Dell S1909WXf Service Manual page 9

2.2 Power PWM circuit
2.2.1) Block diagram :( fig.4)
EMI Filter Rectifier and
filter
PWM controller
2.2.2) AC Input and EMI Filter :( fig.5)
CN850 is a connector for connecting AC Power. F850 is a fuse to protect all the circuit AC.
Input voltage is from 90V to 264V. R850 and R851 are joined between two inputting main circuit
to prevent man from shock. L851 is used to clear up low frequency wave. C850 and C851 are
used to discharge the waves that L851 produced. High frequency waves are damped by C852
and C853.
2.2.3) High Voltage to Low Voltage Control Circuit :( fig.6)
Isolation power
transformer
Switching element
Feedback Isolation
Fig.4
fig.5
8
Rectifier and filter
Rectifier and filter
LDO regulator
Service Manual
Inverter circuit