Akai 1700 User manual

SERVI
AKATI TAPE RECORDER

TABLE OF CONTENTS
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SPECIFICATIONS cesses cceesetseeseceeesessceereeetserseneeressstseees 1
HOW TO MEASURE DESIGNATED VALUES OF
SPECIFICATIONS cceeeeceeesessesssssecceceeeeessesseeetesseceseeeeenae 2
LOCATION OF CONTROLS -eesseeessesseeesecessesseeesterneaee 3
DISASSEMBLY OF TAPE TRANSPORT UNITS
AND! AMPLIFIERS #12004 sS0escved caves ant cassdi paseiesavaacesdetzeat 4
TRANSPORT MECHANISM cscessssscsssceeeeseseee seseeessreeetenee 6
ADJUSTMENT OF TAPE TRANSPORT UNIT ---ssssesseereereres 9
ADJUSTMENT OF AMPLIFIER s++ssessssresseeeeseesrecceeeeeeereeees 10
MAINTENANCE PROCEDURES vveeesssesseeseesesseseeeesseeseeeee W
LIST OF REPLACEMENT PARTS vressess+ssrsreesrseeeeteteeetreeee 12
EXPLODED VIEW OF COMPONENT PARTS vrrs++-+seeeeeeeeees 14
TROUBLE SHOOTING CHART csressssssreesetessseseeesssenseenee 21
SCHEMATIC DIAGRAM creeeeesesereeseeeeeeees
CONNECTING DIAGRAM

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MODEL
NUMBER:
WEIGHT (NET
IN CARTON):
DIMENSIONS
POWER RE-
QUIREMENTS:
POWER CON-
SUMPTION:
RECORDING
SYSTEM:
PLAYBACK
SYSTEM:
TAPE SPEED
TAPE SPEED
DEVIATION :
WOW AND
FLUTTER:
FAST FORWARD
AND REWIND
TIME:
FREQUENCY
RESPONSE:
DISTORTION :
SIGNAL-TO-
NOISE RATIO:
CROSS TALK
CHANNEL
SEPARATION :
I
SPECIFICATIONS
Akai Model 1700, portable 4-track
stereo tape recorder.
33 Ibs (15 kg) without accessories.
13-14”
(H)
x
13-44”
(W)
x
9”
(D)
case
closed.
A.C.
100, 110,
120,
200,
220
or
240
volts
interchangeable.
50-60
cycles.
80 VA.
Inline 4 track stereo and 4-track mon-
aural recording.
Inline
4-track
stereo,
monaural
play-
back.
Three speeds; 7-44” (19cm), 3-34” (9.5
cm) and 1-7” (4.75 cm) per second. (15”
per second with an optional accessory
capstan and pinch wheel.)
Less than +3 per cent at all tape
speeds.
Less than 0.2 % at 7-14 ips. R.M.S.
Less than 0.3 % at 3-% ips. R.M.S.
Less than 0.45 % at 1-% ips. R.M.S.
150 seconds for 1,200 ft. tape at 50 cy-
cles and 120 seconds at 60 cycles.
40 to 18,000 cps. at 7-44 ips:
3db. 80 to 12,000 cps. at 7-44 ips;
& 3db. 80 to 10,000 cps. at 3-34 ips;
£4db. 80 at 4,000 cps, at 1-7 ips.
Within 4% at 1,000cps, 0 VU (total
harmonic)
40 db below recorded level signal at all
speeds.
Within 55 db between each track.
Better than 80 db at 1,000 cps +3 VU.
POWER INPUT
LEVELS:
POWER
OUTPUT:
INSULATION
RESISTANCE;
INSULATION
YIELD
STRENGTH:
MONITORING
SYSTEM :
MOTOR
HEADS
MICROPHONE
USED:
SPEAKER
INCLUDED:
TUBES USED
SILICON
DIODE USED:
REELS USED
RECORDING
LEVEL
INDICATOR:
Microphone input level
—55 db (VR. max.) at 1,000 cps.
Phono and radio input level
—40 db (VR. max.) at 1,000 cps.
Pre-Amplifier output, 0.7V at 1,000
cps, impedance more than 100K ohms.
Main output, 34 dbm. up (in 600 ohms).
More than 50 MEG ohms.
More than one minute at A.C. 1,000 V.
With headphone during recording.
Condenser starting induction two-
speed motor.
1/100 HP. Power factor, 70 per cent.
2,900 to 1,450 r.p.m. at 50 cps,
3,480 to 1,740 r-p.m. at 60 cps.
Inline 4-track stereo/monaural record-
play head;
Impedance...3,500 ohms + 10% at
1,000 cps.
4-track erase head ;
000 ohms 415% at 90
Impedance...
ke.
Round dynamic microphone
Impedance...50,000 ohms
Sensitivity... —55 db.
Frequency Response...70 to 15,000
cps +10db.
Two 5’ x7” dynamic speakers,
Impedance...8 ohms
Allowable Input...6 watts
Frequency Response...80 to 12,000
cps, £10 db.
12AT7 x2, 6BM8 x2.
150D x2
Up to 7” reel
Horizontal, A-model VU meter.

