Akai 1730-SS User manual

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TABLE OF CONTENTS
SPECIFICATIONS ..0ins cede eg ieee pKa eee wees 2
MEASURING METHODS ................00.-0000- 3
CONTROL LOCATIONS .... 20.0.2... eee eee eee 5
DISMANTLING OF TAPE TRANSPORT UNIT
6c AMPLIPIERS 202s ae oes eae deed sone ee coed darade 6
TRANSPORT MECHANISM ........00...0..2-02000- 8
MECHANISM ADJUSTMENT ............-2..0200005 12
AMPLIFIER ADJUSTMENT ..............2-.-00055 14
MAINTENANCE PROCEDURES ..............2005. 16
TROUBLE SHOOTING CHART ................... 17
COMPOSITE VIEWS OF COMPONENTS ............. 22
SCHEMATIC DIAGRAM
When placing order for parts, please use Separate
PARTS LIST or PRICE LIST FOR PARTS.

I. SPECIFICATIONS
WEIGHT
DIMENSIONS
37.5 Ibs. (17.0 kg)
18"(H) x 16.5’°(W) x 9.5'(D)
(H450 x W420 x D240 mm)
POWER SUPPLY 100 to 240 V AC, 50/60 Hz
RECORDING
SYSTEM In-line 4-track 4-channel stereo and
4-track 2-channel stereo recording
PLAYBACK
SYSTEM In-line 4-track 4-channel stereo and
4-track 2-channel stereo playback
POWER CON-
SUMPTION 80 W (Deck 55 W)
TAPE SPEED 3-3/4, 7-1/2 ips.
TAPE SPEED
DEVIATION Within +1.5% at all speeds.
WOW AND
FLUTTER Less than 0.15% R.M.S. at 7-1/2”
Less than 0.2% R.M.S. at 3-3/4"
FREQUENCY
RESPONSE 30 to 22,000 Hz +3 dB at 7-1/2”
40 to 13,000 Hz +3 dB at 3-3/4”
SIGNAL TO NOISE
RATIO More than 48 dB
DISTORTION (Total
Harmonics) Within 2% at 1,000 Hz OVU
recording (LINE OUTPUT)
Within 3% at 1,000 Hz 5 W (when
terminated with 82) (MAIN OUTPUT)
CROSS-TALK Less than —SO dB (track)
Less than —40 dB (channel)
ERASE RATIO Less than 70 dB
INSULATION
RESISTANCE More than 50 MQ
INSULATION
DURABILITY 1,000 V AC for more than one minute
duration
LINE OUTPUT +4 dB 41.5 dB (1.228 V), at OVU indi-
cation, 250 Hz OVU recorded tape
Required load impedance more than
25K
More than 5 W
Impedance ; 8 2
—6 dB +1.5dB when using a 250 Hz
recorded tape
POWER OUTPUT
DIN OUTPUT
Required load impedance more than
50 KQ
Above 40 mV
Impedance ; 330 KQ
Above 0.4 mV
Impedance ; 30 KQ
Above 20 mV
Impedance ; 100 KQ
LINE INPUT
MIC. INPUT
DIN INPUT
FAST FORWARD &
REWIND TIME
MONITOR SYSTEM
(recording)
MOTOR
HEADS
RECORDING
HEAD
PLAYBACK
HEAD
ERASE HEAD
ERASE HEAD
TRANSITORS &
IC USED
DIODES
REELS
90 seconds 1,200 ft. tape at 50 Hz
70 seconds 1,200 ft. tape at 60 Hz
With Record/Play back Switch at “REC”
The program being recorded can be
monitored by using :
built-in speakers
stereo headphones
external speakers
crystal receiver
Hysteresis synchronous 2 speed motor
Horse Power: 1/100 HP
Power Ratio: 85%
Revolutions : 3,000 to 1,500 R.P.M.
at 50 Hz
3,600 to 1,800 R.P.M.
at 60 Hz
Condenser capacity : 3 uF at 50 Hz
2 pF at 60 Hz
In-line 4-track 4-channel stereo (4-track
2-channel stereo)
Impedance : 125 420% at 1,000 Hz
Gap: 4/1,000 mm
In-line 4-track 4-channel stereo (4-track
2-channel stereo)
Impedance : 1,200 2 +15% at 1,000 Hz
Gap : 2/1,000 mm
In-line 4-track 2-channel stereo
Impedance: 195 2 +10% at 100 KHz
In-line Full track
Impedance : 350 2 +10% at 100 KHz
2SC458LG (C) x 4 | apCURDING
28C871 (E,F) x4 | AMPLIFIER
LD-3141 x 4 }
2SC458LG (C) x 8| PLAYBACK
LD-3141 x 4 | AMPLIFIER
STK-011(A) x2 MAIN AMPLIFIER
2SC971 (2,3) (RED) x2 BIAS OSC.
2SD223 (Y)x 1 POWER AMP.
IN34A x4
VO6B x 4
10DC-1 (BLACK) x 1
RD-24A (M) x 1
7'', 5" reels can be used.

