Akai 4000DS Mk-II User manual

AKATI
SERvICE
MANUAL
STEREO
TAPE
DECK
4000DS

SECTION |!
SECTION 2
SECTION 3
STEREO
TAPE DECK
MODEL
4000DS
SERVICE
MANUAL
PARTS
(ESE:
cxccioutcasmeneddhaveniancees
ere
tented
SCHEMATIC
DIAGRAM
eee
oe
a
ee
ec
ro re

VIL.
SECTION 1
SERVICE
MANUAL
TABLE
OF
CONTENTS
SPECIFICATIONS
...
se
Tasahd
cat
tases
cols
gst
aeeieasioages
MEASURING
METHOD
.....
"
DISMANTLING
OF
TAPE
TRANSPORT
UNIT
&
AMPLIFIERS
.....--
MECHANISM
ADJUSTMENTS
HEAD
ADJUSTMENTS
....
AMPLIFIER
ADJUSTMENTS
....-
COMPOSITE
VIEWS
OF
COMPO

il.
SPECIFICATIONS
An asterisk next to a figure indicates the minimum guaranteed performance.
TRACK SYSTEM
REE L CAPAC ITY
‘TAPE SPEED
WOW AND FLUTTER
FREQUENCY RESPONSE
AKAI SRT tape
Regular tape
SIGNAL TO NOISE RATIO
‘DISTORTION
CROSS TALK
ERASERATIO.
INPUTS
Line input
Din input
OUTPUTS Line output
Din output
BIAS FREQUENCY ey
BIASLEAK
HIGH FREQUENCY DEVIATION
RECORDING CAPACITY
FAST FORWARD AND REWIND ‘HIME.
MOTOR
HEADS
Playback Head
frase Head
TRANSISTORS
IC
DIODES
POWER SUPPLY
POWER CONSUMPTION
INSULATION RESISTANCE
INSULATION DURABILITY
DIMENSIONS
WEIGHT
NOTE:
_ Less than 9. 20% (0.30%) RMS at 3-3/4 ips
Mic input
0.4V
| Within 2 dB using an 8,000 Hz 3
Revolutions: |,800/1 500 rpin.
Reeording Head
Impedance:
_4-track 2-channe! stereo/monaural system
_ Up! to reel
_7-1/2 and 3- 3/4 i ips + 2% (43%) | ae
Less than 0.15% (*0.22%} RMS at 7- 1/2 ig ips
30 to 23,000 Hz (*40 to 22,000 Hz) + 3 dB at 7-1/2 ips
30 to 16,000 fiz (440 to 14,000 Hz) £3 dB at 3-3/4 ips
30 to 20,000 Hz (440 to 20,000 Hz) t 3 dB at 7-1/2 ips
30. to t4 000 He (*40 to 14 000 Maz) 3 = 3 dB at 3- “3/4 ips:
Better than 50 dB at 7-1/2 ips
Better than 48 dB at 3- ‘3/4 ps
“Less ‘than 1. 5% (#2. 0%) at 7- 1/2 ips”
Less than 2.5% at 3- 3/4 ips
Better than 70 dB (*60 dB} moda
_ Better than 50 dB (*45 dB) stereo
_ Better than 70 dB
0.8 mv Impedance 5 ka
70 mV Impedance 150 ks
7TmvV
t.228V (4 £1 dB) using a 250 Hz “0 VU recorded tape
10S kliz 45%
Less than 30, vu
60 min, stereo recording using a “4,200 ft. tape at 7-1/2 3 ips boast
152/190 sec, using a FE, 200 ft. tape at 60/50 Hz
4-pole induction |-speed motor
Type: SSM-1
at 60/50 Hz
In-line 4-track 2-channel recording head
Lype: P4-154
Gup: } micron
linpedunce: 9592 + 15% at 1,00 Ete
Indine 4-track 2-chaunnel playback head
Type: P4-150
Gap: Lamicron
Impedance: 1.2509 * 15% wt b.000 He
In-line 4-track 2-channel erase head
Type: 14-200
Gap: 0.6 mm
20082 25% at LOO KHz
More than 5 M&d
1GO00V AC. for more than fan. duration
406 (W)X 314) xX 194 (Dyan (15.9 X 12.4 X 7.67)
EL.4 ke (25 Ibs} . .
Specifications subject to change without notice.
3/4 ips recorded tape at ue 4/2) ips na
2SC971 (2) 3) (red)
Ob45524 28C458 LG (C) (D) Dis dint Bo.
BD” aca atlge tae esCa7i yh) Pol... 28C1098 ¢t.) &M)
4 0.... LDA
2....., IN34A
ree 1OPC.1
ts vicki S339
100 to 240V AC, S0/60 Hz
120V AC. 60 Hz for CSA/UL Models
220V A £. SSO te for Chk model
35W

