Yamaha GX-900 User manual

GX-900
GX-900
100674
SERVICE MANUAL
GX-900
MINI COMPONENT SYSTEM
IMPORTANT NOTICE
This manual has been provided for the use of authorized YAMAHA Retailers and their service personnel.
It has been assumed that basic service procedures inherent to the industry, and more specifically YAMAHA Products, are
already known and understood by the users, and have therefore not been restated.
WARNING: Failure to follow appropriate service and safety procedures when servicing this product may result in
personal injury, destruction of expensive components, and failure of the product to perform as specified.
For these reasons, we advise all YAMAHA product owners that any service required should be performed
by an authorized YAMAHA Retailer or the appointed service representative.
IMPORTANT: The presentation or sale of this manual to any individual or firm does not constitute authorization, certifica-
tion or recognition of any applicable technical capabilities, or establish a principle-agent relationship
of any form.
The data provided is believed to be accurate and applicable to the unit(s) indicated on the cover. The research, engineering, and
service departments of YAMAHA are continually striving to improve YAMAHA products. Modifications are, therefore,
inevitable and specifications are subject to change without notice or obligation to retrofit. Should any discrepancy appear to
exist, please contact the distributor's Service Division.
WARNING: Static discharges can destroy expensive components. Discharge any static electricity your body may have
accumulated by grounding yourself to the ground buss in the unit (heavy gauge black wires connect to this
buss).
IMPORTANT: Turn the unit OFF during disassembly and part replacement. Recheck all work before you apply power to the
unit.
■CONTENTS
TO SERVICE PERSONNEL .....................................1~2
FRONT PANELS ........................................................... 3
REAR PANELS .............................................................4
SPECIFICATIONS .........................................................5
INTERNAL VIEW .......................................................... 6
DISASSEMBLY PROCEDURES ............................7~16
VOLUME RANGE .......................................................17
SYSTEM CONTROL CHECK .....................................17
TEST MODE ................................................................18
SYSTEM TEST MODE................................................18
RECEIVER TEST MODE ......................................19~20
TAPE TEST MODE .....................................................20
CD TEST MODE .........................................................21
ALL FUNCTION TEST MODE....................................22
CD ERROR MESSAGES ............................................ 22
CD STANDARD OPERATION CHART ................23~26
TAPE ADJUSTMENTS .........................................27~29
MD TEST MODE & ADJUSTMENTS ...................30~37
MD ERROR DISPLAY ..........................................38~39
MD TROUBLESHOOTING....................................40~44
IC DATA ................................................................45~58
DISPLAY DATA ..........................................................59
BLOCK DIAGRAM ................................................60~65
MD TEST POINT WAVEFORM ............................66~67
PRINTED CIRCUIT BOARD .................................68~82
PIN CONNECTION DIAGRAM ...................................83
SCHEMATIC DIAGRAM .......................................84~90
PARTS LIST ........................................................91~117
GREASE APPLICATION DIAGRAM................118~120
REMOTE CONTROL TRANSMITTER......................121
NX-GX500..................................................................122
このサービスマニュアルは、エコマーク認定の再生紙を使用しています
。
ThisServiceManualusesrecycledpaper.

GX-900 is composed of GX-900 and NX-GX500.

GX-900
GX-900
■TO SERVICE PERSONNEL
1. Critical Components Information.
Components having special characteristics are marked and
must be replaced with parts having specifications equal to
those originally installed.
CD Laser Diode Properties
●Material : GaAlAs
●Wavelength : 780 nm
●Emission Duration : Continuous
●Laser Output : max. 44.6 µW*
* This output is the value measured at a distance of
about 200 mm from the objective lens surface on
the Optical Pick-up Block.
CAUTION : USE OF CONTROLS OR ADJUSTMENTS OR PERFORMANCE OF PROCEDURES OTHER THAN THOSE
SPECIFIED HEREIN MAY RESULT IN HAZARDOUS RADIATION EXPOSURE.
THE COMPACT DISC PLAYER/MINI DISC RECORDER SHOULD NOT BE ADJUSTED OR REPAIRED BY ANYONE
EXCEPT PROPERLY QUALIFIED SERVICE PERSONNEL.
1
qB, G models
wB, G models
AC LEAKAGE
TESTER OR
EQUIVALENT
EQUIPMENT
UNDER TEST
INSULATING
TABLE
WALL
OUTLET
MD Laser Diode Properties
●Material : GaAlAs
●Wavelength : 785 nm
●Pulse time:
Read mode ... 0.8 mW Continuous
Write mode ... max 10 mW 0.5S
min cycle 1.5S
Repetition
PROTECTION OF EYES FROM LASER BEAM DURING SERVICING
This set employs a laser. Therefore, be sure to carefully follow the instructions below when servicing .
When checking the laser diode emission, keep your eyes more than 30 cm away from the objective lens.

