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Old 04-28-11, 09:09 AM   #1
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Join Date: Apr 2011
Posts: 1
Default nVidia Ion and older plasma TV. Can not display at 1080i

My TV is a Philips 50" plasma, that is fairly old hat now. It has 1 x DVI input (and a separate audio 3.5mm input! Audio is via this so no HDMI audio problems). I have built an HTPC from an asus dual core atom with Ion motherboard. I would like to connect this to my TV via the DVI input at 1080i.

The HTPC has an HDMI output, which I connect to the TV with a HDMI->DVI converter and a DVI cable. This same setup works fine at 1080i when I connect to my HD sat box instead of the HTPC.

The TV has 2 modes I can select via a TV menu, PC mode, and HD mode. When in PC mode it uses the DVI input as a VGA connection (well I think so!). When I boot up my installation of mythbuntu 10.10 when in PC (VGA) mode, all works well. I can select various screen sizes via the nVidia config GUI, which I am pretty sure has picked up by the EDID from the TV(The fonts are too small, but that is a minor problem for now!). I can save the EDID from the GUI. There are no options to connect at 1080i, 720p etc. This is as expected as in PC mode the TV will not work at 1080i etc.

When I switch the TV to HD mode and boot up (the sat box works in HD mode), I get a blank display. In HD mode the TV spec says it works in the following resolutions :-

640 x 480i
640 x 480p
720 x 576p
1920 x 1080i
1280 x 720p

I can still SSH into the machine, but the display is blank during/after boot. I think in this mode the EDID data is either not being read, or the EDID data does not contain any of the suitable formats for HD mode.

So, the question is, what do I need to do in order to display at 1080i in HD mode? Can the EDID data be ignored, or not even attempted to be read, and just use a modeline from the xorg.conf file? I am using the latest drivers from the mythbuntu repo.

This same setup worked fine connected to another (much newer!) TV via HDMI-HDMI at 1080p when I 1st built it, so I do not think there are any hardware problems. I will try to post some extracts from the log files shortly.

Any help greatly appreciated.
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