Samsung TV dims

[JohnDransfield]

I have a Samsung Ue32f5500 smart TV. I have DVD player and BT Youview box plugged into HDMI1 and HDMI2 and both function perfectly. I have attempted to connect a Freesat box to HDMI3, but although the connection seems fine, the picture dims within a minute to the point that it cannot be watched. I tried swapping the devices around. The Freesat box functions perfectly on HDMI1 or 2, but whatever is plugged into HDMI3 the picture dims within a minute. So the fault, if fault it is, appears specific to HDMI3 and not the attached devices. I do not want to adjust brightness etc as this would, presumably, affect the images on all devices not just the HDMI3 source. Does anyone have a solution?
John

 

[basroil]

Most models offer picture settings by input, read the manual and check that. Most likely it's just overcompensating during dynamic dimming

 

[JohnDransfield]

Most models offer picture settings by input, read the manual and check that. Most likely it's just overcompensating during dynamic dimming

 

[JohnDransfield]

Thanks for that - am still wading through the manual so have not yet solved the problem