Canon fax basic 2000 サービスマニュアル

6–7

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FACSIMILE SYSTEM

OFF within the telephone, DC current does not flow and the DC loop is not

formed.

Fig. 6-5   Formation of DC Loop (in standby state)

DC current flows as the HS turns ON when the telephone is made off-

 and the telephone.

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.

B

T1

T2

L1

L2

HS

On-hook

Off-hook

detection circuit

H relay

Exchange

CML relay

DC seiz

circuit

To 2-wire/4-wire
conversion circuit

NCU board

Off-hook

ON

Off-hook

detection circuit

H relay

Exchange

CML relay

DC seize

circuit

To 2-wire/4-wire
conversion circuit

NCU board

B

T1

T2

L1

L2

HS