[mythtv-users] DVI and RGBHV connections

William wmunson at rochester.rr.com
Wed Mar 23 21:31:51 UTC 2005


> I also read a thread in mythtv mailing about interlace bug 
> not evident in 
> VGA port. So, here it is, I was already happy before when I 
> was using DVI 
> but I'm ecstatic now with my new connections, RGBHV and that it's a 
> homebrew. Please see 
> http://restricted.dyndns.org/hookingpc2hdtv.ht> ml for 
> more 
> information.... 
> 

Please be aware that the info you are presenting in that page is somewhat
wrong. The pin out is correct but there is a issue with the signal levels
presented to your tv. The drive levels put out by the VGA connector are
higher than the maximum level allowed by the RGBHV spec. To protect your tv
and to improve the color and saturation of your picture you need to place a
75 ohm resistor in series with all five signals (RGBHV). This should be done
as close to the VGA connector as possible.  This does two things. 1 - It
presents the 75 ohm cable with a 75 ohm drive impedance and 2 - It reduces
the peak to peak voltage to be close to the spec. This may save you from
blowing out the input to your tv. The resistors can be very low wattage, 1/8
watt or smaller is fine.

PS - I use RGBHV on my system with a homemade cable and its by far the best
picture I have ever gotten driving the tv with a computer.

Bill




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