MacBook Air freeze: reset SMC

Daily, I take my MBA to work, and connect it to my 30" cinema display. At the end of the day I disconnect and take it home. Once back home, I plug into the 24" LED display and keep on working. The MBA sleeps while I'm cycling to and fro — and wakes up when I plug it in.

Today, I got home, plugged in, and found a blank screen. I waited; nothing happened. I waited some more. Eventually I gave up waiting and did a forced shut-down, by pressing and holding the power button.

To restart, I pressed the power button. The chimes, and the apple came up just as usual; then the little wheel thing came up, but it didn't move. I waited — nothing. I plugged in, unplugged, opened. closed, shut-down (again) etc. I tried all of this again, and again, in various permutations, and with plenty of waiting — nothing. Frozen as a dead parrot!

So, I reset the System Management Controller — that worked :-)

To reset the SMC: Shutdown; plug in to mains power; hold down shift-ctrl-alt (alt is aka option) on the left side of the keyboard, and press the power key once; then release the keys, wait 5 seconds, and press the power key to restart. Effective magic!

The SMC includes the Power Management Unit (PMU) you may be familiar with from other devices.

Channel 13: Leopard Wireless Card Locale

Channel 13 is legal in the UK and many other locales, but not in the USofA.

Since most default setups use channel 6 or channel 1, those of us looking for uncrowded channels often find 13 is uncluttered.

When I did a recently clean install of Leopard, I found that my channel 13 network disappeared — invisible!

Update (2009-03-09) It seems that the 10.5.6 update (I installed it on 2008-12-27) has changed something so this tip no longer works!

Although my MacBook Time Zone was set to Edinburgh - Scotland (you can set this in System Preferences, under Date&Time), I found that my Wireless Card Locale was set to US (which disables channel 13).

You can check your Wireless Card Locale by going to "About This Mac" > "More Info ..." > "Network; Airport Card".

The solution was to set the Time Zone to Tokyo then restart. Wireless Card Locale is then "Worldwide" and channel 13 is enabled.

Setting the Time Zone back to "Edinburgh - Scotland" and restarting again gives me "Worldwide" — but setting Time Zone to "Los Angeles - USA", and restarting, sets it back to "US".