Silvertone AM tabletop with phono

[zenith2134]

Hey guys its a chassis 528 34900 . It works well, but hums unless you wiggle a tube. i even rigged up an aux input for my computer and it sounds good. How can i clean the socket, and does it need a recap?

[Jeffhs]

Originally Posted by zenith2134

Hey guys its a chassis 528 34900 . It works well, but hums unless you wiggle a tube. i even rigged up an aux input for my computer and it sounds good. How can i clean the socket, and does it need a recap?

Any good contact cleaner (Deoxit, et al.), sprayed into the socket pins, should work to clean up the socket. However, I never heard of a problem such as your radio/phono has, and I've worked with electronics mainly as a hobby for many years. If the hum subsides or disappears entirely when you wiggle a tube, I'd suspect the tube itself as being defective. (If the hum level changes when you tap a tube, that tube is definitely bad--loose elements, etc.--and should be replaced.) Have you checked the tubes for cathode emission, gas, shorts, etc.? A short in any tube in the signal circuits or in the audio output stages can and often does cause hum or other noise in radios and audio amplifiers. A shorted tube in the signal chain may cause tunable hum, i. e. hum which can be heard with the radio tuned to a station, but which is absent between stations. A short in an audio tube will cause a constant hum, regardless of where the radio is tuned or even if the radio isn't even in use (say, if you are listening to the phonograph).

Any very old radio should be recapped before being put into regular use. Capacitors, electrolytic filters in particular, are likely to short and change value over time. Electrolytics older than a few years (this includes all such capacitors in antique radios) are likely to be dried out and useless after two or three decades or more. If your radio makes a very loud hum when plugged in and turned on, the first thing I'd replace would be the main filter cap as it is probably (likely) defective. If it is shorted, you will know it, as the radio will blow a fuse as soon as it is plugged in (these capacitors are electrically located near the AC power cord--the reason they are often referred to as "input" filters--and are electrically directly across the power line). Many times filter capacitors "deform" themselves after a period of disuse; this can cause the equipment in which they are installed to blow fuses immediately after switch-on. I have a small 5-tube AC/DC radio, an ebay score a couple years ago, which blew a pilot lamp because of a deformed filter cap, but the damage caused by deformed filters can be much worse (could even cause parts to smolder under the chassis, if the house fuses don't blow first) if the power supply is not fused.

Play it safe and replace the filters in your Silvertone RP; the set will sound better and be safer to use. Silvertone radios, phonographs and TVs, not to mention Kenmore appliances, were marketed by Sears Roebuck and Company, starting in, IIRC, the '30s or so; they were actually manufactured for Sears by various electronics and probably appliance firms. The Silvertone branded TVs and radios were manufactured by Warwick Electronics and/or RCA, et al. (I once had a Silvertone-branded 21-inch round-tube color TV which was actually made by Warwick, but the chassis design was a dead ringer for RCA's CTC12 chassis.) The original Sears-branded stuff was excellent (my grandmother swore by it--she had Kenmore appliances, Silvertone TV and radios, etc.), but I'm not so sure about today's Sears merchandise. Not sure who actually makes the stuff for Sears these days. However, their older gear is great. Once recapped and the tubes tested/replaced as necessary, your Silvertone radio/phono should sound as good as when it was new. I have several old radios here (Zeniths; just scored a TransOceanic 1000 on ebay earlier this evening and may get a 3000 from another AKer in a few days) and can attest to how well the older sets worked and sounded. They don't make them like that anymore.

BTW, glad to hear about your modification to that Silvertone to allow it to be used with your computer. I did the same thing with my computer system, only the audio from the sound card goes through my stereo system (a 1999 Aiwa bookshelf stereo, 240 total watts, AM/FM/CD/2 full-logic cassette decks). I also ripped many of my audio CDs into the computer's hard drive, using Winamp software (version 5.08). It sounds a heck of a lot better than the two Infinity speakers which came with the computer, and it's more convenient as well; I don't have to load my CDs into the computer's CD drive every time I want to listen to one or more. That's the beauty of using digital-jukebox software such as Winamp and MusicMatch (I have the latter as well); you can listen to all your favorite CDs, in any order, while working at the computer. (I also listen to Internet radio using this system; one of my favorite stations is Real Oldies 1690, WRLL, in suburban Chicago--it's much better than much of what's on regular broadcast radio, AM or FM.) I like it so well I sometimes wonder why I waited so long to get the proper stereo cable to connect the computer to the stereo.