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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
R906, R907
PWM
Control
Over
Voltage
Protect
Rectifier
CMOS
ON/OFF
Control
PWM
Control
Feedback
Circuit
OSC and
Output
Circuit
DC Convert
Circuit
MOSFET
Q203
Over
Voltage
CN102
Transformer
Lamp
5V
12V
ON/OFF
DIM
4.4 INTRODUCTION OF IC
MST8011B (U401):
integrate ADC, OSD, SCALER, LVDS, convert analog RGB into digital and
room and shrink scaling output to LCD panel.
PIN Function:
9
ViewSonic Corporation
Confidential - Do Not Copy
VA502mb-1
Summary of Contents for VA502mb-1
Page 10: ...7 ViewSonic Corporation Confidential Do Not Copy VA502mb 1...
Page 13: ...10 ViewSonic Corporation Confidential Do Not Copy VA502mb 1...
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Page 16: ...PIN Descriptions 13 ViewSonic Corporation Confidential Do Not Copy VA502mb 1...
Page 18: ...Block Diagram PIN Function 15 ViewSonic Corporation Confidential Do Not Copy VA502mb 1...
Page 38: ...5 7 Packing Procedure 35 ViewSonic Corporation Confidential Do Not Copy VA502mb 1...
Page 42: ...39 ViewSonic Corporation Confidential Do Not Copy VA502mb 1 6 Troubleshooting Flow Chart...
Page 43: ...7 Block Diagram 40 ViewSonic Corporation Confidential Do Not Copy VA502mb 1...
Page 53: ...9 PCB Layout Diagrams MAIN BOARD 50 ViewSonic Corporation Confidential Do Not Copy VA502mb 1...
Page 54: ...POWER BOARD 51 ViewSonic Corporation Confidential Do Not Copy VA502mb 1...
Page 56: ...53 ViewSonic Corporation Confidential Do Not Copy VA502mb 1...
Page 57: ...AUDIO BOARD 54 ViewSonic Corporation Confidential Do Not Copy VA502mb 1...
Page 58: ...KEY BOARD 55 ViewSonic Corporation Confidential Do Not Copy VA502mb 1...
Page 61: ...58 ViewSonic Corporation Confidential Do Not Copy VA502mb 1 Packing for Shipping...