You can use TV Out on i.MX27ADS board by following these steps:
See the image before of this process:
And after this process:
See the image for more details:
Add to your Linux command line (in Redboot) the following parameter:
video=mxcfb:TV-NTSC
After this modification, the video signal will operate at 27MHz, that are applicable just with TV-OUT card. The LCD card will not work at this frequency.