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Reassembling the Mechanism Unit
MECHANISM
1. For
repair,
measurement
or
adjustment
with
the
UNIT
|
\
a
Main
Circuit Board
Fig. 11
NOTES:
@® Head azimuth
Tape speed adjustment VR
Jumper wire for
erase current adjustment
TP3
TP1
'
fe
VRQ
Q®&
TP5
i=
VR10
i
VR8
AOC
e
VR201
e Make sure heads are clean
¢ Make sure capstan and pressure roiler are clean
e Judgeable room temperature 20+5°C (68+9°F)
¢ NR switch: OUT
Condition:
¢ Playback mode
¢ Normal tape mode
Equipment:
eVTVM
adjustment
¢ Oscilloscope
MAIN P.B.
VR501
Ap
TP502
C3 \ Ic4
og \ EAT P501
QQ
@&
VR5
VR6
S
VR202
FL METER P.B.
Set switches and controls in the following positions, unless otherwise specified.
¢ Timer start switch: OFF
¢ Input level controls: Maximum
e Balance control: Center
e Test tape (azimuth)...QZZCFM
L-CH/R-CH output balance adjustment
1. Make connections as shown in fig. 2.
. Playback the 8kHz signal from the test tape (QZZCFM).
Adjust screw (B) in fig. 3 for maximum output L-CH and R-CH levels.
When
the output levels of L-CH and R-CH are not at maximum
at the same
point adjust as follows.
. Turn screw (B) shown in fig. 3 to find angles A and C (points where peak output
levels for left and right channels are obtained). Then, locate angle B between
angles A and CG, i.e., and point where L-CH and R-CH outputs are balanced.
(Refer to figs. 3 and 4.)
L-CH/R-CH phase adjustment
4. Make connections as shown in fig. 5.
5S. Playback the 8kHz signal from the test tape (QZZCFM).
Adjust screw (B) shown in fig. 3 so that pointers of the two VTVMs swing to
maximum and a lissajous waveform as illustrated in fig. 6 is obtained on the
oscilloscope.
LINE OUT
Record/
playback head
Playback mode
VTVM
Oscilloscope
Fig. 2
¢
_Record/ playback
head
A
Screw (B}
Fig. 3
L-ch peak levei
R-ch peak Jevet
OUTPUT
LEVEL
Oscilloscope
Record/
playback head
Playback
mode
Horizontal
Condition:
_ @ Playback mode
Equipment:
e Digital frequency counter
* Test tape...QZZCWAT
©) Tape speed
Record/ playback
head
>
|
:
2
Test tape
Tape speed accuracy
1. Test equipment connection is shown in fig. 7.
2. Playback test tape (QZZCWAT 3,000Hz), and supply playback signal to the
digital frequency counter.
3. Measure this frequency.
4. On the basis of 3,000Hz, determine value by following formula:
f—3,000
————
0
3,000
x 100(%)
5. Take measurement at middle section of tape.
Standard value: +1.5%
Playback mode
Seca
ae
Digital frequency counter
Fig. 7
Tape speed fluctuation
Make measurements in same manner as above (beginning, middle and end of tape), and determine the difference between
maximum
and minimum values and calculate as follows:
f,—f
Tape speed fluctuation =
——
x 100(%)
f, =maximum value, f, = minimum value
3,000
Standard value: Less than 1%
NOTE:
Please use non metal type screwdriver when you adjust tape speed on this unit.
© Playback frequency
Condition:
Equipment:
response
e Playback mode
eVTVM
¢ Oscilloscope
¢ Test tape...QZZCFM
¢ Normal tape mode
in the frequency response chart. (Shown in fig. 8).
Playback frequency response
dias
500HZ
1kHz
2kHz
4kHz6kHz]
\ 12.5kHz
8kHz10kHz
Fig. 8
Equipment:
eVTVM
¢ Oscilloscope
¢ Test tape...QZZCFM
Condition:
¢ Playback mode
¢ Normal tape mode
® Playback gain
3. Make measurements for both channels.
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