There are number of things that can be bad and what's more there are number of very different Sanyo DP50749 models which have rather different internals and different known issues.

What you need to find out first is the chassis of the TV, which is going to be on the back label, something like P50749-00 for example, and supply that too.

Here's a link with offer for parts and repairs we have for DP50749 - again, be advised that those may be for practically very different TVs internally and the first thing you need to do is find out what is yours! :

http://www.coppelltvrepair.com/search?Q=DP50749

Hope this helps!