TV Problem (No Picture)

I realize that this group concens high def TVs, but maybe someone will
know the answer to this.  I recently connected a Zenith SR3273DT tube
TV that I haven't used in a long time to a cable output and there's
sound, but no picture.  My first thought was that the tube is shot
BUT, when I press the menu button, setup choices appear on the
screen.  Would words appear if the tube is blown?  Unfortunately, I
can't find my manual to guide me thru setup, so maybe there's
something I need to select to get a picture?