Akai AP-207

Vill. ELECTRICAL ADJUSTMENT
§
VRS VRE
Gone aoe 300KB
ore ‘Ser VOLTAGE
> 2)
VR2,VR3 SPEED
= 20 2i
VR2
10OKB _100KB aed
(a) IDEAL
(All peaks are at the same level)
1. DIRECT DRIVE P.C BOARD ADJUSTMENT
1) Off-set Voltage Adjustment (VR4, VRS)
a) Disconnect the motor, or make open pins 4
through 11 and 14 and 15, leaving the other
pins connected.
b) For VR4, connect a digital DC voltmeter to
pins 6 and 8 (ground).
c) Shortcircuit pins 9 and 10.
d) Move the tone arm to turn the power on.
e) Adjust VR4 until the output at pin 6 is OV +10
mV for the AP-2-7 and 80+10 mV for the
AP-307.
f) For VRS, in turn, connect the digital DC volt-
meter to pins 7 and 8 (ground).
g) Shortcircuit pins 4 and 5.
h) Adjust VR5 until the output at pin 7 is OV +10
mV for the AP-207 and 80 +10 mV for the AP-
AP-307.
TORQUE
DIFFERENCE
O
Fig. 16
(b) BAD
(Peak levels are not equal)
Fig. 17
2) Duty Ratio Adjustment to 1:1 (VR1)
a) Connect an oscilloscope to TP-1.
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 VR1 until the oscilloscope shows such
a waveform as illustrated below.