Here it is with the blue and red pairs too at 640x480 resolution (That
fixed the random mess).
Sorry, it appears that I may have misled you. I thought your "random
mess" looked like a horizontal sync problem.
I still haven't been able to figure out the
other two wires. I read all the info you provided, though comprehension
was around 30% !
The horizontal and vertical sync signals can be either positive or
negative. I believe that's how the earlier monitors were able to
detect the video mode.
___ ___ ___ +5V ___ ___ +5V
| | | | |_| ~2V
___| |___ |_| 0V
positive negative faulty
sync sync sync
In my particular case, the sync polarity changed from positive to
negative when the graphics card switched from text to graphics mode.
Unfortunately the new card was unable to pull the sync signal down to
0V, so that created a "horizontal tearing" issue for me. I resolved
this by modifying the monitor's circuitry.
Tweaking the "vertical size/height" and "horizontal width" should be
OK, although be aware that multisync monitors may have more than one
height or width setting to accomodate the different H and V
frequencies. I wouldn't touch the linearity controls, though. You may
want to use circles and a crosshatch in your test pattern if you are
making big changes. Be aware that the width is sometimes adjusted by
means of a coil with a brittle ferrite slug.
- Franc Zabkar
