MacBook – Why does the MacBook’s monitor go to maximum brightness when waking up from sleep

displaymacbook prosleep-wake

I have my MacBook connected to an external monitor (via HDMI), and the brightness of MacBook monitor is set to 50% of max brightness . I usually put my display to sleep when I leave my computer for a break, and everytime I wake it up, the MacBook monitor will be set to maximum again.

Any idea how do I fix it so that when I wake up the display, I do not need to adjust the screen brightness down again?

I am running Lion on an early 2009 MacBook.

Best Answer

Try to reset the System Management Controller.

Resetting the SMC on Mac portables with a battery you can remove

  1. Shut down the computer.
  2. Disconnect the MagSafe power adapter from the computer, if it's connected.
  3. Remove the battery.
  4. Press and hold the power button for 5 seconds.
  5. Release the power button.
  6. Reconnect the battery and MagSafe power adapter.
  7. Press the power button to turn on the computer.
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