One of my first TVs had vacuum tubes. When it failed, you took he tubes out and tested them at a drug store or radio shack for a failure. You could also take it

One of my first TVs had vacuum tubes. When it failed, you took he tubes out and tested them at a drug store or radio shack for a failure. You could also take it to a repair store or call a rech to come. Very few vacuum tube tvs were easily portable.