Hitachi 42HXT12U, It turns itself on and off at random. The tv is under a year old.

The panel control board on the tv is faulty. Try disconnect the panel connection form the main board and the check.
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This problems the tv itself have a intermittent problems in the tv Tuner signal board.That the tv board that where the tv incomming broadcasting tv signal cable plug into it.This tv problems can't be fixed,because it could be anywhere in the tv Tuner signal board parts problems itself.If u bought this tv by a dealer,reconmendation exchange it for another tv.

Have you check the power supply,that's what it seems to me.

Hitachi WILL replace the part... My tv is over 4 years old and the light engine went bad. They sent me a new light engine free of charge two weeks ago and now it is PERFECT! When you call them make sure to ask for their superior if you get denied by someone.

just soldering your color ic or your RGB ic

You have a defective light engine and you do not have to be under warranty for Hitachi to replace this part. We just went through this and here's what you need to do. Call Hitachi's customer relations department at 800-654-7013 and tell them that you have a defective light engine. They will act like they've never heard of this problem but they have. They will give you the names of some certified dealers in your area to call. Once a tech comes out and confirms that it's the light engine, call Hitachi back and they will send a brand new light engine to the dealer and Hitachi will cover the cost of the part (cost $1500).

Here is the deal, if you're under warranty, Hitachi will cover the part and the install. If you're not under warranty, all you pay is the install. Our install cost $400. Others on this site have paid $200. Do not let anyone tell you that you have to pay for the light engine part...you do not. Hitachi has not recalled this part but they are replacing it for free. Also, deal only with Hitachi customer realations number that I listed. Good Luck

It sounds a lot like a micro/eprom problem and Hitachi addressed this in a service bulletin quite some time ago. Their fix was to add a jumper from I007 pin 1 to cathode of D019... Problems ranged from picture freezing to on/off control without prompting. Not an expensive fix and can easily be done in-home if you get a good reputable shop. We've done several in-home on a simple service call.
Hope this helps!
Bill

possibly a bad power supply board.

sounds like the tac switches on the actual tv which are very hard to get they may be sticking