Fixing 60Hz Hum on Antique Radios
If you own an antique radio and have tried plugging it in, more likely than not you’ve heard the dreaded 60Hz hum. Most times, the radio will only make a loud, volume-independent humming; occasionally, it will have a loud hum superimposed over whatever it’s receiving. This hum means the high voltage power supply filter capacitors in your radio have failed and are shorting together. Running a radio in this condition – even if you can faintly hear a station over the hum – will quickly result in permanent and irreversible damage to your radio and require expensive replacement parts.
This failure can happen in less than a minute, even. Fortunately, it’s an easy fix!
This Grundig Majestic 2035, a German hi-fi radio, came to me in “working” condition. It received stations on AM and FM, but with a loud hum:
Looking from behind, on the far left side of the chassis just to the left of the brown board with the flat cable attached to it, you can see the can filter capacitor can. Old capacitors were much larger than they are now and frequently came multiple sections in a single unit; the body of the can itself serving as the (-) pole of the capacitor with lugs on the bottom serving as each (+) pole.
This one was a very simple replacement: I just cut the wires going to the terminals on the bottom (the + terminals), and attached these to the (+) terminals of new capacitors. I then connected both of the (-) terminals of the capacitors together, and then to one of the attachment points where the can crimps to the chassis. The end result, held in place with a small zip tie to keep it from moving around and shorting:
This repair took about 20 minutes, and the radio plays nice and strong now.