Akai GX-636 User manual

AKAI-00107
SERVICE
MANUAL
THIS MANUAL MUST BE USED AS A SET TOGETHER WITH SEPARATELY
PUBLISHED GX-635D SERVICE MANUAL AND PARTS LIST.
STEREO TAPE DECK
MODEL GX-636

AKAI-00351
SERVICE
MANUAL
PARTS LIST

STEREO TAPE DECK
MODEL GX- 63 ° D
SECTION 1 SERVICE MANUAL.................... 0000005 1
SECTION: 2. PARTS (LIST 3 occis sete eo ic5 aus SO Seay casein tele way ea 43
SECTION 3 SCHEMATIC DIAGRAM.................0 200005 67

VI.
VIL.
Vill.
SECTION 1
SERVICE MANUAL
TABLE OF CONTENTS
TECHNICAL. DATA}. o.45 e685 ee ee a a sh eke ee tee ee 4
DISMANTLING
OF
UNIT...
2.0...
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es
5
CONTROLS
53-23.
bh
ore
iid
BES
RS
DS
lara
er
tte
ea
ER
ee
SSS
7
PRINCIPAL
PARTS
LOCATION
..........
0
cece
e
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8
CIRCUIT
OPERATING
PRINCIPLES
.......
0.0...
eee
eee
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10
1.
SYSTEM
CONTROL
OPERATION
..
0.0...
eee
ees
10
2.
THE
SAMPLE
AND
HOLD
SYSTEM
SERVO
MOTOR
(SCM-200) OPERATION ....... 20
MECHANISM
ADJUSTMENT...
1...
0...
eee
eee
ee
tte
23
1,
GUIDE
ROLLER
LOOSE
PLAY
ADJUSTMENT..........---2+--,
23
2.
TENSION
MICRO
SWITCH
POSITION
ADJUSTMENT
.............
23
3.
ROLLER
BLOCK
HEIGHT
ADJUSTMENT
...........-.-.204
5
ee,
23
4.
REEL
TABLE
HEIGHT
ADJUSTMENT...
.........--0
02s
ee
ee
eee
24
5. CAPSTAN SHAFT LOOSE PLAY ADJUSTMENT......-.---..005- 24
6. BRAKE BAND POSITION ADJUSTMENT AND
BRAKE TENSION ADJUSTMENT ...... 25
7.
PINCH
ROLLER
POSITION
ADJUSTMENT
..........2--5-55005
26
8.
PAUSE
PLUNGER
POSITION
ADJUSTMENT
..........---5---5-
26
9. PINCH ROLLER PRESSURE ADJUSTMENT... ........--005 00055 26
10.
TAPE
SPEED
ADJUSTMENT.
...
2.0.2.
eee
ees
27
HEAD
ADJUSTMENT
..........
0002
ee
eet
28
AMPLIFIER
ADJUSTMENT
.......
2.0.2
ee
ees
30
DC
RESISTANCE
OF
VARIOUS
COILS
...
1...
2.0...
eee
ee
ees
32
CLASSIFICATION
OF
VARIOUS
P.C
BOARDS..........-..-.+--55:
32
1.
P.C
BOARD
TITLES
AND
IDENTIFICATION
NUMBERS
...........
32
2.
COMPOSITION
OF
VARIOUS
P.C
BOARDS
.........-----20506-
33
For
basic
adjustments,
measuring
methods,
and
operating
principles,
refer
to
GENERAL
TECHNICAL
MANUAL.

I. TECHNICAL DATA
TRACK SYSTEM
4 track 2 channel stereo/monaural system
REEL CAPACITY
Up to 10-1/2” reel
TAPE SPEED
19 cm/s +0.8% (7-1/2 ips)
9.5 cm/s +1.0% (3-3/4 ips)
(Pitch control: more than +6%)
WOW & FLUTTER
Less than 0.03% WRMS at 19 cm/s
Less than 0.04% WRMS at 9.5 cm/s
Less than 0.08% DIN 45500 at 19 cm/s
Less than 0.10% DIN 45500 at 9.5 cm/s
FREQUENCY RESPONSE
30 to 27,000 Hz +3 dB at 19 cm/s using WR Tape
30 to 21,000 Hz +3 dB at 9.5 cm/s using WR Tape
30 to 25,000 Hz +3 dB at 19 cm/s using LN Tape
30 to 19,000 Hz +3 dB at 9.5 cm/s using LN Tape
DISTORTION (1,000 Hz “0” VU)
Less than 0.5% at 19 cm/s
SIGNAL TO NOISE RATIO
Better than 62 dB DIN 45500
ERASE RATIO
Better than 70 dB (at 1,000 Hz)
CROSS TALK
Better than 40 dB (at 1,000 Hz)
CHANNEL SEPARATION
Better than 55 dB (at 1,000 Hz)
BIAS FREQUENCY
100 kHz
HEADS
(6): Two GX Recording Heads, Two GX Playback Heads, Two Erase Heads
MOTORS
(3): One AC Servo Motor for Capstan Drive Two AC Eddy Current Motors for Reel Drive
REAL TIME COUNTER
FF & RWD TIME
OUTPUT JACKS
Up to 99 min 59 sec, Less than +1.5%
120 sec using 550m (1,800 ft.) Tape
Line (2): 0.775V (0 VU)
Required load impedance: more than 20 kohms
Phone (1): 100 mV/8 ohms
STE c=nn nuttin PE
INPUT JACKS
DIN JACK
DIMENSIONS
WEIGHT
POWER REQUIREMENT
Microphone (2): 0.25 mV
Required microphone impedance: 600 ohms
LINE (2): 70 mV impedance 100 kohms
Input 2.0 mV, impedance 10 kohms, Output 0.3V
440(W) x 483(H) x 256(D) mm, (17.4 x 19.0 x 10.1")
21 kg (46.4 Ibs)
100V, 50/60 Hz for JPN
120V, 60 Hz for US & Canada
220/240V, 50 Hz for Europe, UK and Australia
110/120/220/240V, 50/60 Hz internally switchable for other countries
* Specifications determined with Akai LN-150-7 or SCOTCH #211 tape unless otherwise noted.
* For improvement purposes, specifications and design are subject to change without notice.

