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UX-A1000U
[3] Circuit description of TEL/LIU PWB
(1) TEL/LIU block operational description
1) Block diagram
LINE
H
HS
DETECTOR
L
CML
EXIT
CI DETECTOR
Q102
RX
TEL MUTE
(H:MUTE)
TX
HANDASET
MIC MUTE
(H:MUTE)
Q103
2) Circuit description
The TEL/LIU PWB is composed of the following 7 blocks.
1. Speech circuit section
2. Dial transmission section
3. Speaker amplifier section
4. Ringer circuit section
5. CI detection circuit
6. Signal/DTMF transmission level & receiving level
7. External phone off-hook detection (HS) section
3) Block description
1. Speech circuit section
•
The receiver volume is an electronic volume type, this model is
switched in 3 steps.
2. Dial transmission section
•
D.P. transmission: The CML relay is turned on and off for control in
the DP calling system. (Refer to the attached sheet.)
•
DTMF transmission: It is formed in the modem, and is output.
3. Speaker amplifier section
•
Ringer volume
:It is controlled by the combination of the
attenuator value of the LINE DRIVER in the
modem and the ringer sending level sent from
the modem.
•
Speaker volume :It is controlled by the attenuator value of the
IC3 and IC16 (VOL-A.B.C).
4. Ringer circuit section
•
The ringer sound is formed in the tone of modem when CI signal is
detected. The amplifier circuit drives the speaker of the main body.
5. CI detection circuit
•
CI is detected by the photo coupler which is integrated in series in
the primary side TEL circuit well proven in the existing unit.
6. Signal/DTMF transmission level & receiving level
•
Signal transmission level setting: ATT -8 dB Circuit output: -11.5 dBm.
• DTMF transmission level setting: HF -2.5 dBm
Thus, set the level.
TEL/LIU PWB
CONTROL PWB
IC101A
TXOUT
RXIN
IC101B
IC101C
TEL IN
IC101D
IC8
SPEAKER
SP MUTE
+24VL
DG
LF -4.0 dBm
(20438 I/A)
SIGTX
SPKRP
SP OUT
SIGRX
MICP
MIC
/LINE
TELOUT
SELECT
LINEIN
LINE IN ENABLE
DTMFMUTE
RCVOL
SPOUT
LINE
OUT
BZOUT1
IC3
SP MUTE
TEL MUTE
CI
CML
MIC MUTE
VOL-A
VOL-B
VOL-C
Fig. 6
7. External phone off-hook detection (HS) section
Line current detection will be switched to ON (LOW) when the main
unit or the external phone is off the hook. When the HS signal is turned
on at CML OFF, the external phone is considered to be off the hook
and, at CML ON, the HS signal is constantly turned on (if connected).
4) 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.
[Control signals from output port]
Signal Name
CML
Line connecting relay and DP generating relay
H: Line make
(The circuit is located
L: Line break
in the TEL/LIU PWB.)
SP MUTE
Speaker tone mute control signal
H: Muting (Power down mode)
(The circuit is located
L: Muting cancel (Normal operation)
in the control PWB.)
Handset reception mute control signal
TELMUTE
H: Muting
L: Muting cancel
Handset receiver volume control signal
RCVOL
DTMFMUTE
(The circuit is located
in the control PWB.)
Note: The DTMF sending listed above is DTMF signal
5 – 13
RTLOOP
0,6dB
0,1
0,0
DAC
DAC
1,0
1,1
ENABLE
MIC ENABLE
LPF
0,20,25,30dB
LINE OUT ENABLE
LINE
SELECT
1,1
0,0
1,0
MUTE,0,-6,-12dB
IC16 SCE214V
FAX CONTROLLER
Description
Volume
High
Middle
Low DTMF sending
RCVOL
L
H
H
DTMFMUTE
L
L
H
sending in the handset OFF-HOOK mode.
SIN
ADC
0,+4dB
SOUT
HS
H
H
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