Line Amplifier And Side Tone Circuit; Calling Line Identification Circuit - Panasonic KX-FP342CX Service Manual

controlled by pin (138) of IC501, makes the pulsedial operation possible.
IC501 (138) LINE RLY Low Level
Loop OFF
IC501 (138) LINE RLY High Level
Loop ON

7.9.6. LINE AMPLIFIER AND SIDE TONE CIRCUIT

1. Circuit Operation
The reception signal output from the line transformer T101 is input
to pin (2) of IC101 via C112 and R112 and then the signal is
amplified at pin (1) of IC101 and sent to the reception system at
11.6dB.
The transmission signal goes through C571 and R579 and enters
IC511-pin (2), where the signal is amplified to about 24.8dB. Then,
it is output from pin (1) of IC101 and transmitted to T101 via C125
and R121. If the side tone circuit is not applied,the transmission
signal will return to the reception amplifier via C112 and R112.
When the side tone circuit is active, the signal output from IC101
pin (1) passes through C125, R123, C122, C115 and R115 and goes
into the amplifier IC101 pin (3). Thiscircuit is used to cancel the
transmission return signal.

7.9.7. CALLING LINE IDENTIFICATION CIRCUIT

1. Function
This unit is compatible with the Caller ID service offered by your
local telephone company. To use this feature, you must subscribe
to a Caller ID service. The data for the caller ID from the telephone
exchange is sent during the interval betweenthe first and second
rings of the bell signal. The data from the telephone exchange is a
modem signal which is modulated in an FSK (Frequency Shift
CN517 (12) CN101 (12)
CN517 (12) CN101 (12)
183
Q102 OFF RLY101 OFF : DC
Q102 ON RLY101 ON : DC