The work day having come to an end (not that the task at hand is actually completed, but I kind of ran out of focus, and it was well past Tinga's usual bedtime), I headed over to my parents' house to investigate a TV issue: the little old usually-dependable analog/CRT set had stopped working usefully, leaving only the big fancy modern set that's forever getting into some wrong mode.
My mother is non-technical, and, while my father is of the technical persuasion, he steadfastly refuses to learn how to operate a TV set, preferring the classic user interface of a book. Ergo, I'm the family TV-figure-outerer.
I carried along a Raspberry Pi (source of composite video) and a portable DVD player (source and sink of composite video)... just in case it was actually the cable box that had gone wonky, 'twould be nice to be able to isolate the problem.
So, turn the TV on, and get what looks like it's trying to be a video signal, possibly the home screen of the cable box, but fuzzy, snowy, and with terrible horizontal hold. This Does Not Look Good.
Hmmm. This thing's so downmarket it doesn't have a composite-video input. What to do, what to do... what the heck, push the MENU button.
The TV's internal menu comes up fine. Ergo, everything associated with the CRT is fine, and the issue is somewhere in the input path.
Poke, poke. Hey, what happens if I play with the channel buttons?
It was on Channel 2. The cable box puts out Channel 3.