GX-900
GX-900
2
wA, B, G models
English
➀THIS PRINTING (SEE POSITION SHOWN IN THE ILLUSTRATION) INFORMS THE USER THAT THE APPARATUS
CONTAINS A LASER COMPONENT.
➁THIS LABEL (SEE POSITION SHOWN IN THE ILLUSTRATION) WARNS THAT ANY FURTHER PROCEDURE WILL
BRING THE USER INTO EXPOSURE WITH THE LASER BEAM.
CAUTION : USE OF CONTROLS, ADJUSTMENTS OR PERFORMANCE OF PROCEDURES OTHER THAN THOSE
SPECIFIED HEREIN, MAY RESULT IN HAZARDOUS RADIATION EXPOSURE.
Swedish
➀DENNA MÄRKNING (SE FIGUR) UPPLYSER OM ATT DET I APPARATEN INGÅR EN LASERKOMPONENT AV
TYP KLASS 1.
➁VARNINGSMÄRKNING (SE FIGUR) FÖR STRÅLNING. INGREPP I APPARATEN BÖR ENDAST FÖRETAGAS AV
FACKMAN MED KÅNNEDOM OM LASER. APPARATEN INNEHÄLLER EN LASERKOMPONENT SOM AVGER
STRÅLNING ÖVERSTIGANDE GRÄNSEN FÖR LASERKLASS 1.
VARNING : OSYNLIG LASERSTRÅLNING NÄR DENNA DEL ÄR ÖPPNAD OCH SPÄRREN ÄR URKOPPLAD.
STIRRA EJ I STRÅLEN OCH BETRAKTA EJ STRÅLEN GENOM OPTISKT INSTRUMENT.
Danish
➀DETTE MÆRKAT ER ANBRAGT SOM VIST I ILLUSTRATIONEN FOR AT ADVARE BRUGEREN OM AT AP-
PARATET INDEHOLDER EN LASERKOMPONENT.
➁DETTE MÆRKAT OM LASEREN ER ANBRAGT PÅ APPARATET SOM EN OPLYSNING OM AT APPARATET
INDEHOLDER ET LASERKOMPONENT.
ADVARSEL : USYNLIG LASERSTRÅLING VED ÅBNING, NÅR SIKKERHEDSAFBRYDERE ER UDE AF FUNKTION.
SE IKKE IND I STRÅLEN-HELLER IKKE MED OPTISKE INSTRUMENTER.
ADVARSEL : USYNLIG LASERSTRÅLING NÅR DEKSEL ÅPNES OG SIKKERHEDSLÄS BRYTES. STIRR IKKE INN
I STRÅLEN ELLER SE DIREKTE MED OPTISKE INSTRUMENTER.
Finnish
VARO! :
AVATTAESSA JA SUOJALUKITUS OHITETTAESSA OLET ALTTIINA NÄKYMÄTTÖMÄLLE LASER-SÄTEILYLLE.
ÄLÄ TUIJOTA SÄTEESEEN ÄLÄKÄ KATSO SITÄ OPTISEN LAITTEEN LÄPI.

GX-900
GX-900
■FRONT PANELS
▼ B, G models
▼ A model
3
1
1
A B C D E F G H I J K L M N O
P Q R S T U V W X Y Z
/
2
2
3
3
4
4
5
5
6
6
7
7
8
8
R. TI ME
C
EDIT
D
+I0
E
MODE REPEAT RANDOM
SPACE
TUNER
DISC SKIP
POWER SLEEP
INPUT VOLUME
9 0
PRESET
TIME
A
PROG
B
CD
/I
YMERSION BASS BOOST MUSIC
INPUT MODE M–MARK SCROLL
TAPE
MD
REC/PAUSE
ENTER DELETE REC/PAUSE
DIRECTION
MD EDIT
SYS20
200(7-7/8")
320(12-5/8")
●NX-GX500