I HOW TO MEASURE DESIGNATED VALUES OF SPECIFICATIONS
TAPE SPEED
DEVIATION:
WOW AND
FLUTTER:
FREQUENCY
RESPONSE:
(OVERALL
FREQUENCY
RESPONSE)
Record the 1,000cps. sine curve of
the tape speed at rating speeds with
a standard sound recorder (AMPEX
351A, for instance) which is little af-
fected by the tape speed deviation
throughout the whole length of the
tape. Put this standard tape on the
tape recorder under test for playing
back, and measure its output by a
counter, then convert the value into
rating power frequency to evaluate
the tape speed deviation.
For a rough measurement, the tape
speed deviation can also be measured
with a testing tape for speed by a stop
watch,
Playback the 3,000 cps. standard tape
that guarantees wow and flutter with-
in 0.07 per cent, and read the effective
value on wow meter.
Since the sensibility of wow and flut-
ter frequency below 2cps. and above
5 cps. drops, the frequency over 5 cps.
is put to 3db/OCT circuit, and the
frequency below 2 cps. is put to 6 db/
OCT circuit for adjustment. This ad-
justed value is called auditory com-
pensated value.
Connect to the input terminal of the
recorder, record a sine curve sweep
frequency at 100 cps —10 db, from
Audio Frequency Oscillator.
Adjust tone vulume to flat, playback
the tape by connecting VTVM to spe-
aker out put then read the frequency
response to adjust a maximum devia-
tion of 6 db.
TOTAL HARMONIC
DISTORTION
FACTOR:
SIGNAL TO
NOISE:
OUTPUT:
CROSS TALK:
Provide the input terminal of th
recorder with 1,000cps. sine curv
signals and record these signals on |
recording tape at the zero level on th
recorder’s VU meter.
Then playback the signals under th
normal recording condition to meas
ure the distortion factor by an oscil
lator. Remove the recording tap:
from the recorder, then read the nois
level on the oscillator to get the requir
ed distortion factor by the followin
formula:
d0=d—dl—d2
di equired
d...overall distortion factor
dl...noise level
d2...distortion factor of the oscilla
tor used
Playback the sine curve, 250 cps. tape
recorded on a standard recorder or
the recorder to measure the voltage.
Remove the tape, then measure the
noise level under the same condition
Calculate the ratio between the twc
in decibel.
Playback on the recorder the 1,000 cps.
sine curve tape which was recorded
at the zero VU level on a standard
recorder. Terminate the test recorder
with eight ohms.
Square the voltage reading, then di-
vide the figure by eight ohms to get
the r.m.s. power output. :
Record 1,000 cps. signal at +3 VU on
the third track, then playback this
signal through a 1,000 cps. Band Pass
Filter.
Compare the output of tracks 1 and 3
in decibels.

Il
LOCATION
OF
CONTROLS
SBSGSBHG8SOGHOHGBHSSGOORODDOOOS
Supply reel shaft
Cycle conversion switch
Capstan storage post
Head cover
Record/Play head
Tape guide
Erase head
Index counter
Right channel volume control
Right channel tone control
Left channel microphone input jack
Right channel microphone input jack
Left channel volume control
Left channel tone control
Speed change switch
Take-up reel shaft
Capstan shaft
Pinch wheel
Automatic stop lever
Record/Play switch
Instant stop lever
SGE6GGOSHOSSBBSHBHOHHHBHS
Rewind/Fast-forward switch
Record safety button
Automatic stop switch
Stereo headphone jack
VU meter conversion switch
Power switch
VU meter
Track selector switch
Fuse post
Cycle conversion switch
Speaker switch
Hum adjust (right)
Speaker output jack (right)
Speaker output jack (left)
Voltage selector switch
Preamp output jack (right)
Preamp output jack (left)
Phono/Radio input jack (left)
Hum adjust (left)
Phono/Radio input jack (right!

VV DISASSEMBLY OF TAPE TRANSPORT UNITS & AMPLIFIERS
(1) Loosen the RETAINING SCREW {a} of PINCH ROL- (3) Loosen the SCREWS marked from (a) to (d) in order to
LOR (b} using a phillips-headed screw driver to remove remove DECK PANEL (P).
the PINCH ROLLER (b).
(2) Remove the DECK CONTROL KNOBS (a) and (b) by (4) Loosen the SCREWS marked from (a) to (d).
loosening their retaining screws using a phillips-headed
screw driver.

