remove
the metal cover, the CD changer mechanism
assembly, the rear panel and the tuner board.
1.
Disconnect the card wires from connector CN870,
CN871 and CN315 on the main board.
2.
Disconnect the flat wires from connector CN704 and
CN706 on the amplifier board.
3.
Remove the screw H attaching the main board on
the right side of the body.
4.
Disconnect connector CN211 and CN212 on the
main board from the regulator board.
CN315
Amplifier board
CN704
CN706
Front panel assembly
Main board
CN871
Plastic rivet
CN870
Fig.16
Front panel assembly
Main board
Removing the speaker board
(See Fig.18)
Prior to performing the following procedure, remove
the metal cover, the CD changer mechanism
assembly and the rear panel.
REFERENCE:
Disconnect connector CN217 on the speaker board
1.
from the regulator board.
It is not necessary to remove the main
board.
Regulator board
Regulator board
H
Fig.17
Fig.18
CN212
CN211
Speaker board
CN217
1-10
MX-G70
Removing the amplifier board / voltage
board / heat sink (See Fig.19 and 20)
Prior to performing the following procedure, remove
the metal cover, the CD changer mechanism
assembly and the rear panel.
1.
Disconnect the wires from connector CN703, CN704
and CN706 on the amplifier board respectively.
2.
Remove the two tie band attaching the wire to the
amplifier board and the voltage board.
3.
Disconnect connector CN215 on the amplifier board
and CN216 on the voltage board from the regulator
board (The heat sink and heat sink bracket will be
detached at once).
4.
Pull out the upper and lower heat sink brackets from
the heat sink respectively.
5.
Remove the four screws I attaching the amplifier
board to the heat sink.
6.
Remove the two screws J, the board bracket and
the voltage board.
Tie band
Voltage board
Regulator board
Heat sink
Voltage board
Amplifier board
CN704
CN706
CN216
Heat sink bracket
Tie band
CN703
CN215
Fig.19
Amplifier board
I
J
Heat sink bracket
I
Fig.20
1-11
MX-G70
Removing the power transformer
assembly (See Fig.21 and 22)
Prior to performing the following procedure, remove
the metal cover, the CD changer mechanism
assembly and the rear panel.
1.
Disconnect the wires from connector CN220 and
CN250 on the transformer board.
2.
Disconnect the wire from connector CN204 on the
regulator board.
3.
Remove the four screws k attaching the transformer
assembly.
Removing the regulator board
(See Fig.23)
Prior to performing the following procedure, remove
metal cover, CD changer mechanism assembly, rear
panel, tuner board, main board, amplifier board,
voltage board and speaker board.
Voltage board
Power cord
Base chassis
Regulator board
CN204
Transformer board
Tie band
Power cord stopper
Fig.21
Transformer board
CN220
CN250
CN220
Power transformer assembly
K
Power transformer
assembly
1.
Disconnect the wire from connector CN204 on the
regulator board.
2.
Remove the two screws L attaching the regulator
board.
Removing the power cord (See Fig.21)
Prior to performing the following procedure, remove
the metal cover, the CD changer mechanism
assembly and the rear panel.
1.
Disconnect the wire from connector CN250 on the
transformer board.
2.
Remove the tie band from the voltage board.
3.
Move the power cord stopper upward and pull out it
from the base chassis.
CN250
CN204
L
Regulator board
K
Tie band
Power cord stopper
Fig.22
Power transformer assembly
L
Fig.23
1-12
MX-G70
<Front panel assembly>
Prior to performing the following procedure, remove
the metal cover, the CD changer mechanism
assembly and the front panel assembly.
Removing the cassette mechanism
assembly (See Fig.24)
Disconnect the card wire from connector CN306 on
1.
the head amplifier & mechanism control board.
Remove the four screws M and three screws M'
2.
attaching the cassette mechanism assembly.
Removing the display system control
board (See Fig.25 to 27)
Remove the five screws N attaching the stay bracket.
1.
Disconnect the card wires from connector CN316 and
2.
CN880 on the display system control board.
