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EU/AU/AS/C models
NCU board ( Line1 )
RLY3
CML relay
1
5
T1
4
Lb
4
0
Line
1
8
3
La
9
0
+12V
AG
1
12
The line monitor circuit consists of the CML relay (NA/TW: RLY2, EU/AU/AS/C: RLY3), analog switch
(NA/TW: IC51, EU/AU/AS/C: IC3), the ASIC (IC29 [IC26]) and analog switches (IC3, IC9 [IC3, IC2]) on
the FAX board, and other peripheral devices. It switches the telephone line path using the analog
switch and monitors the line status and ringer signal in the FAX transmission and reception using the
speaker connected to CN503 on the FAX board. It also switches the analog switch to output a buzzer
tone from the speaker.
The signal to be monitored is selected by switching the analog switch (IC3) according to SP-SEL signal
and MON signal which are output from the ASIC.
To monitor the line during the transmission and reception, the ASIC makes the CML1 signal become
HIGH to switch the analog switch and connect the line to the MODEM side.
For the line path switching control, refer to
The relation between the signal levels and monitoring signals is as follows.
Monitoring signal
LINE Monitor
Ringer/Alarm
The monitoring signal selected by IC3 is input to the analog switch (IC9 [IC2]) to select the output
sound volume. The sound volume is selected by switching IC8 according to the VOLSEL0-2 signals
output from the ASIC and selecting an input resistance for the monitoring signal.
GD-1210/1250/1270/1160/1260
ELECTRICAL CIRCUITS
IC6
1
2
IC3
IC4
Analog
6
7
switch
IC6
R11
5
7
1
1
15
2
0
13
1
14
0
11
10
Q4
AG
NCU board ( Line2 )
Speaker
Fig. 4-14
P. 4-5 "4.2.2 Line path switching control circuit".
Line 1
Line 2
4 - 14
08/04
FAX board
1
1
TXOUT1
2
2
RXIN1
6
6
3
3
13
R273
14
R272
15
R271
12
2 RXIN2
R270
1
IC9
[ IC2 ]
R268
Analog
5
switch
R267
2
IC10 [ IC1 ]
R266
SP+
1
5
3
4
SP-
2
AG
11
SG
10
9
SP-SEL
LOW
HIGH
-
© 2006 - 2011 TOSHIBA TEC CORPORATION All rights reserved
28,29 [ 25,26 ]
IC12
[ IC9 ]
32 [ 9 ]
MODEM
IC45
[ IC12 ]
2
12
12
RING
43
1
CPU
IC3
Analog
switch
9
9
MF-SEL
6
14
10
10
SP-SEL
15
11
11
MON
26
IC29
ATT3DB1
22
[ IC26 ]
CML1
21
ASIC
VOLSEL0
16
VOLSEL1
17
VOLSEL2
18
MON
HIGH
HIGH
LOW
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