[Coco] [HW] Coco 3 video output corrupt when using cart port

[Robert Gault]

Mike Pepe wrote:
> I would also suggest using one of the other outputs to see if the
> problem follows the CoCo or is specific to that particular monitor.
> 
> 1702's are pretty vintage these days.
> 

Or just leave the monitor on for an hour with the Coco3 off. Then turn 
on the Coco3 and see if the problem is still present.