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- 16 –
ViewSonic Corporation
Confidential - Do Not Cop
VA1721wmb
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
R904, R905,ZD901
PWM
Control IC
Over
Voltage
Protect
Rectifier
CMOS
ON/OFF
Control
PWM
Control IC
Feedback
Circuit
OSC and
Output
Circuit
DC Convert
Circuit
MOSFET
Q805
Over
Voltage
CN902
Transformer
Lamp
5V
12V
ON/OF
DIM
Summary of Contents for VA1721wmb - 17" LCD Monitor
Page 22: ...22 ViewSonic Corporation Confidential Do Not Cop VA1721wmb Block Diagram...
Page 36: ...36 ViewSonic Corporation Confidential Do Not Cop VA1721wmb...
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Page 41: ...41 ViewSonic Corporation Confidential Do Not Cop VA1721wmb 5 7 Packing Procedure...
Page 42: ...42 ViewSonic Corporation Confidential Do Not Cop VA1721wmb 6 Troubleshooting Flow Chart...
Page 56: ...56 ViewSonic Corporation Confidential Do Not Cop VA1721wmb Packing For Shipping...
Page 60: ...60 ViewSonic Corporation Confidential Do Not Cop VA1721wmb Picture 19...
Page 61: ...61 ViewSonic Corporation Confidential Do Not Cop VA1721wmb 10 Block Diagram...
Page 71: ...71 ViewSonic Corporation Confidential Do Not Cop VA1721wmb 12 2 MAIN BOARD PCB BUTTON VIEW...
Page 72: ...72 ViewSonic Corporation Confidential Do Not Cop VG1721wm VA1721wm 12 3 POWER PCB TOP VIEW...
Page 73: ...73 ViewSonic Corporation Confidential Do Not Cop VG1721wm VA1721wm 12 4 POWER PCB BUTTON VIEW...
Page 75: ...75 ViewSonic Corporation Confidential Do Not Cop VA1721wmb 12 7 POWER PCB TOP BUTTON VIEW Q...