Panasonic UF-490 / UF-4000 / UF-4100 / UF-490YC / UF-490YR Service Manual ▷ View online
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1.1.10. Modem and Peripheral Circuit
This circuit consists of Modem, DAA (Primary/Secondary) and peripheral circuit. This modem conforms to
ITU-T V.34, V.33, V.17, V.29, V.27ter, V.21 channel 2 (FSK), T.4, and T.30. Modem transfers/receives data
from Secondary DAA chip and serial communication. Secondary DAA chip communicates with the line
through Primary DAA chip and its peripheral circuit.
ITU-T V.34, V.33, V.17, V.29, V.27ter, V.21 channel 2 (FSK), T.4, and T.30. Modem transfers/receives data
from Secondary DAA chip and serial communication. Secondary DAA chip communicates with the line
through Primary DAA chip and its peripheral circuit.
Modem
MN195006
To Line
DAA
(Secondary)
Si3021
DAA
(Primary)
Si3015
Monitor
Circuit
Dial
Pulse
Circuit
To Speaker
Modem Circuit Block Diagram
Secondary
Circuit
Primary
Circuit
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1.1.11. Receive Signal Control Circuit
This circuit consists of operational DAA and its peripheral circuit.
Up to this time, from Primary circuit to Secondary circuit such as Hybrid circuit, Analog circuit, Analog Front
End (AFE : A-D / D-A convertor) and Modem through Line transformer, and all the Received Signals to the
AFE are processed with Analog signals.
However at this time, the Received Signal is converted from Analog to Digital with DAA of Primary circuit,
and the Digital Signal is transferred to DAA (Si3022) of Secondary circuit as serial data. Therefore, unlike
other machine, this machine has No Analog Circuit of Secondary circuit, because of the DAA (Si3022) of
Secondary Circuit is able to transfer the Digital Signals directly to the Modem. Even at standby, this circuit is
connected with the Line via capacitor cutting Direct Current, this means it can be detected any Signals for
Ringer, CNG and DTMF remote commands.
Up to this time, from Primary circuit to Secondary circuit such as Hybrid circuit, Analog circuit, Analog Front
End (AFE : A-D / D-A convertor) and Modem through Line transformer, and all the Received Signals to the
AFE are processed with Analog signals.
However at this time, the Received Signal is converted from Analog to Digital with DAA of Primary circuit,
and the Digital Signal is transferred to DAA (Si3022) of Secondary circuit as serial data. Therefore, unlike
other machine, this machine has No Analog Circuit of Secondary circuit, because of the DAA (Si3022) of
Secondary Circuit is able to transfer the Digital Signals directly to the Modem. Even at standby, this circuit is
connected with the Line via capacitor cutting Direct Current, this means it can be detected any Signals for
Ringer, CNG and DTMF remote commands.
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1.1.12. Transmission Signal Control Circuit
This circuit consists of operational DAA and its peripheral circuit.
As the same way as the Receiving Signal Control Circuit, Modem and DAA of Secondary Circuit are
connected. The Transmit Signals are transferred as serial data to the DAA of Primary Circuit. Therefore,
there is no Analog circuit, the signal level is adjusted with internal setting of Modem. It has no Hybrid
circuit, because of the Modem for transmit and the Receiving Signals is connected with exclusive port. The
Digital Signals transferred to Primary Circuit are converted from Digital to Analog and sends out to the LIne.
As the same way as the Receiving Signal Control Circuit, Modem and DAA of Secondary Circuit are
connected. The Transmit Signals are transferred as serial data to the DAA of Primary Circuit. Therefore,
there is no Analog circuit, the signal level is adjusted with internal setting of Modem. It has no Hybrid
circuit, because of the Modem for transmit and the Receiving Signals is connected with exclusive port. The
Digital Signals transferred to Primary Circuit are converted from Digital to Analog and sends out to the LIne.
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1.1.13. Line Monitor Circuit
The Line Monitor Circuit consists of an operational DAA (The secondary side chip) and its peripheral
circuits.
Its function is to monitor the dial tone, DTMF tone, response signals, etc. over the speaker. It also sounds
the output of the key touch tones, alarm tones, etc. from the panel CPU over the speaker. The Received
Signals are output from DAA of Secondary circuit, and through Analog AGC, Electronic Volume, Amplifier
and over the speaker.
The monitor tone from the phone line and the buzzer tone from the panel can be adjusted from the Control
Panel.
circuits.
Its function is to monitor the dial tone, DTMF tone, response signals, etc. over the speaker. It also sounds
the output of the key touch tones, alarm tones, etc. from the panel CPU over the speaker. The Received
Signals are output from DAA of Secondary circuit, and through Analog AGC, Electronic Volume, Amplifier
and over the speaker.
The monitor tone from the phone line and the buzzer tone from the panel can be adjusted from the Control
Panel.
Analog AGC
Electronic Volume
(Monitor)
DAA
(Secondary)
Si3021
Amplifier
Electronic Volume
(Buzzer)
Buzzer Signal from Panel
AOUT
Speaker
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