ll.
MEASURING
METHOD
1.
TAPE
SPEED
DEVIATION
3.
FREQUENCY
RESPONSE
i
ena
4000DS
—_]
counter
|
Line
output
input
Audio
|
Line
4000DS
|
Frequenc,
or
AQT.
i
Gesu
pe
ca
input
sae
|
output
Fig. 1
‘As
shown
in
Figure
1,
connect
a
Frequency
Counter
to
the
Line
Output
of
Model
4000DS,
Take
a
frequency
counter
reading
at
the
beginning,
middie,
and
end
of
tape
winding
during
playback
The
maximum
value
of
these
respective
readings
will
represent
tape
speed
deviation.
2.
WOW
AND
FLUTTER
[
4000DS
|
=
|
Wow
and
aren
[
Line
output
i
ae
oa
(ee
input
A
Fig. 2
Method A
‘As
shown
in
Fig.
2,
connect
the
Line
Output
of
Model
4000DS
to
the
Input
of
a
Wow
and
Flutter
Meter,
Use
a
3,000
Hz
pre-recorded
test
tape
and
take
a
wow
and
flutter
meter
reading
at
the
beginning,
middle,
and end
of
tape
winding.
The
maximum
value
of
these
respective
readings
will
represent
the
wow
and
flutter.
Method B
Supply
a
3,000
Hz
sine
wave
signal
from
an
Audio
Frequency
Oscillator
and
make
a
recording
on
4
blank
tape
at
the
beginning,
middle,
and
end
of
tape
winding.
Rewind
and
playback
tape.
Measure
wow
and
flutter
with
a
Wow
and
Flutter
Meter.
(The
wow
and
flutter
value
of
Method
B
will
be
close
to
twice
that
of
Method
A.)
|"
Sensitivity
VI-VM.
oa
Fig. 3
For
measuring
frequency
response,
connect
instru-
ments
as
shown
in
Fig.
3 and
proceed
as
follows:
1)
Supply
a
1,000
Hz
sine
wave
to
the
Line
Input
of
Model
4000DS
from
an
Audio
Frequency
Oscil-
lator
through
an
Attenuator.
Set
recorder
to
re-
cording
mode
and
turn
recording
level
volume
control
to
maximum.
Adjust
Attenuator
to
obtain
a+4
dB
V.T.VM.
reading.
2)
Under
conditions
described
in
1)
above,
re-adjust
‘Attenuator
so
that
the
Line
Output
Is
-16
dB,
and
record
40
to
20,000
Hz
spot
frequencies.
3)
Rewind
tape
and
playback
from
the
beginning.
Take
V.T.V.M.
spot
frequency
readings
and
plot
values
on
a
graph
NOTE:
When
measuring
frequency
response,
new
tape
should
be
used.
4.
SIGNAL
TO
NOISE
RATIO
4000DS
Line output
High
Sensitivity
VTVM.
Fig. 4
‘As
shown
in
Fig.4,
connect
a
High
Sensitivity
V.T.VM.
to
the
Line
output
of
Model
4000DS.
Playback
a
250
Hz
“Q”
VU
pre-recorded
test
tape
and
measure
the
output.
Then
remove
the
tape
and
measure
the
noise
level
under
the
same
condition.
Convert
each
of
the
measured
values
into
decibels.

