External display not working with El Capitan

[dMilluh]

I'm running a late 2010 Macbook Air. I previously ran it to my 55' Element via Minidisplayport to HDMI adapter and it worked flawlessly until I updated to El Capitan.

I have researched about as much as I can but I cannot find any info with similiar problems as mine. The computer detects the TV now when I plug it in but will not mirror my laptop display onto my TV.

I had no issues with this before updating to El Capitan.

Any suggestions?

So far I have tried to reset the SMC ONCE but it did nothing.

 

[pm-r]

I don't know if it will help, but whenever I've come across display problems I've always ended up solving the problem using SwitchResX.

You can always try:
http://www.madrau.com

 

[dMilluh]

Tried resetting the pram and rram, nothing changed. Tried unplugging TV for 30 seconds while connected, nothing changed. Tried res switcher as suggested, nothing changed.

It's so wierd..the TV is detected and connected but still blue screen no signal.

 

[Slydude]

Are you sure the TVs input is set to the right setting to receive signals from the computer. Your remote probably has a button to do that. It usually says something like Input or Source. With the TV on and computer set to mirroring cycle through the inputs on the TV to see if a signal registers. Since it was working you've probably checked that but it will sometimes reset itself. When the batteries on one of my remotes are low pushing one button will often change an unrelated function making a mess of things till I figure it out.