Akai GXC-570D Troubleshooting guide

SERVICE MANUAL
PARTS LIST
MODEL
GAC
_
OD

CASSETTE STEREO TAPE DECK
voor. GXC-570D
* SECTION 1 SERVICE MANUAL......................... 3
SECTION 2 PARTS LIST .............................. 4
SECTION 3 SCHEMATIC DIAGRAM...................... 64
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SECTION 1
SERVICE MANUAL
TABLE OF CONTENTS
TECHNICAL DATA: scien su cles ser stig oa aoe wees 4
DISMANTLING OF UNIT 2255.5/2043, se ee Ge Seca deecees 5
PRINCIPAL PARTS LOCATION ..........0-20-0002ecceeeeeeeee 7
CIRCUIT OPERATING PRINCIPLES .............. Pp snse. cateret 8
1. SYSTEM CONTROL OPERATION ..........-2--2002002000- 8
2. TOUCH BUTTON SYSTEM OPERATION ............-2.-2-5- 12
MECHANISM ADJUSTMENT .........---2--20200 ccc eee eee 14
1. CAPSTAN SHAFT LOOSE PLAY ADJUSTMENT ”............-- 14
2. MOTOR PULLEY INSTALLATION POSITION ADJUSTMENT ..... 14
3. REEL TABLE INSTALLATION POSITION ADJUSTMENT ........ 14
4. PINCH ROLLER PRESSURE ADJUSTMENT ...............-- 15
5. PLAY SOLENOID INSTALLATION POSITION ADJUSTMENT ..... 15
6. ADJUSTMENT OF EJECT MICRO SWITCH ACTUATION POSITION. 16
7. ADJUSTMENT OF RECORDING MICRO SWITCH (SW3) AND
CASSETTE MICRO SWITCH (SW6) ACTUATING POSITION .. 16
8. REEL MOTOR (GSM-300) REPLACEMENT ..........--.--+-- 17
9. FRONT PANEL LID CASE SPACING ADJUSTMENT ........... 17
10. POSITION ADJUSTMENT OF LID CASE ............-----0-- 18
11. CLEARANCE ADJUSTMENT BETWEEN HALL IC AND
ROTARY MAGNETS: 9609 aden bogs cry eae ewevsaues 18
HEAD ADJUSIMEND ©. 2..6.044 4 222i o$vass ow ee eae kee twas 19
1. TAPE GUIDE HEIGHT ADJUSTMENT..........-...-2..-05- 19
2, . HEIGHT ADJUSTMENT OF RECORDING/PLAYBACK
COMBINATION HEAD...........--200-0005- uasaes 19
3. AZIMUTH ALIGNMENT ADJUSTMENT OF
RECORDING/PLAYBACK COMBINATION HEAD.......... 19
AMPLIFIER ADJUSTMENT ...........-0 02002002 cece eee ee ee 20
1. RECORDING/PLAYBACK AMPLIFIER ADJUSTMENT .......... 22
2. DOLBY NOISE REDUCTION CIRCUIT ADJUSTMENT .......... 23
3. RECORDING DOLBY NOISE-REDUCTION AMPLIFIER
JADTUSTMENT scx S4 cieonca wi tone a a8 Marmara oz 23
4, PLAYBACK DOLBY NOISE REDUCTION AMPLIFIER
ADJUSTMENT ...........-..-- sens Dease eases 23
DC RESISTANCE OF VARIOUS COILS ...... 2.222200 -0 002 eee ee 24
CLASSIFICATION OF VARIOUS P.C BOARDS ..........-...--.+- 25
1. RELATION OF VARIOUS P.C BOARDS TITLE AND. NUMBER ..... 25
2. COMPOSITION OF VARIOUS P.C BOARDS ....... wseuiated, gush sew rea 26
For basic adjustments, measuring methods, and operating principles, refer to GENERAL OPERATING
