My view sonic VA712 monitor doesn't display any picture even after power supply light shows green.

Go to a electronic store and bring your adaptor and ask them if they have that kind of adaptor...

Look for bad caps with domed tops. Theu should be replaced in a set.
If you are going to DIY and already try the monitor with another PC, and have proper tools and know safety precaution then please read on:
Most common failures in the LCD monitors are bad capacitors (bulging top/seal or leaking) in the power supply (they should be replaced in a set), blown fuses; poor solder joints, failed inverter circuits (blown fuse, shorted transistors, shorted/open transformers), bad lamps (poor solder connections or worn out lamps). You will need to open it up and inspect the inside, see example of failed VIEWSONIC monitors to get some ideas what to look for: http://s807.photobucket.com/albums/yy352/budm/
Post back what you see inside so we can guide you further and it will help out other people in the future also.

Basic LCD monitor and TV troubleshooting guide:
http://www.fixya.com/support/r6150077-basic_lcd_monitors_troubleshooting
http://www.fixya.com/support/r5093881-lcd_flat_panel_tv_troubleshooting_guide
http://www.fixya.com/support/r7406380-tv_training_manuals
Failed TV and Monitors: http://s807.photobucket.com/albums/yy352/budm/

Learn about bad caps: http://en.wikipedia.org/wiki/Capacitor_plague

Capacitors kit: http://lcdalternatives.auctivacommerce.com/ he can make you a set of caps for you.

Or www.digikey.com just make sure to use caps with low ESR, 105c, high ripple current, long life rating such as PANASONIC FM or FC series.
Please leave rating if it helps.

It may have blown fuse in the backlight inverter board, that will be the first place to look.
Post pictures if you can.

Basic LCD monitor and TV troubleshooting guide:
http://www.fixya.com/support/r6150077-basic_lcd_monitors_troubleshooting
http://www.fixya.com/support/r5093881-lcd_flat_panel_tv_troubleshooting_guide
Failed TV and Monitors: http://s807.photobucket.com/albums/yy352/budm/

Learn about bad caps: http://en.wikipedia.org/wiki/Capacitor_plague

Capacitors kit: http://lcdalternatives.auctivacommerce.com/ he can make you a set of caps for you.
Or www.digikey.com just make sure to use caps with low ESR, 105c, high ripple current, long life rating such as PANASONIC FM or FC series

This a problem related to powerboard ,needs electronis repairs expertise to open and resolve.

Very common problem with Viewsonic and all other brands of failed moniotrs is due to bad caps as you can see here:
Failed TV and Monitors: http://s807.photobucket.com/home/budm/allalbums
http://en.wikipedia.org/wiki/Capacitor_plague
Capacitors kit: http://lcdalternatives.auctivacommerce.com/ he can make you a set of caps for you.
Please post back what you find for further help.

bholesir, If unit covered by ViewSonic warranty, USE IT!!! The units "switch-mode-power-supply" is in need of service!! Unit WILL require inspection and repair of possible bad (poor quality soldering) soldering of electronic components to the prinded circuit cards and or need replacement of bad (poor quality) electrolytic filter capacitors on the unit's "switch-mode-power-supply"/"CCFL inverter circuit" that have failed!! Do a visit to YOUTUBE for "LCD monitor disassembly" and "LCD monitor repair" so you can familarize FYI with what is inside your monitor, and possibly make a decision to do a DIY repair or contract out the work to a local TV/LCD monitor repair shop. If your pocket is deep enough, maybe you will repair and buy a new unit, keeping VA712 as spare unit for a rainy day. Read more of my responses to other owners in my FIXYA profile for more options not mentioned here. Good luck with repair. 12fixlouie

look inside for bad caps, see example of failed Viewsonic monitors here: http://s807.photobucket.com/home/budm/allalbums

You should have 5v and 12v in the power supply sections.

replace the logic board, not the power supply board. you can find logic board on ebay as low as $29...

My VA712 is exactly the same as yours. Did you ever get a solution?
Thanks,
John