Most likely cause for this are some bad capacitors on the power source section of your circuit boards. Look for these:
http://meyermed.com/wp-content/gallery/miscellaneous/close-up-of-blown-capicators-in-lnt4065fx.jpg
If the top is not flat anymore, but has a rounded shape, they will need replacement. The ones you replace them with may have the same values as the original, or higher. The only problem with higher value resistors is, that they might not fit in there physically.
https://www.youtube.com/watch?v=YCSNWi3UHf4
This video will give you a basic idea.
Keep me posted!