Panasonic KX-FT71LA-B Service Manual page 160

[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.
The following is an overview of how the power supply unit is controlled.
The control method of this power supply unit is pulse width modulation.
When Q is ON, the energy is charged in the transformer primary coil according to E . When Q
1 1 1
is OFF, the energy is output from the secondary transformer as follows.
L D Load L
1
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