Toshiba ESTUDIO170F, Руководство по обслуживанию

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7
January 2005 © TOSHIBA TEC e-STUDIO170F Circuit Description
7 - 63
EU/AU models
Fig.7-45
The CI detect circuit consists of the photo-coupler (PC1), ASIC (I/O port: IC38) on the Main PBA, and
other peripheral devices to detect a ring signal input from the telephone line.
The ASIC causes the CML signal to go 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
causes Q5 to turn on and off allowing the CISX signal to be a pulse signal and input to the ASIC on the
Main PBA, thereby detecting the ring signal.
Signal Name Type Active Description Destination
CISX I - CI detect signal ASIC
CN3
Lb
La
Line
0
1
0
1
+12V
RLY3
CML relay
CML
Q4
3
4
12
3
10
1
4
9 3
3 49
35 17
NCU PBA Main PBA
IC38
ASIC
(I/O port)
CISX 17
1
2
4
3
AG
Q5
SG
+5VPS
R34
R35
CN4
CN16
PC1
ZD3 ZD2 C8 R4
D2