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Brightness lines scrolling from bottom to top of screen?
http://forums.linhes.org/viewtopic.php?f=2&t=16315		 Page 1 of 1
Author:  cheesebourgeois [ Mon Sep 03, 2007 9:57 pm ]
Post subject:  Brightness lines scrolling from bottom to top of screen?
Hi, I am a new Linux user, this is the first distro I've ever used. I got knoppmyth purely to function as a rom/emu/internet radio/jukebox center for my house. I have a regular 20" CRT tv with s-video inputs, no fancy component cables or HD nonsense. When I hook up my computer to my TV, I get these thick, couple inch thick lines that scroll up my TV, wherever they pass becomes brighter than everywhere else and it is real annoying looking. They also stick around for a while, even when I'm not on the video channel on which the computer is plugged in. For example, if I watch a DVD, the lines are still present until I've turned off my TV for a while. I fear this may become permanent, so I am coming here for help.

Specs of comp:
750 mhz Athlon with 256 MB ram, unknown motherboard (someone gave it to me)
GeForce FX 5200 (this: http://www.newegg.com/product/product.a ... 6814130210 )
Currently using onboard sound, not that it matters for this problem
Knoppmyth distro: R5F1

I went into the xorg.conf file and set my TVOutFormat to SVIDEO and messed with the refresh rates like it says to in the guides, but this problem still occurs. It really scares me that it lasts until I turn off my TV for a while. If anyone can help, please go ahead.

edit: I forgot to mention that I have it set to NTSC, and am in an NTSC region with an NTSC TV
Author:  cecil [ Mon Sep 03, 2007 10:13 pm ]
Post subject: 
Could it be your TV? Does it still occur w/o the computer attached?
Author:  cheesebourgeois [ Mon Sep 03, 2007 10:28 pm ]
Post subject: 
cecil wrote:
Could it be your TV? Does it still occur w/o the computer attached?


The problem has never occurred before plugging my computer into my TV, and the problem subsides after having the computer turned off for a bit, not displaying anything (still plugged in, not outputting anything)/
Author:  stevetv [ Tue Sep 04, 2007 4:46 am ]
Post subject:  Re: Brightness lines scrolling from bottom to top of screen?
cheesebourgeois wrote:

I went into the xorg.conf file and set my TVOutFormat to SVIDEO and messed with the refresh rates like it says to in the guides, but this problem still occurs. It really scares me that it lasts until I turn off my TV for a while. If anyone can help, please go ahead.


hi there. you dont need to play with modelines or refresh rates when using tv out through a svideo (or composite or componenet).

i dont believe that the knoppwiki section on tv out to crt tv's is particularly correct.. im referring to this page
http://www.knoppmythwiki.org/index.php? ... Transition

you need only to tell xorg that youre connecting to a crt tv through the tv out, a metamode (or it can select it's own) and your region.

check out this thread.. specifically the 3rd post.
http://www.mysettopbox.tv/phpBB2/viewto ... ght=hd720p

its specifically related to hd via component.. but relevant to you. obviously swapping the tv standard to NTSC-M

you'll also need to select a TVOutFormat ... which will be SVIDEO.


id suggest, if you havent, using the xorg.conf.nvidia.tv.out.sample (or similar) file.. it should work straight out of the box. .well.. at least it does for me. unless you tv is ancient old.. id hope it to work for you also

its located in /etc/X11/

err... hopefully this isn't overly simplistic.. sorry if it is..i dont mean to be patronizing.

as root do this

Code:
mv /etc/X11/xorg.conf /etc/X11/xorg.conf.bak
mv /etc/X11/xorg.conf.nvidia.tv.out.sample /etc/X11/xorg.conf
reboot
Author:  mjl [ Tue Sep 04, 2007 1:13 pm ]
Post subject: 
Hi,

Typically the slow moving lines up the tv screen is referred to as a "hum bar" In the old days it was often accompanied with an audible "hum" hence the name. This is frequently caused by a ground loop between two different power sources, very common in older homes.

If everything is powered from the same outlet source then usually the problem will vanish. (power strip) Note that any and all external connections come into play, cable / antenna connection, speaker amplifier, and now your KM machine.

As you watch the hum bar, disconnect wires until it vanishes, then you can probably figure out what to rearrange for a permanent fix..

Also, be aware that if there is a ground loop, you could receive a little "tingle" if you become a part of the electrical path, just enough to get your attention for sure.

Mike
Author:  cheesebourgeois [ Thu Sep 06, 2007 4:59 pm ]
Post subject: 
Thanks! You've fixed my problem :)
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