lil. MEASURING METHOD
TAPE SPEED DEVIATION
1. Method involving use of pre-recorded tape
Playback a tape pre-recorded at 1000 Hz (+0.1%) on
recorder to be tested. Connect the appropriate
output to a frequency counter meter in order to
measure the tape speed deviation.
2. Method involving use of timing tape. (designed for
tape speed measurement)
This method utilizes a timing tape marked at
intervals of 7-1/2". The running time of over 60
marked sections of tape is measured in order to
calculate the deviation of the tape speed. In
applying this method, however, it should be kept in
mind that timing tape stretch or contract measure-
ment error is inevitable, so that it is necessary to
measure the total length of the tape in advance.
WOW AND FLUTTER
Playback a 3,000 Hz pre-recorded tape, of which the
wow and flutter level is guaranteed to be smaller than
0.07%, and measure with a wow meter. It is also possible
for a 3,000 Hz sine wave to be recorded and played back
for measurement with a wow meter. In this case,
however, the wow meter will indicate a value as much as
twice that given in the specifications.
SIGNAL TO NOISE RATIO
1730-SS
ae = atv
Set the Equalizer Switch to the “7-1/2 ips” position and
playback a tape containing a 250 Hz sine wave recorded
at “Q’ VU level on a standard recorder. Connect a
V.T.V.M. to the line output jack of the recorder and
measure its output. Next, remove the tape and measure
the noise level under the same conditions. Convert each
of the measured values into decibels.
TOTAL HARMONIC DISTORTION FACTOR
1 KHz
Audio 1730-SS Distortion
Oscillator meter
Connect the measuring instruments as shown above, and
record a 1,000 Hz sine wave at “0” VU. Playback the
resultant signal and measure the overall distortion factor.
Measure the noise level of the tape recorder with the
tape removed ; connect the audio oscillator directly to
the distortion meter for measurement of the distortion
factor of the oscillator.
The resultant distortion factor can be obtained from the
results of the above measurement by using the following
formula :
do = d—d, —d2
where, do = Required
d = Overall distortion factor
d,; = Noise level
d2 = Distortion factor of the oscillator
(Note : New tape of particularly good quality should be
used for measurement of the distortion factor. Fuji L is
recommended).
POWER OUTPUT
Playback a tape containing a sine wave of 250 Hz
recorded at “0” VU ona standard recorder.
Measure
the
Voltage
at
the
output
of
the
recorderto
be
tested
when
terminated
with
8
Q..
Then use the following formula :
By P = Desired output (W)
P= E = Measured Voltage (R.M.S.)
R=8Q2

