Quote:
Originally Posted by radiotvnut
Then, there were the later Arvin metal midget sets that had a cap between circuit ground and chassis; but, those could still be dangerous.
|
Many years ago, I had a metal-case Arvin 540T 4-tube radio. It worked, and well as I recall, but I think it could very well have been an accident waiting to happen due to the metal cabinet. I never got shocked from it, but I'm sure the external antenna terminal could have been charged with line voltage -- even with a blocking capacitor between it and the chassis, which I am sure it had. If anyone were to touch that terminal and a grounded object at the same time while the radio was plugged it (it wouldn't have to be switched on), they would receive a shock they would never forget -- if the shock didn't kill them first.
If I still had that radio today (it is long, long gone, having been lost in a move 38 years ago
), I would certainly have replaced that cap with a modern one before I even thought of using the radio again. Those old paper caps can't be trusted after a certain length of time, which of course is why everyone here on VK (and AK as well) warns anyone trying to restore any kind of vintage or antique radio or TV not to trust the original caps to be usable after 40-50 years or more, especially the 3-section can type(s) in the power supply. While I am against so-called "shotgun" recapping of vintage/antique radios, TVs or other electronic devices using capacitors unless the goal is to restore absolute peak performance, I do agree that, at the very least, the filter cap and any blocking capacitors be replaced as a matter of routine.
Another problem the metal-cased AC/DC 3-, 4- and 5-tube radios had was poor or no insulation between the cabinet and the chassis; those that did have such isolation usually had rubber grommets between the mounting screws and the chassis. While these grommets did a passable job of insulating the chassis from the cabinet when the radio was new, they do harden and deteriorate over time, eventually losing much if not most of their efficiency as insulators. I also remember reading somewhere here in this forum of the ill-advised practice of omitting those grommets altogether when the radio was reassembled after repairs were done. The radio will work without them, but without the insulation between the chassis and the cabinet, the metal case will be charged with the full line voltage, creating, once again, an accident waiting to happen if the cabinet and a grounded object are touched simultaneously. I shudder to think how many people were injured or even killed by these radios because of this potential hazard.
