JVC MX-GT90 User manual

SERVICE MANUAL
COMPACT COMPONENT SYSTEM
No.20996
Jun. 2001
COPYRIGHT 2001 VICTOR COMPANY OF JAPAN, LTD.
MX-GT90
MX-GT90
Area Suffix
US
UW
UY
Singapore
Brazil,Mexico,Peru
Argentina
SP-MXGT90
CA-MXGT90
SP-MXGT90
Safety precautions
Important for laser products
Preventing static electricity
Disassembly method
Adjustment method
1-2
1-3
1-4
1-5
1-25
Flow of functional operation
until TOC read
Maintenance of laser pickup
Replacement of laser pickup
Description of major ICs
1-29
1-30
1-30
1-31~50
Contents
PLAY& EXCHANGE
STANDBY/ON
CD-R / RW PLAYBACK
STANDBY
MX-GT90
(No MIC jack and MIC LEVEL volume for UY ver.)

MX-GT90
1-2
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 current 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 each exposed metal part,
particularly any exposed metal part having a return path to
the chassis, and measure 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.).
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
!
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.
In regard with component parts appearing on the silk-screen printed side (parts side) of the PWB diagrams, the
parts that are printed over with black such as the resistor ( ), diode ( ) and ICP ( ) or identified by the " "
mark nearby are critical for safety.
When replacing them, be sure to use the parts of the same type and rating as specified by the manufacturer.
(Except the JC version)

MX-GT90
1-3
Important for laser products
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.
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.
VARNING : Osynlig laserstrålning är denna del är öppnad
och spårren är urkopplad. Betrakta ej strålen.
VARO : Avattaessa ja suojalukitus ohitettaessa olet
alttiina näkymättömälle lasersäteilylle.Älä katso
säteeseen.
ADVARSEL : Usynlig laserstråling ved åbning , når
sikkerhedsafbrydere er ude af funktion. Undgå
udsættelse for stråling.
ADVARSEL : Usynlig laserstråling ved åpning,når
sikkerhetsbryteren er avslott. unngå utsettelse
for stråling.
POSITION OF LABELS
WARNING LABEL
!CAUTION Please use enough caution not to
see the beam directly or touch it
in case of an adjustment or operation
check.
DANGER : Invisibie laser radiation
when open and interlock or
defeated.
AVOID DIRECT EXPOSURE TO
BEAM (e)
VARNING : Osynlig laserstrålning
är denna del är öppnad och spårren
är
urkopplad. Betrakta ej strålen.
(s)
VARO : Avattaessa ja suojalukitus
ohitettaessa olet alttiina
näkymättömälle lasersäteilylle.Älä
katso säteeseen. (d)
ADVARSEL :Usynlig laserstråling
ved åbning , når
sikkerhedsafbrydere er ude af
funktion. Undgå udsættelse for
stråling. (f)
CLASS 1
LASER PRODUCT

MX-GT90
1-4
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.
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
Conductive material
(conductive sheet) or iron plate
(caption)
Anti-static wrist strap
Attention when traverse unit is decomposed
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.
*Please refer to "Disassembly method" in the text for pick-up and how to
detach the CD traverse mechanism.
Soldering
Fig.1
Fig.2
CD changer
mechanism
assembly
CD traverse
unit
Flexible cable

MX-GT90
1-5
Remove the six screws Aon the back of the body.
Remove the two screws Bon both sides of the
body.
Remove the metal cover from the body by lifting the
rear part of the cover.
1.
2.
3.
Disassembly method
<Main body>
Removing the metal cover
(See Fig.1 to 3)
Do not break the front panel tab fitted to
the metal cover.
CAUTION: Fig.1
Fig.2
Fig.3
A
A
A
Metal cover
Metal cover
B
Metal cover
B

