The power icon in the lower right portion of my three-month old 17"
Apple Cinema display started blinking recently and I cannot determine
what to do about it.

I went to the Apple Support site and found an FAQ which very closely
described the problem, as follows:

"If you see a repeating sequence of three short flashes, the monitor
is detecting input in the wrong video format. Check that your monitor
is compatible with your graphics card and that you've installed the
correct display software, if your monitor came with installation
software."

(The blinking is really two short blinks followed by one long blink,
and about five seconds of no blinking.)

I have no idea how to check to see if the "monitor is compatible with
(my) graphics card." And if it IS incompatible, I don't know how it
got that way as it was fine until I upgraded the OS from 10.2.6 to
10.2.8 or perhaps most importantly, how to restore that compatibility.

Also, it may be my imagination but the monitor seems a bit dimmer
today, although the brightness control in the Preferences panel, is
maxed out.

I'm using a G4 Titanium PowerBook. The computer and the monitor were
put into service simultaneously. The monitor did NOT come with
installation software.

Is it possible to un-install OS 10.2.8 and revert to an earlier OS?
I've downloaded the OS 10.2.6 Update. Is there any risk to simply
installing it...whether or not it repairs the display light blinking
problem?

Thanks!

Ed Flesch

I had the same problem with my Apple 17" Cinema Display. 
Unfortunately, I don't have good news for you and hope you are under
warranty.  Two short blinks followed by one long blink means that one
of the backlights has gone out, which also explains the dimness.  I'd
be willing to bet that the dimness is concentrated mostly at either
the top or the bottom, as I believe there are two backlights that
illuminate the display.

Quoting the Apple knowledge base article at:

http://docs.info.apple.com/article.html?artnum=51810

"If you see a sequence of two short flashes and a long flash, the
monitor is detecting a problem with a backlighting lamp. Contact an
Apple-authorized dealer or service provider."

So I hope you're in your first year or you have AppleCare!

You might try looking through the website MacInTouch to see if anyone
has reported a similar problem (and perhaps solution).  The 10.2.8
saga reports start here:
http://www.macintouch.com/mosxreader10.2pt74.html

A nice potential solution would be to install Panther (10.3) when it
comes out tomorrow!  )

Also, can you plug the monitor into another mac (ideally perhaps a G3
Powerbook) to see if continues to blink?