Speaker hum caused by my receiver

Discussion in 'General Audio Discussion' started by Signal-Green, Jun 25, 2008.

  1. Signal-Green

    Signal-Green New Member

    I'm a newbie to receiver maintainance.
    I get a hum through any speakers I use only with this HK receiver ever since I bought it used. After 2 seconds on, the hum loudness drops to half strength and stays there; but its still loud. I've tried alot of configurations. Its there no matter what knobs I turn; and with nothing connected to it.

    FYI - there are 3 fuse knobs on the back, and a GND screw.

    Any simple things I can try? Thanks.
  2. toxcrusadr

    toxcrusadr AK Subscriber Subscriber

    What's the model # and approx. age?

    Does the volume of the hum change when you change the volume knob?

    You might have failing filter capacitors in the power supply.
  3. westend

    westend Audiopile Subscriber

    You could try running a wire from the chassis ground screw to the faceplate screw on the receptacle it's plugged into. That might cause more hum or it might eliminate it. It's an easy thing to try. Another thing to try is looking inside the receiver and look for any oxidation on any of the chassis grounding points. Tighten down the transformer, also.
    Besides these grounding issues, most hum problems are causd by a failing/failed capacitor and that is a little more work to nail down. Look for any bulging or leaking caps.
  4. Signal-Green

    Signal-Green New Member

    Interesting you should ask. That was my next thread. But I just opened the receiver and found this printed inside: "APR2967. I assume thats a date. Model says "Two Hundred" on the front. On the bottom is says THK-21.

    No(edit: Yes - on phono and phono mono, but not tape.)

    It's my 1st time opening a receivr, so I don't know what a transformer looks like.
    there's a little red and brown stuff on them.
  5. cademan

    cademan Addicted Member

    If you don't know what a transformer looks like, it might not be a good idea to go poking around inside. If you want to learn, now there's a good idea.
  6. titanstats

    titanstats Go Habs Go!

    Try flipping the plug over, seeing if the polarity change will help, if not, try using a different electrical outlet. Do you have your cable hooked up to it for FM? That can give a hum, as well as your computer, if it's hooked up. Sometimes it's the little things...
  7. Signal-Green

    Signal-Green New Member

    I'm tried all the above and still have the hum.

    I was mistaken on one thing: The hum DOES increase in volume as I turn up volume - on phono and phono mono, but not tape.
  8. westend

    westend Audiopile Subscriber

    Are you using a Turntable? What is the condition/type of interconnects you are using? Give us a little more infromation about your system
  9. terra1

    terra1 Addicted Member

    Does it get really hot to the touch?
  10. x_25

    x_25 Big Vandies!! Mwahahah...

    Try flipping the plug around. Even though the plug for the wall is non polarized, some times it can cause a hum if it is in backwards. As for the phono hum, if you have a Turn table hooked up do you have the ground wire for the turn table connected to the receiver?

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