MX-GT90
1-6
Prior to performing the following procedure, remove
the metal cover.
Disconnect the card wire from connector CN561 on
the main board.
Remove the two screws Con the upper side of the
body and the two screws Don the back of the rear
panel.
Remove the plastic rivet attaching the main board.
Remove the fan connector CN705.
Pull both the rear panel and the front panel assembly
to the outside, then remove the CD changer
mechanism assembly by lifting the rear part of the
assembly. it is assembly to remove the fan's card
wire.
1.
2.
3.
4.
5.
Removing the CD changer mechanism
assembly (See Fig.4 to 6)
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.
CAUTION:
Fig.4
Fig.5
Front panel assembly
C
C
CD changer
mechanism assembly
Rear panel
Main board
CN561
CD changer mechanism assembly
D
Main board
CN561
Front panel assembly
Plastic rivet
Rear panel

MX-GT90
1-7
Remove the four screws Eon the bottom of the
body.
Release the two joints aon the lower right and left
sides of the body using a screwdriver, and remove
the front panel assembly toward the front.
4.
5.
Prior to performing the following procedure, remove
the metal cover and CD changer mechanism
assembly.
Disconnect the card wires from connector CN870,
CN871 and CN315 on the main board respectively.
Remove the tie band and disconnect the wire from
connector CN703 on the amplifier board.
Disconnect the wire from connector CN220 on the
transformer board.
1.
2.
3.
Removing the front panel assembly
(See Fig.6 to 10)
Fig.8
Fig.9
Fig.10
E
(Bottom)
Front panel assembly
Joint a
Joint a
Front panel assembly
Front panel assembly
Fig.7
Front panel assembly Main board
Fig.6
Tie band
Amplifier board
CN703 Main board
CN870
CN871
CN315
Transformer board
CN220
Front panel
assembly
CN705

MX-GT90
1-8
Prior to performing the following procedure, remove
the metal cover and the CD changer mechanism
assembly.
Disconnect the card wire from connector CN1 on the
tuner board on the right side of the body.
Remove the plastic rivet fixing the tuner board.
Remove the two screws Fon the back of the body.
1.
2.
3.
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.
Remove the screw Gattaching the rear cover on the
back of the body.
Push each tab of the four joints bin the direction of
the arrow and release.
Remove the ten screws H and two screws H' (US,
UW only) attaching the rear panel.
Release the joints con each lower side of the rear
panel using a screwdriver and remove the rear panel
backward.
1.
2.
3.
4.
Removing the rear cover / rear panel
(See Fig.12 to 15)
Note : Remove the tuner board in case of necessity.
(Refer to Fig.22)
Fig.11
Fig.12
Fig.14
Fig.15
CN1 Plastic rivet
Tuner board
Rear panel
Rear panel
G
F
Joint b
Joint b
Rear cover
Rear panel
F
H
H
Joint c
Joint cRear panel Rear panel
H
(US,UW only)
H'

MX-GT90
1-9
Prior to performing the following procedure, remove
the metal cover, the CD changer mechanism
assembly, the rear panel and the tuner board.
Disconnect the card wires from connector CN870,
CN871 and CN315 on the main board.
Disconnect the flat wires from connector CN704 and
CN706 on the amplifier board.
Remove the screw I attaching the main board on the
right side of the body.
Disconnect connector CN211 and CN212 on the
main board from the regulator board.
1.
2.
3.
4.
Removing the main board
(See Fig.16 and 17)
Prior to performing the following procedure, remove
the metal cover, the CD changer mechanism
assembly and the rear panel.
Disconnect connector CN217 on the speaker
terminal board from the regulator board.
1.
Removing the speaker terminal board
(See Fig.18)
It is not necessary to remove the main
board.
REFERENCE:
Fig.16
Fig.17
Fig.18
Front panel assembly
Amplifier board
CN704,CN706
Main board
CN870
CN871
CN315
Plastic rivet Main board
Front panel assembly
ICN211
CN212
Regulator board
Regulator board CN217
Speaker terminal board

