Second Output Rectifying And Smoothing Circuit; Second Error Detection Amplifier Circuit - NEC MultiSync FP1370 Service Manual

8-14. Second Output Rectifying and Smoothing Circuit

The fly-back voltages which are generated at the secondary windings of T651 are rectified by D6L1 and D6M1.
Then, these voltages are smoothed by C6L1, C6L2, C6M1 and C6M2 so that DC voltages are obtained.
The DC voltages are maintained constantly by controlling the ON period duty cycle of MOSFET(internal
IC651) in the second converter circuit.

8-15. Second Error Detection Amplifier Circuit

The output voltage +20.0V is compared with the reference voltage at the error amplifier IC652.
An error signal is applied to the control circuit via the photocupler PC651.
CONTROL
CIRCUIT
D6L1
+
C6L1
-
+
C6M1
-
D6M1
(Fig.8-15) Second Output Rectifying and smoothing Circuit
R662
PC651
C659
3
IC652
1
2
(Fig.8-16) Second Error Detection Amplifier Circuit
+
L6L1
C6L2
-
+
C6M2
-
L6M1
R663
R665
R664
8-52
+20.0V
GND
-20.0V
+20.0V
GND