i
5.
TOTAL
HARMONIC
DISTORTION
7.
ERASE
RATIO
FACTOR
As
shown
in
Fig.
4,
connect
a
High
Sensitivity
V.T.V.M.
to
the
Line
Output
of
Mode!
4000DS.
So
a
]
.
Playback
a
virgin
tape
and
take
a
V-T.V.M.
reading
of
|
Audio
i
ee
ane
4000DS
the
output
level.
Next,
record
a
1,000
Hz
sine
wave
|
eee
py
ATT.
4
input
Line
signal
at
+3
dB,
then
playback
this
recorded
signal
pe
es
ot
output
|
and
tape
a
V.T.V.M.
reading
of
the
output
level.
|
|
Next,
using
this
pre-recorded
tape,
record
under
a
|
aaa
]
non-input
condition
and
take
a
reading
of
the
noise
re
ae
level
output
of
the
erased
signal
and
obtain
a
ratio
between
the
two
from
the
following
for
mula:
Meter
Seer
beesGiiasictl
Ot
Fig.
5
Er
=
20
log
ee
{dB)
Where,
Er
-
Desired
erase
ratio
(dB)
Connect
the
measuring
instruments
as
shown
in
Fig,
5
Eg-
1,000
Hz
signal
output
level
and
record
a
},000
Hz
sine
wave
signal
at
“O”
VU.
Ez
-
Non-input
signal
recorded
level
Playback
the
resultant
signal
and
measure
the
overall
FE,
-
Virgiti
tape
noise
output
level
distortion
factor.
Measure
the
noise
level
of
the
tape
recorder
without
the
tape.
Connect
the
Audio
Fre-
quency
Oscillator
directly
to
the
distortion
meter
tor
measurement
of
the
distortion
factor
of
the
oscilla-
tor,
The
required
distortion
factor
can
be
obtained
from
the
results
of
the
above
measurement
by
the
following
formula:
dg
=d-
d,
—d2
where,
dg
—
Required
distortion
factor
d
—
Overall
distortion
factor
dy
--
Noise
level
dy
—
Distortion
factor
of
the
oscillator
NOTE:
When
measuring
the
distortion
factor,
new
tape
should
be
used.
6.
CROSS
TALK
(Cross
talk
between
the
tracks)
(TAPE)
—_~—
mime
TAPE
DIRECTION
Fig. 6
As
shown
in
Fig.
6,
first
record
a
|
000
Hz
sine
wave
signal
on
Track
No.
3
at
+3
VU
Jevel.
Next,
record
under
a
non-input
condition.
Then,
playback
the
tape
on
Tracks
No.3
and
4
through
the
B.P.F.
(band
pass
filter
sensitivity
...
1:1)
and
obtain
a
ratio
between
the
two
from
the
following
formula:
a
Ep
where,
C
-
Desired
cross
talk
ratio
(dB)
Eg
-
1,000
Hz
signal
output
level
ees
Ex
—
1,000
Hz
cross
talk
level
LLB
Ey
-
Non-input
signal
recorded
level
#RRRRy
A
RR

DISMANTLING OF
TAPE TRANSPORT UNIT & AMPLIFIERS
In
case
of
trouble,
etc.
necessitating
disassembly,
please
disassemble
in
the
order
shown
in
photographs.
Re-
assemble
in
reverse
order.
a4
SE KN
track sevecror Knog PAUSE JNOF
——
252
gt
rete
aIgestats
y
ri
t
PrUsrer
SIDI GID IS GID ISIS II GS
eg tags Pag Posy
PINCH WHEEL CAPI
> INCH WHERE
fT ce ty =
o
S22 tg
a
Peg?
gate tees

Iv.
MECHANISM
ADJUSTMENTS

1.
PINCH WHEEL ADJUSTMENT
It is important that the pinch wheel shaft be kept in
perfect alignment with the capstan shaft. Proper
pinch
wheel
pressure
is
between
1,000
and
1,150
grams
when
the
unit
is
operated
at
the
tape
speed
of
7% ips. Any deviation from this specification will
result in wow and flutter. Check pinch wheel pressure
with a spring scale, and if necessary, adjust the pinch
wheel load spring.
Fig.
8
Fig.
9
2. SUPPLY REEL SHAFT ASSEMBLY
ADJUSTMENT (See Fig. 7 at left)
Felt clutch material (2) is used between the lower
side of the ree! table base plate (1) and the rewind
pulley (3) to protect recording tape from excessive
tension during rewind operation. To check the
amount of friction of this part, install a 5-inch reel
with a 60 mm diameter tape, and gently pull the end
of the tape upward with a spring scale. Adjust the
conical spring (4) so that the amount of tension is
kept between 400 and S00 grams. Other felt clutch
material (5) is attached to the supply roller (6) to
provide proper slippage during FWD and REC oper-
ation. The procedure for checking friction of this part
is the same as the foregoing, and between 80 and 100
grams of tension gives best result. Adjust the spring
(7) just under the supply roller (6). When the unit is
set to fast forward operation, the amount of friction
will decrease to from tS to 20 grams. Check to see
whether this is satisfactory. If not, adjust the spring
plate (8) and the pressure of the pulley. (9).
4)