Akai AT-2650

| DUMMY NOISE
{
(1) OPTIMAL ADJUSTMENT
AA
LAT AN
LOOP GAIN= |
(2)MISS ADJUSTMENT
LOOP GAIN => |
Fig.
20
Pilot
signal
generating
circuit
adjustment
and
pin
wave
form
(non-modulated stereo signal)
STEREO SIGNAL
GENERATOR
40 to 6048
NON MODULATED
STEREO SIGNAL
FM-VHF
OSCILLATOR
PULSE
OSCILLATOR
PULSE tus, !Vp
lto 3KHz
VY
AT-2650
vuP STEREQ A
DEMODULATOR
; O OUTPUT
O
VR
“ep
OSCILLOSCOPE
5 [SYNC
Fig. 21 Pilot signal generating circuit adjustment method
. ADJUSTMENT METHOD FOR THE PILOT
SIGNAL GENERATING CIRCUIT
(Refer to Figs. 20, 21 and 23)
To compensate the pilot signal, the 19 kHz sine wave
amplitude must be equal to the amplitude before the
gate is opened. To do this, set the loop gain of the
pilot signal generating circuit to 1 with the adjust-
ment volume as in Fig. 20 (1).
Actual adjustment involves the following: make con-
16
nections as in Fig. 21 and switch the noise cancel
switch on. Oscillate non modulated stereo signal and
pulse, and observe the wave forms on the oscillo-
scope. Next, adjust the adjustment volume VR5 5 kB
so that the amplitude at the gate is equal to the
amplitude before and after.
Although the adjustment can be made as above, it
has been fully adjusted at the factory and should
not need readjustment unless it has been touched
otherwise.