Quote:
Originally Posted by Penthode
I do not know what the fuss is about always changing the filter caps?
Sure, they should be replaced if you are not going to reform them. Certainly they will explode if the equipment is powered up after sitting idle for thirty or forty years.
I have had no problem with most can electrolytics. I simply reform the dielectric. It is important to ensure the dielectric reforms; eg the leakage current remains low. After ensuring the dielectric reforms okay, monitor the capacitors while the equipment is powered: I'll bench test for at least a couple of weeks. If the capacitors get even slightly warm, they must be replaced. If they remain cool, they'll probaby last another 50 or 60 years.
I have a number of old radios and TV's with most or all original electrolytics and they work fine.
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I have a Zenith H511Y radio that I won in an eBay auction in 2002. Made the mistake of plugging it in as soon as I removed it from the shipping box. The radio worked, but the pilot light (#47) burned out with a bright white flash as soon as I turned the set on. I think this was because the 3-section filter capacitor had become deformed after decades of disuse; when I replaced the pilot light, the new one didn't burn out so the cap must have reformed -- or else the old bulb was ready to burn out anyway, after 40+ years.
Don't know for certain, but I think this radio may have been sitting in its former owner's garage, basement or attic for years or decades, unused, before he/she listed it on eBay, which would account for the deforming of the filter capacitor. Haven't yet checked the cap for temperature, but the radio isn't humming (at least not loud enough to hear), so the filter must still be OK.
My next project is finding the cause of a hum in my Zenith C-845. I'd check the filter in that radio to see if it's warm, indicating a defective capacitor (it may well be defective and on its way to shorting, since this radio is 52 years old), but I don't have a cheater cord that will fit the set's interlock plug (the pins seem thicker and slightly wider spaced than most standard interlocks) and, of course, I don't want to defeat the radio's own safety interlock system if I can possibly avoid it. Better to be safe than sorry.