Head amplifier
& Mechanism control board
CN306
M
M'
Cassette mechanism
assembly
Fig.24
N
M
M
M'
M'
N
Remove the seven screws O attaching the display
3.
system control board.
If necessary, disconnect the wire from connector
4.
CN911 on the front side of the display system control
board and unsolder FW915.
If necessary, remove the CD play board. (Fig. 28)
Removing the CD play board
(See Fig.27 and 28)
Remove the three screws P attaching the CD eject
1.
board.
If necessary, unsolder FW915 on the CD eject
2.
board.
CD play board
FW915
(Soldering)
P
P
Display system control board
O
FW915
(Soldering)
O
Fig.25
O
CN316
CN880
Fig.26
CN911
Stay bracket
O
O
Display system control board
CD play board
FW915
Display system control board
FW915
Fig.27Fig.28
1-13
MX-G70
Removing the preset / tuning switch
board (See Fig.29 and 30)
Prior to performing the following procedure, remove
the display system control board.
Pull out the preset knob on the front panel.
1.
Remove the five screws Q attaching the preset /
2.
tuning switch board.
Removing the operation switch board
(See Fig.30 and 31)
Prior to performing the following procedure, remove
the display system control board and the preset /
tuning switch board.
Pull out the volume knob on the front panel and
1.
remove the nut. Pull out the surround mode knob
and the surround woofer level knob toward the front.
Q
Preset / tuning switch board
Q
Fig.29
Preset knob
Surround mode knob
Surround woofer
level knob
Remove the twelve screws R attaching the
2.
operation switch board.
Release the wire clamp.
3.
Remove the screw R' attaching the earth terminal
extending from the switch board.
4.
Release each tab of the seven joints g retaining the
operation switch board.
Joint g
Joint g
R
R
Joints g
Nut
Volume knob
Fig.30
R
Operation
switch board
Joint g
1-14
R
Joints g
R
Fig.31
R
R
Wire clamp
R'
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 four screws A retaining the CD servo control
board.
4.Absorb the four soldered positions "a" of the right and
left motors with a soldering absorber.
5.Pull out the earth wire on the CD changer mechanism
assembly.
6.Disconnect the connector CN854 on the CD servo
control board.
7.Disconnect the card wire CN601 and the connector
CN801 on the CD servo control board.
MX-G70
A
a
a
CN854
A
CN651
CD servo control board
CN652
CN801
CN601
CN151
Removing the CD tray assembly
(See Fig.2~4)
Remove the front panel assembly.
1.
Remove the CD changer mechanism assembly.
2.
Remove the CD Servo control board.
3.
Remove the screw B' retaining the lod stopper.
4.
From the T.bracket section "b" and clamper base
5.
section "c" , remove both of the edges fixing the
rod(See Fig.2 and 3).
Remove the screw B retaining the disc stopper
6.
(See Fig.3).
Remove the three screws C retaining the T.bracket
7.
(See Fig.3).
Remove the screw D retaining the clamper assembly
8.
(See Fig.3).
From the left side face of the chassis assembly, remove
9.
the one screw E retaining both of the return spring and
lock lever(See Fig. 4).
10.
By removing the pawl at the section "d" fixing the return
spring, dismount the return spring(See Fig.4).
11.
Remove the three lock levers(See Fig.4).
T.Braket
Disc stopper
B
Earth
wire
Fig.1
A
Clamper base
A
b
Rod
c
T.Braket
Fig.2
d
CC
B'
a
Lod stopper
(C/J version only)
C
D
b
Lock lever
Clamper ass'y
Fig.3
Fig.4
Return spring
E
1-15
MX-G70
11.
Check whether the lifter unit stopper has been caught
into the hole at the section "e" of CD tray assembly as
shown in Fig.5.
Make sure that the driver unit elevator is positioned as
12.
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 "e" of CD tray assembly(See Fig.8).
Pull out all of the three stages of CD tray assembly in
the arrow direction "f" until these stages stop
(See Fig.6).
At the position where the CD tray assembly has
stopped, pull out the CD tray assembly while pressing
the two pawls "g and g' " on the back side of CD tray
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.
