Turns off and on

Check the speaker/s first. If found OK; check and replace the damaged component/s at its audio output section circuit board. If needy, replace this board as card basis. If you wish to get some details; check the site linked here. Surf the site with patience. Pull up older posts. Surf the site with patience.
http://electronicshelponline.blogspot.com/

The power supply board is the problem. You can get parts from here:
TV Parts Universal TV Stands DLP Chips ShopJimmy

There is some incompatibility issue. Did you check the format is set correctly for PAL/SECAM etc.?

that problem is on the back-light lamp of your LCD TV it is busted or weak need to replace it

Yes,it have a Digital Tuner inside.It can get free air signal tv.No,need for a converter box like a Analog CRT tvs.

It really doesn't have a reset for the picture. I would be looking at the inverter and power supply. If it is four years old most likely it is the inverter. The inverter is on the left side looking at it from the back. Have a repair shop check it out for you. Thanks

The RX-326 does not have a digital tuner, only an analog.

I don't know about your particular tv, but most of the LCD tv's have a power off option that it will turn off after 3 hours of no activity.

Why it would turn itself off at 3 and 30 minutes is beyond me. But I did want to write so you can check your settings to see if maybe someone has programmed in some shutdown times or something.

Hope this helps at least some. Good luck!

If you have any vertical lines appearing in a LCD flat panel TV, you are looking a defect in the panel itself. If you no longer have any kind of warranty you are best to watch the TV as is and save your money towards a new TV as the LCD panels will cost in most cases twice the amount that you paid for the TV brand new.

Digital brd has a heat related problem..If you did not get a extended warranty then it could be cheaper to just replace the TV...