(5)
Loosen
the
SCREWS
marked
from
(a)
to
(d).
(6)
Lift
TAPE
DECK
and
AMPLIFIER
(D)
from
the
cabinet
(B).
(7)
Disconnect
the
PINS
of
speaker
marked
{a)
and
(d},
the
PLUGS
of
motor
marked
(e}
and
(f)
and
the
PINS
of
head marked (g) and (j).
(8) Loosen the RETAINING SCREWS of deck frame
marked from {a} to (d)
(9} Separate TAPE DECK (M) from AMPLIFIER (A)

Fig. 1
VY TRANSPORT MECHANISM
Driving of Capstan
Figure 1.
{A) Motor
(B) Driving Belt (flat belt)
(C) Capstan
(D) Flywheel
High-speed rotation of Motor (A) is reduced by Driving
Belt (B) and transmitted to Capstan (C), which is connected
to Flywheel with ample inertia and enables rated rotation
by absorbing minor rotation distortion of motor itself.
Capstan Rotation 606 r.p.m. at 7-14” (19 cm) per sec.
303 r.p.m. at 3-34” (9.5 cm) per sec.*
151.5r.p.m. at 1-1" (4.75m) per sec.
Motor Rotation —_ 2,900 to 1,450 r.p.m. at 50 cps.
3,480 to 1,740 r.p.m. at 60 cps.
Driving of Pinch Roller
Put tape between rotating capstan and pinch roller and
push pinch roller against capstan, this will transport the
tape at rated speed. The appropriate pressure of pinch
roller is between 1,000 to 1,150 grams at the tape speed
of 7-14 (19 cm) per second.
Recording and Play Back
Turn the RECORD, PLAYBACK knob (A) to “PLAY”
position, and pinch roller presses against capstan to move
tape at the rated speed. At the same time, /dler (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 is made up of two plas-
tic rollers (1 and 2) with a clutch felt in between. The Idler
is rotating the plastic roller (2) under. Therefore, the tape-
winding friction is adjusted by the slipping of the felt to
enable rated winding of the tape.
On the other hand, the Supply Reel Spindle (H) has a
Brake roller (E) hung on the Plastic Roller (4) under which
provides appropriate back tension by the clutch felt slipp-
ing to the rotation of the Pulley (3) above.
To prevent accidental erasure, the Record Interlock But.
ton (F) must be depressed before the RECORD, PLAY-
BACK knob can be moved to the “REC” position. The
Safety device (G) is depressed to enter the record mode.
(See Figures 2 and 3)
Braked Rotation Slipping Rotation
io
Fig. 3

FAST-FORWARD MECHANISM
Turn the FAST FWD-REWIND knob (A) to “FAST
FWD” position, and he cam (B) under the knob pushes up
the Lever (C). The Idler (D) moves into the space between
the 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 the Supply Reel Spindle (G), thereby allowing
fast winding of the tape onto the take-up reel.
(See Figures 4 and 5)
Free Rotation High-Speed Rotation
NF =
o } f °
Wwe Wye
2 E
Fig. 5 oO
T
REWIND MECHANISM
Turn the FAST FWD-REWIND knob (A) to “REWIND”
position, and the cam (B) under the knob pushes the Levey
(C) up. The Idler (D) moves into the space between the up-
per 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 the Supply
Reel Spindle (G). At the same time, Brake Rollers (H) and (I)
come off the reel spindle to free the take-up reel spindle (J),
thereby rewinding the tape into the supply reel at a fast
speed,
(See Figures 6 and 7}
High-Speed Rotation Free Rotation
Cro Op
Fig. 7
STOP CONTROL
Pinch |fake-up Rewin Meee Supply Push the stop lever to “STOP” position, Brake Rollers
Roller jWitcet Wheel [Brake | ‘Brake (A) and (B} depress reel spindles to stop rotation of the reel
| spindles.
As the brake rubber depresses the plastic rollers under
the reel spindles, no friction works on the tape itself.
Modes of Operation
(a) STOP
4
(b) FAST-FORWARD
(c)
REWIND
Supply
Reel
Spindle
Rewind
Idlerwhecl
Take-up
Reel
Spindle
Motor Take-up Side
(a)
RECORDING
_Brake
PLAYBACK
Supply Side Resid
NOTES:
x-marks
indicates
“open”
and
Brake
Idlerwheel
:
i
ra
f
O-marks “engaged Guide Roller Fizad
O Pinch Wheel
H
Fig. 8

RECORD/PLAYBACK CHANGING MECHANISM
By turning the RECORD/PLAYBACK KNOB (N) to the recording position, the LEVER {a} pulls the RECORDING
LEVER (b) and (c), as illustrated in dotted line, then the RECORD/PLAYBACK CHANGE SWITCH (SWI) turns
to recording position.
If the LEVER (c) does not turn properly, SW! does not operate properly so may occur the abnormal oscillation and
also can’t record.
Then must adjust the LEVER (c) to proper position by loosing the SCREW (d).