Panasonic KX-FM330GR Service Manual page 23

3.1.3. AUTO DISCONNECT CIRCUIT
Addition to original page 173 (6.9. NCU SECTION)
1. Function
This circuit is used to detect that the telephone connected in parallel to the same line is OFF-hook while the unit picks up the
line. If this detection circuit is activated when TAM is being delivered, the delivery stops and the circuit is automatically released.
2. Circuit Operation
If the line is picked up, C19 is charged by following the path shown below.
D6 (+) → Q3 → R24 → D12 → C19
When the electric potential difference between the base and emitter of Q4 becomes less than about 0.3V, Q4 and Q6 and PC5
turn off, then the IC5 pin 5 becomes a high level.
In this condition, if a telephone connected in parallel goes into OFF-hook status, the base of Q4 becomes low. On the other
hand, the emitter of Q4 goes down because the capacitor (C19) is charged. Q4 turns on when the electric potential difference
between the base and emitter of Q4 becomes more than 0.6 V while being charged.
When Q4 turns on, Q6 and PC5 also turn on, then the IC5 pin 5 becomes a low level.
3.1.4. REMOTE FAX ACTIVATION CIRCUIT
Change from original page 174 (6.9.7. REMOTE FAX ACTIVATION CIRCUIT)
1. Function
Another telephone connected to the same line activates the unit to the FAX mode by using a DTMF signal.
2. Signal Path
Refer to 2.3.3.5. Analog Board Section.
3.2. SPECIAL CIRCUIT ON THE ANALOG BOARD......Deleted
Change from original page 176 (6.12. SPECIAL CIRCUIT ON THE ANALOG BOARD)
3.2.1. CURRENT DETECTION CIRCUIT......Deleted
Change from original page 176 (6.12.1. CURRENT DETECTION CIRCUIT)
3.2.2. LOW PASS FILTER......Deleted
Change from original page 176 (6.12.2. LOW PASS FILTER)
23
KX-FM330GR