Does it look like this?
Don't plug it in any more. You may burn things up and reduce the value. Every TV that old needs electronic work, so knowing that it has power tells you nothing.
There's no official price book for old TVs, so value is what someone will give you. In my book, it would be somewhere around $100 - $150. Others may disagree. Much of the value depends on whether the picture tube is good, something you can't tell unless you have a picture tube tester.
Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html