Play Station 2 problem.?

I got a PS2 from Dubai, UAE and I lived in Pakistan. Over there the voltage is 220 volts. I used it for 2 years then I changed it's lens because it's lens had become faulty. It still worked. When I came to USA where the voltage is 110 volts, the PS2 played the games in black and white. Only some games are colored. plzz tell me why this happens and any solutions.