Hi, I have a 4 year-old Hitachi C28W511TN widescreen TV. Recently, and only
75% of the time, when I switch it on, it turns itself off about a minute
later.

Strangely it doesn't make the familiar click and fizz inside the box that I
hear when I turn it off with the remote, it almost switches the tube off
'silently' (like a PC monitor going into blank screensaver mode) and there
appears to be a brief moment just before it does this when it 'thinks about
it' as the picture rapidly disappears once, then reappears, then switches
off (I think! - it's all very fast).

When I press ON on the remote, it doesn't 'click' on, the picture just comes
back silently without a standard 'I'm turning on' click.

It then turns off again 30 seconds later!

I repeat this 2-7 times, then it stays on for the rest of the night until I
choose to turn it off. It's like it gives up fighting with me and just
stays on, displaying a perfect picture.

It's not an IR issue as when I turn off with IR, I hear a click and fizz in
the box.

Any ideas? Help much appreciated. I'm tech-savvy and would like to attempt
a home repair if you can advise a simple part I need to replace.

John