UX-178DE/FO-175DE
NX-76DE/NX-72DE
2. Noise filter7. Signal selection
The noise filter comprises the RF choke coil, L4A, L4B.The following signals are used to control the transmission line of TEL/
FAX signal. For details, refer to the signal selector matrix table.
3. Dial pulse generation circuit
[Control signals from output port]
The pulse dial generation circuit comprises the photo-coupler PC2,
PC3, polarity guard REC1, and resistor R1.
Signal NameDescription
The photo-coupler PC3 shunts the line current using the DP signalCMLLine connecting relay and DP generating relay
before transmitting the dial signal, then turns off the CML(The circuit is located relay.H: Line make
in the TEL/LIU PWB.)L: Line break
After the pulse dial signal is transmitted by turning on/off the DP sig-
nal, the CML relay is turned on again.SP MUTESpeaker tone mute control signal
(The circuit is locatedH: Muting (Power down mode)
4. CML relayin the TEL/LIU PWB.)L: Muting cancel (Normal operation)
The CML relay switches over connection to the matching transformerHandset reception mute control signal
T1 while the FAX or built-in telephone is being used.RX MUTEH: Muting
L: Muting cancel
5. Matching transformer
DP generating relay
The matching transformer performs electrical insulation from the tel-DP ONH: DP make
ephone line and impedance matching for transmitting the TEL/FAXL: DP break
signal.Speaker volume control signal
VOL AVRSEL1 VRSEL2 matrix
6. Hybrid circuit
VOL BBUZZER
VOL A VOL B VOL CRING SP.REC.
The hybrid circuit performs 2-wire-to-4-wire conversion using the IC101VOL C/DTMF
HLLHigh HighN
of operational amplifier, transmits the voice transmission signal to the
line, and feeds back the voice signal to the voice reception circuit as(The circuit is locatedLHLNMiddle N
the side tone.in the control PWB.)LLHMiddleNN
LLLLowLow Fixed
TXOUT mute signal
TXCONT
H: Signal sending, when transmitting
(The circuit is located
L: During reception, transmission mute,
in the control PWB.)
(during standby)
GAIN-CReception gain switching signal
(The circuit is locatedL: When connected to line, 1: 1 gain
in the control PWB.)H: When not connected to line, HIGH gain
BZCONTSpeaker output signal switching
(The circuit is locatedH: Buzzer signal output
in the control PWB.)L: When monitoring line signal
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ACEC
