Dreamcast VGA box problem

[Vlcice]

I've noticed that my DC VGA box is showing what looks like colour dithering in all 3D games. Is this normal? I would have thought that DC games would have a higher colour depth and wouldn't need to dither. Could this be a problem with my VGA box?

I don't have it hooked up right now to check for sure, but I'm pretty sure the box's s-video out shows the same thing. I don't have any other DC video cables.

Here's what it looks like, using the sky from Shenmue.

http://img695.imageshack.us/img695/5149/dithering.jpg

[JimmyDean]

A 200uf cap needs to be on each of the RGB lines, or you get a screen like that.

[Vlcice]

Oh, okay. So it's a problem with the VGA box? I don't have any electronics skills, so maybe I should just get a new one.

[PapaStu]

Moved to tech & resto

[Vlcice]

Sorry, didn't realize it belonged in this forum.

Just to check - the 200uf caps you're talking about, are those something that need to be modded in the system, or is it something in the VGA box?

[JimmyDean]

It'd probably be easier to put the caps in the VGA box. There's a certain polarity you have to know, though. I forgot it, sorry...

[jb143]

If it's just soldering in 1 cap to each of the 3 lines, then that's pretty simple for a beginner to do. The caps will have polatiry marked...usually +. I have not done this mod but I'm fairly certain that you would just stick 1 cap between each signal line and ground with the negative leads connected to ground. That's pretty much the standard way to install a filter cap.

[pdcool27]

I am having the same problem, can anyone post pics of where to solder these caps or if i have to replace the ones already in the vga box

[pdcool27]

ok I tried those caps and they did nothing to help the picture btw im speaking about dithering on the dreamcast bootup logo and the backgrounds on code veronica, re3, and re2

[gravitone]

The image issue you describe in shenmue is not a bad signal artifact but entirely caused due to the 256 color paletted texture that shenmue uses for the skydome. This whole thing is made worse by the fact that the resolution for said texture is very low. (256x256 if memory serves me right). Why is it done? well, shenmue uses heaps of textures, so the 8bit paletted format was the way to go to save its sparse 8megabytes of ram. It also allowed the dawn/day/dusk/night cycle to work by simply adjusting the palette values. You can also be sure that the very basic texture compression algorithm used is causing some display artifacts when a 256x256 texture is stretched to fill half the screen.

[pdcool27]

ok that explains one game but what about all of the others