ll. DISMANTLING OF UNIT
In
case
of
trouble,
etc.
necessitating
dismantling,
please
dismantle
in
the
order
shown
in
the
photographs.
Reassemble
in
reverse
order.
SIDE BOARD
i]
.
¢
4
FOOT
}OTTOM
SCREWS
Bi
PLATE
SCREWS
————
2}
=
7
SIDE BOARD
a d
bd °
c f
birac soa SCREWS
SCREWS
—
|
b
PINCH ROLLER SCREWS
SCREWS
HEAD
COVER
BASE

MECHA PANEL BLOCK
AMP PANEL BLOCK
SCREWS
10

i CONTROLS
Se arent Saat Bie
PARBN >
ON Oa P ON >
PITCH CONTROL
SUPPLY REEL TABLE
BUILT-IN REEL RETAINER (Left)
LEFT TENSION ARM
PINCH ROLLER
RECORDING MUTE SWITCH (REC MUTE)/TIMING LAMP
REEL SIZE SELECTOR
REVERSE SELECTOR
POWER SWITCH
VU METER (Right)
. VU METER (Left)
TAPE SELECTOR
TAPE SPEED SELECTOR
. TIMER START
HEADPHONE JACK
. OUTPUT LEVEL CONTROL
17.
18.
19.
20.
21.
22.
23.
24,
25.
26.
27.
28.
29.
30.
31.
32.
Fig. 1 Controls
MONITOR SWITCH
REAL TIME COUNTER and RESET BUTTON
TAKE-UP REEL TABLE
BUILT-IN REEL RETAINER (Right)
RIGHT TENSION ARM
HEAD COVER
RECORDING INDICATOR LAMP
PAUSE INDICATOR LAMP
REVERSE DIRECTION/STAND BY INDICATOR LAMP
FORWARD DIRECTION/STAND BY INDICATO2 LAMP
MODE BUTTONS
MICROPHONE INPUT CONTROLS
MEMORY MARKERS
LINE INPUT CONTROLS
MICROPHONE JACKS (Left/Right)
RECORDING MODE SWITCH

IV. PRINCIPAL PARTS LOCATION
BRAKE MICRO SWITCH
sws06
BRAKE PLUNGER SL903
PINCH ROLLER
PLUNGER SL902
PITCH CONTROL VOLUME
VR9OI
PAUSE
PLUNGER
SL904
REAL
TIME
COUNTER
TENSION ARM (L) TENSION ARM (R)
REC MUTE SWITCH SW904
HEAD BLOCK
REEL SIZE SWITCH SW903
REVERSE SELECTOR SWITCH
POWER SWITCH Sw90i OPERATION BLOCK
B
REC
MODE
INDICATOR
VU
METER
L
MIC
i
REC
LEVEL
LINE
VOLUME
PHONES
JACK
REC
MODE
SWITCH
MIC
JACK
OUTPUT
LEVEL
CONTROL
VOLUME
TAPE
SELECTOR
SWITCH
MONITOR
SWITCH
TAPE
SPEED
SWITCH
TIMER START SWITCH
Fig.2 Front View

REEL MOTOR RIGHT
M902 24X0-TD
OPERATION P.C BOARD
TH-2041
OPERATION P.C BOARD
TH -2042
VOLUME PRC BOARD
TH-5002
REMO.CON JACK J905
VOLTAGE SELECTOR
FUSE RC BOARD
TH-2040
SYS.CON PC BOARD
TH-l015
CAPSTAN MOTOR
M903 SCM-200
PRE AMP ®C BOARD
TH-5014
Fig.3 Rear View

V. CIRCUIT OPERATING PRINCIPLES
1. SYSTEM CONTROL OPERATION
SYMBOL TRUTH TABLE
CIRCUIT
CIRCUIT
O= LOW LEVEL
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1-1. CIRCUIT CONSTRUCTION OF IC1 M54410P
18
The design of M54410P until now had STOP, PLAY,
REC, FF, RWD, PAUSE and REC preventing AR as
its input terminals. GX-635D circuit is constructed
with FWD in place of PAUSE and REV in place of
PLAY. Pause is controlled by a flip flop with a
separate IC.
1) Block Diagram
Fig. 4 M54410P