Chosen Solution
Recently my TV started showing this dark shadow on one side:
I managed to get it away when fiddling with the left ribbin on the T-Con board, but only for like 5 minutes. This problem returns every time. What could it be? And is it fixable?
Roan de Graaf that does not look like a T-con error. It looks like a dim light and a fix for that would be a new power board. Of course, there is always a possibility that this is a bad panel. Start with a new power board and see what it does. Update (11/08/2018) Odd behavior for a T-con board but if you can resolve it by moving the hasp on the board, consider changing the T-con. I’d purchase one that could be returned just in case it does not resolve the issue.
