Toshiba ESTUDIO170F, Service Manual

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e-STUDIO170F Circuit Description January 2005 © TOSHIBA TEC
7 - 56
EU/AU models
Fig.7-38
The line path switching control circuit consists of the relays (RLY3, RLY4, RLY5) and analog switches
(IC3, IC5), the ASIC (I/O port: IC38) on the Main PBA, and other peripheral devices. It changes the path
for facsimile send/receive signals and connects it to each control circuit.
The CML relay (RLY3) is switched according to the CML signal output from the ASIC on the Main PBA.
When the CML signal goes HIGH, Q4 turns on and +12V is applied to the CML relay to turn on.
The relay (RLY4) is switched according to the RLADJ1 and RLADJ2 signals. When the RLADJ1 and
RLADJ2 signals goes LOW, Q9 turns on and +12V is applied to the relay to turn on.
The relay (RLY5) is switched according to the EXTTEL signal. When the EXTTEL signal goes HIGH,
Q12 turns on and +12V is applied to the relay to turn on.
The analog switch (IC3) is switched according to the CML signal and ATT3DB signal. When the CML
signal or ATT3DB signal goes HIGH, the analog switch turns on.
The analog switch (IC5) is switched according to the RLADJ1 and RLADJ2 signals. The analog switch
is switched according to the states of the RLADJ1 and RLADJ2 signals.
Turning on the CML relay and analog switch allows the MODEM to be connected to the line.
Signal Name Type Active Description Destination
CML O H CML relay control signal Q4, IC3
RLADJ1, 2 O H Return loss adjust signal IC5, IC7
EXTTEL O H External TEL relay control circuit Q12
ATT3DB O H Attenuator control signal IC3
+12V
AG
Q4
CN3
Lb
La
0
1
0
1
+12V RLY3
CML relay
+12V
T1
4
3
a2
b2
2
5
CN5
a2
b2
3
4
13
11
3
10
1
7
2
4
5
14
15
12
AG
Ring signal
detection
circuit
External TEL
control
circuit
0
1
2
3
R28
R29
R31
R32
IC5
Analog switch
C13
C7
R36
C12
R30
C14
RLY4
Relay
IC6
IC7
R11
1
2
13
12
14
15
10
11
0
1
0
1
IC3
Analog
switch
R25
Line current
detection
circuit
CML
ATT3DB
RLADJ1
RLADJ2
TXOUT
RXIN
3
1
2 6 7
1 2
6
IC4
IC6
6
3
2
1
54
49
8
7
8
7
57
EXTTEL
5 5 53
55
32
28,29
IC38
ASIC
(I/O port)
IC53
MODEM
Main PBA
NCU PBA
CN4
CN16
AG
Q9
Q12
AG
0
1
0
1
RLY5
Relay
External
TEL
Line
4
1 12
5
3
8
10
9
9
1
2
4
12
8
3
1
10
5
3
4