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Old 07-11-2011, 11:43 AM   #1
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HUM from radio when hooked to shore power

Greetings,

I was working on the A/S recently and wanted to listen to some tunes. I was plugged into shore power and turned on the radio. There was an underlying huge hum coming out of the speakers along with the music. When I disconnected from shore power the hum went away and the speakers played the music quite clearly. what could be causing this hum?

Please and thank you,

Pat Phalen
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Old 07-11-2011, 12:54 PM   #2
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The hum is most likely a function of your converter in conjunction with the grounding plane of your trailer. I would suggest you check the grounds on both the radio and the converter.

I hope this helps.
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Old 07-11-2011, 01:24 PM   #3
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Aviator's right, maybe, a bad ground will produce 60 cycle hum. But the subwoofer is also a source of problems—hum or booming sound.

There are two controls on the subwoofer—I think one is volume (or gain) and the other may be "frequency". Turn down the latter until the sound goes away may solve it. Try both if that doesn't work. By fooling around with them I eliminated sound problems. Some people have installed a noise suppression capacitor (I think it is a capacitor) in the wires, but I didn't have to.

Some subwoofers have the controls located at the back depending where it is installed. Thus, you have to remove the 2 screws holding it down (good to replace the plastic hold downs which will break eventually with metal ones) to get to the control panel.

The subwoofer is always on and drains batteries. I installed a switch to turn it off and have left it off.

Gene
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Old 07-11-2011, 01:48 PM   #4
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Aviator and Crawford Gene, thanks for the info, i will check these when i get home tonite, I will check the "frequency" and metal screws, I did not know the subwoofer drew current (one more thing to unplug) BTW Crawford Gene, when I turned the radio on, Joe Cocker (Crawford Colorado's other famous person) was playing.

Stupid question time:

Would the ground wires be a specific color and would they be grounded close to each device? Or do I have to chase wiring all over the trailer to find where they ground to?

Again, please and thank you,
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Old 07-11-2011, 02:02 PM   #5
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In my "classic radios" group, the oldest joke is that the radio hums because it doesn't know the tune...

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Old 07-12-2011, 06:42 AM   #6
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As a general rule, ground wires are either green or bare.
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