Akai GX-747 dbx Service Manual page 18

4-1-8 POWER SUPPLY CIRCUIT (For dbx NR Circuit)
(Refer to Figs. 6-23 an_d 6-24)
+
ISV
n------,-------..
(I)
..,
u
R58
330
TR5
25B764
7
..,
~ (I)
:::::
u
ci
IC?
..,
M5230L
,._
..,
u
R59
330
N
' °
i '
ci
.,.
,0:
,n
(I)
!!?
CX)
N
0
a:
..,
'
(I)
u
Q
,n
0
:8
GND
o------+----+-----------------------1-----uGND
-ISV
n---------
- - - - - - - - - - - - - - - - - - - - - - - - u
-II. 6V
TR6
2S0863
Fig. 6-23 Power Supply Circuit for dbx NR Circuit
STARTER
STANDARD
1--+----1
VOLTAGE
GENERATOR
_>---_._---I
OVER CURRENT 1-------<
PROTECTION
VOLTAGE ADJ
' - - - - - - + - - - - - - - - - - - - - - - - - - - - - - - - - - ~ I GNO
IC7 (M5230L) is an IC for the dual tracking regulator.
The tracking regulator is a stabilized power supply in
which a change in either the positive or negative
output voltage due to the load ( or otherwise), is
followed by a similar change in the other voltage.
When it is used for the DC amplifier, etc., any offset
voltage due to supply voltage fluctuation can be
prevented.
Figs. 6-23 and 6-24 show the power supply circuit
and IC M5230L block diagram respectively. In the
power supply circuit of Fig. 6-23, the output voltage
is controlled by changing the reference voltage
BALANCE ADJ
H OU1 PUT
' - - - - - I
OVER CURRENT!-------< 4 (-)IN p UT
PROTECTION
Fig. 6-24 IC M5230L Block Digram
applied to Pin
Ci)
of IC (M5230L) though the
resistor dividing circuit consisting of R6 l, R.69, R60,
and VR 7. In addition, C38 sets the rise tim constant
of the output voltage, improves the ripple suppres-
sion ratio, and improves the output noise v~lt age.
R64 and R65 are resistors for balancing tle positive
and negative output voltages. Though th1 positive/
negative output voltage ratio can be cliar--iged by
changing this resistance ratio, the po1[tjve and
negative output voltages are made identical
1y-
making
R64 equal to R65.
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