January 2001 © TOSHIBA TEC
5 - 13
GD-1060 CIRCUIT DESCRIPTION
5.4.2 Dial pulse generation circuit
NAD/SAD/TWD models
Fig. 5-4-5
The dial pulse generation circuit consists of the diode bridge (DB1), photo-coupler (PC1), the I/O port
GA-2 (IC6) on the Main PWA, and other peripheral devices. It generates dial pulses in facsimile transmis-
sion and dialing outside.
The I/O port GA-2 causes the CML1 signal to be HIGH to connect the line to the MODEM side. To achieve
a dial make, the I/O port GA-2 causes the LD1 signal to be HIGH to turn on Q53. This allows the photo-
coupler to turn on and allow current to flow through the diode bridge for sending dial pulses to the line.
CML1
LD1
3
4
AG
Q51
CN10
Lb
La
Line
0
1
0
1
+12V
RLY2
CML relay
4
3
3
4
73
74
Main PWA
NCU PWA
IC6
I/O port GA-2
Ring signal
detection
circuit
CN9
CN3
-
PC1
DB1
+
~
~
Q53
SG
+5V
CN11
a2
b2
External
telephone
3
4
C5
R4
05-04-03-U
Signal Name
I/O
Active
Description
Destination
LD1
O
H
Dial Pulse Generate Signal
Q53