(E) Error Detection Amplifier Circuit; Oscillating And Control Circuit - NEC MultiSync 4FGe Service Manual

(e)
Error detection amplifier circuit
The output voltage 80V is divided by the network resistors. This divided voltage is compared to the reference
voltage at the error amplifier lC651. An error signal is applied to the control circuit via the photocoupler PC601.
(f)

Oscillating and control circuit

The oscillating, control, and drive circuits are contained in IC601.
IC601 has a built-in oscillator whose frequency is determined by R608, and C605 connected to pin @ and pin @J
respectively.
The output of the error detection amplifier circuit is fed back to the control circuit pin @ from pin @via PC601 to
control the duty cycle of Q601 so that output voltages are kept constant.
C653
A R
R654
(Fig l-l-5)
Error Detection Amplifier Circuit
R612
(Fig l-l-6) Oscillating and Control Circuits
R655
VR651
R654
I C601
0
R608