PRINCIPLES AND ADJUSTMENTS. ;
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|. TECHNICAL DATA
TRACK SYSTEM
4 track 2 channel stereo system
TAPE Philips type cassette
TAPE SPEED 1-7/8 ips (Pitch Control +5%) =e
WOW AND FLUTTER Less than 0.06% WRMS
Less than 0.17% (DIN 45500)
FREQUENCY RESPONSE
. 30 Hz to 19,000 Hz (+3 dB) using Fe-Cr tape -
30 Hz to 15,000 Hz (+3 dB) using low noise tape
30 Hz to 16,000 Hz (+3 dB) using C,O, tape
DISTORTION Less than 1% (1,000 Hz “0” VU) using low noise tape
SIGNAL-TO-NOISE RATIO Better than 52 dB (measured via tape with peak recording level of +5 VU)
Dolby Switch ON: Improves up to 10 dB above 5 kHz g
ERASE RATIO Better than 70 dB ‘
BIAS FREQUENCY 100 kHz :
HEADS GX recording/playback head and erase head (3 head system)
MOTORS One AC Servo outer rotor motor for capstan drive and two DC motors
for reel drive
FAST FORWARD AND REWIND TIME 60 to 80 seconds (variable) using 4 C-60 cassette tape
OUTPUT JACKS Line (2): 0.775V (0” VU)
Required load impedance: More than 20 k ohms’
Phono (1): 50 mV/8 ohms ies.
INPUT JACKS = Microphone (2): 0.3 mV
ae Required microphone impedance: 600@’ohms -
Line (2): 70 mV/100 k ohms
TRANSISTOR 2SA628 (E) (F) .....-....--- 3 -
2SB605 (K) (L) ..........:-. 2
2SC458LG (C) ..... Waites: ahah ate 8
2SC945L (P) (Q) (R).-.--. ee 75
2SC1175 (E) (F) -....-.-+.-- 3
2SC1211 (E) (F) ...-. 6.6666. 1
28C1222 (E) (F) .....-.----. 4
2SC1647 (S) (E) ............ 6
2SC1683 (P) (Q) ............ 1 gses
2SD360 (D) (E) .........-.. 1
2SD361 (D) (E) (D1) ........ 2
2SD401 (K) (L) .....-...6.- 1
2SD571 (K) (L) (M)...... bad
FET 2SK30A (D) (GR) ....-...--5 10
2SK68A (L) (M) ...........- 2
IC wPCLO23H..............-..- 2
wPC10O24H.... 0... eee 4
TATL22AP posit ata ee 8 2
DN835) 2 2. eee eee esis 1
DIODE ENB 4 Aire oi. eens ane Meter eee 8
18247330 ei et ee es 59
IS2473VE «5 eee-o ed sere eae 88
LOD 2S te ee aes pa 4
MODS i. 2 eee AAS Se os 1
LODS tes canted seat ePned ". 6
7 WZ085 ....... 02 cee eee 2
WZ 240» iio cia Decale pirat ae 2
POWER REQUIREMENTS
CSA, UL and LA Models: 120V, 60 Hz only
CEE Models: 220V, 50 Hz only
Other Models: 100V to 240V, 50/60 Hz, (switchable)
DIMENSIONS
WEIGHT .
440(W) x 255(H) x 225(D) mm
(17.3 x 10.0 x 8.9")
13.5 kg (28.5 Ibs)
NOTES: 1. For improvement purposes, specifications and design are subject to change without notice.
2. Noise reduction circuit made under license from Dolby Laboratories Inc.
The word ‘DOLBY’ and the Double-D symbol are trademarks of Dolby Laboratories Inc.

