Hello, I read all threads but did not found solution.

Have E6400, win10, display port to hdmi adapter  and pretty new 4K Sony tv.

When connected, dell shows TV Sony as a new display and allows me change resolution and all other settings. 

But TV only shows that at selected input is "something" connected but "no signal" appears.

Same adapter with hdmi cable works fine on this TV with my other notebook (HP). I tried different cable no change.

And idea how to solve it?

Thank you