GX-900
GX-900
▼ A model ▼ B, G models
4
343(13-1/2") 12
(1/2")
9
(3/8") 364(14-5/16")
100
(3-15/16")
172(6-3/4")
280(11")
320(12-5/8")
■REAR PANELS

GX-900
GX-900
■SPECIFICATIONS
■AMPLIFIER SECTION
Minimum RMS Output Power per Channel
1kHz, 0.9% THD, 6Ω......................................80W + 80W
1kHz, 10% THD, 6Ω...................................100W + 100W
Input Sensitivity/Impedance
AUX............................................................... 200mV/47kΩ
Spectrum Analyzed Band .............................................5 band
(100Hz, 350Hz, 1kHz, 3.5kHz, 10kHz)
■TUNER SECTION
FM Tuning Range .................................... 87.50 to 108.00MHz
AM Tuning Range .......................................... 531 to 1,611kHz
FM Usable Sensitivity (75Ω)
DIN Mono, S/N 30dB................................................1.8µV
■CD CHANGER SECTION
Type .......................................... 3-Disc Carousel Auto-changer
Signal Readout......................................................Non-contact,
3-beam semi-conductor laser pick-up
D/A Converter............................................................. 1bit DAC
Filter ........................................8-time oversampling digital filter
Wow & Flutter ....................................................Unmeasurable
Laser Diode Properties
Meterial : GaALAs
Wavelength : 780 nm
Emission Duration : continuous
Laser Output : max. 44.6 µW*
*This output is the value measured at a distance of about
200 mm from the objective lens surface on the Optical
Pick-up Block.
■TAPE DECK SECTION
Type ..................................................................... Auto Reverse
4-Track 2-Channel playback/recording stereo Cassette Deck
Heads
REC/PB..................................................... Hard permalloy
Erase................................................... Double Gap Ferrite
Motors
Main ......................................................... DC servo motor
Tray Loading ...................................................... DC motor
Wow & Flutter
W.PEAK ................................................................. ±0.19%
W.RMS ..................................................................... 0.09%
Frequency Response (–20dB)
Type I/Normal tape........................ 50 to 15,000Hz ±3dB
Type II/High (CrO2) tape ............... 50 to 16,000Hz ±3dB
S/N Ratio
NR off.........................................................................58dB
Dolby B NR on...........................................................66dB
■MD SECTION
System .........................................Minidisc digital audio system
Recording Method ...........Magnetic field moduration overwrite
Reading Method ............................ Non-contact optical pick up
Coding............ATRAC (Adaptive TRansform Acoustic Coding)
Laser Diode Properties
Meterial : GaALAs
Wavelength : 785 nm
Pulse time :
Read mode..............................0.8 mW continuous
Write mode .............................max. 10 mW 0.5S
min. cycle 1.5S
Repetition
■SPEAKER SECTION (NX-GX500)
Type ................................................. 3-Way Bass-reflex Design
(Magnetic-Shielding Type)
Speakers .................................................. 13cm (5-1/8”) woofer
5cm (1-15/16”) tweeter
2cm (13/16”) super tweeter
Frequency Range............................................. 60 to 20,000Hz
Maximum Input ................................................................240W
Impedance ............................................................................ 6Ω
Sound Pressure Level....................87dB/1m • 2.45V (1W/6Ω)
■GENERAL
Power Supply
A model...................................................... AC240V, 50Hz
B, G models ............................................... AC230V, 50Hz
Power Consumption........................................................150W
(approx. 1W when set to the standby mode)
Dimensions (W X H X D)
GX-900............................................. 280 X 320 X 364mm
(11” X 12-5/8” X 14-5/16”)
NX-GX500........................................ 200 X 320 X 218mm
(7-7/8” X 12-5/8” X 8-9/16”)
Weight
GX-900............................................. 10.5kg (23 lbs. 2 oz)
NX-GX500....................................3.8kg (8 lbs. 6 oz)/each
Accessories ............................................ AM loop antenna X 1
Indoor FM antenna X 1
Remote Control Transmitter X 1
Battery (size “AA”, R06) X 2
Speaker Cord X 2
* Specifications subject to change without notice.
* Manufactured under license from Dolby Laboratories Li-
censing Corporation. “DOLBY” and the double-D symbol
Vare trademarks of Dolby Laboratories Licensing Cor-
poration.
G..................European model
B ....................... British model
A .................Australian model
5

