USB+Problems

Friday, August 24 2007 @ 01:20 AM PDT

Tutorial: **Common fixes for USB device issues** (unrecognized, etc.)
USB device issues can crop up at anytime, but are most common after a significant system update. Here's a quick rundown of workarounds, in increasing order of complication and potential for side-effects (i.e., try the first-listed ones first) for eliminating problems with lack of device recognition, conflicts between devices and more.
 * Unplug, then re-plug** It might seem almost too rudimentary, but this is an oft-overlooked fix that's successful in a surprising number of cases: Unplug your USB device along with any external power it may use, wait a few seconds, then plug it back in. As an example, we recently noted that some users experienced USB device failure after the application of Security Update 2007-007, in particular with regard to Wacom tablets. In response, MacFixIt reaer Len Willaims wrote: "I've noticed that all it takes to get my Wacom tablet working is to unplug the USB cable and plug it back in again."
 * Update firmware** If your USB device's firmware is out-of-date, you might see issues, particularly after system updates. Check your device manufacturer's site or [|VersionTracker] for any new revisions.
 * Re-apply the Mac OS X combo updater** And oldie but goodie: navigate to Apple's download page, then retrieve apply the combination updater that matches your system (e.g. [|Mac OS X 10.4.10 Combo Update [Intel]]). The reasons why this workaround is so effective are varied, but one is that re-installing the combination update can replace components -- including those related to USB functionality -- that were damaged during the initial update process (the combo update is larger in size than the version-to-version [i.e. 10.4.8 -> 10.4.9] or "delta" update and makes any incremental release current [e.g. 10.4.1 -> 10.4.9])
 * USB Prober** You might try running **USB Prober**. It is located in /Developer/Applications/Utilities, provided you have installed the Xcode developer tools. (These are probably present on your Tiger installer DVD, if you have one, but the best way to obtain them, if you have a broadband Internet connection, is to go to [|http://developer.apple.com], join the Apple Developer Connection as a free online member, and log in to obtain the most recent Xcode tools installer as a 1GB download.) Apparently, just running USB Prober does some sort of USB reset that can "wake up" unresponsive USB ports.
 * Clearing caches** Use a tool like [|Cocktail], [|OnyX], [|MacPilot], or [|Tiger Cache Cleaner] to perform a cache cleaning on your Mac. Start at the shallow levels (offered by some of the programs) and move onto the deeper routines.
 * Reset NVRAM/PRAM** Shut down your Mac, then start it back up while immediately holding the following keys: Command, Option, P and R. Hold the keys down until the computer restarts and you hear the startup sound for the third time
 * Check for interference/add hub** In many cases, connectivity and recognition issues are solved by simply disconnecting other power-drawing USB devices from the same bus or adding an externally powered hub.
 * Re-ins**