UX-B800A
5 – 13
[3] Circuit description of LIU PWB
1. LIU block operational description
1.1. Block diagram
1.2. Circuit description
The 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. Power supply and bias circuit
1.3. 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 SPEAKER DRIVER in the modem and the ringer send-
ing level sent from the modem.
• Speaker volume: It is controlled by the attenuator value of the
SPEAKER DRIVER in the modem.
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: According to soft switch list.
• DTMF transmission level setting: According to soft switch list
7. Power supply and bias circuit
• The voltage of +24 V are supplied from the control PWB unit.
LIU PWB
CONTROL PWB
IC301 MODEM CX20452
IC401A
IC403
IC401B
IC101B
IC101A
CI DETECTOR
IC101D
IC101C
Q104
TELMUTE
Q105
MICMUTE
RX
TX
HANDSET
LINE
POHOT
INTERRUPTOR
SPEAKER
TELIN
VOLA
BZOUT
IC600 INK CONTROL
14D0830
IC100 FAX CONTROLLER
CX93310
SPMUTE
RCVOL
DTMFMUTE
CI
TELMUTE
MICMUTE
RHS
CID_SEL
CML
CML
Fig. 5
Summary of Contents for UX-B800A
Page 118: ...UX B800A 7 9 MEMO ...