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Provides a description from AC input to the rectifier smoothing circuit.

1. Filter circuit

Consisting of the following parts, removes exogenous noise and noise generated by the power source.
C1/C2: Normal mode filter (X capacitor) 
L1/L2: Common mode noise filter
C3/C4: Common mode filter (Y capacitor) 

2. Rectifier circuit

Consisting of the following parts, the rectifier circuit converts alternating current to direct current. 
D1: Diode bridge
C5: Primary smoothing capacitor

3. Surge absorber circuit

Consisting of Z1, the surge absorber circuit protects the equipment from exogenous surge such as lightning surge. 
Z1: Varistor

4. Rush current prevention

Suppresses rush current to smoothing capacitor immediately following AC input by the following parts. 
NTC1: Thermistor

5. AC voltage detection circuit

Consisting of the following parts, the AC voltage detection circuit detects presence of AC input voltage input. 
D80, D81, R80-R95, Q80, Q81, Q82, PC80 Rectifies AC voltage by D80 and D81. 
If AC input voltage exceeds threshold voltage, Q82, Q80 and Q81 turn "on" and the secondary side is informed of presence of
AC input through PC80. 

6. CN2/CN3

Connector for PCC casing switch connection.