Tascam 122 Service Manual page 22

122
3-8-2 DC power supply system
The DC power supply system is shown in Fig.
3-18. This comprises the main regulator des­
cribed in the previous section and minor regulat­
ed power supplies from independent transistors
0512, 0513, and 0507 .
For these transistors,
the +23 V regulated output of the main regula ­
tor is used' as a reference voltage to simplify
the circuitry.
The output voltages of the minor power supplies
are roughly given by the following equations:
POWER
TRANSFORMER
0533
...
Fig. 3-18 DC power supply system
R527
VOUT (Q512)
= •
x
(+23V)- VBE
R526 + R527
R530
VOUT(Q513)
= - - -- -- x
(+23V)-VBE
VOUT(Q507)
=
where VBE is 0.6
UNREG. +39V
[
to' ' '
0534
>-­
R517
0~2
...
I ...
0531
UNREG . +19V
J,
C506
R516
!
R514
0542
>
[
R545
1
~
. .
MAIN
. 0541
REGULATOR
r
0~3
C520T
0517,0519
-...
I
0520,0512
0544
,, __ , 0513
: ~ {l
,
R529
R526
~ .
R528
-
C511
R531
F'
C514
I
R530 C512
fR515
Jr
J
REG. + 13V
0507
~--
,
REG . + 13V
:~~)
REG. +13v
f
C505 TC503
REG . +23V
~
c517
REG . +13v
REG. + 1 3v
Lg~512
REG. +5.3V
R525 :::: C509
R527
f
C510
J,
R529 + R530
R515
x
(+23V)- VBE
R514+ R515
- 0.7 V.
SOLENOID
] DRIVE CIRCUIT
OV
REEL MOTOR
DRIVE CIRCUIT
CAPSTAN MOTOR
DRIVE CIRCUIT
OV
AMPLIFIERS
OV
CONTROL CIRCUIT
PHONE AMPLIFIER
SYSTEM CONTROL IC
AND LEO
OV
22