My ms470sl turn off itself

Could be a bad connection that disconnects when heat in the system causes it to expand. Take to a pro or call manufacturer, they might have a recall or free repair available.

When heats up, the supply voltage from the main power supply board goes less. Check all the soldering to this board for any loose solder terminals. Resolder all the suspected solder terminals by applying a little more solder. If it do not help you, replace the board as card basis.

You are having trouble with a thermal protection switch in the TV. The power supply will have to be replaced. It is also possible that your lamp (tubes behind the LCD panel) are going bad and drawing too much current and causing the power supply to protect itself.

-Mark

Thats a common symptom which is usually caused by the Small signal board. You can get a replacement small signal board from www.tvrepairworld.com

IF YOUR IMAGE IS ALL WHITE YOUR LOGIC BOARD IS DEFECT BUT IM SAD TO SAY DO NOT REPLACE THE LOGIC IT WILL ONLY TEMPORARLY SOLVE THE PROBLEM THE PANEL IS OVERLOADING THE LOGIC BOARD PANEL IS BAD

I had this problem a few years ago. The service technician replaced the bulb which he said was over-heating, and that fixed it.

How long since the last time the bulb was replaced? It sounds like the bulb is overheating and triggering a safety shutdown.

It's probably in need of nothing more than a good cleaning (open it up, clean off the boards with a can of air) and *may* be time to replace the bulb.