ll. DISMANTLING OF UNIT
In case of trouble, etc. necessitating disassembly, please disassemble in the order shown in photographs. Reassemble
in reverse order. ie
‘ Co
SCREWS
SCREWS
SCREWS
10 PANEL -
He SCREWS
CONNECTORS
SCREWS & CONTROL KNOBS
otis 5.

at
SCREWS
SCREWS
AMP BLOCK
MECHA BLOCK
“-

lll.
PRINCIPAL
PARTS
LOCATION
TAPE SELECTOR REC CALIBRATION DOLBY N.R
_. ae
PiTCH CONT CAL TONE DOLBY N.R IND MPX FILTER
FF-RWD SPEED
LIMITER
VU METER
DOOR
EVECT
PEAK METER
VU METER
TAPE COUNTER
HEAD BLOCK
METER SELECTOR
LINE REC LEVEL
MIC REC LEVEL
TOUCH
BUTTON
SWITCH
OUTPUT
MIC
JACK
REPEAT
MEMORY
SES.
MONITOR
Py
POWER
SUPPLY
&
OSC
DOOR
SWITCH
PC
:
PRE
AMP
P.C
BOARD
CA-5205
RC
BOARD
CI-5030
BOARD
Cl-5026
CAPACITOR C4 330/160
POWER TRANSFORMER
POWER
HEADPHONE JACK
Fig.1 Front View
DOOR OPEN MOTOR
RF -260-09400
CAPSTAN MOTOR SCM-700
SERVO PRC BOARD CI-2020
cit-1
f : VOLT SELECTOR
REMOTE CONTROL JACK
MONITOR SWITCH PRC
BOARD CI-5003 i
SYSCON
PC
BOARD
TOUCH
SWITCH
RC
BOARD
CB
-
5004
cl-
2012
at
CAPACITOR C3 6/150
oe oe
= wah.
Fig.2 Rear View

IV. CIRCUIT OPERATING PRINCIPLES
1. SYSTEM CONTROL OPERATION
|, |NOSE FILTER
'* | PRC BOARD C8-2027
WIND SPEED CONTROL,
BACK TENSION CASSETTE PACK OETECTION
=
ar
en
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STOP DETECTION RC
Board cB-2026
MAGNETIC BRAKE
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rove serten cwcuiT
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TOP DETECTION P.C
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SCHEMATIC-3 PLAY MODE
TOVeH Senfen CMCUIT
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sav
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STOP DETECTION BC
BOARD CB~ 2026,
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BOARD Cl:
£ SYSTEM CONTAOL PC
BOARD CB-5004
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}. NOISE FILTER
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A. SYSTEM CONTROL PC Soa 7 =
. 1
To Tove swrten cimcuiT
ta------- +--+ +--+
TOUCH SIMTK CHU
1-1. TAPE SLACK ELIMINATION CIRCUIT
1)
Because this deck employs a double capstan drive
system, if tape with a great deal of slack is used,
trouble with the tape tangling around the capstan
is likely to occur. Even if only slight tape slack
exists, it takes time after effecting a forward mode
to obtain proper tape tension, which results in a
continuous poor head-to-tape contact condition.
The purpose of this circuit is to prevent such
trouble by taking up tape slack prior to operation
for proper tape tension at-all times.
2) When a cassette is not loaded, TRIS assumes an
ON condition and TR16 an OFF condition. When
a cassette is loaded, cassette detection micro
switch SW6 contacts NC side (contact point), and
a charge current flows to C7. Within this charge
current period, TR15 is turned OFF and collector
voltage increases. Charge current flows to R52 and
C8 and at the end of the charge current period,
TR16 is turned ON and collector current flows.
This current passes D81, causing the take-up
motor to rotate, and at the same time passes D82,
causing the supply motor to rotate. Thus, the tape
is pulled from both directions, and any existing
slack is eliminated. This process continues until
the C7 charge current ends, at which time the
circuit returns to it’s previous state, stopping both
reel motors.
H SCHEMATIC-5 RWD MODE
1-2. PINCH ROLLER OPERATION AND
REEL MOTOR ROTATION TIMING CIRCUIT
1) If reel motor starts to rotate before the pinch
roller reaches the capstan, momentary brake
tension will be applied, causing the tape to break
or stretch. This circuit is for the purpose of elim-
inating such trouble by activating reel motor
revolutions after the pinch roller has contacted
the capstan when playback mode is effected.
2) When the deck is set to Play mode, TR23 collector
voltage is increased, TR24 is turned ON, the relay
functions, and the pinch roller plunger operates.
At the same time, as a result of an increase in
TR23 collector voltage, charge current passes R11
and D84 and flows to C4. During the period of
this flow of charge current, TRS base voltage is
lowered, and because TR5 is turned OFF, the
take-up motor does not rotate. However, at the
end of this flow of charge current, TRS base
voltage increases, TRS is turned ON, and motor
Starts to rotate.
The period of time until TRS is turned ON is
about 0.1 to 0.2 seconds.