CROSS TALK
1. Between the tracks (2 Channel)
(TAPE)
ZENG
BKC
Tape direction
As shown in the figure, first record a 1,000 Hz sine wave
on track No.3 at +3 VU level. Next, remove the
1,000 Hz input signal and record under a non-input
condition. Then, playback the tape on tracks 3 and 1
(reversed condition of tape) through the 1,000 Hz B.P.F.
(Band Pass Filter, Sensitivity ... 1: 1) and obtain the
ratio between the two by using the following formula.
C = 20 log? (AB)
2°c= 1
C= Desired cross talk ratio (dB)
Eo = 1,000 Hz signal output level BES
E2 = 1,000 Hz cross talk output level
E, = Non-input signal record level CERRY
2. Between the channels (4 Channel)
Tape direction ©)
As shown in the figure, first record a 1,000 Hz sine wave
on track No.1 at +3 VU level. Next, remove the
1,000 Hz input signal and record under a non-input
condition.
Then, playback the tape on track No.1 and No. 2
through the 1,000 Hz B.P.F. (Band Pass Filter, Sensiti-
vity ... 1:1) and obtain a ratio between the two from
the following formula.
E
C = 20 log = (dB)
2 I
C= Desired cross-talk ratio (dB)
Eo = 1,000 Hz signal output level fest |
E, = 1,000 Hz cross-talk output level CLA
E, = No-input signal record level RES
Tape direction
FREQUENCY RESPONSE
Audio 1730-SS
Oscillator Input Output
Connect the measuring instruments as shown in the
above diagram, and measure the frequency response in
the following sequence :
RECORD :
1) Introduce a sine wave of 1,000 Hz to the Line Input
of the recorder being tested through an attenuator
from an audio frequency generator.
2) Set the Record/Playback Lever to ‘‘Rec” position
and adjust the line input volume so that the VU
meter needle indicates “0” VU.
3) Under the conditions described in (2), lower the
input level 20 dB with the attenuator.
4) Record the spot frequency from the audio fre-
quency generator in the range of 30 to 23,000 Hz.
PLAYBACK :
5) Set the Record/Playback Lever to “Play” position.
6) Connect a V.T.V.M. to the Line Output.
7) Playback the previously recorded tape.
8) Adjust the output level to “0” dBm at 1,000 Hz
(indicated on range selector of V.T.V.M.).
9) Playback the recorded spot frequencies under the
conditions in (8); make a memo of Output Level
and plot the value ona graph.
(Note : New tape of particularly good quality should be
used for measurement of the frequency response. Fuji F
tape is recommended).
In case of trouble, etc. necessitating disassembly, pleas
disassemble in the order shown in photographs. Reas-
semble in reverse order.

lil. CONTROL LOCATIONS
RESET BUTTON
INDEX COUNTER
TAKE-UP REEL TABLE
REEL RETAINER
——~~— AUTOMATIC SHUT-OFF LEVER
PLAY/RECORD LEVER
~—-REWIND/FAST FORWARD LEVER
PAUSE LEVER
SUPPLY REEL TABLE
REEL RETAINER
PINCH WHEEL
CAPSTAN
CYCLE CONVERSION SWITCH {A}
HEAD COVER
HEADPHONE JACK ‘Front?
HEADPHONE ‘JACK ‘Rear’
RECORD SAFETY BUTTON
VU METER (Right)
VU METER (Left}
TAPE SPEED SELECTOR
RECORDING LEVEL CONTROL (Left)
RECORDING LEVEL CONTROL(Right)
MICROPHONE JACK (Left)
MICROPHONE JACK (Right)
MONITOR SWITCHES
AUTOMATIC SHUT-OFF SWITCH
POWER SWITCH
RECORDING LEVEL CONTROL {Left}
RECORDING LEVEL CONTROL (Right)
SPEAKER VOLUME CONTROL
STEREO SELECTOR
MICROPHONE JACK (Right)
MICROPHONE JACK (Left)
VU METER [Right)
VU METER (Left)
AC CORD
VOLTAGE SELECTOR PLUG
FUSE POST
CYCLE CONVERSION SWITCH (B)
SPEAKER SWITCH
LINE OUTPUT JACK (Right)
DIN JACK (Front)
LINE OUTPUT JACK (Left)
LINE INPUT JACK (Left)
LINE INPUT JACK (Right)
SPEAKER JACKS (Left. Right)
LINE OUTPUT JACK (Left)
LINE OUTPUT JACK (Right)
LINE INPUT JACK (Right)
DIN JACK (Rear!
LINE INPUT JACK (Left)

IV. DISMANTLING OF TAPE TRANSPORT
UNIT & AMPLIFIERS
In case of trouble, etc, necessitating disassembly, please
disassemble in the order shown in photographs. Reas-
semble in reverse order.
EAY, REC.-LE'
Le RWOMLEVER >
"MECH.
AMP. BLOCK
| CASE BLOCK

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4
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£
12
RETAINING PLATE

