I just got a sega saturn through a trade and the guy said he had it previously modded to play japanese games via a little switch on the side but he said it only plays US games now.

anyway, when i plug it in with the RF switch, the screen blinks. The system works and boots up and displays the 'enter time / date etc' screen (i do know it needs a new battery). but as it's working, the screen will blink (or pulsate) continuously as i'm doing whatever it is i'm doing on the system.

Could it be a problem with the system internally? or does it have to do with the battery? or maybe does it have anything to do with the RF switch (it's 3rd party and looks like the wires have been pulled harshly at one point)