netic braking to the proper motor when stop mode
is being effected from Fast Forward or Rewind.
2) At Fast Forward,“BRbaeis turned ON and the take-
1-3. FAST FORWARD AND REWIND SPEED
CONTROL CIRCUIT
1) The, reel motors employed in this deck are
DC motors which at a non-load condition rotates
at about 3,000 rpm. Consequently, when Fast
Foward or Rewind is effected, there is a possibility
of tape damage due to a gradual build-up of inertia
and increased revolutions. This circuit is for the
purpose of controlling supply voltage to the take-
up reel motor for suppression of increased motor
revolutions.
2) When the deck is set to Fast Forward mode, TR1I2.
is turned ON and the take-up motor begins to
rotate. When the supply reel motor is not rotating,
because bias is not supplied to the base of TR3,
the resistance between TR3 collector and emitter
is infinite, and a fixed bias is supplied to TR4
through R8 and R9, a fixed DC voltage is supplied
to the take-up reel motor, and there is a build-up
of inertia and gradual increase in motor revolu-_
tions. F
However, at Fast Forward Mode, the supply reel
motor of this deck functions as a generator.
Consequently, the electromotive force generated
by the supply reel motor passes D6, D85, R6 and
R119 and becomes TR3 base bias, and the
resistance between TR3 collector and emitter is
varied proportionately according to the extent of
the generator’s electromotive force.
That is to say, R9 and the resistance between TR3
collector and emitter becomes parallel composite
resistance and bias to TR4 is varied by this com-
posite resistance. Momentarily, when the take-up
reel motor begins to rotate at high speed, this
counterbalanced electromotive force is generated
by the supply reel motor and this generated
voltage increases the resistance between TR4
collector and emitter and the supply voltage to the
take-up reel motor is decreased. Thus, motor
revolutions are slowed for a decrease in speed.
In this manner, the take-up speed always corre-
sponds with the supply reel motor speed, thus
avoiding high speed motor revolutions.
3) Speed control also functions in exactly the same
way at Rewind mode. However, in this case, the
right hand side reel motor functions as a generator,
and left hand side reel motor revolutions are
controlled by means of supply voltage control.
Therefore, Rewind speed is controlled in the same
way as at Fast Forward.
1-4. MAGNETIC BRAKING CIRCUIT
1) This deck differs from other 3 motor system decks
to date in that instead of a mechanical braking
system, tape travel is stopped electrically, and a
magnetic braking system is employed. When Fast -”
Forward or Rewind is being effected, the take-up
motor rotates while being controlled by the
rotation of the supply side motor. ;
This circuit is for the purpose of applying mag-
up motor rotates. The supply side motor rotates
and functions as a generator to maintain proper
take-up motor revolutions. At this time, the
magnetic braking circuit maintains TR8 and TR10
at ON, and TR9 and TRi!I at OFF condition.
D12 is grounded through D13 and D12 anode
becomes identical to grounding electrical potential.
Consequently, TR7 assumes an OFF condition.
(In other words, current does not flow to the
supply side motor).
3) When the deck is stopped from Fast Forward
mode, TR12 is turned OFF, and the current to the
take-up motor ceases. Also TR14 is turned ON and
’ TR13 turned OFF, and at the same time, D1
anode assumes a floating condition. Current flows
by means of the electromotive force from the
take-up sige motor, and this current turns ON TR7
and voltage is supplied to the supply side motor.
This voltage becomes the braking voltage of the
supply side motor.
4) When magnetic braking is first applied, because the
take-up motor is rotating fairly fast, a large
electromotive force is generated, TR17 is turned
completely ON, and maximum voltage is supplied
to the supply side motor. Thus, speed is reduced
and at the same time, this voltage is decreased.
Also the take-up motor electromotive foree~~
disappears, and at the same time, the supply side
motor rotation stops. :
5) When the deck is stopped from Fast Forward
mode, the operation is the same as described
above. Only the circuit components differ..
1-5. AUTOMATIC SHUT-OFF MECHANISM CIRCUIT
1) This circuit is for the purpose of effecting auto-
matic shut-off when tape travel has stopped after
play, recording, fast forward, or rewind mode.
2) During tape travel, because the rotary magnet
. rotates, Stop Detection circuit TR1 performs the
ON + OFF switching operation. Also during tape
travel, because D30 anode becomes grounding
electrical potential, TRI7 is turned OFF.
However, charge and discharge current alternately
flows to C9 by means of the Stop Detection
circuit. At charging time, current flows to
R55 > C9 + D31 + C10, and TR17 is turned ON.
At discharging time, current flows to R56 > D27
+ C9 > TRI (stop detection circuit). During this
time, C10 discharge current passes R58 and TR17
is maintained at ON condition. When tape travel
has stopped, C9 charge and discharge current will
not flow, C10 discharge current also ends, and
TR17 is turned OFF. Then TR18 is turned ON,
and the diode connected to TR18 collector for
instance, if automatic shut off is effected from
play mode, D70 is grounded, play circuit TR32 is
turned OFF, and Shut-off mode is effected.
11

