This is a known problem that's been discussed a bit before (I think occurs on all Cruis'n games)... I believe the issue is actually a combination of the LCD converters and synchronization between the two cabinets. Presumably the two cabinets synchronize periodically, which probably causes a small jump in the video sync... which an analog monitor would basically ignore. But the LCD converter flips out when it sees it and loses sync.
To confirm that's the problem, change which side is master/slave, and the jumpiness should switch to the other one. Since the master/slave setting is saved on the board, that's why the problem followed the board. I'm not sure that there's a fix for it, other than go back to CRT, or don't link the cabs (or maybe there's a model of monitor or converter that doesn't have problems with the goofy sync).
Edit - a couple links where it was previously discussed:
Working on two Cruis'n USAs at a local arcade in attempt to find out why these two will not link. The situation is both units will not link regardless and whatever cab is the slave machine will have its respective monitor cut out every few seconds. For example, left cab is master and right cab...
forums.arcade-museum.com
I'm looking for help here. I have a pair of cruisin exoticas and the one side with an LCD monitor blanks out every so often. I believe it's an issue with the PCB as I plugged in a known working monitor and it exhibited the same behavior. Basically if you're in attract or game mode every minute...
forums.arcade-museum.com
DogP