KX-TDA0103X, KX-TDA0103XJ, KX-TDA0104X, KX-TDA0104XJ, ETX1KM753MB, ETX1KM752MB - Panasonic PBX Service Manual (repair manual). Page 17

17

This section converts the AC to a stable DC voltage

1. Rectifier

Convert the AC voltage to DC
D003 : Bridge Rectifier Diode

2. AC Detection Circuit

Detect the AC voltage is of sufficient magnitude before starting the Main convertor. 
The detection is also sent to the secondary side to output the AC ALM and DC ALM
D001, D002 : rectify AC to DC for detection of voltage magnitude.
ZD001, ZD002, R011 - R064: voltage detection level setting
Q006 : turn on when the voltage level is sufficiently high

3. Start circuit

Provide start up voltage to start Main convertor and PFC convertor
R004, R065 : drop the Main DC voltage to IC Vcc

4. Active PFC circuit

Stabilized the DC voltage and convertor the AC input current to near sine wave
Q001, Q002 : switching MOSFETs for PFC convertor
D007 : PFC boost convertor diode
D006 : PFC bypass diode
L002 : PFC boost convertor choke

5. PFC control and bias circuit

MC001 : control module with PFC convertor IC on board
Q007, Q009 : PFC switch driver transistors
C006 : Bias voltage capacitor

6. Inrush Current Limiter

Limit the inrush current into the power supply at AC power on
TH001: limit the inrush current at first power on
CR001 : bypass TH001 after the inrush period is over, to reduce power loss in TH001
PC005 : Quick reset of CR001 when AC is off. 

7. C007, C008 : DC smoothing capacitors (Bulk cap)