I have an article here that can help you troubleshoot this issue. The article can be found here:
The specific section you will want to see in this article will be here:
When using an external display be sure to check the following:
- If you're using an Apple notebook, confirm the AC power cable or adapter is securely connected to the computer and the cable providing power to the display is also secure. It is always good to have your notebook connected to AC power when an external display is in use.
- Confirm display adapters are fully seated in their respective connections and that they are supported models and for the computer and display. Refer to these articles to assist you with adapter compatibility and further configuration information:
- Remove all display cable extenders, KVM switches, or other like devices and retest to determine if the issue is resolved.
- Try unplugging the video adapter or cable and then plug it back in.
- If more than one video adapter is in use (or "daisy-chained"), troubleshoot by using only one adapter.
- Example: A mini DisplayPort to DVI adapter connected to a DVI to HDMI adapter is an unsupported configuration because there is a series of adapters in use.
- If available, try using a different display and or adapter (or use a different connector by using DVI instead of VGA, for instance).
Reset the system
Reset the resolution
Start by resetting the Mac's parameter RAM. If the display does not come up, was previously set to an unsupported resolution, and still results in no video:
- Start up in Safe Mode.
- From the Apple () menu, choose System Preferences.
- Choose Displays from the View menu to open the preferences pane.
- Select any resolution and refresh rate that your display supports.
- Restart your computer.
You will want to also make sure that your system preferences are set to detect displays. More information on that option in your system preferences can be found here:
Thanks for using the Apple Support Communities!
I made an attempt at everything you posted. Nothing's worked. I can't even find the "drivers" for the HDMI cable I have. Thought if I downloaded those, it'd work...but can't find any. Unfortunately, I didn't have my timemachine on either to revert back to 10.8.3 Got any other suggestions??
Hi again yasmin24601,
Thank you for using the Apple Support Community. Due to the nature of your issue or question you may find more information by using another one of Apple's support resources - https://expresslane.apple.com/GetproductgroupList.action.
I have the same issue.
I have a Samsung SyncMaster B2430 connected to MacBook Pro by HDMI cable to minidisplay port into the MBP port. The connection worked smoothly until I installed OS 10.8 and of course all of the update. The two hardware items are communicating, but I cannot get a visual on the external display. Rather, the display prompts "Check Signal Cable." I replaced the HDMI cable to several others that I have, but the prompt is still displayed.
I followed the instructions that you posted above, but to no avail.
The next step is to purchase a new mindisplay port, which is not expensive, but will be a waste of money if that is not the solution.