The NEW Build Your Own Arcade Controls

Main => Monitor/Video Forum => Topic started by: quadmasta on May 06, 2005, 08:31:03 pm

Title: What would cause these problems?
Post by: quadmasta on May 06, 2005, 08:31:03 pm

I bought a converted R-type cabinet and the monitor gives a good picture just has a few issues.  There's a blue layer around the whole perimeter of the screen and there's some horizontal lines across it but only at the top.

Title: Re: What would cause these problems?
Post by: AlanS17 on May 07, 2005, 12:05:07 pm

If you were going to make me guess I'd say it's magnetic interference. To tell the truth, though, I don't honestly know.

Title: Re: What would cause these problems?
Post by: dabone on May 07, 2005, 02:40:40 pm

Damaged shadow mask???


Later,
dabone

Title: Re: What would cause these problems?
Post by: quadmasta on May 07, 2005, 11:53:28 pm

I forgot to mention that grid test pattern is from a Neo Geo board.  Someone told me that all Neo boards do that but I'm not sure.

Title: Re: What would cause these problems?
Post by: RayB on May 09, 2005, 02:19:09 pm

Looks to me like the blue is over-driven.

Do you have a test pattern with all colors present on screen at the same time?

Title: Re: What would cause these problems?
Post by: MonitorGuru on May 09, 2005, 02:55:38 pm

You're overscanning the vertical on the top causing a fold-over of the test pattern lines making for the extra blue lines appearing stretched out at the top of the screen. Shrink the vertical with the VSIZE control to make it all fit and the extra lines will disapppear.

As far as the strange blue edge... are you sure the test pattern generator isn't doing that?  The only other thing that could possibly cause that is some really wacked up convergence rings AND additional magnetism around the neck or back of the tube that would not be allowing the RED and GREEN guns to deflect to the entire width of the screen.

Either that or the edges of the Red and Green grids are toasted (the grids help propel the electrons to the front of the tube). However that would be very very unlikely.

If this is indeed the problem of the tube and not the pattern being generated, Ken will have to help on this one!