Akai AP-207

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Fig. 18
ISP
5
6
7
98
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TP-I
[o)
OF
3) Torque Difference Adjustment (VR6)
a) Connect a dual-channel AC voltmeter to pins
6, 7 and 8 (common ground).
b) Set the SPEED selector to the “33-1/3’’ posi-
tion. For the AP-307, release the QUARTZ
LOCK button to the OFF position.
c) Move the tone arm to rotate the motor.
d) Adjust VR6 until the outputs at pins 6 and 7
are of the same level.
NOTE: As the output frequency is as low as a
few Hz, the voltmeter needles will vibrate
minutely. In the state of correct adjust-
ment, the two needles will seem inter-
wining as shown below.
CAUTION: In this adjustment, the voltages are
determined by the motor rpm so
they should only be matched in as
much as that vary.
4) Speed Adjustment (VR2, VR3)
a) Set the SPEED selector to the “33-1/3’’ posi-
tion. For the -AP-307, release the QUARTZ
LOCK button to the OFF position.
b) Set the PITCH control to the center.
c) Move the tone arm to rotate the motor.
d) For the AP-207, adjust VR3 until the strobo-
scope pattern on the first line for 50 Hz power
or the second line for 60Hz power is seen
standing still. For the AP-307, also adjust VR3
until the single stroboscope pattern is seen
standing still.
O VC} osc FREQUENCY
p QUARTZ - LOCKED PHASE ANGLE
ROW |
ROW 2
Row 3
ROW 4
Fig. 19
e)
In
turn,
reset
the
SPEED
selector
to
the
“45”
position. ©
f) For the AP-207, similarly adjust VR2 until the
stroboscope pattern on the third line for 50 Hz
power or the fourth line for 60 Hz power is
seen standing still.
NOTE: It is important that the pattern should
not rotate in the reverse direction of the
motor, or rightward as in the above line
drawing.
2. PLL P.C BOARD ADJUSTMENT
(AP-307 Only)
1) Oscillation Frequency Adjustment (VC1)
a) Connect a frequency counter to TP-1 and pin
5 (ground).
b) Set the SPEED selector to the “33- Bs, posi-
tion.
c) Move the tone arm to turn power on.
d)
Adjust
VC1
until
the
frequency
counter
reads
4,423,680 +10 Hz.
CAUTION: For turning VC1, use a RF adjusting
screwdriver.
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17