Akai ABTS- M10 User manual

AKAL TAPE RECORDER
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TABLE OF CONTENTS.
SPECIFICATIONS
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1
MEASURING
METHOD
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2
CONTROL
LOCATIONS
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DISMANTLING
OF
TAPE
TRANSPORT
UNIT
&
AMPLIFIERS
....
2.6.06.
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5
TRANSPORT
MECHANISM
..........0-02
02
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7
MECHANISM
ADJUSTMENT
............-2+2
2000)
11
AMPLIFIER
ADJUSTMENT
...
1.0.0...
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19
MAINTENANCE
PROCEDURES
.......-..-2--00055
21
COMPOSITE
VIEWS
OF
COMPONENTS
..........--
22
TROUBLE
SHOOTING
CHART
..........------
05s
25
SCHEMATIC DIAGRAM

I. SPECIFICATIONS
STYLE : Portable
WEIGHT 37.4 lbs (17 kg)
DIMENSIONS 14” x 14” x 8-7/8”
(358 x 358 x 227 mm)
POWER SUPPLY AC 100 to 240 V, 50/60 Hz
RECORDING SYSTEM
In-line 4-track stereo, monaural record-
ing by using Cross-field Bias Head.
PLAYBACK SYSTEM
IN-line 4-track stereo, monaural play-
back.
TAPE SPEED 1-7/8, 3-3/4 and 7-1/2 ips.
TAPE SPEED DEVIATION
Within + 0.8%
WOW AND FLUTTER
(Play back only) : Less than 0.1% 1r.m.s. at 7-1/2 ips.
Less than 0.2% r.m.s. at 3-3/4 ips.
Less than 0.3% r.m.s. at 1-7/8 ips.
FREQUENCY RESPONSE
30 to 25,000 Hz + db at 7-1/2 ips.
30 to 18,000 Hz + db at 3-3/4 ips.
40 to 9,000 Hz +4 db at 1-7/8 ips.
SIGNAL TO NOISE RATIO
: Better than 48 db (Forward Operation)
- Better than 45 db (Reverse Operation)
DISTORTION Within 3% at Line Output, 1,000 Hz O
VU Recording and Playback.
CROSS TALK Less than —65 db (Monaural)
Less than —43 db (Stereo)
ERASE RATIO Less than —70 db
INSULATION RESISTANCE :
More than 50 M.Ohms
INSULATION DURABILITY
: $00 V. AC for more than one minute
duration.
LINE OUTPUT Output Impedance ........ 100 Ohms.
Required load impedance more than 25
K.Ohms.
1.23 V (+4 dbs)
POWER OUTPUT 8 Watts (r.m.s.) per channel, total 16
(External watts
. Speaker Jack) Inpedance: «4 vscceas coeds 8 ohms
DIN OUTPUT : O4V
Output Impedance ....... 10 K.Ohms.
Required load impedance more than 50
K.Ohms.
LINE INPUT Above 50 mV (~25 dbs)
Impedance .......:..... 175 k.Ohms.
DIN INPUT High ........ Above 50 mV (—25 dbs)
Impedance ........ 150 mV (—45 dbs)
LOW exe ee ont Avove 5 mV (—45 dbs)
Impedance ............. 27 K.Ohms.
MIC. INPUT Above 0.5 mV (—65 dbs)
Impedance ............. 4.7 K.Ohms.
FAST FORWARD AND REWIND TIME
: 85 seconds for a full 1,200 foot tape at
50 Hz.
65 seconds for a full 1,200 foot tape at
60 Hz.
MONITOR SYSTEM : The program being recorded can be
monitored by using.
Stereo Headphonc (8 Ohms) .......
Stcteo Headphone Jack.
Crystal Receiver . Line Output Jack.
MOTORS
CAPSTAN MOTOR
Hysteresis Synchronous 3-speed (2-4-8
pole) motor
Condenser Capacity 3 uF (50 Hz)
2 uF (60 Hz)
Revolution 3,000 — 1,500 750r.p.m. (50 Hz)
3,600 — 1,800 900r.p.m. (60 Hz)
REEL MOTOR
i112,outer-rotor motors.
Revolutions 930 r.p.m. at 50 Hz 100 V
1,120 r.p.m. at 60 Hz 110 V
HEADS
REC/PLAY HEAD
: In-line 4-track stereo and monaural
Impedance ... 1,200 Ohms at 1,000 Hz.
Capi: fii ote Bae OF Se 2/1,000 mm
ERASE HEAD In-line 4-track stereo
Impedance ...... 500 Ohms at 60 KHz.
Gap: erected Be 0.2mm
BIAS HEAD In-line 4-track stereo
Impedance ...... 500 Ohms at 60 KHz.
Gap: :onccrseea ea taal aca Se 0.2 mm
RECORDING LEVEL INDICATOR
VERTICAL Indication VU Meter x 2
TRANSISTOR & IC USED
2 ICAA-072D 4 2SD92
2 2SC458 (B) 7 28C372
4 2SC693FU 4 2SC971
1 2SD223
DIODE USED 1 SB-3-01P 3 IN34A
1 10D4 15B2
4 V06C 1 RD24A (M)
REELS USED 7”, 5”, 3” reels
10-1/2” Reel Adaptor available optional
accessory)
a