2.
PULSE GENERATOR CIRCUIT
CS. a ee
* output
EQUIVALENT
E CIRCUIT
FET PROTECTION
RESISTOR
COMMERCIAL
CURRENT
w
‘
4
ae DISCHARGE CURRENT
HUMAN BODY (SIGNAL SOURCE)
TOUCH BUTTON SYSTEM OPERATION
2-1. TOUCH BUTTON SYSTEM CIRCUIT
COMPONENT (Refer to Fig. 13)
As shown in Fig.3, generally divided, the touch
button system circuit is comprised of a pulse genera-
tor circuit, a rectifier circuit, and an integration
circuit and includes a malfunction prevention
capacitor and FET protection resistor, etc.
Because it is necessary for the malfunction prevention
capacitor shown by the dotted line to have a fairly
high voltage, a shielded wire distribution capacitor is
used with a capacitance of 50 to 60 PF.
As shown by the equivalent circuit in the diagram,
last stage transistor Q3 performs the exact same
function as a micro switch.
2-2. WHEN TOUCH BUTTON IS TOUCHED WITH
FINGER, OPERATION IS SAME AS MICRO
SWITCH SYSTEM USED TO DATE
(Refer to Figs. 4, 6)
Because of inductance in our bodies from commercial
power supply (50 Hz or 60 Hz), if we touch one of
the touch buttons with our finger, our body becomes
a signal source as-shown in Fig. 4 and the same thing
takes place as in the case of a micro switch system to
date. Therefore, when a button is touched with a
finger, a signal is supplied to FET Q1 gate as shown
in Fig. 4.
The charge at C3 when a signal is not supplied is only
equivalent to the drain voltage. Base bias is supplied
to Q2 from R7 and R8 and no signal is emitted at
Q2 collector. Consequently, Q3 base becomes
unbiased and Q3 does not function.
Fig. 4
The signal supplied to QI gate works to reduce the
impedance between FET drain and source, and the
electric charge charged at C3 passes Q1 > R6 > and
R8 and is discharged. ,
C3 discharge causes a large minus bias at Q2 base,
_ collector voltage increases, and this pulse is rectified
‘at DI and integrated at C10, R10 and supplied to Q3
as base. bias. Consequently, Q3 is turned ON and
functions in exactly the same way as a micro switch
has functioned to date.
2-3. WHEN A BUTTON IS TOUCHED WITH
A FINGER AND AT THE SAME TIME THE
DECK CHASSIS IS TOUCHED WITH ANOTHER
FINGER OR A HAND (See Fig. 5)
As previously explained our body acts as a signal
source to operate the touch buttons, but when
considering that in this case the high resistance of
the human body is utilized, the QI gate circuit
operation is different. As shown in Fig. 5, when a
button is touched with a finger and the chassis is
touched simultaneously, by means of the. resistor
shown in the circuit diagram, C2 electric charge
passes RI] > Ro > R4 and is discharged. From
looking at the circuit, it can be understood that
discharge is completed in an extremely short time.
In this very short discharge time period, FET is cut,
the drain voltage increases, and condenser C3 is
charged. When C2 discharge is complete and the
voltage of both terminals becomes equal, FET drain
current flows and the electric charge charged at C3 is
discharged. Consequently, Q2 base is minus biased
and ceases to opérate. Thus, Q3 functions in the same
way as a micro switch as outlined in item 2-2 above.
12
nls. 5,

