CGA ATI Resolution Help ARCADEOSD modes

[thewebexpert]

I have searched over the board and cannot find an answer, I hope I am not asking a duplicate question.
 
I have a 25" xenith WG arcade monitor (g-a63adg25x) from a TNMT cab, an ATI video card, using a JPAC card.

I am running the Calamity drivers, and 640x480i works perfect, however most of the modes available on ArcadeOSD do not work, the JPAC does not sync and there is no picture and compressed noise. a lot of the modes marked "native" but are gray work just fine, almost all custom modes in AracdeOSD do not work.

I have tried to run VMMaker, with the standard CGA settings, which does not produce better results.

I am confused. And I am assuming because I am seeing resolution modes that do not work, that would be why mame/grovy etc all screw up on a lot of games..

[Calamity]

Hi thewebexpert,

There may be a combination of issues going on there, the fact that the jpac doesn't sync is rather suspicious as this device is very tolerant provided you feed it with frequencies between its defined ranges.

Please concrete the model of your ATI card, it could be one of the chipsets that don't allow for low dotclocks.

[thewebexpert]

Thank you for the reply. The video card is a x1550 series ati radeon card

It is wierd, I can do res modes like 320x220 60p and 75p  but 320x240p does not work

512x448 60i works too

help! thanks

[Calamity]

Thank you for the reply. The video card is a x1550 series ati radeon card

Bingo, that's one of the dotclock problematic models.

It is wierd, I can do res modes like 320x220 60p and 75p  but 320x240p does not work

Well 320x220 60p CUSTOM shouldn't work but anyway.

You need to define a min dotclock value both in vmmaker.ini and mame.ini, so that low horizontal resolutions are scaled. That's the only workaround. Search this forums, there should be some topics explaining this.

[thewebexpert]

figured it out. video card sucks sh*t ... found an older x500 card and it works perfect. sorry to be a pest.