MX-GT90
1-10
Prior to performing the following procedure, remove
the metal cover, the CD changer mechanism
assembly and the rear panel.
Remove the two tie band attaching the wire to the
amplifier board and the voltage board.
Disconnect the wires from connector CN703, CN704
and CN706 on the amplifier board respectively.
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).
Pull out the upper and lower heat sink brackets from
the heat sink respectively.
Remove the four screws Jattaching the amplifier
board to the heat sink.
Remove the two screws K, the board bracket and
the voltage board.
1.
2.
3.
4.
5.
6.
Removing the amplifier board / voltage
board / heat sink (See Fig.20 and 21)
Prior to performing the following procedure, remove
the metal cover, the CD changer mechanism
assembly and the rear panel.
Disconnect the wires from connector CN218, CN219
and CN250 on the voltage selector board
respectively.
Remove the two tie band attaching the wire to the
voltage selector board.
Disconnect connector CN213 on the voltage selector
board from the regulator board.
1.
2.
3.
Removing the voltage selector board
(See Fig. 19)
Fig.20
Fig.21
Amplifier board
CN704
CN706
CN216
Regulator
board CN215
Tie band
CN703
Voltage
board
Amplifier board
Heat sink
Voltage board
JJ
K
Fig.19
Voltage selector board
Tie band
Tie band
CN218
CN219
CN213

MX-GT90
1-11
Prior to performing the following procedure, remove
the metal cover, the CD changer mechanism
assembly and the rear panel.
Disconnect the wires from connector CN218 and
CN219 on the voltage selector board.
Remove the two tie band from the voltage selector
board.
Disconnect the wire from connector CN204 on the
regulator board.
Remove the plastic holder.
Remove the four screws L attaching the transformer
assembly.
1.
2.
3.
4.
5.
Removing the power transformer
assembly (See Fig.22 and 23)
Prior to performing the following procedure, remove
metal cover, CD changer mechanism assembly, rear
panel, tuner board, main board, amplifier board,
voltage board, voltage selector board.
Disconnect the wire from connector CN204 on the
regulator board.
Remove the two screws M attaching the regulator
board.
1.
2.
Removing the regulator board
(See Fig.23)
Prior to performing the following procedure, remove
the metal cover, the CD changer mechanism
assembly and the rear panel.
Disconnect the power cord from connector CN250
on the voltage selector board.
Remove the tie band from the voltage selector board.
Move the power cord stopper upward and pull out it
from the base chassis.
1.
2.
3.
Removing the power cord (See Fig.24)
Fig.22
Fig.23
Fig.24
Tie band
Voltage selector
board
Power transformer
assembly
Power cord
stopper
Base chassis
Power cord
Power
transformer
assembly
Regulator board
CN204
Transformer
board
L
L
M
Regulator board
CN219
Power transformer assembly
Transformer board CN220
CN250
CN218
Tie band CN250
Power cord
stopper
Power cord
CN219
CN218
Voltage selector board
Plastic
holder

MX-GT90
1-12
<Front panel assembly>
Prior to performing the following procedure, remove
the metal cover, the CD changer mechanism
assembly and the front panel assembly.
Disconnect the card wire from connector CN306 on
the head amplifier & mechanism control board.
Remove the four screws M and three screws M'
attaching the cassette mechanism assembly.
1.
2.
Removing the cassette mechanism
assembly (See Fig.25)
Remove the four screws Oattaching the stay
bracket.
Disconnect the card wires from connector CN316 and
CN880 on the display system control board.
Remove the seven screws P attaching the display
system control board.
If necessary, disconnect the wire from connector
CN911 on the front side of the display system control
board and unsolder FW915.
If necessary, remove the CD play board. (Fig. 29)
1.
2.
3.
4.
Removing the display system control
board (See Fig.26 to 28)
Remove the three screws Qattaching the CD eject
board.
If necessary, unsolder FW915 on the CD eject
board.
1.
2.
Removing the CD eject board
(See Fig.28 and 29)
Fig.25
Fig.26
Fig.27
Fig.28
Fig.29
Head amplifier
& Mechanism control board
CN306 N
N
N'
N'
N'
N
Cassette mechanism
assembly O
Display system control board Stay bracket
P
P
P
P
CN316
CN880
FW915
(Soldering) P
Display system control board
FW915
FW915
CD eject board
CN911
Display system control board
CD eject board
FW915
(Soldering)
Q
Q

