Main Power Supply On/Off Circuit - NEC MultiSync LCD2080UX -BKA Service Manual

2.9.2 MAIN Power Supply ON/OFF Circuit

When the power switch (SW901) is turned on, at fast, the SUB SW.REG converter circuit starts oscillation.
And the voltage of secondary output (5VA) is raised to 5V.
The Micro-computer on MAIN PWB starts operating, and SW.REG PWB is received "PMS" signal (approx
3V). Q9E1 turned on, and the signal is transmitted to the primary side through PC911.
On the primary side, Q930 is turned on, Q932 is turn on, and Q931 is turned off.
Therefore, Q933, Q908 is turned on, and the MAIN Power Supply and Power Factor Collector (PFC) circuits
begin operating. The voltage of secondary outputs 18VC are raised.
When the PMS (power save) MODE, "PMS" signal drops to low. Opposite operation is done, and The
Voltage of secondary outputs 18VC are stopped.
D901
R904
R905
R906
Q908
R935
R936
R937
Q931
R933
R908
IC901
ZD908
Q930
(Fig. 2.9.2) MAIN Power Supply ON/OFF Circuit
R911 T901
D911
D915 Q933
C910
R908
D930
Q932
ZD930
R934
7-11
D9A2 L9A1 T9A1
C9A2
5VA
R931
PC911
PMS
(ON/OFF
SIGNAL)
R9E7
PC911
Q9E1