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- 17 –
ViewSonic Corporation
Confidential - Do Not Copy
VG720
4.3 PWPC BOARD BLOCK FUNCTION DESCRIPTION
PWPC board combines to adapter and inverter, Adapter which commonly consists
of bridge rectifier and filter, start circuit, PWM control circuit, protection circuits and
convert to 12V, 5V DC voltage by input 90V-240V AC voltage that provide power supply
for each chips in the main board and inverter. Inverter is DC TO AC circuit. It changes
the 12v DC of power supply to about 600-800v AC that drives the backlight. It mostly
consists of starting circuit, PWM controller, DC changing circuit, LC surging circuit,
output circuit and protection circuit etc.
AC input
EMI filter
Bridge
Rectifier
and Filter
Start Circuit
R903, R904,R905
PWM
Control IC
Over
Voltage
Protect
Rectifier
CMOS
ON/OFF
Control
PWM
Control IC
Feedback
Circuit
OSC and
Output
Circuit
DC Convert
Circuit
MOSFET
Q203
Over
Voltage
CN902
Transformer
Lamp
5V
12V
ON/OF
DIM
Summary of Contents for VG720 - 17" LCD Monitor
Page 37: ...37 ViewSonic Corporation Confidential Do Not Copy VG720 Sep2 Inpute the S N and execute Enter...
Page 38: ...38 ViewSonic Corporation Confidential Do Not Copy VG720...
Page 39: ...39 ViewSonic Corporation Confidential Do Not Copy VG720 Sep3 Key the Enter and write the data...
Page 41: ...41 ViewSonic Corporation Confidential Do Not Copy VG720 5 7 Packing For Shipping...
Page 43: ...43 ViewSonic Corporation Confidential Do Not Copy VG720 6 Troubleshooting Flow Chart...
Page 62: ...62 ViewSonic Corporation Confidential Do Not Copy VG720...
Page 63: ...63 ViewSonic Corporation Confidential Do Not Copy VG720...
Page 80: ...80 ViewSonic Corporation Confidential Do Not Copy VG720 12 2 MAIN BOARD PCB BUTTON VIEW...
Page 82: ...82 ViewSonic Corporation Confidential Do Not Copy VG720 12 5 POWER PCB TOP VIEW...
Page 83: ...83 ViewSonic Corporation Confidential Do Not Copy VG720 12 6 POWER PCB BUTTON VIEW...
Page 84: ...84 ViewSonic Corporation Confidential Do Not Copy VG720 12 6 AUDIO PCB TOP VIEW...
Page 85: ...85 ViewSonic Corporation Confidential Do Not Copy VG720 12 6 AUDIO PCB BUTTON VIEW...