Have a n3251w deadset replaced all the bad caps in power supply now when power button pressed green led flickers momentarily and goes back to red dont have a schematic can you help

Replacement power supply is used?
You need to verify the DC output voltages of the power supply first and make sure this power supply has no bad caps with leaking/bulging tops. It goes into standby can also be that it detects fault some where in the set.
Please see my basic troubleshooting guide here:
http://www.fixya.com/support/r5093881-lcd_flat_panel_tv_troubleshooting_guide
http://www.fixya.com/support/r6150077-basic_lcd_monitors_troubleshooting
Failed TV and Monitors: http://s807.photobucket.com/albums/yy352/budm

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

Parts: www.shopjimmy.com
Capacitors kit: http://lcdalternatives.auctivacommerce.com/Default.aspx he can make you a set of caps.
Or www.digikey.com, just make sure to use caps with low ESR, 105c, high ripple current and long life rating such as PANASONIC FM or FC series.
Please post back what you find.

you have some bad capacitors in your power supply you could have someone look for domed electroletic caps that have vented replace the domed ones the part value is written on the side

The defective power supply module will cause the following symptoms:
No Display and no Sound, Then Power indicate light changes from Green to Red.
Turns OFF by itself.
Needs to be unplug to make it work.
Works for a few minutes then turns OFF.
I repair these power supplies, if you need further assistance let me know where to contact you.

the problem is located within the power supply printed circuit board. best bet to replace whole PCB .

I believe that is a bad power supply board. You can unplug set ,open the back access panel and look for swollen electrolytic capacitors they will most likely be slightly rounded on top instead of flat top like the others.Not sure if just replacing caps is enough we mainly swap out whole board.Some models' replacement power supply is slightly different from original in that a couple of the plugs are in different spots and require an extension cable.

the tv dude

If the power supply outputs are good! Then I would say the back light inverter is bad! If the screen stays black and does not come on.

7 blink error is 8.6 volt error on that model. usually tied to y sustain board located on left side of set looking from back. disconnect y main from power supply and power on and if comes on verify power supply primary voltages located on label on pdp itself. if voltages present you would need to replace that board as not designed for component level repair. however if you find failed components like swollen caps or burnt ic's you could replace those. also when replacing the y main board there are two y buffer boards to left of main board that also would be recommended to be replaced at same time as they work as circuit and replacing one board without other could cause failure to other boards still in set

You have a 8.6v supply error according to the 7 error code being displayed, what you can try is when the set goes to blinking disconnect the Y sustain board (if looking at the tv from the back the board on the left) from the upper left side of the power supply, if the error code stops then you know your Y sustain board is pulling down your power supply and causing the error, if the error code continues you have a probelm with your Logic Board (located under your Small Signal Board) disconnect this from the Y sustain board and see if the error code stops if it does you know that the Logic board is bad, if the error code is still blinking then the 8.6v supply line from the Power supply is faulty and the Power Supply needs to be replaced

Solution... Call viewsonic and **** till you get a new one (diff model). Good luck, you're going to be on hold forever.