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Macbook Pro screen dims

Message #1 - Posted 2007/02/04 - Phillip Walters

I have a Macbook Pro 17" C2D, and on the odd occasion the screen dims slightly for a split second, then goes back to the preset brightness level. This only seems to happen while watching video, eye tv recordings especially, just happened while watching a streaming video clip as well. But I have not noticed it with DVDs, yet ! Has anyone else experienced this ?

Phil

Message #2 - Posted 2007/02/05 - Dorian Gray

Previously, Phillip Walters wrote:

I have a Macbook Pro 17" C2D, and on the odd occasion the screen dims slightly for a split second, then goes back to the preset brightness level. This only seems to happen while watching video, eye tv recordings especially, just happened while watching a streaming video clip as well. But I have not noticed it with DVDs, yet !

The screen dims automatically under two circumstances:

1. Your System Preferences > Energy Saver settings have the screen set to go to sleep after some period of inactivity (lack of keyboard/mouse/trackpad input). Then the screen will dim shortly before it would have gone to sleep. It will recover to previous brightness after a mouse movement or keypress. This will not happen if watching a DVD.

2. You are using a laptop and the power cord is removed, either deliberately or because it is not seated correctly. The display dims by three notches. It goes back to full brightness when external power is restored.

HTH.

Message #3 - Posted 2007/02/05 - Phillip Walters

Dorian Gray wrote:

Previously, Phillip Walters wrote:

I have a Macbook Pro 17" C2D, and on the odd occasion the screen dims slightly for a split second, then goes back to the preset brightness level. This only seems to happen while watching video, eye tv recordings especially, just happened while watching a streaming video clip as well. But I have not noticed it with DVDs, yet !

The screen dims automatically under two circumstances:

1. Your System Preferences > Energy Saver settings have the screen set to go to sleep after some period of inactivity (lack of keyboard/mouse/trackpad input). Then the screen will dim shortly before it would have gone to sleep. It will recover to previous brightness after a mouse movement or keypress. This will not happen if watching a DVD.

2. You are using a laptop and the power cord is removed, either deliberately or because it is not seated correctly. The display dims by three notches. It goes back to full brightness when external power is restored.

HTH.

Thanks for the reply, I realise that my energy saver settings would dim the screen, but perhaps I should have explained my problem a little better, it dims for maybe less than a second, but recovers itself almost immediately without any mouse or keyboard input.

Phil

Message #4 - Posted 2007/02/05 - Tim Auton

Phillip Walters wrote:

Dorian Gray wrote:

Previously, Phillip Walters wrote:

I have a Macbook Pro 17" C2D, and on the odd occasion the screen dims slightly for a split second, then goes back to the preset brightness level. This only seems to happen while watching video, eye tv recordings especially, just happened while watching a streaming video clip as well. But I have not noticed it with DVDs, yet !

[snip]

2. You are using a laptop and the power cord is removed, either deliberately or because it is not seated correctly. The display dims by three notches. It goes back to full brightness when external power is restored.

Thanks for the reply, I realise that my energy saver settings would dim the screen, but perhaps I should have explained my problem a little better, it dims for maybe less than a second, but recovers itself almost immediately without any mouse or keyboard input.

That probably eliminates 1, but a dodgy power cable or power supply providing intermittent power could cause 2 without any input from you by rapidly switching from power supply to battery and back. You can eliminate that as a possibility by switching off "Reduce the brightness of the built-in display when using this power source" in System Preferences > Energy Saver > Settings for: Battery > Options. Or you could just run it off battery, he realises after typing all that :)

If that doesn't work, I'd try to find a way to reliably reproduce the problem. A particular video clip might do the trick, but it might not. Decoding video is reasoanbly hard work for the processor and video chip, so try running whatever applications you have which will stress the machine a bit. To give the processor a workout, open Terminal from Applications > Utilities and type in "yes" <return>. Hit ctrl-c (and wait a second or two) to stop it. A 3D game will give the graphics chip a workout, as would opening lots of windows and banging the Expose keys repeatedly.

Tim

Message #5 - Posted 2007/02/05 - Phillip Walters

Tim Auton wrote:

Phillip Walters wrote:

Dorian Gray wrote:

Previously, Phillip Walters wrote:

I have a Macbook Pro 17" C2D, and on the odd occasion the screen dims slightly for a split second, then goes back to the preset brightness level. This only seems to happen while watching video, eye tv recordings especially, just happened while watching a streaming video clip as well. But I have not noticed it with DVDs, yet !

[snip]

2. You are using a laptop and the power cord is removed, either deliberately or because it is not seated correctly. The display dims by three notches. It goes back to full brightness when external power is restored.

Thanks for the reply, I realise that my energy saver settings would dim the screen, but perhaps I should have explained my problem a little better, it dims for maybe less than a second, but recovers itself almost immediately without any mouse or keyboard input.

That probably eliminates 1, but a dodgy power cable or power supply providing intermittent power could cause 2 without any input from you by rapidly switching from power supply to battery and back. You can eliminate that as a possibility by switching off "Reduce the brightness of the built-in display when using this power source" in System Preferences > Energy Saver > Settings for: Battery > Options. Or you could just run it off battery, he realises after typing all that :)

If that doesn't work, I'd try to find a way to reliably reproduce the problem. A particular video clip might do the trick, but it might not. Decoding video is reasoanbly hard work for the processor and video chip, so try running whatever applications you have which will stress the machine a bit. To give the processor a workout, open Terminal from Applications > Utilities and type in "yes" <return>. Hit ctrl-c (and wait a second or two) to stop it. A 3D game will give the graphics chip a workout, as would opening lots of windows and banging the Expose keys repeatedly.

Tim

The fault occurs on running battery, I have'nt noticed it on mains, so could be something to do with the energy saver settings on battery, I have not noticed it with up to 8 windows open and can swap between them with no problem. Will try to reproduce reliably as you suggest.

Cheers

Phil

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