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EU/AU/AS/C models
NCU board
RLY3
CML relay
1
5
T1
1
4
Lb
4
0
Li n e
1
8
3
La
9
0
IC6
+12V
AG
5
7
1
12
Q4
AG
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), analog switches (IC9, IC10) on the FAX board, ASIC (IC23) and
SoC (IC53) on the MAIN 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 (IC9) according to TONESEL sig-
nal and RING/TONE 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
© 2006 - 2008 TOSHIBA TEC CORPORATION All rights reserved
FAX board
IC6
2
1
1
IC3
IC4
Analog
6
7
2
2
switch
R11
1
1
15
6
6
2
0
3
3
13
1
14
0
11
10
Speaker
SP+
1
SP-
2
Fig. 4-13
P. 4-4 "4.2.2 Line path switching control circuit".
TONESEL
LOW
-
4 - 13
08/08
28,29
[ 25,26 ]
IC2
32
[ 29 ]
MODEM
TXOUT1
12
[ 2 ]
RXIN1
3
IC9
Analog
switch
13
[ 4 ]
15
9,10
11
R273
14
[ R31 ]
[ 2 ]
R272
15
[ R30 ]
[ 5 ]
R271
12
[ R29 ]
[ 1 ]
R270
1
[ R32 ]
[ 12 ]
IC10
R268
Analog
5
[ R35 ]
switch
[ 15 ]
R267
[ R33 ]
2
[ 14 ]
R266
[ R36 ]
IC10
4
[ R37 ]
[ 13 ]
5
3
3
AG
11
SG
10
9
RING/TONE
HIGH
LOW
MAIN board
RING
25
IC53
[ SPKCLK ]
25
A5
SoC
TONESEL
59
59
152
RING/TONE 23
23
153
ATT3DB1
62
62
142
IC23
CML1
27
27
144
ASIC
SPVOL0
58
58
151
SPVOL1
57
57
150
SPVOL2
24
24
149
GD-1220/1221
ELECTRICAL CIRCUITS
4
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