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January 2001 © TOSHIBA TEC
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GD-1060 CIRCUIT DESCRIPTION
5.4.4 CI detect circuit
NAD/SAD/TWD models
Fig. 5-4-9
The CI detect circuit consists of the photo-coupler (PC2), I/O port GA-2 (IC6) on the Main PWA, and other
peripheral devices to detect a ring signal input from the telephone line.
The I/O port GA-2 causes the CML1 signal to be LOW to connect the CI detection circuit to the telephone
line. When a ring signal is input from the telephone line, the photo-coupler repeats turning on and off. This
allows the OCI1 signal to be a pulse signal and input to the I/O port GA-2 on the Main PWA, thereby
detecting the ring signal.
CN10
Lb
La
Line
0
1
0
1
+12V
RLY2
CML relay
CML1
Q51
3
4
3
3
73
19
17
NCU PWA
Main PWA
IC6
I/O port GA-2
OCI1
17
SG
AG
5VPS
R79
CN9
CN3
PC2
ZD3
ZD1
C1
R2
D52
05-04-05-U
Signal Name
I/O
Active
Description
Destination
OCI1
I
-
CI Detect Signal
I/O port GA-2