I all but laughed out loud when I read the description of that set on ebay. That sounds like the kind of description I would expect from someone who doesn't know much (or anything) about television or electronics. Apparently the seller falls into that category. I agree, however--the person's claim that "today's electricity may be too much" for a TV made in the fifties is ridiculous to the point of being funny, as is his/her fear that modern electricity "may cause the tubes to burst . . . "
Where the seller got these ideas is beyond me.
I have never heard or read such nonsense in my life. The AC line voltage from all electric power companies in the United States was 115 volts in the 1950s (when that Zenith was made) and it still is today. A television set (or anything else powered by electricity) made 50+ years ago will work on today's electricity (to use the ebay seller's phrase) every bit as well as it did on the electricity in homes in its own era.
Doug Harland, drh4683, asked: if the seller knew little or (more likely) nothing about electricity or the inner workings of televisions, why did he take the back off the set in the first place? That's a good question, and he makes a valid point to boot. Television sets (monochrome as well as color), as all of us on this board know, operate with extremely high (read lethal) voltages, especially on the CRT. These voltages can kill in an instant if they surge through the person's heart; however, most television owners do not realize this. There used to be warnings on TVs of 1950s and (probably) earlier vintage against anyone other than qualified television technicians removing the back cover: "WARNING. HIGH VOLTAGE. DO NOT REMOVE THIS BACK UNDER ANY CIRCUMSTANCES." (I wrote this in capital letters for emphasis.) This warning was meant to deter the average set owner from removing the fiberboard back of his/her TV and fooling around with things they don't know about or understand, not to mention being shocked (all too often to death) by lethal voltages once the chassis is exposed.
Today's televisions are made so that it is impossible to remove the back cover without special tools available only to qualified service personnel, and the service adjustments, all of which are in on-screen menus on all current sets, are inaccessible to anyone but qualified technicians as well.
In my opinion, this design was implemented fifty years too late. If TV sets had been made this way from the start, many deaths or injuries by severe electric shock (not to mention problems caused by knob-fiddlers messing around with service adjustments) could have been prevented. To prevent the latter problem, set manufacturers should have put solid backs (except, of course, for ventilation holes and/or slots), with no holes for access to the service controls, on them. (Qualified technicians could still get to the service controls by removing the back, of course.) This way, the set owner would have had no access whatsoever to the service adjustments, which in turn would have meant fewer "nuisance" service calls to correct troubles caused by set owners fooling around with adjustments they had no business altering in the first place.
One more thing (as Lt. Columbo on the 1970s NBC-TV crime drama of the same name used to say). This is for Carmine. The phrase "plug it up" means, I think anyhow, to plug a power cord into a wall socket, though I have no idea where the expression itself originated. However, I honestly don't believe it means anything derogatory, disrespectful or vulgar. Again, this is the sort of terminology I would expect from a person who knows little or nothing about electronics. I'd just consider the source and ignore it, if I were you.