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  #1  
Old 06-25-2008, 05:01 PM
Signal-Green Signal-Green is offline
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Speaker hum caused by my receiver

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.
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Old 06-25-2008, 05:28 PM
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toxcrusadr toxcrusadr is offline
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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.
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Old 06-25-2008, 05:33 PM
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westend westend is offline
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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.
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Old 06-25-2008, 07:53 PM
Signal-Green Signal-Green is offline
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Quote:
What's the model # and approx. age?

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

Quote:
Does the volume of the hum change when you change the volume knob?
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.
Quote:
oxidation on any of the chassis grounding points
there's a little red and brown stuff on them.
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Old 06-25-2008, 10:21 PM
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cademan cademan is offline
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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.
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Old 06-25-2008, 11:15 PM
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titanstats titanstats is offline
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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...
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  #7  
Old 06-27-2008, 10:10 PM
Signal-Green Signal-Green is offline
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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.
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Old 06-27-2008, 10:26 PM
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westend westend is offline
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Are you using a Turntable? What is the condition/type of interconnects you are using? Give us a little more infromation about your system
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Old 06-27-2008, 10:26 PM
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terra1 terra1 is offline
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Does it get really hot to the touch?
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  #10  
Old 06-28-2008, 01:04 PM
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x_25 x_25 is offline
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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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