Macbook Pro freezing when external displays connected

adam · 09-23-2010, 08:22 AM

Hi,
I am new on this forum but had a problem with my displaylink products.

I am using a 2010 model i7 Macbook Pro. I have 3 24" BenQ monitors connected via 3 display link DVI units which feed into a Belkin powered hub.

I have read the article on running the debug tool after the problem occurs but my issue means that I cannot do that straight after the problem. This is because when I plug in the hub, my Macbook freezes. I can move the mouse but cannot access anything, even via shortcut keys. I am forced to hold the power button down and then start the machine up again. This issue does not occur all the time and I have not found a pattern to it yet.

Would you like me to run the debug tool after the machine has started back up?

Thanks for any help.

Carlo · 09-23-2010, 12:53 PM

Hi Adam,
The debug tool just after the boot will contain all the useful information so it's fine.
However given the usage pattern and the kind of but it's possible that the hub is not supplying enough power (just) for the three adapters and they behave erratically confusing our driver and/or the USB stack.
Even a power supply with an output of 2-2.5A might not be enough for three adapters, depending on the adapters and the resolution of the screens.
I'd first of all try to connect just two devices to the hub and the third device to a separate USB port. If you can't reproduce the issue then I'd look for a bigger power supply for the hub.

adam · 09-23-2010, 09:12 PM

Hi,
Thanks for the quick reply. Looks like you were right. Two adaptors through the hub work fine but 3 and it cannot cope. Can you recommend a hub that is suitable?

On another note, is there a way of getting the Macbook to remember the display arrangement? Every time I plug the monitors in they are in the wrong order and sometimes it wipes the wallpaper on one.

Thanks for any further help.

Carlo · 09-23-2010, 10:43 PM

About the hub probably a 7 port hub will have a bigger power supply. You can also change just the power supply, that usually works.

About the screen configuration I have a suspicion that having three identical displays might be the cause of the confusion. Might be a bug or somethign wrong with the displays. Without having to attach the full logs can you just compress the /Library/Application Support/DisplayLink folder and attach it to a reply?

adam · 09-25-2010, 10:51 AM

Hi,
I have had a look and don't have a DisplayLink folder at that location (I have attached a screenshot). I am using the beta drivers for mac 1.6b2 (24548).

I have found a Dr Bott 7 port hub which states it provides true 500ma per port. The hub I have also apparently provides that but the Dr Bott one seems more convincing as it's the main selling point:
http://www.computeruniverse.net/products/e90157551.asp

Carlo · 09-25-2010, 11:57 AM

For some reason the screenshot is not visible. In any case you're probably looking at the Library folder in your user home. You should open the hard drive root folder instead ('Macintosh HD' in the DEVICES on the left navigation bar if you haven't changed the name) and look for the Library folder there.

About the hub, some adapters use more than 500mA especially when showing high resolutions. Most bus powered hard drives do the same, and minimons etc.
That's why many computers are able to provide even more than 1A on the USB ports nowadays.

adam · 09-26-2010, 06:35 PM

Sorry, I was looking in the wrong place! I have attached the zip of the folder as requested.

Is there a hub that you know of that can provide that much current per port?

Carlo · 09-26-2010, 10:14 PM

All the displays have unique EDID and the three adapters have unique serials, the layout should be remembered correctly. And there is still the wallpaper problem to explain. Can you send me the full logs please?

Please use the tool at http://www.displaylink.com/support/ticket.php?id=269
You can attach the file here or send it through http://www.displaylink.com/support/ask_question.php

About the hub I really can't recommend one. I Googled a bit and found a good review of the cheaper Belkin 7 ports hub: http://www.brighthub.com/computing/w...cles/1756.aspx
Amazon (UK) says that it has a 4amp power supply that should be enough.
Again, I can't recommend any and have not tried it!

adam · 09-27-2010, 12:12 PM

Hey Carlo, thanks for your continued help. I have downloaded the tool and will try to get the problem to replicate itself and then pull the logs and upload them here.

Thanks for the information on the hub. I have done a bit more investigating and what is interesting is that I tried another hub I have which provides 2.5A. The interesting thing is that if I connect each monitor in turn and let it fire up, everything is fine. If I connect them all at once, it locks the mac. It's almost like the Mac wants a phased start to the devices.

adam · 09-28-2010, 04:42 PM

Hey again Carlo, I have attached the log as requested. Before taking these logs, I did some various tasks. This included:

Plugging in my USB hub with 2 monitors connected, letting it fire up and settle, then plugging in the third. The monitors displayed fine although they were in the wrong arrangement, so I rearranged them.

I then tried unplugging the hub, switching the monitors off, then plugging the hub back in with all three connected at once (to see if it would still lock up without the monitors actually on). My mac froze and I had to switch it off by holding the power button.

After switching it back on, I plugged my hub in with 2 monitors connected to the hub and they displayed. I then plugged in the third which also displayed. They were again, in the wrong order. I rearranged them, then unplugged the hub and connected it again with 2 monitors connected. This time, interestingly, it froze again (even though normally with just 2 it is ok).