ll.
MEASURING
METHOD
TAPE SPEED DEVIATION
1. Method involving use of pre-recorded tape.
For measuring the tape speed diviation, play back the
pre-recorded tape at 1,000Hz+ 0.1%. Connect the
appropriate output to a frequency counter meter in
order to measure the tape speed deviation from the
resulting deviation of the measured frequency.
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 the timing tape stretch or
contract measurement enor is inevitable, so that it is
necessary to measure the total length of the tape in
advance.
WOW AND FLUTTER
Playback the 3,000 Hz pre-recorded tape of which the
wow and flutter level is guaranteed to be smaller than
0.07% for measurement by means of a wow meter. It is
also possible for a 3,000 Hz sine wave to be recorded
and played for measurement by means of the wow
meter. In this case, however, the wow meter indicates a
value as much as twicc the value given in the specifi-
cations on the first page.
FRQUENCY RESPONSE
RECORD :
1) Give a sine wave of 1,000 Hz to the Line Input of
the recorder to be tested through an attenuator
from an audio frequency generator.
2) Set the Record/Playback Knob to “Rec” position
and adjust the line input volume so that the VU
Meter needle indicates “O”’ VU.
3) Set the Equalizer Switch to 7-1/2” or 3-3/4”
position.
4) Under the condition described in (2), lower the
input level 16 db by means of the attenuator.
5) Record the spot frequency in the range of 30 Hz to
25,000 Hz from the audio frequency generator.
PLAYBACK :
6) Set the Record/Playback Knob to “Play” position.
7) Connect a Vacuum Tube Volt Meter to the Line
Output Jack. (VTVM with milli volt scale.)
8) Playback the reocrded tape.
9) Playback the recorded spot frequencies and make a
memo of output level and plot the value on a graph.
Mic. input
Oscillator
Microphone Line output jack
TOTAL HARMONIC DISTORTION FACTOR
1 KHz
Distortion
meter
Audio
Oscillator
Connect
the
measuring
instrument
as
shown
above,
and
record
the
1,000
Hz
sine
wave
at
“O”
VU.
Playback
the
resulting
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
required
distortion
factor
may
be
obtamed
from
the
results
of
the
above
measuement
by
the
following
formula
:
do=d-di_ dz
where, do = Required
d = Overall distortion factor
di = Noise level
d2 = Distortion factor of the oscillator
(Note
:
New
tape
of
particularly
good
quality
should
be
used for measurement of the distortion factor.)
SIGNAL TO NOISE RATIO
M-10
Set the Equalizer Switch to “7-1/2 ips” position and
playback a tape containing a 25 Hz sine wave recorded
at “O” VU level on a standard recorder. Connect a
V.T.V.M. to the line output jack of the recordir and
measure its output. Then remove the tape and measure
the noise level under the same condition. Convert into
decibels each of the measured values.

CROSSTALK (Crosstalk between the tracks)
(TAPE)
Tape direction 2 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 track No.3 and
No.
1
(reversed
condition
of
tape)
through
the
1,000
Hz
B.P.F.
(Band
Pass
Filter,
Sensitivity....
1:1)
and
obtain
a
ratio
between
the
two
from
the
following
formula.
Eo
C = 20 log ——*— (db
eee Bi (db)
C = Desired crosstalk ratio (db)
Ls 2] Eo = 1,000 Hz signal output level
CLZLZZZ2 E2 = 1,000 Hz crosstalk output level
RES Ei = Non-input signal record level

lll.
CONTROL
LOCATIONS
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|

IV.
DISMANTLING
OF
TAPE
TRANSPORT
UNIT
&
AMPLIFIERS
sen
a
ee
In
case
of
trouble,
etc,
necessitating
disassembly,
please
disassemble
in
the
order
shown
in
photographs.
Remantle
in
reverse
order.
DISASSEMBLY
OF
TAPE
TRANSPORT

jai
tl
BACK PAN

DISASSEMBLY OF AMPLIFIER

V. TRANSPORT MECANISM
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—He— NORMAL CLOSED CONTACT
——{}-— NORMAL OPEN CONTACT Fig. 5-2
1. SUPPLY VOLTAGE OF BOTH TORQUE 2. PINCH ROLLER PRESSUR 1.5 Kgr
MOTORS DURING RECORDING/PLAYBACK TO 1.8 Kgr.
Recording/Playback (Normal Recording)
[ee a a SUPPLY Set Recording/Playback Knob (A) to Playback Position.
30 V (50 to 60 gr) The Pinch Roller presses against Capstan to move the
47 V (100 gr) tape at the rated speed. The Brake Levers free the Brake
severse and the Lever Spring (G) turns ‘“‘ON’’ Microswitch
60
V
(180
gr)
(SW006)
(F)
so
that
both
torque
motors
become
operative (at shown in diagram illustration).