V. TRANSPORT MECHANISM
Fig. 1
Braked Rotation
1. CAPSTAN DRIVE
Figure 1.
(A) Motor
(B) Drive Belt (flat belt)
(C) Capstan
(D) Flywheei
High-speed rotation of Motor (A) is transmitted by Drive
Belt (B) to Capstan (C); which is connected to a
flywheel that provides necessary inertia. This flywheel
maintains the rated rotation and absorbs minor rotation
variations of the motor.
Capstan Rotation :
606 R.P.M. at 7-1/2” (19 cm) per sec.
303 R.P.M. at 3-3/4” (9.5 cm) per sec.
151.5 R.P.M. at 1-7/8" (4.75 cm) per sec.
Motor Rotation :
3,000 to 1,500 R.P.M. at 50 Hz
3,600 to 1,800 R.P.M. at 60 Hz
2. PINCH WHEEL DRIVE
The pressure of the pinch wheel as it pushes against
capstan, transports tape between rotating capstan and
pinch wheel at the rated speed. The proper pinch wheel
pressure is between 1,000 to 1,150 grams at the tape
speed of 7-1/2’ (19 cm) per second.
3. RECORD AND PLAYBACK MECHANISM
Turning the RECORD/PLAYBACK LEVER (A) to
“PLAY” position causes the pinch wheel to press against
the capstan and move the tape at the rated speed. At the
same time, Idler (B) moves between Motor Bushing (C)
and the Take-Up Reel Spindle (D) to transmit the motor
rotation to (D) so that the tape is moved and wound on
the take-up reel. The Take-up Reel Spindle Base,
composed of two plastic wheels (discs) (1 and 2) witha
felt clutch between, is rotated from below by the idler.
Tape-winding friction is adjusted by the slipping of the
felt and maintains rated winding of the tape. The Supply
Reel Spindle (H) hasa Brake Roller (E) contacting plastic
wheel (disc) (4) from below which provides appropriate
back tension by the slipping of the felt clutch to the
rotation of the Pulley (3) above. To prevent accidental
erasure, the Record Safety Button (F) must be depressed
before the RECORD/PLAYBACK LEVER can _ be
moved to the “REC” position. Safety device (G) is
depressed to operate the recording mechanism.
(See figure 2)

4. FAST-FORWARD MECHANISM
Turning the FAST FWD-REWIND LEVER (A) to
“FAST FWD” position, causes cam (B) under the knob
to push up Lever (C). Idler (D) moves into the space
between Plastic Roller (F) above the Take-Up Reel
Spindle and the upper part of the rotating motor drive
bushing to transmit the motor rotation to the take-up
reel spindle. At the same time, Brake Rollers (H) and (I)
come off the reel spindle to free Supply Reel Spindles
(G) and (F), thereby allowing fast winding of the tape
onto the take-up reel.
(See figure 3)
5. REWIND MECHANISM
nee
Turning
the
FAST
FWD-REWIND
knob
(A)
to
“REWIND” position, causes cam (B) under the knob to
push up Lever (C). Idler (D) moves into the space
between the upper part of the rotating Motor drive
bushing (E) and the Intermediate Pulley (F) to transmit
the high-speed rotation of the motor through the
intermediate pulley to Supply Reel Spindle (G). At the
same time, Brake Rollers (H) and (I) come off the reel
spindle to free take-up reel spindles (J) and (G), thereby
rewinding the tape onto the supply reel at a fast speed.
(See figure 4)
6. STOP CONTROL
Turning the stop lever to “STOP” position, causes Brake
Rollers (A) and (B) to depress the reel spindles andstop
rotation.
ie ~P take-up Reel Sendie’
Ba
ier
Ax
/F7w
°
As
the
brake
rubbers
depress
the
plastic
rollers
below
the
a
‘
reel
spindles,
no
friction
is
applied
to
the
tape.
(See figure 5)
=
Pinch | ake-up | Rewind | Take-up | Swp ly
Modes
of
Operation
Wheel
Idler
Idler
side
ide
Wheel Wheel Brake Buk €
=
aie
STOP
x
x
£
Guide
Roller
caemas
‘
:
:
a
t + t +
(b)
FAST-FOR
WARD
x
oO
x
x
if
{c)
REWIND
x
x
a
x
i
+ +
RECORDING os O
‘)
PLAYBACK
cs
.
x
*
L i —
NOTES : X-marks indicates “open” and
“)-marks “engaged”