GX-900
GX-900
6
■INTERNAL VIEW
Left side
Top side
qP.C.B. TUNER
wP.C.B. MAIN (5)
eP.C.B. MAIN (1)
rP.C.B. INPUT (1)
tMD MECHANICAL UNIT
yP.C.B. MAIN (2)
uP.C.B. MAIN (3)
iP.C.B. MAIN (6)
oDECK MECHANICAL UNIT
!0 P.C.B. INPUT (2)
!1 CD MECHANICAL UNIT
!2 P.C.B. CD
q w e r t
i oy
!0 q !1 !2 r
u
u y i o t

GX-900
GX-900
■DISASSEMBLY PROCEDURES (Remove parts in the order as numbered.)
Fig. 2
Fig. 1
7
1. Removal of Top Cover
Remove 11 screws ( q) in Fig. 1.
2. Removal of CD Mechanical Unit
a. Disconnect the power cord from the AC outlet.
b. Push the Friction Arm ( the bottom side of the CD
Mechanical Unit ) with the Ejecting Tool or a tool like
as shown in Fig. 2.
c. Pull the Tray forward approx. 5cm ( 2" ) and remove
the CD Lid in Fig. 2.
d. Push the Tray back to the original, closed position.
e. Disconnect the Flat Connecting Cables ( CB9 ) and
remove 2 connectors ( CB8 and CB7 ) in Fig. 2
f. Remove 4 screws ( w) and then remove the CD
Mechanical Unit in Fig. 1.
Ejecting Tool for CD Tray (TX946040)
3. Removal of Panel Unit
a. Rotate the Loading Gear, then open the Tray and
remove the Cassette Lid in Fig. 2.
b. Push the Tray back to the original, closed position.
c. Disconnect the flat connecting cables ( CB10 and
CB13 ) and remove a connector ( CB805 ) in Fig. 2.
d. Remove 6 screws ( eand r) and then remove the
Panel Unit in Fig. 1.
FRONT
Friction
Arm
q
q
q
q
Top Cover
Panel Unit
CD Mechanical Unit
q
w
w
e
e
w
r
e
CB9
CB8 CB7
CD Lid
CB13
CB805
CB10
Cassette Lid
Loading Gear
u

GX-900
GX-900
Fig. 3
8
4. Removal of Deck Mechanical Unit
a. Remove 4 screws ( t) and then remove the Deck
Mechanical Unit in Fig. 3.
b. Remove 3 connectors ( W2, W3 and W4 ) in Fig. 3.
t
t
t
t
Deck Mechanical Unit
W3
W2
W4
5. Removal of MD Mechanical Unit
a. Remove 3 screws ( y) in Fig. 3 and 1 screw ( u) in
Fig. 1.
b. Remove 4 connectors ( CB1, CB3, CB4 and CB5 ) in
Fig. 3.
c. Remove the MD Mechanical Unit.
y
(Bottom side)
y
MD Mechanical Unit
CB3
CB5
CB1
CB4
6. Removal of MD Mechanism
a. Disconnect the flat connecting cable in Fig. 4.
b. Remove 4 screws ( i) in Fig. 4.
c. Remove 2 screws ( o) in Fig. 4.
d. Remove 2 screws ( !0 ) in Fig. 4.
P.C.B. MD
MD Mechanism
Fig. 4
i
i
o
o
!0
!0
Flat connecting cable

GX-900
GX-900
9
Fig. 5
Fig. 6
7. Operation Check of P.C.B. CD
a. Remove the CD Mechanical Unit.
b. Remove 4 screws ( !1 ) and then remove the P.C.B. CD in Fig. 5.
c. Place blocks (at 3 locations) to hold the CD Mechanical Unit horizontally as shown in the Fig. 6.
d. Connect the Flat Connecting Cable ( CB9 ) and 2 connectors ( CB8 and CB7 ) in Fig. 5 and Fig. 6.
e. Connect the power plug and turn on the Power Switch.
!1
CB9
CB8
CB7
P.C.B. CD
Block
Block
P.C.B. CD
Block

