Akai 1700 Service Manual

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.

Akai 1700 Specifications

General

Brand	Akai
Model	1700
Category	Tape Deck
Language	English