i
A
i
|
CHARGE CURRENT
HUMAN BODY
{RESISTOR}
DISCHARGE CURRENT
DISCHARGE CURRENT
Fig. 5
QI GATE
e
Q! DRAIN
Q2 BASE
Q3 BASE
.Q3 COLLECTOR
WHEN TOUCH BUTTON IS TOUCHED
Fig. 6
13
i“
NS

V. MECHANISM
ADJUSTMENT
CAPSTAN SHAFT
PLAY SOLENOID
PLUNGER SLI
FLYWHEEL
(RIGHT }
ORIVE BELT
FIXATION NUT
ROTOR PLATE
FIXATION SCREW
MOTOR PULLEY
FS SSS SENS SOOT SHS SOTNNN NOT
ORIVE BELT
N MOTOR
CAPSTA
sc
Fig. 8
FIXATION SCREW
REEL TABLE
REEL MOTOR SHAFT
Fig. 9
FLYWHEEL
(LEFT)
CAPSTAN MOTOR SCM- 700
ADJUSTMENT SCREW Fig. 7
1. CAPSTAN SHAFT LOOSE PLAY
ADJUSTMENT (Refer to Fig. 7)
Adjust by turning adjustment screws to obtain a
0.1 mm degree of loose play (space indicated by
* mark in Fig. 7) when the capstan shaft is moved as
indicated by the arrow mark. Tighten fixation nut to
maintain optimum adjusted condition.
2. MOTOR PULLEY INSTALLATION
POSITION ADJUSTMENT (Refer to Fig. 8)
Tighten fixation screw at position at which the parts
indicated by the * mark in Fig. 8 makes contact with
the rotor plate.
NOTE: After above adjustment, in case the drive
belt does not run on the center of Motor
Pulley, re-adjust installation position of
Motor Pulley so that the drive belt comes to
the center of the Pulley.
3. REEL TABLE INSTALLATION POSITION
ADJUSTMENT (Refer to Fig. 9)
As shown in Fig. 9, with reel table firmly and com-
pletely fitted on motor shaft, tighten fixation screw.
eomn
dy.
i tte
—_

CAPSTAN
PINCH ROLLER
(LEFT)
PW ARM SPRING
aa]
Pe}
CAPSTAN SHAFT
eer aaa cena
FIXATION SCREW PINCH ROLLER
. XN
t<—— PLAY SOLENOID SLI
CAPSTAN
PINCH ROLLER
(RIGHT) sree
ARM A
PW ARM SPRING
Fig. 10
CAPSTAN SHAFT
PINCH ROLLER
o——. PLUNGER
7——E_ RING
\
0.5 to LOmm /
mee 4
4. PINCH ROLLER PRESSURE
~ ADJUSTMENT (Refer to Fig. 10)
Pull back the Pinch Roller with a spring gauge, and
‘then gently return. Take a reading of the spring gauge
scale indication at the moment the Pinch Roller
touches the capstan and begins to rotate. Adjust
pressure to specified value by changing position of
the PW ARM SPRING.
Specified Pinch Roller Pressure:
Pinch Roller (right) _.400 + 50 gr
Pinch Roller (left) 300 + 50 gr
;<—— SILENSER CUSHION
PLAY SOLENOID SL!
Fig. 12
5. PLAY SOLENOID INSTALLATION
POSITION ADJUSTMENT
(Refer to Fig. 11 and Fig. 12)
As shown in Fig. 11, at stop mode, when the tip of
plunger is gently depressed, the pinch roller contacts
the capstan shaft, at this time confirm that the gap
between “E” ring and silencer cushion is 0.5 to
1.0 mm. (See Fig. 12)
If
not,
adjust
play
solenoid
installation
position
as
indicated
by
the
arrow
mark
in
Fig.
10
to
obtain
specified gap.
a
ea
15
ales
*,
ene ete

