Noob question - Donkey Kong resolution with Arcade VGA

[hullcitytiger]

Hi all.

I've just acquired a ready built MAME cabinet running GameEx (JAMMA cabinet with PC connected up with Ultimarc JPAC and Arcade VGA) so I'm not completely au fait with exactly how it all works TBH. I've owned upright arcade games before but my computer expertise is rather limited.

The cabinet is set up with the 15khz monitor set vertically to play games such as Galaxian, Terra Cresta, Slap Fight, Commando, Flying Shark (these are some examples of what I have in my favourites already ). Everything so far has displayed and played OK until I tried to launch Donkey Kong. When this game boots up, half of the picture on screen is missing. I can't see the right hand side or the top of the picture as this has all been shifted off the screen. It's the same in all versions of Donkey Kong too.

I'm guessing this is something to do with the resolutions being incorrect, although I'm sure Galaxian and some of the other games I've tried are a much lower resolution than the default 640 x 480 settings I seem to have set. The options are set up to use Arcade VGA settings I believe.

Can anyone tell me exactly what I need to change in the options to be able to play this game (and hopefully all the others still) without any trouble.

Thanks

Derek

PS. I will post a pic of my MAME setup tomorrow although it's nice and simple, just how I like things.