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EU/AU/AS/C models
NCU board
Line current
detection
circuit
RLY3
+12V
CML relay
1
12
1
5
R26
4
Lb
4
0
3
Line
1
8
3
La
9
0
10
a2
2
External
telephone
b2
5
The line path switching control circuit consists of the CML relay (RLY3) and analog switch (IC3, IC5) on
the NCU board, the ASIC (IC23) on the MAIN board, and the other peripheral devices. It changes the
path for the FAX send/receive signals and connects it to each control circuit.
The CML relay is switched according to the CML1 signal output from the ASIC on the MAIN board.
When the CML1 signal goes HIGH, Q4 comes on to turn ON the CML relay.
The analog switch (IC3) is switched according to the CML1 signal and ATT3DB1 signal. When the
CML1 signal or ATT3DB1 signal goes HIGH, the analog switch is turned ON.
The analog switch (IC5) is switched according to the RLADJ11 and RLADJ12 signals.
The analog switch is switched according to the states of the RLADJ11 and RLADJ21 signals.
Turning ON the CML relay and analog switch allow the MODEM to be connected to the line.
Signal Name
Type
CML1
O
ATT3DB1
O
RLADJ11, 21
O
* Values in [ ] are GD-1221 in case that the descriptions vary between GD-1220 and GD-1221.
© 2006 - 2008 TOSHIBA TEC CORPORATION All rights reserved
Q4
AG
Analog switch
C7
R28
T1
13
0
R29
14
1
RLY4
C13
15
2
Relay
16
3
R31
R36
2
3
AG
C12
+12V
4
1
R32
R30
C14
IC6
5
7
IC7
1
4
Q9
2
Ring signal
detection
AG
circuit
Fig. 4-5
Active
H
Line 1 CML Relay Control Signal
H
Line 1 Attenuator Control Signal
H
Line 1 Return Loss Adjustment Signal
4 - 5
08/08
3
6
7
IC5
8
IC6
3
1
2
11
IC3
11
10
10
Analog
switch
R11
1
1
1
15
2
0
IC4
13
1
14
6
7
2
0
12
Description
FAX board
MAIN board
3
CML1
21
21
144
ATT3DB1
6
22
22
142
IC23
RLADJ11
7
29
29
141
ASIC
8
RLADJ21
63
63
140
28,29
TXOUT1
[ 25,26 ]
1
IC12
[ IC2 ]
32
RXIN1
[ 29 ]
2
MODEM
Destination
RLY3, IC3
IC3
IC5
GD-1220/1221
ELECTRICAL CIRCUITS
4
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