RELEASE LEVER
: EJECT KEY
a
EJECT MICROSWITCH Sw8&
MECHA FRAME
Fig. 13
FIXATION SCREW
RECORDING MICROSWITCH SW3
CASSETTE MICROSWITCH SW6
FIXATION SCREW
Fig. 14
6. ADJUSTMENT OF EJECT MICRO SWITCH
ACTUATING POSITION (Refer to Fig. 13)
Adjust by bending Eject Key so that when the Eject
Key is depressed, Eject Micro Switch (SW8) shown in
Fig.13 is perfectly actuated. After adjustment,
depress Eject Button and confirm that Eject Micro
Switch (SW8) switches before the Release Lever
operates.
7. ADJ USTMENT OF RECORDING MICRO |
SWITCH (SW3) AND CASSETTE MICRO
SWITCH (SW6) ACTUATING POSITION
(Refer to Fig. 14)
Move M Switch Plate A as indicated by the arrow
marks in the figure and adjust so that when the parts
of Recording and Detection Levers marked with
* mark in Fig. 14 are at a horizontal level, Recording
Micro Switch (SW3) and Cassette Micro Switch (SW6)
are turned ON respectively. Further, confirm that
when a cassette from which the recording safety tabs
have been removed is loaded, Recording Micro Switch
(SW3) switches, and when the cassette is removed,
Cassette Micro Switch (SW6) switches. Tighten
fixation screws to maintain ideally adjusted positions
of M Switch Plates A.
16

TAKE UP REEL MOTOR SUPPLY REEL MOTOR
GSM-300L.
GSM-300R
MOTOR SPACER
(WHITE)
TAKE UP REEL MOTOR
GSM-300R
HOOKS
8. REEL MOTOR (GSM-300) REPLACEMENT
(Refer to Fig. 15)
While the reel motors of this Deck are basically the
same, because left and right characteristics differ,
check as described below prior to replacement.
1) Serial No. 10216-0001 to 10216-0060
, 10511-0001 to 10511-0150
10612-0001 to 10612-0300
Supply Reel Motor: L mark on thrust cap
Take up Motor: No marking
2) Serial Noz From 10716-0001
. Motor Spacers of Supply Reel Motor and Take Up
‘ Motor are of different colors as shown in Fig. 16.
NOTES: 1. Because brush noise, etc. will occur if
left or right motor is substituted, be
sure to replace with the correct type for
left or right.
2. For the reason outlined in NOTE 1, the
motors are clearly distinguishable, but
the motors themselves are uniform.
:
= MOTOR SPACER
(BLACK)
SUPPLY REEL MOTOR
GSM-300L
* Fig. 16
vet oT
HOOKS
Fig. 17 Inner Side of Lid Panel
9. FRONT PANEL LID CASE SPACING
ADJUSTMENT (Refer to Fig. 17)
In case the Lid Case comes too far toward either side,
adjust by bending the two lower hooks as indicated
by the arrow marks in Fig. 17.
17

