Panasonic KX-T7565RU Service Manual ▷ View online
(3) BUSY STATION CALLING TONE
852 Hz and 697 Hz signals are output from Pin 60 of IC2 alternately at intervals of 60 ms.
The signal flow is shown below.
The signal flow is shown below.
(4) DTMF SIGNAL
A DTMF tone is generated by IC2 and the signal flow is shown below.
High Group
1209 Hz
1336Hz
1477Hz
697 Hz
1
2
3
Low
770 Hz
4
5
6
Group
852 Hz
7
8
9
941 Hz
*
0
#
(5) KEY-IN TONE
An 852 Hz single tone is used as the key-in tone. A tone is generated from IC2 and is heard at the speaker.
The signal flow is shown below.
The signal flow is shown below.
CONDITION
IC8 SWA
IC8 SWB
IC8 SWC
IC8 SWD
Ringing
OFF
OFF
OFF
ON
Call Waiting
OFF
OFF
ON
OFF
Tone Dial (Handset)
ON
ON
OFF
OFF
Tone Dial (Speakerphone)
ON
OFF
ON
OFF
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KX-T7565RU
7.7. HANDSET CIRCUIT
(1) TRANSMISSION SIGNAL PATH
The analog input signal for the handset microphone is changed to a digital signal and sent through the telephone line via the
following path:
following path:
(2) RECEPTION SIGNAL PATH
The digital input signal from the telephone line is changed to an analog signal by IC3 and sent to the receiver via the following
path:
path:
(3) CIRCUIT DIAGRAM FOR TRANSMISSION / RECEPTION SIGNAL PATH.
7.8. SPEAKER-PHONE CIRCUIT
(1) FUNCTION
This circuit controls the automatic switching of the transmitted and received signals to and from the telephone line, when the
unit is used in the hands-free mode.
unit is used in the hands-free mode.
(2) CIRCUIT OPERATION
The speakerphone can only provide a one-way communication path.
In other words, it can either transmit an outgoing signal or receive an incoming signal.
This switching circuit is contained in IC8 and consists of a Voice Detector, Tx Attenuator, Rx Attenuator, Comparator and
Attenuator Control. The circuit analyzes whether the Tx (transmit) or Rx (receive) signal is louder, and then it processes the
signals so that the louder signal is given precedence.
The Voice Detector provides a DC input to the Attenuator Control corresponding to the Tx signal. The Comparator receives a
Tx and Rx signal, and supplies DC input to the Attenuator Control corresponding to the Rx signal. The Attenuator Control
provides a control signal to the Tx and Rx Attenuator to switch the appropriate signals ON and OFF. The Attenuator Control also
detects the level of the volume control to automatically adjust the volume for changing ambient conditions.
In other words, it can either transmit an outgoing signal or receive an incoming signal.
This switching circuit is contained in IC8 and consists of a Voice Detector, Tx Attenuator, Rx Attenuator, Comparator and
Attenuator Control. The circuit analyzes whether the Tx (transmit) or Rx (receive) signal is louder, and then it processes the
signals so that the louder signal is given precedence.
The Voice Detector provides a DC input to the Attenuator Control corresponding to the Tx signal. The Comparator receives a
Tx and Rx signal, and supplies DC input to the Attenuator Control corresponding to the Rx signal. The Attenuator Control
provides a control signal to the Tx and Rx Attenuator to switch the appropriate signals ON and OFF. The Attenuator Control also
detects the level of the volume control to automatically adjust the volume for changing ambient conditions.
(3) CONTROL SIGNAL PATH
Control signals for transmission and reception are input to IC8 via the following path:
(Transmission Control Signal Path)
(Reception Control Signal Path)
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KX-T7565RU
(4) TRANSMISSION / RECEPTION SWITCHING
The comparison result between Tx and Rx output is a DC level at IC7 Pin 23.
Tx level is high............. ............
Pin 23=Pin 20-6mV
Rx level is high............. ...........
Pin 23=Pin 20-150mV
The comparator output is connected to the attenuator control inside IC7.
(5) VOICE DETECTOR
The output of the mic amp (Pin 10 of IC7) is supplied to Pin 13 of IC7 as a control signal for the voice detector.
(6) ATTENUATOR CONTROL
The attenuator control detects the setting of the volume control through Pin 24 of IC8 and automatically adjusts the volume for
changing ambient conditions.
changing ambient conditions.
(7) TRANSMISSION SIGNAL PATH
The input signal from the microphone is sent through the circuit via the following path:
(8) RECEPTION SIGNAL PATH
Signals received from the telephone line are output to the speaker via the following path:
(9) OFF-HOOK MONITOR CIRCUIT
The input signal from the handset microphone is output through the speakerphone circuit.
(10) CIRCUIT DIAGRAM FOR SIGNAL PATH
Refer to page Schematic diagram.
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KX-T7565RU
8 TROUBLE SHOOTING GUIDE
8.1. NO OPERATION
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KX-T7565RU
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