Home > Radios and Tubes > Fixing 60Hz Hum on Antique Radios

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.

  1. Mike S.
    January 30, 2015 at 4:25 pm

    I just replaced the filter caps in my Grundig 2068 with two new 47uf caps, and the radio plays well, but there is still a soft, persistent hum… Not sure what else to check (Noob)…

    • jwk
      January 30, 2015 at 4:31 pm

      Hmm. See if there’s a cathode bypass electrolytic capacitor in there as well. Also test the tubes and see if you have any heater-cathode leakage which would introduce 60 Hz into the radio. Hum coupling from heater wiring running too close to signal wiring is another possibility. It’s likely the radio could benefit from having the rest of the caps replaced at this age, though. My Grundig lasted about a year of normal use with just the filter caps replaced but the rest of the caps finally wore out and it stopped performing acceptably.

  2. jwk
    February 17, 2013 at 8:40 pm

    It definitely wasn’t good for it, but as long as you stopped it before the music faded out entirely and was replaced with exclusively noise, it’s probably fine. If it got to the point of melting down and releasing smoke, you’ll need a new one.

    To check for basic completeness, use a multimeter to measure ohms on the transformer’s windings. You should have continuity on all of them; the filament ohms fairly low resistance, the high voltage a hundred to five hundred, maybe a bit more, and the primary varying a bit. To actually check for shorted turns inside a winding you’d need a signal generator and oscilloscope, but if you got it early it’s probably fine.

    • Mike S.
      January 30, 2015 at 5:19 pm

      As a noob, I’m not entirely sure what a bypass electrolytic is, or heater wiring… What are you calling the heater? The EL84? FYI, I’ve done a few things to this set, most of which can be followed here:

      Thanks for the help, by the way…

  3. thomas n
    February 17, 2013 at 3:24 pm


    I found your site through some googling. I was all set to buy some capacitors and get my radio running, but this part scares me: “will quickly result in permanent and irreversible damage to your “.

    When it first started, it was bearable, so I kept running the radio. It got progressively worse so I stopped, but I’d say that I ran it for ~ 2 hours. Did I kill it? Should I even bother replacing the capacitors?

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