Vince Inscribed thus:

Hi!
I have a Sanyo Mdl DP42848 HD Digital TV that comes on with a
great
picture for about a second and goes out with the sound staying on, I'm
thinking it is the video if & signal board causing it. What o you
think?
Thank You
Vince

More than likely the backlight inverter has gone faulty.

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Best Regards:
Baron.