FIXATION SCREW
ROTARY MAGNET
TAPE COUNTER
FIXATION SCREW
STOP DETECTION PC BOARD
CB- 2026
Fig. 19
18
"EJECT GUIDE
tesa =e
FRONT PANEL
ee ay
Fig. 18 Left Side of the Deck
10. POSITION ADJUSTMENT OF LID CASE
(Refer to Fig. 18)
Move the Eject Guide shown in Fig. 18 (direction
indicated by arrow mark) up and down and adjust
Lid Case so that it is even with the front panel. If
the upper part of Lid Case comes too far inward, raise
the eject guide, and if too far outward, lower eject
guide.
11. CLEARANCE ADJUSTMENT BETWEEN
HALL a AND ROTARY MAGNET
(Refer to Fig, 19)
This adjustment is necessary for the perfection of the
Automatic Stop Function. If adjustment is necessary
due to poor Automatic Stop Function or instability,
proceed as follows:
1) As shown in Fig. 19, move Stop Detection P.C.
Board as indicated by the arrow ‘mark in the
figure, and adjust position so that the clearance
between the HALL IC and rotary magnet is 1 mm.
2) In case this clearance is over 1 mm, faulty Auto-
matic Stop Function will occur.
wy Ore

VI.
HEAD
ADJUSTMENT
TAPE GUIDE C
CAPSTAN |
TAPE GUIDE A
TAPE GUIDE A
HEIGHT ADJUSTMENT NUT
TAPE GUIDE 8B
TAPE GUIDE 8B
HEIGHT ADJUSTMENT NUT
——
Q OT hl O
ECTS ama ores rae EE ns
MIRROR
Fig. 21
. TAPE GUIDE HEIGHT ADJUSTMENT
(Refer to Fig. 20 and Fig. 21)
1) When using an ordinary cassette, the tape guides
and heads, etc. are not visible. As shown in Fig. 21,
use a cassette tape from which part of the cassette
case has been cut out and a mirror installed for
easy visibility of the head area when making tape
guide height adjustment.
2) At playback mode, using the erase head guide C
shown in Fig. 20 as standard for height, adjust
tape guide A and tape guide B height with tape
guide height adjustment nuts so that the tape runs
smoothly and does not touch on the tape guides.
. HEIGHT ADJUSTMENT OF RECORDING/
PLAYBACK COMBINATION HEAD |
(Refer to Fig. 20)
1) Utilize the cassette tape used in Tape Guide Height
Adjustment above, and playback the leader tape
part of cassette tape.
2) As shown in Fig. 20, adjust head height with
screws (A), (B), and (C) until the upper edge of
the tape is the same height as the upper edge of
the left channel REC/PB Comb. head core.
TAPE DIRECTION
Fig. 20
3. AZIMUTH ALIGNMENT ADJUSTMENT
OF RECORDING/PLAYBACK
COMBINATION HEAD (Refer to Fig. 20)
1) Playback a 10 kHz pre-recorded cassette azimuth
shes
alignment test tape and adjust screw (A) shown in
Fig.20 to obtain maximum output on both
channels.
2) Invert cassette and confirm that the output level
does not change from that obtained in Item 3-1)
above. If the output level differs, adjust in the
same way as in Item 3-1) above until both sides of
the test tape display equal output.
3) Supply a 10 kHz signal from an audio frequency
oscillator to the line inputs and record at -20 VU
on a blank tape.
4) Set Monitor Switch to “TAPE” position and
adjust screw (A) shown in Fig. 21 to obtain max-
imum output on both left and right channels.
5) The recording and playback heads are joined to
‘form a single structure. Therefore, when making
azimuth alignment adjustments, because both head
cores (recording and playback) move, repeat
adjustments outlined in Items 3-1) through 3-4)
above until optimum azimuth alignment of the
two head cores are obtained.
NOTES: 1. Be-sure to clean the heads prior to head
adjustment.
‘2. Be careful not to use a magnetized
driver or other magnetized tools in the
. vicinity of the heads.
3. Be sure to demagnetize the heads with a
Head Demagnetizer before and after
head adjustment.
4. When a mirror installed cassette test
tape as shown in Fig. 21 is required, it
can
be
ordered
from
AKAI
Electric
Co.
ne
EEEEEEIEE
EERO
19