Hello,
I have two old Atari XEGS game consoles (both showing the same
problems). When I plug the consoles in and turn it on the image on the
TV is vertically scrolling.
After leaving the consoles on for about 10 minutes to half an hour the
image on the screen stabalises. There is still some vertical scrolling
bars (They are about a third of the screen). These bars don't hide the
picture, they just lighten whatever is behind it.

I have plugged in one atari and let it warmed up then changed the
cables over to the other atari and the image is stable there too which
I think means it is the power supply.
I have tried getting out my multimeter and opened up the Atari and
checked the voltage and amps from the plug when the image is scrolling
and later when the image is stable but I'm getting the same readings.

I hope someone here can help me.
Thanks,
Jim Tink