Main Converter - Panasonic KX-NS700 Service Manual

2) Rectification Smoothing Circuit
This circuit consists mainly of the following components and performs AC-DC conversion.
D2: Diode Bridge
C4: Primary Smoothing Capacitor
3) Surge Absorber Circuit
As the main component of this circuit, VR1 protects the system against exogenous noise such as lightning surge.
VR1: Varistor
4) Inrush Current Avoiding Circuit
Immediately after AC input applies voltage, the following components control inrush current to the Smoothing Capacitor.
RT1: thermistor
5) AC Detection Circuit
This circuit consists of the following components and detects AC input voltage.
Main components: D9, D10, D24, Q8, Q12, Q13, U1, Z7
AC voltage commutates through D9, D10.
When AC voltage is over the threshold, Q8, Q12, and Q13 are switched ON to allow AC Detection Circuit to transfer AC input
status to the secondary side AC alarm signal delivery section through U1.
1.3.

Main Converter

Added into the Original Service Manual as section 4.7.
This section describes the main converter circuit which insulates the primary DC voltage and converts the voltage to a Secondary
voltage " Vout" (41V).
1) Main Converter Section (Primary)
This main converter consists of the following components.
Q6: main switch FET
T1: isolation transformer
U2: Controls Q6
U4: device for transfer control secondary side
Other peripheral circuit
Secondary side output condition is transferred by U4 to the primary side.
Q6 is switched to ON/OFF in U2 to control the secondary side voltage.
2) Main converter section (Secondary)
T1: The output of this isolation transformer is 41V, and is the power supply for output voltage in section 3.
RT2: If the heatsink of Q6 become too hot.
Vout:
This output consists of the Rectification Smoothing Circuit of D6, C10, C11, C36.
This is the source of 15V output and 41V output of PSU.
The thermistor RT2 decreases the resistance value.
3