Stopper
e
CD tray
assembly
Fig.5
Refer to Fig.7
Pulley gear
Pawl
Fig.6
CD tray assembly
g
CD
CD
CD
f
Drive unit of elevator
Fig.7
3
2
1
CD tray assembly
1-16
Motor pulley
Fig.8
Pawl ,
g
Fig.9
g'
MX-G70
Removing the CD loading mechanism
assembly(See Fig.10)
1.2.While turning the cams R1 and R2 assembly in the
arrow direction "h" ,align the shaft "i" of the CD loading
mechanism assembly to the position shown in Fig.10.
Remove the four screws F retaining the CD loading
mechanism assembly.
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 "j" of the CD loading mechanism
assembly to the position shown Fig.11 while turning the
cam R1 and R2 assembly in the arrow direction "k" .
By raising the CD loading mechanism assembly in the
2.
arrow direction "l", remove the assembly from the lifter
unit
Cam R1, R2 assembly
Cams R1, R2 assembly
Arrow
h
i
F
F
CD loading mechanism assembly
Fig.10
F
F
CD traverse mechanism
Arrow
k
j
Fig.11
Removing the CD pick unit
(See Fig.13 )
1.
Move the cam gear in the arrow direction "m" . Then,
the CD pickup unit will be moved in the arrow direction
"n" .
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 "o" , pull out the shaft in the arrow
direction "p".
After dismounting the shaft from the CD pickup unit,
4.
remove the CD pickup unit
Lifter unit
o
Stopper
Shaft
Fig.12
CD Pickup unit
n
m
Shaft
p
Stopper
Fig.13
Arrow
CD loading
mechanism
Shaft
Cam gear
l
1-17
MX-G70
Removing the try select switch board
(See Fig.14)
1.2.Remove the two screws G retaining the tray select
switch board.
Disconnect the tray select switch board from connector
CN804 on the CD servo control board.
Removing the cam unit
(See Fig.15 ~17 )
1.
Remove the CD loading mechanism assembly.
2.
While turning the cam gear "q", align the Paul "r"
position of the drive unit to the notch position(Fig.16) on
the cam gear "q".
Pull out the drive unit and cylinder gear(See Fig.17).
3.
While turning the cam gear "q", align the Paul "s"
4.
position of the select lever to the notch position(Fig.18)
on the cam gear "q".
Remove the four screws H retaining the cam unit(cam
5.
gear "q" and cams R1/R2 assembly)(See Fig.18).
Chassis assembly
Drive unit
CN851
CN854
Fig.14
Cam gear
Tray select
switch board
CN804
q
G
Drive unit
Cylinder gear
r
Cam gear
H
s
Fig.15
H
q
Cams R1, R2 assembly
Cam unit
J
1-18
Fig.16
Select lever
Fig.17
MX-G70
Removing the actuator motor and belt
(See Fig.18~21)
1.
Remove the two screws I retaining the gear bracket
(See Fig.18).
2.
While pressing the pawl "t" fixing the gear bracket in the
arrow direction, remove the gear bracket
(See Fig.18).
From the notch "u section" on the chassis assembly
3.
fixing the edge of gear bracket, remove and take out the
gear bracket(See Fig. 19).
Remove the belts respectively from the right and left
4.
actuator motor pulleys and pulley gears(See Fig. 18).
After turning over the chassis assembly, remove the
5.
actuator motor while spreading the four pawls "v" fixing
the right and left actuator motors in the arrow
direction(See Fig. 20).
[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. 21.
Chassis assembly
Pulley gear
Gear bracket
Belt
Motor pulley
I
Fig.18
Actuator motor
Pulley gear
Belt
Motor pulley
I
Pawl
t
u
Gear bracket
Fig.19
Assembly and Configuration Diagram
Pulley gear
Gear B
v
v
Fig.20
Pulley gear
Gear B
Cylinder gear
Gear C
Select gear
Gross gear L
Fig.21
Gross gear U
Gear C
1-19
MX-G70
Removing the cams R1/R2 assembly
and cam gear q(See Fig.22)
Remove the slit washer fixing the cams R1 and R2
1.
assembly.
