Q: My HDMI cable was working fine before I updated to OS X 10.8.4. How can I use the same HDMI cable without purchasing a new one? MacBook Pro is not even recognizing signals for detection. Please advise.

Hey yasmin24601!

I have an article here that can help you troubleshoot this issue. The article can be found here:

Apple computers: Troubleshooting issues with video on internal or external displays

http://support.apple.com/kb/ht1573

The specific section you will want to see in this article will be here:

Check connections

When using an external display be sure to check the following:

1. 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.
2. 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:
   • Monitor and Display Adapter Table
   • About Mini DisplayPort to HDMI adapters
   • Apple Mini DisplayPort adapters: Frequently asked questions (FAQ)
   • Thunderbolt ports and displays: Frequently asked questions (FAQ)
3. Remove all display cable extenders, KVM switches, or other like devices and retest to determine if the issue is resolved.
4. Try unplugging the video adapter or cable and then plug it back in.
5. 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.
6. 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

You can reset the Mac's parameter RAM and SMC.

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:

1. Start up in Safe Mode.
2. From the Apple () menu, choose System Preferences.
3. Choose Displays from the View menu to open the preferences pane.
4. Select any resolution and refresh rate that your display supports.
5. 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:

OS X Mountain Lion: About the Display pane of System Preferences

http://support.apple.com/kb/ht5369

Thanks for using the Apple Support Communities!

Cheers,

Braden

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.

Cheers,

Braden