FO-2970MU
5) Matching transformer
The matching transformer performs electrical insulation from the tel-
ephone line and impedance matching for transmitting the TEL/FAX
signal.
6) Hybrid circuit
The hybrid circuit performs 2-wire-to-4-wire conversion using the IC1
of operational amplifier, transmits the voice transmission signal to
the line, and feeds back the voice signal to the voice reception circuit
as the side tone.
7) Signal selection
The following signals are used to control the transmission line of TEL/
FAX signal. For details, refer to the signal selector matrix table.
8) CI detection circuit
The CI detection circuit detects the CI signals of 15.3 Hz to 68 Hz.
A CI signal, which is provided to the photo-coupler PC2 through the
C3 (0.82 uF), R3 (22 K), and ZD3 when the ring signal is inputted
from the telephone line.
9) Power supply and bias circuits
The voltages of +5VA and +24V are supplied from the control PWB
unit.
Signal Name
Description
Line connecting relay and DP generating relay
CML
H: Line make
L: Line break
Speaker tone mute control signal
SP MUTE
H: Muting (Power down mode)
L: Muting cancel (Normal operation)
Handset reception mute control signal
TEL MUTE
H: Muting
L: Muting cancel
Handset receiver volume control signal
RCVOL
(The circuit is located
in the control PWB.)
Set the line driver of MODEM (FM336)
to – 6
dBm
Speaker volume control signal
VOL A
VRSEL1 VRSEL2 matrix
VOL B
VOL C
(The circuit is located
in the control PWB.)
GAIN-C
Reception gain switching signal
(The circuit is located
L: When connected to line, 1: 1 gain
in the control PWB.)
H: When not connected to line, HIGH gain
BZCONT
Speaker output signal switching
(The circuit is located
H: Buzzer signal output
in the control PWB.)
L: When monitoring line signal
MIC MUTE
Handset mic mute control signal
H: Muting
L: Muting cancel
Signal Name
Function
TEL IN
Receiving signal from line or modem
TEL OUT
Transfer signal to line
TXOUT
Transmission (DTMF) analog signal output
from modem
RXIN
Reception (DTMF, others) analog signal input
into modem
[Other signals]
[Signals for status recognition according to input signals]
VOL A
VOL B
VOL C
RING./
Buzzer
DTMF
Receiving
H
L
L
High
—
High
L
H
L
Middle
—
Middle
L
L
H
Low
—
Low
L
L
L
—
Fixed
—
Volume
High
Middle
Low
RCVOL
H
L
L
[Control signals from output port]
Signal Name
Function
RHS
H: The handset is in the on-hook state.
(On the HOOK-SW PWB) L: The handset is in the off-hook state.
CI
Incoming call (CI) detection signal.
H: The handset or external telephone is in the
HS
on-hook state.
L: The handset or external telephone is in the
off-hook state.
No.
Signal Name (CNLIU)
No.
Signal Name (CNLIU)
1
+24V
7
RHS
2
DG
8
TXOUT
3
+5VA
9
RXIN
4
CML
10
TELMUTE
5
CI
11
TELOUT
6
HS
12
TELIN
No.
Signal Name (CNHS 1 and 2)
No.
Signal Name (CNHS 1 and 2)
1
RHS
2
DG
5 – 22
Summary of Contents for FO-2970M
Page 70: ...FO 2970MU 6 10 Control PWB parts layout Top side ...
Page 71: ...FO 2970MU Control PWB parts layout Bottom side 6 11 ...
Page 73: ...FO 2970MU 6 13 TEL LIU and Hook SW PWB parts layout Top side ...
Page 74: ...FO 2970MU 6 14 TEL LIU and Hook SW PWB parts layout Bottom side ...
