UF-490 - Panasonic Fax Other Service Manuals (repair manual). Page 28

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The Line Control Circuit consists of CML relay, DP circuit, DAA (Direct Access Arrangement), Ring Detect 
Circuit for power-save and DC hold circuit. A Jack for an external telephone, which can be used for  either 
an external telephone or an optional Handset Kit. The block diagram of the Line Control Circuit is shown 
below.

DP Control

Ringer Signal Detection,

TAM i/f,

DTMF Remote Detection

Off-Hook

Detection

Speech

IC

DAA

Line

I/F

Si3015

(IC12)

DP

Circuit

DC Hold

Circuit

Ringer Signal

Detector

for Wake-up

(PC2)

Ringer

IC

+
-

~
~

Hook SW

External

Telephone

Jack

Connect only to

one module

Line

CML Relay

Optional Handset Kit

+
-

~
~

DAA

Ccontrol

I/F

Si3021

MODEM

MN195006

CPU

PNL

10MW

Line Control Circuit