Akai X-2000SD - Page 24

VIL.
AMPLIFIER
ADJUSTMENT
CASSETTE HEAD BLOCK
Ccl4l
560P
Fig. 1
TRIOG. TRIOS
2SC9T7IBX2
1. ADJUSTMENT OF RECORDING BIAS
FREQUENCY (See Fig. 1)
a)
b)
c)
d)
Put on the resistor 10 or 50 Ohms in series with
the Bias Head and connect the Vertical Input
Terminal of the Oscilloscope to points (a) and
(b).
Feed in a sine wave signal from an Audio
Frequency Oscillator to the Horizontal Input of
the Oscilloscope and tune the Dial of the Audio
Frequency Oscillator until the Oscilloscope
displays a circular or linear pattern. Then read
the figure on the Dial of the Audio Frequency
Oscillator.
If it reads 80kHz, the Recording Bias Fre-
quency is correct.
If not correct, it may be adjusted by inserting,
another condenser (C-140) value 1000 PF.
|OOOP/SOOV
Fig. 2
. ADJUSTMENT OF RECORDING
BIAS VOLTAGE
a)
b)
c)
Reel (See Fig. 2)
Connect a V.T.V.M. to point (a) and (b) and
adjust the recording bias voltage by turning L-3
in the bias oscillator circuit until it reads the
same as the voltage stamped on the back of the
head assembly.
Note : There is no way of adjusting the erasing
bias voltage, but the correct bias voltage is
between.AC 25 to 30 V.
Cartridge (See Fig. 2)
Connect a V.T.V.M. to point (b) and measure
the
Bias
Voltage.
Correct
bias
voltage
is
between AC 12 to 15 V. It can be adjusted by
changing R (236) (136).
Cassette (See Fig. 3)
Connect a V.T.V.M. to point (g) or (h) and
adjust the recording Bias Voltage by turning
VR 207, VR 107, in the bias oscillator circuit.
Proper bias voltage is about 11 V.
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