(C) Converter Circuit; (D) Output Rectifying Circuit - NEC MultiSync 4FGe Service Manual

(c) Converter circuit

converter circuit consists of the primary winding of the switching transformer T601,
The
Q601, and surge absorbers (C602, R602, C609, R620, D606, and D611) that are connected to the primary
winding.
The oscillating signal-from IC601 pin @ is applied to the gate of Q601 causing the drain-source to be turned
OFF and ON so that the oscillating voltage is applied to the primary winding of T601.
FILTERING
CIRCUIT
DRIVE
CIRCUIT
(d)
Output rectifying circuit
The flyback voltages generated at the secondary windings of the switching transformer T601 are rectified
by D651, D681, and D691. Then, these voltages are filtered by C692, C693, C651, C652, C656, C681, and
C682 so that rectified DC voltages are obtained.
Constant flyback voltages are maintained by controlling the duty cycle of Q601 in the converter circuit.
T601
From IC601 Pin@_
(Fig l-1-3) Converter Circuit
(Fig l-1 -4) Output rectifying Circuit
C602 f R602
37
switching device
a
T601
+ 80V
+24V
GNO