Panasonic KX-FP105BX, Service Manual

Page: 196 / 238

6.10.2. CIRCUIT OPERATION
The TAM INTERFACE circuit consists of an EXT. TAM HOOK detection circuit, CNG signal from the other party’s detection circuit,
VOX detection circuit (to judge sound/no-sound) and RL101 (to separate EXT. TAM).
1. EXT. TAM HOOK detection circuit
A bell is received at EXT. TAM and EXT. TAM is connected to the line, making a DC LOOP. Then, PC105 detects this voltage.
During detection, PC105 (4) becomes low.
(DC LOOP)
Tip
→
L101
→
LF101(4, 1)
→
L104
→
Tip1
→
(EXT.TAM)
→
Ring 1
→
L105
→
R113
→
RL101(5, 3)
→
PC105(1, 2)
→
LF101(2, 3)
→
L102
→
POS101
→
Ring
2. CNG signal detection circuit
The CNG signal from the other party’s FAX is detected in MODEM IC505 (digital board).
(Signal path)
Refer to 2.3.3.5. Analog Board Section.
3. VOX
The VOX circuit detects if there is a signal or voice on the line. This is why the VOX circuit reacts to the OGM of the EXT.TAM
and ICM from the other party.
4. Remote receiving
This is the parallel-connected DTMF signal for the TEL or EXT.TEL mode between T and R. When the other party is a FAX,
the unit switches to FAX receiving.
(Signal Path)
Detects the DTMF signal in the MODEM.
{ } : Inside the digital board
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KX-FP101