Over Voltage Protection (Sub Switching Regulator) - NEC MultiSync LCD2080UX -BKA Service Manual

2.9.11 Over Voltage Protection (SUB Switching Regulator)

If some failure occurs and the output voltage of the secondary windings of T9A1 increase, the voltage of the
auxiliary winding of T9A1 also will increase proportionally. When the voltage of C9A2 increases beyond the
zener voltage of ZD9A4, terminal "3" to "6" of IC9A2 is short and latch.
As a result, the voltage of "C" terminal of IC9A1 decreases, and the oscillation is stopped.
This operation is maintained until the AC cable is pulled out or the power switch (SW901) is turned off.
D
IC9A1
S
R9A8
C
C9A4
IC9A2
(Fig. 2.9.11) Over Voltage Protection (SUB Switching Regulator)
PC9A1
ZD9A4
3
R9A4
5
6
R6A5
7-18
D9A2 L9A1
C9A2
T9A1