Read Panasonic KX-T7440CB / KX-T7440C Service Manual online
−
8
−
KX-T7440C/KX-T7440C-B
This circuit is used for transmission of a reset pulse to the CPU (IC3) at the following times, connecting the telephone line jack,
circuit operation. The timing chart is shown below.
circuit operation. The timing chart is shown below.
The +16V DC, provided from the DSS console is converted to +5V by the voltage regulator IC (IC1. IC4).
CIRCUIT OPERATIONS
1. RESET CIRCUIT
2. POWER SUPPLY CIRCUIT
1) Circuit Operation
1) Circuit Operation
V1
Q42
R41
IC3
Power ON
Q42 OFF
The reset signal wiu increase
along with the power voltage.
along with the power voltage.
R40
R42
C2
D72
R39
5
D11 zener diode ON
Q42 ON
Negate the reset signal
Start current to C2.
Increase the base voltage of Q42.
Increase the base voltage of Q42.
Reset signal assert.
Reset nagate
Circuit Diagram
Circuit Diagram
+5V(V1)
Q42(Base)
Reset signal
IC3 5
First reset assert
+5V(V1)
+5V(V2)
C8
C7
C6
H
1
2
3
L
D1
IC1
JK1
+
∼
∼
C11
C10
C9
1
2
3
IC4
Click on the first or last page to see other KX-T7440CB / KX-T7440C service manuals if exist.