You may need to adjust the display settings on the Mac before you can see any picture on the tv.
Try the following:
- Go into the System Settings
- Go into the Display Settings
- On one of the Tabs in the Display Settings Window there will be a button on the lower right hand corner that says “Detect Displays”. Click on it.
- On one of the other tabs in the Display Settings Window will be a list of different resolutions, such as 1920x1080. Try them all until you find one that works, it can vary from setup to setup depending on the devices.
- On some models of Mac’s you can disable the discrete video card. When discrete video is disable the external display does not work. Reenabling discrete video fixes the issue. To check if it is enabled go into the system settings and it will be under the energy saver options in the upper left hand side.
~ Should that not work ~
6. Run the graphics and EFI updates. Some firmware updates for Intel based Macs may not be displayed automatically using Software Update. If they do not appear in Software Update, they must be manually downloaded from the Apple Downloads site. If you are unsure whether your computer needs a particular update, simply download and open the update installer. The installer will alert you if the firmware update is already installed or not needed.