The Tech Bench

As Mac users, we often take for granted that the OS works with all Mac hardware.

Sometimes what can appear to be a hardware issue (the sound card not showing up in System Profiler) is in fact caused by an incompatible version of the OS.

The 13″ MacBook Pro sound card requires a slightly different OS driver that only comes with the OEM install disks (10.5) for this book. If you attempt to install another version of 10.5, the sound card will not show up and there will be no audio out through the speakers or headphone jack.

We saw this kind of issue previously when the PPC models starting including the scrolling trackpad. Only the OEM install disks could be used to install the OS in order to get the trackpad to work.

What can make this even more tricky is that if the wrong version of 10.5 is installed on a 13″ MBP, only a clean install with the right OEM disks will install the right sound drivers (Archive and Install & Software Update won’t work.)

If you need to re-install your OS, use the disks that came with your Mac first and then run Software Update. Installing 10.6 will also fix this issue.

Sometimes hardware-like symptoms such as loss of sound, input problems and loss of wireless connectivity can be caused by software issues.

To first verify that an issue is in fact caused by a hardware failure, the first step we take is to make sure that the issue is not caused by software.

Here are 3 ways to isolate your Mac’s software to test your hardware.

1. We usually boot the system off of a different test hard drive to completely by-pass the software on the Mac we’re troubleshooting. This is the easiest and best way to determine if the issue is hardware or software. Target-disk mode can also be useful if you have access to a friend or colleagues (same model or similar) Mac. You can boot your Mac using their hard drive. If the problem goes away, you know you’re Mac has a software issue, if not, you’re looking at hardware.

2. Some software issues are caused by (corrupt) settings at the user level. If you have another user set up on your Mac, log into their account and see if the issue goes away. If you’re the only user, you can quickly setup a new test account in System Prefs. Log into the account, if the symptom goes away, you know that there is either a setting that needs to be changed or a corrupt pref.

3. Most hardware-like symptoms that are caused by software live at the OS level, so re-installing the OS is a good way to make sure that a corrupt OS is not causing your issue. Using your restore disks, select the Archive and Install option when re-installing the OS. Archive and install saves your user settings and files but replaces the system files. Note: if your software issue lives at the user level, this may be carried over, so try step 2 before a re-install.

If none of the above steps rectify the issue, you’re most likely looking at a hardware issue that will need to be repaired or replaced. If your issue is software related, an archive and install usually solves the issue, but if your issue lives at the user level, check your settings and do some online searches to see if their are any known application conflicts or settings that may have been set.

For hardware service, checkout our MyService Free Diagnostic.
For software, try the Apple or MacLife discussion boards.

Hold down the "D" Key on boot.

The Apple Hardware Test (AHT) is a diagnostic program that tests the basic functionality of your Mac’s hardware.

All MacBook Airs and MacBook Pros (2008 later) have the AHT loaded on the hard drive, other Macs will list the AHT version on one of their restore disks.

While the AHT is not always accurate in determining a hardware issue, it’s a great first troubleshooting step.

The AHT tests basic functionality like the GPU, processor, HD and RAM and may provides error code(s) that can be useful in determining an issue.

To run the AHT, disconnect any peripherals like printers or keyboards. Connect your Mac to power and either:

Insert the restore disk that contains the AHT and hold down the “d” key on boot.

or

If you have a late model MacBookPro or Air, you may just need to hold down the “d” key on boot.

Note: The AHT can take up to an hour to run.