By removing the two pawls "w" fixing the cam R1,
2.
separate R2 from R1.
Remove the slit washer fixing the cam gear "q".
3.
Pull out the cam gear "q" from the C.G. base assembly.
4.
Removing the C.G. base assembly
(See Fig.22 and 23)
Remove the three screws J 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 "x" on the drive unit to that of the notch on
the cam gear "q". Then, make sure that the
gear unit is engaged by turning the cam gear
"q" (See Fig. 24).
Slit washer
Cam gear q
J
Slit washer
Cam R2
Pawl
w
Cam R1
Cam switch board
C.G. base assembly
Pawl
w
Notch
Pawl
x
Cylinder
gear
Drive unit
Fig.22
Cam gear q
Cam R1, R2 assembly
Gear unit
Gear bracket
Fig.23
1-20
MX-G70
< Cassette mechanism section >
Removing the playback,recording and eraser
heads (See Fig.1~3)
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 / recording & eraser 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. Remove the flexible P.C.board from the chassis
base.
5. Remove the spring "a" from behind the playback /
recording head.
6. Loosen the reversing azimuth screw retaining the
playback head.
7. Take out the playback head from the front of the
head mount.
8. The recording and eraser heads should also be
removed similarly according to Steps 1~7 above.
Flexible
P.C.board
Cassette mechanism
Trigger armHead mount
Fig.1
Playback/Recording &
eraser head
(Mechanism A side)
Flywheel R
Spring "a"
Trigger arm
Reassembling the playback, recording
and eraser heads (See Fig.3)
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
as shown in Fig.3.
5. The recording and eraser heads should also be
reassembled similarly according to Steps 1~4
above.
CN301
Head amplifier & mechanism
control P.C. board
Fig.2
Playback head
Spring "a"
CN302
FPC holder
Fig.3
Flywheel R
(Mechanism A side)
Reversing azimuth
screw
Head
mount
Flexible
P.C.board
Head amplifier &
mechanism control
P.C. board
(Mechanism B side)
1-21
MX-G70
Removing the head amp. and mechanism
control 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 amplifier & mechanism control board.
3.Disconnect the connectors CN303 on the board
and the connectors CN301 and on CN302 both
the right and left side reel pulse boards.
4.When necessary, remove the 4pin parallel
wire soldered to the main motor
Removing the capstan motor assembly
(See Fig.5 to 7)
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).
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.(See Fig.6 and 7)
A
Flexible
board
Head amplifier &
mechanism control board
AA
CN303
CN302 CN301
Flexible
board
Fig.4
BB
Capstan motor
assembly
AA
1-22
Capstan
belt A
Fig.5
Capstan motor
Capstan
belt A
Capstan
belt B
Motor pulley
Fig.7 Fig.6
BBBB
Capstan
belt B
MX-G70
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 two slit washers "a" & "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
Fig.8
Flywheel R Flywheel L
Flywheel R Flywheel L
Fig.10
Removing the reel pulse 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
d
Slit
washer "a"
Fig.9
e
f
b
Slit
washer "b"
Reel pulse board
g
Solenoid
Fig.11
1-23
MX-G70
< Speaker section >
Attention which adheres to speaker box
The speaker box of this model is a unit supply.
Therefore, we do not supply it as individual parts though
the method of disassembling the speaker box has been
described.
Removing the side cover (See Fig.1)
Remove the six screws A on the side of the body.1.
Removing the squawker speaker
(See Fig.2)
Prior to performing the following procedure, remove
the side cover.
Remove the four screws B on the side of the body.
1.
Disconnect the red and black wires from the speaker
2.
terminals on the squawker speaker.
A
A
Side cover
A
A
Fig.1
B
Squawker speaker
Removing the front cover (See Fig.3 to 6)
Prior to performing the following procedure, remove
the side cover.
Pull out the saran net toward the front while
1.
disengaging the four joints a.
Remove the two screw cover and two screws C
2.
attaching the inner front cover.
