[mythtv-users] Stupid S-Video Problem Continues

[Brian Wood]

On Jun 8, 2006, at 9:19 AM, Will Constable wrote:

> Yea—I was very aware of the ‘rule breaking’ I was doing… I  
> origionally planned on putting the computer by the TV and running  
> network to it.  Lets just say that wouldn’t fly for aesthetic  
> reasons—the computer is a piece of junk with noisy drives and fans,  
> and an ugly case—it belongs out of sight and the room the TV is in  
> has been decorated nicely and everything… So I decided to try the  
> video and audio—I really hope I can make it work—before I  
> terminated the cable as it is now, I put s-vid ends on the two ends  
> of the spool of cat 5 and ran the whole 100 ft from my main myth  
> server to the TV and found the picture to be fine; that’s a Geforce  
> 4 ti4200 while my new box uses an ‘el cheapo’ mx420 that was lying  
> around—it could be anything you mentioned regarding ground loops/ 
> vga signal differences, but my first try will be a friend’s geforce  
> fx that’s lying around at work.. if that fixes things, I’ll just be  
> happy at that.
>
>

As I said, different video cards will behave differently simply  
because of slight differences in the crystal oscillator frequencies,  
sometimes.

If you are handy with electronics here's trick that can sometimes work:

Locate the quartz (actually tourmaline) crystal on the card, there  
are usually 2 or more of them so you might have to try this with each.

Solder a short (1 inch or so) piece pf #30 or 32 AWG Kynar wire (the  
kind used for wire-wrapping) to each side if the crystal.

Twist the two wires together for 2 or 3 turns, making sure the  
exposed metal ends do not touch each other or anything else.

See if it makes a difference, if not try adding or subtracting a turn  
or 2, or moving the wire towards or away from the circuit board.

If you get to where things work the way you want, put a dab of RTV  
silicone over the whole thing to protect and stabilize it.

What you are doing is creating a "gimmick" capacitor of a few  
picofarads, thus shifting or "trimming" the exact frequency of the  
crystal a little bit. Note that you can only move the frequency down  
by this method, not up, which requires a different sort of hack.

Obviously I can't be responsible for any damage you might do to your  
card, your self or your manly self-image by trying such things, but  
they have worked for some folks.
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