GX-900
GX-900
Fig. 8
Fig. 7
Fig. 9
8. Operation Check of P.C.B. Main (1)
a. Remove the CD Mechanical Unit.
b. Remove the Panel Unit.
c. Remove the Deck Mechanical Unit.
d. Remove the MD Mechanical Unit.
e. Remove 5 screws ( !2 ) in Fig. 7.
f. Remove 1 screw ( !3 ) and then remove the P.C.B. Main (2) in Fig. 8.
g. Remove 3 screws ( !4 ) in Fig. 8.
h. Remove 4 screws ( !5 ) and then remove the Power Transformer in Fig. 9.
i. Place the main unit on its left side (viewed from the front) and remove the Bottom Cover in Fig. 10.
j. Install the Panel unit to the main unit in Fig. 10.
k. Connect the flat connecting cables ( CB10 and CB13 ) and remove a connector ( CB805 ) in Fig. 2.
l. Connect the power plug and turn on the Power Switch.
Fig. 10
10
!2 !2
!2
!3
!4
P.C.B. Main (2)
!5
!5
P.C.B. Input
P.C.B. Main (1)
CAUTION
When the power to this equipment is turned on with the CD/MD Mechanical Unit disconnected, the capacitor C255(4700/
16) of the Main P.C.B. (CD/MD power supply section) is charged. Connecting the CD/MD P.C.B. in this state may cause
damage to its IC. Therefore, when installing the CD/MD Mechanical Unit, be sure to discharge the capacitor C255(4700/
16) of the Main P.C.B. before making connections. (To discharge it, short the W201 terminal +B and GND with a
resistor(270Ω1W).)

GX-900
GX-900
9. Removal of Tray & Traverse Unit
a. Remove 4 screws ( !6 ) and then remove the Clamp Bracket in Fig. 11.
b. Remove 2 screws ( !7 ) and then remove the Tray Brackets in Fig. 11.
c. Push the Friction Arm ( the bottom side of the CD Mechanical Unit ) with a screwdriver or the like and pull out the Tray
forward as in Fig. 11.
d. Remove 4 screws ( !8 ) and take out the Slider in Fig. 12.
e. Disconnect the Flat Connecting Cable ( 16P ) and connectors ( 6P ).
f. Remove the Traverse Unit in Fig. 12.
!6
!6
CD Mechanical Unit
Friction
Arm
Clamp Bracket
Fig. 12
●Precaution for Installation of Tray
Be sure to fit the shaft of the Friction Gear into
the groove in the Tray.
●Installation of Traverse Unit & Slider
a. Fit the Traverse Unit into the Chassis.
b. Turn the Cam Gear until its Guide Pin comes to the
position as shown in Fig. 12.
c. Fit the Slider into the Traverse Unit. Set the Spring of
the Slider so that it holds down the Guide Pin of the
Cam Gear (as shown in Fig. B).
(Press the Spring of the Slider once and release it,
and it will hold down the Guide Pin of the Cam Gear.)
d. After installation, check that the Clamp moves up and
down by turning the Load Gear.
Fig. B
Tray
Tray Bracket
!7
Spring
Spring
Spring Load Gear
FRONT
Groove
Guide Pin
OK NG
Tray
Bracket
Friction
gear
Shaft
Tray
Slider
Traverse
Unit
Guide
Pin
Cam Gear
Fig. 11
!8
no marking
side
!8
Guide Pin
Cam Gear
Traverse
Unit
Spring
Slider
Fig. A
11

GX-900
GX-900
Fig. 15
Disc Table
19.4mm
Fig. C
Pick-up Head Gear A
Sled Shaft
Sled Shaft
Stopper
Fig. 13
11.Removal of Cassette Mechanism
Remove 4 screws ( !9 ) and then pull out the Cassette
Mechanism in Fig. 14.
12.Removal of Main Motor
Remove 2 screws ( @0 ) in Fig. 14.
13.Removal of Pinch Roller
Detach the hook and then remove the Pinch Roller
in Fig. 15.
14.Removal of Head Ass’y
a. Remove 1 screw ( @1 ) and then remove the Relay
P.C.B. in Fig. 15.
b. Remove 2 screws ( @2 ) and then remove the Head
Ass’y in Fig. 15.
* Perform the adjustment of azimuth after installing
the Head Ass’y.
10.Removal of Pick-up Head
a. Remove the Gear A in Fig. 13.
b. Pull out the Sled Shaft and remove the Pick-up Head
in Fig. 13.
●Check that the disc table height is as specified
below.
Fig. 14
12
!9 !9
!9 !9
@0 @0
@1@2 @2
Pinch Roller (L) Pinch Roller (R)
Hook Hook
Head Ass'y

