[mythtv-users] Stupid S-Video Problem Continues

Will Constable willconstable at gmail.com
Thu Jun 8 16:18:27 UTC 2006


Some very helpful suggestions!  I am interested in this idea of tuning the
crystals-might not come to that if the card im taking home today does the
trick, but I guess this way could save me from having to buy anything short
of a few inches kynar wire.  A few questions:

 

1)     Last night I tried putting ceramic magnets near and on the s-video
plug to see if this would somehow shield it from weaker oscillating fields
generated by the vga cord nearby or the card's internal electronics.. don't
think it made a difference but I was running up and down the stairs trying
to notice the difference as I made changes. not all that reliable.  

2)     If I try the crystal trick-first of all, is the crystal (only one of
these on the geforce FX board I have on my desk here) a little silver, oval
shaped canister with two connections soldered to the board?  If so, I would
simply solder a wire to each of the two pins on the back and then experiment
with number of twists?  Leaving the insulation on, of course.

 

Thanks

Will

 

 

  _____  

From: mythtv-users-bounces at mythtv.org
[mailto:mythtv-users-bounces at mythtv.org] On Behalf Of Brian Wood
Sent: Thursday, June 08, 2006 11:41 AM
To: Discussion about mythtv
Subject: Re: [mythtv-users] Stupid S-Video Problem Continues

 

 

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.

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://mythtv.org/pipermail/mythtv-users/attachments/20060608/e9cd3315/attachment.htm 


More information about the mythtv-users mailing list