MX-GT90
1-13
Prior to performing the following procedure, remove
the display system control board.
Pull out the preset knob on the front panel.
Remove the five screws Rattaching the preset /
tuning switch board.
1.
2.
Removing the preset / tuning 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
remove the nut. Pull out the SOUND MODE knob
and the SUB WOOFER level knob MIC LEVEL
volume knob(Only US, UW) toward the front.
Remove the twelve screws S and the screw S' (Only
US, UW) attaching the operation switch board.
Release the wire clamp.
Remove the screw Tattaching the earth terminal
extending from the switch board.
Release each tab of the seven joints gretaining the
operation switch board.
1.
2.
3.
4.
Removing the operation switch board
(See Fig.31 and 32)
Fig.30
Fig.31
Fig.32
Preset / tuning switch board
R
R
VOLUME knob
Nut
SUB WOOFER
level knob
SOUND MODE knob
PRESET knob
S
ST
S
S
S
S
S
Joint g
Joint gJoint g
Wire clamp
Joints g
Joints g
Operation
switch board
MIC LEVEL
volume knob
(US,UW only)
S'
(US,UW only)

MX-GT90
1-14
Removing the CD Servo control board
(See Fig.1)
Removing the CD tray assembly
(See Fig.2~4)
1.
2.
3.
4.
5.
6.
7.
8.
9.
Remove the front panel assembly.
Remove the CD changer mechanism assembly.
Remove the CD Servo control board.
Remove the screw B' retaining the lod stopper.
From the T.bracket section "b" and clamper base
section "c" , remove both of the edges fixing the
rod(See Fig.2 and 3).
Remove the screw B retaining the disc stopper
(See Fig.3).
Remove the three screws Cretaining the T.bracket
(See Fig.3).
Remove the screw Dretaining the clamper assembly
(See Fig.3).
From the left side face of the chassis assembly, remove
the one screw Eretaining both of the return spring and
lock lever(See Fig. 4).
By removing the pawl at the section "d" fixing the return
spring, dismount the return spring(See Fig.4).
Remove the three lock levers(See Fig.4).
10.
11.
Fig.1
Fig.2
Fig.3 Fig.4
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 Aretaining 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.
CN601
CN801
b
c
E
Rod
T.Braket
Clamper base
T.Braket Disc stopper
Lod stopper
(C/J version only)
Clamper ass'y
b
a
CC
B'
D
C
d
Lock lever
Return spring
CD servo control board
CN651
CN854
aa
A
A
A
A
CN151
CN652
B
Earth
wire

MX-GT90
1-15
11.
12.
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
shown in Fig.6 from to the second or fifth hole on the
left side face of the CD changer mechanism assembly.
Fig.5
Fig.7
Fig.6
Fig.8 Fig.9
[Caution] 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.
13.
14.
15.
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.
CD 3
CD 2
CD 1
CD tray
assembly
e
Drive unit of elevator
CD tray assembly
f
Refer to Fig.7 Pawl
Chassis assembly
Pulley gear
Motor pulley
Pawl ,
CD tray assembly
Stopper
g
gg'