GX-900
GX-900
13
Disassembly of MD Mechanism Unit
Remove the MD mechanical unit according to Steps 1 ~ 6 of the disassembly procedure (page 7).
Removal of Magnetic Head (Fig.18)
1. Remove a screw (A1). Caution
a. When removing the magnetic head, hold its base and
do not touch the magnetic head itself or the leaf
spring.
b. Place the magnetic head upside down.
c. Use special care so as not to cause any damage to
the magnetic head when installing it.
(A1)x1
ø1.7x5mm
Fig. 18
( Q2 ) x 1
( Q1 ) x 4
1.7 x 3mm
( Q2 ) x 1
( Q2 ) x 3
(Q2)x1
(R1)x4
ø1.7x8.9mm
Removal of MD Main P.C.B. (Fig. 16)
1. Remove 4 screws (Q1).
2. Remove 6 connectors (Q2).
Removal of MD Mechanism (Fig.17)
1. Remove 4 screws (R1).Caution
Almost the entire surface of the cartridge holder is
coated with oil. When removing the mechanism, hold it
at the rear end (where marked with arrows in the figure)
and avoid touching the oiled surface.
Fig. 17
Fig. 16
Flexible P.C.B. for
optical pickup (*1) MD Main P.C.B.
(*1) After pulling off the flexible P.C.B.
for the optical pickup from the
connector, cover its end with
aluminum foil or the like which is
electrically conductive so as to prevent
the optical pickup from being
damaged by static electricity.
Frame
Cartridge Holder
Magnetic Head
MD Mechanism
Black
Gray
Gray
MD Mechanism
Leaf Spring
Sheet, Head

GX-900
GX-900
14
Removal of Cartridge Holder (Fig.19)
1. Open the roller arm lever in the arrow direction and move the clamper lever to the rear.
2. With a +5V voltage (*2) applied to the red line side of the blue connector of the loading
motor, push the rack gear in the arrow direction until the cam plate lever clicks.
(*2) A +5V voltage can be obtained from the pluspol (D6.5/5V) of C35 and the ground
terminal of the MD P.C.B.
3. Remove a screw (B1 and B2, 1 each) from the holder arm and remove the cartridge
holder by moving it to the left.
Slider Lever
Cartridge Holder
Clamper
Lever
Rack Gear
Roller Arm Lever
Loading
Motor
Cam Plate
Lever
(B1) x1
Ø1.7x5mm
(B2) x1
Fig.19
Caution
Be careful so that oil does not get on the clamper lever
which contacts the roller of the roller arm lever.
Installation of Cartridge Holder
•To install the cartridge holder, the rack of the mechanism must be
lowered toward the rear.
•While pushing the roller arm lever outward, push in the slider lever.
•Apply a +5V voltage to the loading motor (until clicking sound is
heard) and push in the rack gear.
•With the slider lever and the rack gear installed as described above,
fit the cartridge holder as shown in the figure and tighten screws.
C35
Pluspol (D6.5/5V)
P.C.B. MD

GX-900
GX-900
15
Removal of Mechanism SW P.C.B. (Fig.20)
•Once the mechanism switch P.C.B. is removed, it will
be necessary to perform “Adjustment of Lead-in Switch
Position”. (See page 34.)
1. Remove 2 screws (E1) and then remove the Mecha-
nism SW P.C.B.
(E1)x1
Ø1.7x3mm
(E1)x1
Ø1.7x9.5mm
Fig.20
Fig. 21
Removal of Sled Motor/Loading Motor (Fig.21)
1. Remove 4 screws (D1) and then remove the sled
motor/loading motor.
(D1)x2
Ø1.7x2mm
(D1)x2
Ø1.7x2mm
Mechanism SW P.C.B.
Loading Motor
Sled motor
Caution
Use care so as not to cause any damage to the gear.
(The damaged gear will cause abnormal noise to occur
while searching.)
Installation of Mechanism SW P.C.B.
•Set the mechanism to the eject mode by applying -5V
to the loading motor.
•Install the mechanism SW P.C.B. so that the boss fits
in the hole in it.
•Push the lead switch on the mechanism SW P.C.B.
toward the optical pickup side (so that looseness in the
boss hole is eliminated).
•Tighten screws and apply thread lock.
•Measure the lead-in switch position. (See page 34.)
(Enter the result in EEPROM.)
Lead-in switch
Mechanism SW P.C.B.
(E1)x1
Ø1.7x9.5mm
(E1)x1
Ø1.7x3mm

