Tam Interface Circuit; Pulse Dial Circuit And On / Off Hook Circuit; Line Amplifier And Side Tone Circuit - Panasonic KX-FHD332C Service Manual

7.9.4. TAM INTERFACE CIRCUIT

This circuit is to switch between FAX receiving and the external TAM's message recording
automatically. This circuit consists of an EXT. TAM OFF-HOOK detect circuit, monitor
transformer, multiplexer, amplifier, and VOX detect circuit.
For details, please refer to

7.9.5. PULSE DIAL CIRCUIT AND ON / OFF HOOK CIRCUIT

While OFF-HOOK, RLY101 is ON. Q102 turns on by pin (138) of IC501 as well. On the other hand,
while ON-HOOK, Q102 turns OFF by pin (138) of IC501, then the line turns OFF. ON/OFF-HOOK,
controlled by pin (138) of IC501, makes the pulse dial 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). This circuit is used to cancel
the transmission return signal.
TAM INTERFACE SECTION
CN517 (12)
CN517 (12)
186
().
CN101 (12) Q102 OFF
CN101 (12) Q102 ON
RLY101 OFF : DC
RLY101 ON : DC