Mac Pro doesnt recognize the display on firewire. Getting short-short-short

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Level 1

5 points

Mac Pro doesnt recognize the display on firewire. Getting short-short-short

Hi!

I recently got a new apple cinema display 20' after my old one
got it's inverter board fault after a power failure.

Now the new display works except for the + and - buttons on the side.
This doesn't really bother me, because the display is already on max brigthess and
I have no intention of turning it lower..

The problem is that I get a very very distracting short-short-short signal from
the little led light at the bottom corner. I think it is because my Mac Pro
doesn't communicate properly on my firewire port. I've looked at what the computer
think is connected to the FW port I plugged the display into and it says "unknown device".

Any suggestions at all for solving this is much appriciated.

Mac Pro, MacBook Air, Mac OS X (10.6.2)

Posted on Nov 29, 2009 4:15 AM

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Answer 1

Best reply

Malcolm Rayfield

Level 7

28,123 points

Nov 29, 2009 4:56 AM in response to CarlBjrk

The display's FireWire connection is only for the FireWire ports on the display, and is not otherwise needed. Three short flashes means "Displays" system preference is not set correctly (1680 x 1050 60 Hz).
<http://docs.info.apple.com/article.html?path=Mac/10.6/en/8806.html>

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Answer 2

CarlBjrk Author

Level 1

5 points

Nov 29, 2009 5:04 AM in response to Malcolm Rayfield

Thanks for the reply!

I think the problems with the + and - buttons not working and
the triple short flashes are related.

Because the display setting are correct, it's just that the display communicates all
non-video-realted IO through the FW connection (such as the adjustment of brightness).
And I think it is thought the FW connection that the display can get the knowledge that the resolution is indeed valid.
Or something like that.. Of course my hypotheses can be completely wrong.. 🙂

As I said.. the screen is otherwise working. I get the correct screen output.
At the moment I'm having a pice of blu-tack on the led light. I really wish I could find a more tasteful solution 🙂

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Answer 3

Nov 29, 2009 5:57 AM in response to CarlBjrk

USB is used for computer control of brightness. Does "Displays" system preference have a brightness slider? It won't if there is a USB problem. Resolution information uses the DVI port. FireWire is not used for anything other than the FireWire ports.

Try running it with its USB cable unplugged. If you're using the correct resolution, and the light still flashes and the buttons don't work, the problem is in the display. If it's not under AppleCare, it's probably not worth fixing. Just put black tape over the flashing light.

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Answer 4

CarlBjrk Author

Level 1

5 points

Nov 29, 2009 6:05 AM in response to Malcolm Rayfield

The display USB hub is working properly. However the display shows no change in light flashing wether I have the USB connection pluged in or not.
Is is possible that there is some problems with the drivers?

Since I just got this new display as a replacement (I had to pay the price for a new one) I think it might be under AppleCare..

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Answer 5

Nov 29, 2009 8:56 AM in response to CarlBjrk

If the display's brightness buttons don't work with USB disconnected, the problem has to be in the display. You could try it on a different computer to confirm it. If you just got it from Apple, they should fix it for no charge. Since that model was discontinued about a year ago, they may have sent you a refurbished unit that wasn't fixed properly.

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Answer 6

CarlBjrk Author

Level 1

5 points

Jan 6, 2010 10:47 AM in response to CarlBjrk

Thanks for all the help.
I'd like to give an update!

Until now I've took the advice to just block the light (I used blu-tack.. unfortunatly tainted green).

What I didn't mention in my original problem statement, (I didn't think it could be of relevance,) was that I actually hadn't used the power cable that came with the adapter. With the power cable, I'm refering to the cable between the adapter and the wall socket. I thought that the cable naturally must really just be three separete wires with no electronic components involved whatsoever.
I might have been wrong or the material itself had effect because I just recently replaced this temporary cable I've been using (,the temporary cable is suppose to supply power to and old, no unused iMac G3,) and suddenly, all the problems mentioned with the flashing led lamp and the non-reacting side-buttons magically disappered! 🙂

Again, thanks for all the effort in trying to help me even though it was my own
fault all along!

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