GX-900
GX-900
16
Removal of Optical Pickup Head (Fig.23 and Fig.24)
1. Remove 3 screws (F1).
Caution
Use care so as not to cause any damage to the gear.
(The damaged gear will cause abnormal noise to occur
while searching.)
2. Remove a screw (F2).
The leaf spring (A) attached to the P.U. will be reused
when replacing the pickup. It is not supplied with the
optical pickup.
3. Using tweezers or the like, pull the PU shaft from the
base a little. Pull only enough to allow the pickup to
come off. If it is pulled off completely, the oil on the
shaft will be scraped off.
Be sure to keep oil on the shaft!
Fig. 23
Fig.22
Removal of Spindle Motor (Fig.22)
•Once the spindle motor is removed, it will be neces-
sary to perform “Pickup Rating”. (See page 35.)
1. Remove 3 screws (C1).
2. Remove the spindle motor by moving it in the arrow
direction.
Caution
a. Be careful not to scratch the gear.
(Scratched gear will produce noises during searching.)
b.As the turn-table is magnetized, keep foreign objects
from being attracted.
(C1)x1
Ø1.7x2.1mm
(C1)x3
Ø1.7x2.5mm
(F1)x3
Ø1.7x9.5mm
Turn Table
Spindle Motor
Optical Pickup Head
Fig. 24
Assembly of Optical Pickup
•When installing the pickup to the MD guide (A), be
sure to tighten the leaf spring (A) with it.
•When installing the pickup to the MD mechanism, fit
the pickup into the MD guide (B) first, match the boss
of the MD guide (A) and its hole in the chassis and
tighten them with a screw.
(F2)x1
Ø1.4x2.2mm
MD Guide (A)
PU Shaft
Leaf Spring (A)
Optical Pickup
Fit the pickup into the MD guide (B) first
MD Guide (B)

GX-900
GX-900
DISPLAY
VOL MIN
VOL 01
VOL 02
VOL 03
VOL 04
VOL 05
VOL 06
VOL 07
VOL 08
VOL 09
dB
–∞
–79
–73
–68
–64
–61
–59
–58
–57
–56
DISPLAY
VOL 10
VOL 11
VOL 54
VOL 55
dB
–55
–54
–11
–10
DISPLAY
VOL 56
VOL 57
VOL 58
VOL 59
VOL 60
VOL 61
VOL 62
VOL 63
VOL 64
VOL MAX
dB
–9
–8
–7
–6
–5
–4
–3
–2
–1
0
■VOLUME RANGE
○○○○○○○○
1dB step
NOTE) When VOLUME is at minimum, MUTE of AMP is on.
■SYSTEM CONTROL CHECK
wFUNCTION →CD ?
DISC No. display on?
↓
no
In case that CD doesn’t play : [RECEIVER →CD]
(SYSCK, CDCE, SYSO) NG
In case that DISPLAY doesn’t change : [CD →RECEIVER]
(SYSI) NG
yes
qFUNCTION AUX is selected
CD PLAY KEY ON (remote control transmitter)
↓
17
SYSCK: Pin 20 of IC8
CDCE: Pin 25 of IC8
SYSO: Pin 21 of IC8
SYSI: Pin 22 of IC8
rFUNCTION →MD ?
MD display on?
↓
no
In case that MD doesn’t play : [RECEIVER →CD]
(SYSCK, CDCE, SYSO) NG
In case that DISPLAY doesn’t change : [MD →RECEIVER]
(SYSI) NG
yes
eMD PLAY KEY ON (remote control transmitter)
↓
CHECK OK SYSCK: Pin 20 of IC8
CDCE: Pin 25 of IC8
SYSO: Pin 21 of IC8
SYSI: Pin 22 of IC8

