yes it should give a stable screen almost immediately,if it doesn't try different combinations on your sync in line on your jamma harness. for instance i have a WG K7191, for a jamma game it only requires H- (from the monitor chassis)to be hooked up to the sync line on the jamma harness for a stable picture, However, when running it through a jpac i need the H- AND V- to be connected to the sync line of the harness. Then it was just a matter of fine tuning the adjustment knobs. is it horizontal sync (screen looks like its tearing itself to shreds) or vertical sync (cnstant rolling)--just checking.