Panasonic KX-FT21BX

-11-
(Model KX-FT21BX/KX-FT21BX-W)
KX-FT21BX/KX-FT21BX-W
10. POWER SUPPLY BOARD SECTION (Change from original page 146)
This power supply board uses the switching regulator method.
[Input Circuit]
The input current goes into the input rectifier circuit through the filter circuit. The filter circuit decreases the noise voltage and
the noise electric field strength.
[Rectifier Circuit]
The input current is rectified by D101,D102,D103 and D104 and charges C106 to make DC voltage. Then it supplies power
to the converter circuit.
[Kick-on voltage circuit]
Bias is applied to the Q101 gate via this circuit when the AC power is turned on and Q101 begins operating.
Input
Circuit
AC
Input
Surge
absorber
circuit
G
H
5V
24V
Kick-on
Voltage
Circuit
E
IC101
F
GND
Control
Circuit
R102
R103
Converter
Circuit
C
D
5V
Output
Circuit
24V
Output
Circuit
+
-
Rectifier
Circuit
A
B
C106
Error Detecting
Circuit
Surge
absorber
circuit
O.C.L
Over voltage
Q101
A-B Voltage Wave Form
C-D Voltage Wave Form
E-F
G-H
Voltage Wave Form
0
0
0
Block Diagram