MX-GT90
1-16
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 Fretaining the CD loading
mechanism assembly.
Removing the CD traverse mechanism
(See Fig.11 and 12 )
1.
2.
For dismounting only the CD traverse mechanism
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
arrow direction "l", remove the assembly from the lifter
unit
Fig.10
Fig.12
Fig.11
Fig.13
Removing the CD pick unit
(See Fig.13 )
1.
2.
3.
4.
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
the center position.
While pressing the stopper retaining the shaft in the
arrow direction "o" , pull out the shaft in the arrow
direction "p".
After dismounting the shaft from the CD pickup unit,
remove the CD pickup unit
Cams R1, R2 assembly
i
CD loading mechanism assembly
h
F
F
FF
Arrow
Lifter unit
CD traverse mechanism
l
n
op
m
Arrow
Cam R1, R2 assembly
k
Arrow
j
CD Pickup unit
CD loading
mechanism
Shaft
Cam gear
Shaft
Shaft
Stopper Stopper

MX-GT90
1-17
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.
Fig.15
Fig.14
Fig.16
Removing the cam unit
(See Fig.15 ~17 )
1.
2.
3.
4.
5.
Remove the CD loading mechanism assembly.
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).
While turning the cam gear "q", align the Paul "s"
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
gear "q" and cams R1/R2 assembly)(See Fig.18).
Cam gear q
Drive unit
r
G
H
J
H
Chassis assembly
Tray select
switch board
CN854
CN851
CN804
Cylinder gear
Drive unit
Fig.17
Select lever
Cams R1, R2 assembly
Cam unit
Cam gear q
s

MX-GT90
1-18
Fig.18
Fig.20
Fig.19
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. 21.
Removing the actuator motor and belt
(See Fig.18~21)
1.
2.
3.
4.
5.
Remove the two screws Iretaining the gear bracket
(See Fig.18).
While pressing the pawl "t" fixing the gear bracket in the
arrow direction, remove the gear bracket
(See Fig.18).
From the notch "usection" on the chassis assembly
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
actuator motor pulleys and pulley gears(See Fig. 18).
After turning over the chassis assembly, remove the
actuator motor while spreading the four pawls "v" fixing
the right and left actuator motors in the arrow
direction(See Fig. 20).
Pulley gear
Belt
Motor pulley
Belt
Pulley gear
Motor pulley
Gear bracket
t
I
I
Pawl
v
Actuator motor
v
Chassis assembly
u
Gear bracket
Pulley gear
Gear B
Cylinder gear
Gross gear U
Gear C
Gross gear L
Select gear
Gear B
Gear C
Pulley gear
Assembly and Configuration Diagram

MX-GT90
1-19
Fig.22
[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. 23).
Removing the cams R1/R2 assembly
and cam gear q(See Fig.22)
1.
2.
3.
4.
Remove the slit washer fixing the cams R1 and R2
assembly.
By removing the two pawls "w" fixing the cam R1,
separate R2 from R1.
Remove the slit washer fixing the cam gear "q".
Pull out the cam gear "q" from the C.G. base assembly.
Removing the C.G. base assembly
(See Fig.22 and 23)
Remove the three screws Jretaining the C.G. base
assembly.
Fig.23
Slit washer
Pawl
Cam R2
Slit washer
Cam gear q
Cam switch board
C.G. base assembly
Cam R1
Pawl
Cam gear q
Notch
Cylinder
gear
Gear bracket
Cam R1, R2 assembly
Gear unit
Drive unit
x
Pawl
w
w
J

MX-GT90
1-20
< 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.
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.
Cassette mechanism
Flywheel R
Trigger armHead mount
(Mechanism A side)
(Mechanism A side)
Playback/Recording &
eraser head
Flexible
P.C.board
Spring "a"
Trigger arm
Head amplifier & mechanism
control P.C. board Flywheel R
CN301
Fig.1
Fig.2
Playback head Reversing azimuth
screw
Head
mount
Flexible
P.C.board
Spring "a"
FPC holder Head amplifier &
mechanism control
P.C. board
CN302
(Mechanism B side)
Fig.3