I then unplugged my hub and everything sprang back to life with iPhone and iTunes open for some reason. I plugged them back in and my Macbook froze again. This time, when unplugging my hub my Macbook remained frozen.

I tried some key combos and front row launched. Upon exit, my Macbook was back to life.....strange.

Hope something there is helpful

09-23-2010, 08:22 AM	#1
adam Junior Member Join Date: Sep 2010 Posts: 13	Macbook Pro freezing when external displays connected Hi, I am new on this forum but had a problem with my displaylink products. I am using a 2010 model i7 Macbook Pro. I have 3 24" BenQ monitors connected via 3 display link DVI units which feed into a Belkin powered hub. I have read the article on running the debug tool after the problem occurs but my issue means that I cannot do that straight after the problem. This is because when I plug in the hub, my Macbook freezes. I can move the mouse but cannot access anything, even via shortcut keys. I am forced to hold the power button down and then start the machine up again. This issue does not occur all the time and I have not found a pattern to it yet. Would you like me to run the debug tool after the machine has started back up? Thanks for any help.

09-23-2010, 12:53 PM	#2
Carlo Mac Team Join Date: Feb 2009 Posts: 606	Hi Adam, The debug tool just after the boot will contain all the useful information so it's fine. However given the usage pattern and the kind of but it's possible that the hub is not supplying enough power (just) for the three adapters and they behave erratically confusing our driver and/or the USB stack. Even a power supply with an output of 2-2.5A might not be enough for three adapters, depending on the adapters and the resolution of the screens. I'd first of all try to connect just two devices to the hub and the third device to a separate USB port. If you can't reproduce the issue then I'd look for a bigger power supply for the hub.

09-23-2010, 09:12 PM	#3
adam Junior Member Join Date: Sep 2010 Posts: 13	Hi, Thanks for the quick reply. Looks like you were right. Two adaptors through the hub work fine but 3 and it cannot cope. Can you recommend a hub that is suitable? On another note, is there a way of getting the Macbook to remember the display arrangement? Every time I plug the monitors in they are in the wrong order and sometimes it wipes the wallpaper on one. Thanks for any further help.

09-23-2010, 10:43 PM	#4
Carlo Mac Team Join Date: Feb 2009 Posts: 606	About the hub probably a 7 port hub will have a bigger power supply. You can also change just the power supply, that usually works. About the screen configuration I have a suspicion that having three identical displays might be the cause of the confusion. Might be a bug or somethign wrong with the displays. Without having to attach the full logs can you just compress the /Library/Application Support/DisplayLink folder and attach it to a reply?

09-25-2010, 10:51 AM	#5
adam Junior Member Join Date: Sep 2010 Posts: 13	Hi, I have had a look and don't have a DisplayLink folder at that location (I have attached a screenshot). I am using the beta drivers for mac 1.6b2 (24548). I have found a Dr Bott 7 port hub which states it provides true 500ma per port. The hub I have also apparently provides that but the Dr Bott one seems more convincing as it's the main selling point: http://www.computeruniverse.net/products/e90157551.asp

09-25-2010, 11:57 AM	#6
Carlo Mac Team Join Date: Feb 2009 Posts: 606	For some reason the screenshot is not visible. In any case you're probably looking at the Library folder in your user home. You should open the hard drive root folder instead ('Macintosh HD' in the DEVICES on the left navigation bar if you haven't changed the name) and look for the Library folder there. About the hub, some adapters use more than 500mA especially when showing high resolutions. Most bus powered hard drives do the same, and minimons etc. That's why many computers are able to provide even more than 1A on the USB ports nowadays.

09-26-2010, 10:14 PM	#8
Carlo Mac Team Join Date: Feb 2009 Posts: 606	All the displays have unique EDID and the three adapters have unique serials, the layout should be remembered correctly. And there is still the wallpaper problem to explain. Can you send me the full logs please? Please use the tool at http://www.displaylink.com/support/ticket.php?id=269 You can attach the file here or send it through http://www.displaylink.com/support/ask_question.php About the hub I really can't recommend one. I Googled a bit and found a good review of the cheaper Belkin 7 ports hub: http://www.brighthub.com/computing/w...cles/1756.aspx Amazon (UK) says that it has a 4amp power supply that should be enough. Again, I can't recommend any and have not tried it!

09-27-2010, 12:12 PM	#9
adam Junior Member Join Date: Sep 2010 Posts: 13	Hey Carlo, thanks for your continued help. I have downloaded the tool and will try to get the problem to replicate itself and then pull the logs and upload them here. Thanks for the information on the hub. I have done a bit more investigating and what is interesting is that I tried another hub I have which provides 2.5A. The interesting thing is that if I connect each monitor in turn and let it fire up, everything is fine. If I connect them all at once, it locks the mac. It's almost like the Mac wants a phased start to the devices.