GX-900
GX-900
■TEST MODE
To facilitate inspection, measurement and location of any faulty point, 6 types of built-in Test Mode are provided, one
for each section.
•System Test Mode : Test mode for the system section. It is also used when entering the test mode for each section.
•Receiver Test Mode : Test mode for the receiver section
•Tape Test Mode : Test mode for the deck section
•CD Test Mode : Test mode for the CD section
•MD Test Mode : Test mode for the MD section
•All Function Test Mode : Test mode for all functions
■SYSTEM TEST MODE
This test mode is used for the system section. Also, this mode must be executed first when entering the test mode
for each section.
Starting Procedure
In the STANDBY mode, press the STANDBY/ON button while pressing the RANDOM button and the PLAY/
PAUSE(CD) button simultaneously. Once the SYSTEM TEST MODE is set, causal factors for the previous power
off appear on the FL display.
Causal factors for power off at starting
Display Description
<Key Operate Power off by button operation
<Off Timer Power off by Off Timer setting
<Sleep Timer Power off by Sleep Timer function
<Auto Off Power off by Auto Power Off function
<I-Protect Power off by detection of an abnormal current value
<V-Protect Power off by detection of an abnormal voltage value
<Temp Over Power off by detection of an abnormal temperature value
<AC Cut Power off by AC power cut
<?? Unknown
Operation Procedure (Selection/finalizing of TEST MODE for each section)
1) Select the TEST MODE by the section name, pressing the wINPUT (up) or qINPUT (down) button.
Display Description Ref. page
<Key Operate Causal factors for power off are displayed. 14
(This state is available immediately after starting.)
Test RECEIVER RECEIVER TEST MODE 15
Test TAPE TAPE TEST MODE 16
Test CD CD TEST MODE 17
Test MD MD TEST MODE 30
Test All Func ALL FUNCTION TEST MODE 18
Escape Test The test mode is canceled. —
2) Pressing the MUSIC button will shift the mode to the selected test mode.
For the details of the selected test mode, refer to the Ref. page in the above step 1).
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GX-900
GX-900
No. & DISPLAY
01 G , E , TEST
02 FL + CLEAR
03 FL FULL
04 APO - ON/OFF
05 RDS - OFF/ON
06 A , PS - ON/OFF
07 A , M , - RDS/ALL
08 CT > C - ON/OFF
09 L > CT - ON/OFF
10 PSR2 - ON/OFF
11 RTBL - ON/OFF
12 SEC - OFF/ON
13 Temp
14 PEAK - ON/OFF
15 AMPC - OFF/ON
16 CDCH - ON/OFF
17 REM CODE
18 L , EN - ON/OFF
19 ALL CH >
20 RDS E / F
21 SUR TEST
22 KEYC - OFF/ON
23 AM - IF
24 CANCEL
25 DEST
FUNCTION
Equalizer check mode
FL display full lighting,
RAM CLEAR
FL display full lighting
PURPOSE & OPERATION
Used to check EQ.
Pressing the STANDBY/ON button will set the Equalizer Test mode.
For the details, refer to page 20.
Used for lighting of all display segments and clearing of RAM. (Note that
the user memory will be cleared.)
At the first pressing of the STANDBY/ON button, all display segments light
up and at the second pressing, MEMORY and M-CLEAR light up for 2
seconds and RAM of CPU is initialized. (The product mode is restored.)
(Presetting of the tuner becomes the manufacturer preset state.)
Used to check lighting of all display segments.
At the first pressing of the STANDBY/ON button, all display segments light up and
at the second pressing, this mode is canceled. (The product mode is restored.)
Do not use No. 04 to 23 functions as they are not for servicing.
Used to cancel the test program.
(The product mode is restored when the STANDBY/ON button is pressed.)
Destination display mode
■RECEIVER TEST MODE
When RECEIVER TEST MODE is set through SYSTEM TEST MODE, “01 G.E.TEST”appears on the FL display. (01
is the test program No.)
Test programs from 01 to 25 are incorporated in RECEIVER TEST MODE.
Operation Procedure (Selection/execution of Test Program)
1) Select the test program by pressing the rTAPE (up) or eTAPE (down) button.
2) Pressing the STANDBY/ON button will execute the selected test program.
3) Repeat selection/execution of the test program as necessary.
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