Sanyo SBM-20 Service Manual page 6

4.
Operational Principles
1 )
Operation procedures
L
Refer to the separate instruction manual.
Block diagram
Power
transformer
Power circuit
7=
( I
Motor control
— - >--------lz51-
Heater control
------------
3) Power circuit
"Circuit diagram
ICI
Indicator circuit
E
EIEEEcl -
Ezcl
POWER SUPPLY UNIT
< >
CONTROL UNIT
1
'1
x
!
K :': :
,- --------
----- - - .
Rll
+
+
Clm C107 CI08
G
PTIOI '- -----D;o;--"- "-:
IN
OUT
(!)
I
A
Iclol
'/)
B
Voltage at each point (Ground is shown as VDD)
@ -13V @ -5V
.Description of operation
(1) VDD-VSSPower supply (-5V)
The secondary output of the power transformer (PT101 ) is given
l-l--r
21
VDD
k
1
cl
42
ICI
Vss
I
bridge-rectification by the diode
stack (D101 ) and the condenser (Cl 07) to produce -13V voltage at A. The voltage at A is used to
compose B -5V power supply by the operation of constant voltage circuit consisting of 3-terminal
output
voltage regulator (pRIMARY:lCl 01 ).
4
5