A very common problem with power supply boards, motherboards and generally all PCs and TVs which are produced between 1999 and 2007 is the premature defect on some Taiwanese made electrolyte capacitors with bad electrolyte formula. Although this problem is said to be solved for gears produced after 2007 (according to Wikipedia), if you happen to be one of the unfortunate owners of such gears, the good news is you can simply replace these capacitors and give a few more years of joy to your affected equipment.
Here is a video I published a few years ago. It is a quite simple repair, granted that you know what are you doing and taking all the safety measures first!
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