Front cover
Screw cover
Screw cover
B
Fig.2
Joints a
Joints a
1-24
Fig.4
Saran net
Fig.3
Remove the two screws D and E respectively.
3.
Remove the front cover toward the front and
4.
disconnect the yellow and black wires from the two
tweeter speaker terminals.
MX-G70
DD
Front cover
Removing the woofer speaker (See Fig.7)
Prior to performing the following procedure, remove
the side cover and the front cover.
Remove the four screws F on the front of the body.
1.
Pull out the woofer speaker toward the front and
2.
disconnect the wire (yellow and black,blue and
black) from the two speaker terminals.
Removing the tweeter speaker
(See Fig.8)
Prior to performing the following procedure, remove
the side cover and the front cover.
Remove the two screws G attaching the tweeter
1.
speaker on the back of the front cover.
C
Tweeter speaker
C
EE
Fig.5
Front cover
G
Tweeter speaker
F
Fig.6
F
Woofer speaker
Fig.7Fig.8
1-25
MX-G70
Adjustment method
Measurement instruments required
for adjustment
1. Low frequency oscillator,
This oscillator should have a capacity to output 0dBs
to 600ohm at an oscillation frequency of 50Hz-20kHz.
2. Attenuator impedance : 600ohm
3. Electronic voltmeter
4. Frequency counter
5. Wow flutter meter
6. Test tape
VTT712 : For Tape speed and wow flutter ( 3kHz)
VTT724 : For Reference level (1kHz)
TMT7036 : For Head angle(10kHz),Play back frequency
characteristics(1kHz),and dubbing frequency
characteristics(63,1,10kHz)
Because of frequency-mixed tape with 63,1k,10k and
14kHz(250nWb/m -24dB).
Use this tape together with a filter.
7. Blank tape
TAPE : AC-225
8. Torque gauge : For play and back tension
Forward ; TW2111A, Reverse ; TW2121A
Fast Forward and Rewind ; TW2231A
9. Test disc
: CTS-1000(12cm),GRG-1211(8cm)
10. Jitter meter
Measurement conditions
Power supply voltage
AC120V(60Hz)
Measurement
output terminal : Speaker out
:TP101(Mesuring for TUNER/DECK/CD)
:Dummy load 6ohm
Radio input signal
AM modulation frequency : 400Hz
Modulation factor : 30%
FM modulation frequency : 400Hz
Frequency displacement : 22.5kHz
Frequency Range
AM 531kHz~1710kHz
FM 87.5MHz~108MHz
Standard measurement positions of volume
and switch
Power : Standby (Light STANDBY Indicator)
Sub woofer VOL. : Minimum
Sound mode : OFF
Main VOL. : 0 Minimum
Traverse mecha set position : Disc 1
Precautions for measurement
1. Apply 30pF and 33kohm to the IF sweeper output
side and 0.082 F and 100kohm in series to
the sweeper input side.
2. The IF sweeper output level should be made as
low as possible within the adjustable range.
3. Since the IF sweeper is a fixed device, there is
no need to adjust this sweeper.
4. Since a ceramic oscillator is used, there is no need
to perform any MPX adjustment.
5. Since a fixed coil is used, there is no need to adjust
the FM tracking.
6. The input and output earth systems are separated.
In case of simultaneously measuring the voltage
in both of the input and output systems with an
electronic voltmeter for two channels, therefore,
the earth should be connected particularly.
7. In the case of BTL connection amplifier, the minus
terminal of speaker is not for earthing. Therefore,
be sure not to connect any other earth terminal
to this terminal. This system is of an OTL system.
1-26
Arrangement of adjusting positions
MX-G70
Cassette mechanism section (Mechanism A section)
Head azimuth
adjusting screw
(Forward side)
Playback
head
Head azimuth
adjusting screw
(Reverse side)
Cassette mechanism section (Back side)
Head azimuth
adjusting screw
(Forward side)
Playback, recording and eraser
heads or playback head
Head azimuth
adjusting screw
(Reverse side)
Cassette Mechanism Unit Section
Tape speed ADJ
Bias ADJ L
Bias ADJ R
1-27
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