Electrical Adjustment; Clock Frequency Adjustment; Photo Transistor Sensitivity - Akai GX-747 dbx Service Manual

IX. ELECTRICAL ADJUSTMENT
PHOTO TRANSISTOR
SENSITIVITY
VR3
I
~J
TP3
t
t
CLOCK
FREQUENCY
IFT I
TPI
~~J
~~~g~ENCY
IFT2
YSCON PCB T1009A2570
Fig. 9-2
Fig. 9-1 Syscon P.C Board TI009A2570
1. CLOCK FREQUENCY ADJUSTMENT"
(Refer to Fig. 9-1)
Connect the frequency counter between TPl ([ Cl Pin
(D )
and GND, and adjust with IFTI so tt,.at the
indicating values will be from 390 to 400 kHz.
Also for the IC2, make the same adjustmell- t with
IFT2.
2. PHOTO TRANSISTOR SENSITIVITY
(Refer to Figs. 9-L , 9-2)
Connect the oscilloscope between TP3 and Gt{D. For
the reel size 1 O", adjust with VR3 so that the ~N and
OFF widths of the pulse will be equal (A::::=B) as
shown in Fig. 9-2 when the rotation is stabi]::zed in
FF or REW mode.
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