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Re: powerbook wakeup/boot display issue



On Wed, 2007-01-17 at 22:49 +0900, Joseph Sanger wrote:

> http://forums.gentoo.org/viewtopic-t-473838.html
> 
> What do you think?

I don't think that makes sense. The higher the applied voltage is, the
more twisted the crystals become and the pixel is black. So how can a
white display have any adverse effect when that means that there is no
voltage on the pixels?

To me, the other explanation (backlight on, lcd off) makes more sense
because I imagine that if you turn off the lcd then it'll stop
refreshing and start losing voltage in the pixels meaning it'll slowly
go to white, probably from the edges to the center since the electrons
have to flow out the edges...

The cite you linked is actually taken from
http://tstotts.net/linux/gentoopb.html but that has no explanation of
what should cause this "process of frying the video card and panel
permanently!"

But keep in mind that I don't have any idea about electronics. Maybe we
should bring this question to someone more knowledgeable.

> BTW I forgot to mention, it sometimes happens on boot as well (maybe 1 
> in 10?). Once it happened just before the penguin appears at the top of 
> the screen, but usually just before the debian login window.

The first instance is when the kernel driver initialises the panel, and
the second when X starts up, so those points clearly make sense. I
haven't seen the effect in a long time though I did see it a few times.

johannes

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