Canon FACSIMILE BASIC 2000 Service Manual page 279

OFF within the telephone, DC current does not flow and the DC loop is not
formed.
On-hook
T1
B
HS
T2
L1
Exchange
L2
Fig. 6-5 Formation of DC Loop (in standby state)
DC current flows as the HS turns ON when the telephone is made off-
hook, and a DC loop is formed between the
Off-hook
T1
ON
B
HS
T2
L1
Exchange
L2
Fig. 6-6 Formation of DC Loop on Telephone Side
When the facsimile side is set to receive automatically, the CML
turns ON when the calling identification (CI) is detected, and the DC loop
is formed between the DC seize (RET) circuit and the exchange.
Off-hook
detection circuit
H relay
CML relay
exchange
Off-hook
detection circuit
H relay
CML relay
FACSIMILE SYSTEM
DC seiz
To 2-wire/4-wire
circuit
conversion circuit
NCU board
and the telephone.
To 2-wire/4-wire
DC seize
circuit conversion circuit
NCU board
relay
6–7
1
2
3
4
5
6
ït
çi