Canon FACSIMILE BASIC 2000 Service Manual page 301

6.1.5 Oscillation/Control and output error amplification cir-
cuits
The oscillation/control circuit (IC1) is located on the primary side, and the
output error amplification circuit is located on the secondary side. The out-
put error amplification circuit detects the error with the reference voltage
according to the fluctuation in the output voltage. When the output voltage
is higher than the reference voltage, the diode of PC1 lights. When it is
lower, the diode goes out. This lighting ON/OFF information is relayed to
the feedback port (FB) of the oscillation/control circuit (IC1) on the pri-
mary side via the phototransistor of PC1. The oscillation/control circuit
outputs the transistor ON/OFF signal from the OUT port based upon this
lighting ON/OFF information to control the input voltage to the trans-
former so that the output voltage is maintained at a fixed voltage.
Transistor
OUT
IC1
Oscillation/control circuit
Fig. 6-31 Oscillation/Control/Output Error Amplification Circuit
Transformer
FB
PC1
(photocoupler)
Primary side
FACSIMILE SYSTEM
Output voltage
Output error amplification circuit
Secondary side
1
2
3
4
5
6
ït
çi
Reference
voltage
6–29