Solved

Strange Display / Screensaver Problem

Posted on 2011-03-21
8
377 Views
Last Modified: 2012-05-11
Hello!

I'm having a strange problem with an Ubuntu machine connected to an LGE flatscreen TV via RGB / VGA cable. I don't know if it's a screensaver or a power saver problem, but after 10 minutes on, the screen will black out and show a "no signal"-on-a-black-screen screensaver.

Then, when I switch the TV to another channel and back again to RGB input, the Ubuntu screen will come back, but will go black again after 10 minutes.

There is no input device connected to the Ubuntu machine (i.e. no mouse, keyboard).

I have Ubuntu configured to capture a screenshot every 15 minutes and have it uploaded to one of my web servers. According to the screenshots, everything is fine, but yet the screen is showing "no signal" on a black background.

"/apps/gnome-power-manager/timeout/sleep_display_ac" is set to "0" (never)

I also had dpms disabled like so:
/usr/bin/xset -dpms -display :0

Open in new window


I'm now going to try and enable dpms but set all the timeouts to 0 like this:
/usr/bin/xset -display :0 dpms 0 0 0

Open in new window


I'm not sure if that will work though. Is there anything else I can try?

I'm sure it's not a problem with the TV itself because I had a different Ubuntu machine connected to it recently, and I didn't have this problem. I had to replace it because of a hardware fault.

Thanks for any help in advance!
0
Comment
Question by:Julian Matz
  • 4
  • 3
8 Comments
 
LVL 34

Assisted Solution

by:Duncan Roe
Duncan Roe earned 125 total points
ID: 35188040
The normal way of power-saving is to drop sync. A TV might well interpret that as "No Signal" - in fact my monitor does but unlike your typical TV it goes quiet after a few seconds. Interesting that changing your TV channel wakes up the Ubuntu X server - I have no explanation for that.
0
 
LVL 18

Assisted Solution

by:TobiasHolm
TobiasHolm earned 375 total points
ID: 35188147
Hi!

Maybe there's a setting in the TV that dims the screen if the picture hasn't changed in 10 minutes? Does the picture change during the 10 minutes?

Regards, Tobias
0
 
LVL 18

Assisted Solution

by:TobiasHolm
TobiasHolm earned 375 total points
ID: 35188169
Also, can you try connecting another screen to the computer and see if that turns off in 10 minutes as well?

Regards, Tobias
0
 
LVL 21

Author Comment

by:Julian Matz
ID: 35192017
The picture is constantly changing. It shows a sort of looped slideshow of images and video. It's basically a digital information display. I can't connect another screen. Well, I could, but it would be a big hassle.

I need to check again to see if enabling dpms worked. I didn't get a chance yesterday to investigate, but will try and find out today.
0
IT, Stop Being Called Into Every Meeting

Highfive is so simple that setting up every meeting room takes just minutes and every employee will be able to start or join a call from any room with ease. Never be called into a meeting just to get it started again. This is how video conferencing should work!

 
LVL 18

Assisted Solution

by:TobiasHolm
TobiasHolm earned 375 total points
ID: 35192481
Is the slideshow running on the web? Or do you have à special app for it? If it's a webb app you could try booting an Ubuntu Live CD and see if the screen blacks out after you have removed the screen power save/screen saver in Ubuntu.

Regards, Tobias
0
 
LVL 21

Accepted Solution

by:
Julian Matz earned 0 total points
ID: 35316392
Sorry for the delay. It has been a little difficult to test and troubleshoot in the production environment, but from what I can tell, it's now working fine.

It looks like the following command actually did fix the issue:

/usr/bin/xset -display :0 dpms 0 0 0

So, setting everything to 0 seems to be preferrable over disabling dpms completely.
0
 
LVL 18

Expert Comment

by:TobiasHolm
ID: 35316653
julianmatz, you can select your own comment as the solution to close the question.

Regards, Tobias
0
 
LVL 21

Author Closing Comment

by:Julian Matz
ID: 35356950
I appreciate the help, thanks!
0

Featured Post

Do You Know the 4 Main Threat Actor Types?

Do you know the main threat actor types? Most attackers fall into one of four categories, each with their own favored tactics, techniques, and procedures.

Join & Write a Comment

Little introduction about CP: CP is a command on linux that use to copy files and folder from one location to another location. Example usage of CP as follow: cp /myfoder /pathto/destination/folder/ cp abc.tar.gz /pathto/destination/folder/ab…
The purpose of this article is to show how we can create Linux Mint virtual machine using Oracle Virtual Box. To install Linux Mint we have to download the ISO file from its website i.e. http://www.linuxmint.com. Once you open the link you will see …
Connecting to an Amazon Linux EC2 Instance from Windows Using PuTTY.
Get a first impression of how PRTG looks and learn how it works.   This video is a short introduction to PRTG, as an initial overview or as a quick start for new PRTG users.

757 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

20 Experts available now in Live!

Get 1:1 Help Now