Power turn off after 45 minutes to 1 hour used

Power supply regulator board problem. Contact any service technician. If you wish to get some details; check the site linked here. Viewing it in "Mosaic" will make surf easy.
http://electronicshelponline.blogspot.com/

id check the capacitors again,esp near the one you changed.was the one that was put in the correct one? you may increase the voltage but not the uf

use a power strip.

U have a small power surge somewhere.Disconnect all connections to the tv and unplug the tv and replug it back like about an hour later.Reconnected all connections.Go into the the tv Sound Setting to do a resetting of the sound setting back to the factory reset.The tv sound should work find now.If still have the same problems,then the main tv Tuner signal board it is shorted and have intermitten dying parts on the tv Tuner signal board.Only choice now is tries buy a refurbish tv Tuner signal board for the replcement.Tries websites like Shopjimmy.com,Ebay.com to buy LCD tvs refurbishes pcb boards.

do nothing except reset, if in warranty call Mitsubishi.

When tv it shutting itself off by it own does the tv power LED light indication flashes?Tv turn on now,the tv power light indication,just flashes?Yes,than ur tv power supply board is the causes and the problems.That the board,where the power a/c cord plug into it.Tries websites like Shopjimmy.com,Ebay.com to buy a whole refurbish power supply board for the replacement.

make sure you have not accidentaly scheduled a power off and on if yes torn off/disable them if not check that your power cable is secure

Sounds like the "deflector board". The part is about $400.

Its the power supply!!
well i migrated to this issue from having no sound and video with just the power button illuminated. I replaced the power supply with one from an online salvage store and it worked fine for about two hours and then it shut off, turned it back on and then twenty minutes later off again...repeat... need an electronics person to trouble shoot and trace which resistors and or capacitors are overloading.
anyone??