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PINCH
ROLLER
PRESSURE
CHECK
1) Place the unit in play mode.
2) Push the pinch roller, at the point (A) shown in Fig.10—1,
by using a tension gauge (500 gr.) so that it will come off
the capstan. Then, slowly release the tension until the pinch
roller hits the capstan again (i.e., the pinch roller is about
to rotate again). Check, then, the tension gauge is reading
270 gr. to 320 qr.
3) If the reading is outside the range of 270 gr. to 320 gr.
bend
the pinch
roller spring or replace.
A
&Q
Figure 10—1
TORQUE
CHECK
AT PLAY, FAST
FORWARD
AND
REWIND
MODES
Put a torque meter cassette in the cassette compartment
of the
unit,
and see that the measured
torque
in each
mode
is normal
as follows:
[Mode [Toraue meter cassette | Measured torque
TW2231
Rewind
MECHANICAL
ADJUSTMENT
RECORD/PLAYBACK
HEAD
AZIMUTH
ADJUSTMENT
1) Make
connection
of instruments as shown
in Fig. 10—2.
2) Set the mode
selector switch
at ''tape'' position.
3) Put a test tape (TEAC,
MTT-114,
10 kHz
250 pWb/m,
—10dB
prerecorded)
into the unit and
play it.
4) Adjust
the
head
azimuth
adjusting
screw
so that
the
electronic
voltmeter
reading
is maximal.
Note:
If a dual-trace
oscilloscope
is available, perform
the adjust-
ment so that the reading of the oscilloscope is maximal and
with
the
least
phase/output
difference
between channels.
After the work, check that the head azimuth adjusting screw
has been
secured
completely.
oscilloscope
line output
jack (L-ch)
test tape
MTT-114
electronic
voltmeter
record/playback
line output jack (R-ch)
head
Figure 10~2
TAPE
SPEED
ADJUSTMENT
1) Connect
a wow/flutter meter, across
a 100 kohm resistor,
to the headphones jack.
2) Play a test tape (TEAC,
MTT-111,
3kHz
prerecorded).
3) Put
a plastic
screwdriver
into
the
hole
of the motor
and
adjust
the semi-variable
resistor so that the output
frequency is 2960 ~ 3015 Hz on the wow/flutter meter.
ELECTRICAL
ADJUSTMENT
BIAS OSCILLATOR
FREQUENCY
CHECK
1) Make a connection of instruments as shown in Fig. 10—3.
2) Set the function selector switch at ''tape'', the tape selector
switch
at "normal''
and the beat cancel switch
at "A"
position.
3) Place the unit in record mode, and see that the frequency
counter
is reading 60 + 5 kHz.
Change the beat cancel switch from "A" position to 'B"'
position,
then
see
that the present
frequency
counter's
reading
60 + 5 kHz is changed by +1.0 kHz ~ +1.5 kHz.
ERASE
CURRENT
CHECK
1) Make a connection of instruments as shown in Fig. 10—3.
2) Set the tape selector switch at "'metal'' position.
3) Place the unit in record mode, and see that the electronic
record mode
electronic
frequency
voltmeter
counter
Figure 10-3
voltmeter
is reading 30 + 4V.
Change
the tape
selector
switch
from
''metal"
position
to "normal" position, then see that the electronic voltmeter
indicates
16 + 3V.
PLAYBACK
AMPLIFIER
SENSITIVITY
CHECK
1) Make a connection of instruments as shown in Fig. 10—4.
2) Set the function selector switch at ''tape'' the tape selector
switch
at
"normal",
the volume
control
knob
at '10
(max),
and the tone control
knob at "center" position.
3) Playback a test tape (TEAC MTT-118, 1 kHz, 250 pWb/m,
—10dB
prerecorded).
4) See that the electronic voltmeter is reading about 60 mV.
5) Then
see
that the electronic
voltmeter
indicates
about
1.2V
if it is connected
to the DIN Jack.
electronic
voltmeter
oscilloscope
headphones jack
ne
my
_B_|por
net 5
record/playback
head
test tape
MTT-118
Figure 10—4
—10—
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