I bought generic brand vga converter box to watch computer on old Toshiba tv (not HD ready but should't matter, i think). I have mini-display port cable to VGA, then that's hooked to converter box, which is hooked to VGA to component (RGB) cable to back of tv, and all I get are wavy purple lines when I move browser windows to the extended screen. basically no image. It doesn't help converter box has minimal instructions, on most amazon reviews for product, they specify what switches to hit and there's little problem. At least they get an image at all. I have everything connected before turning on Macbook Pro, and reduced resolution to 800 X 600 on MBP, still nothing. Please help!