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.
--------------SERVICE MANUAL GX-747dbx ---------------
34

Akai GX-747 dbx Specifications

General

Track System	4-track, 2-channel stereo
Reel Size	up to 10.5 inch reel
Type	Reel to Reel
Heads	2 x erase
Motor	1 x capstan, 2 x reel
Tape Speed	9.5 cm/s, 19 cm/s
Wow and Flutter	0.03% (19 cm/s)
Signal to Noise Ratio	65dB
Input	1 x line, 1 x microphone
Output	1 x line
Dimensions	440 x 480 x 260 mm