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AMPLIFIER ADJUSTMENTS
Measurement condition:
Power voltage
Sets DC 9V
Equipment required:
VTVM, AF OSC, ATT, oscilloscope, resistors (600Q, 100Q, 8Q).
SIGNAL SOURCE
CONNECTION
Volume control ....
OUTPUT
CONNECTION
Maximum
ADJUSTMENT
!
REMARKS
Measurement of
bias oscillation
frequency.
| Oscilloscope with
AF OSC to both
ends of record/
playback head.
See fig. 7.
| Adjust the AF OSC so
that the Lissajous'
| Pattern on the
oscilloscope becomes a
stationary circle, and
the oscillation
frequency is indicated
by the scale of the AF
OSC.
Measurement of
recording bias
current.
VTVM with 100Q.
| See fig. 8.
Record
Bias current
(400+80A)
Voltage value
(40+8 mV)
~ Resistance value
(1009)
Measurement of
recording level.
| 1 kHz —64+5 dB
| to MIC input jack.
VTVM with 100Q.
| See fig. 10.
Record
Stop the bias oscillation
by resoldering R31.
Measurement of
erase current.
VTVM to both
ends of erase
head.
See fig. 9.
Record
Measurement of
playback amplifier
gain.
1 kHz —77+3 dB
to playback head
lead wire.
See fig. 11.
VTVM with 80
resistor to EXT SP
jack.
Playback
Head angle
adjustment.
Thread the 3 kHz
adjustment tape.
VTVM with 80
resistor to EXT SP
jack.
See fig. 12.
Playback
Head angle
adjustment
screw @.
| Maximum
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