Technical > Audio/Video Chat > audio ground hum on tv thru Directv receiver

audio ground hum on tv thru Directv receiver

Do you have a cable TV hookup?

Are all devices powered from the same AC circuit on your breaker panel?

reply to datguy11
Are all plugs and extension cords polarized? Back in the day a hum could be cured by unplugging a device and plugging it back in after rotating the plug 180 deg. Polarizing plugs and outlets should have cured that, but an adapter or extension cords can undo it.
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Oh, no, not clown shoes. They mean I'm in for some mighty bad news.

reply to datguy11
Bad electrical ground to the TV, or some other device with leakage current to ground on the TV's circuit.

I dont have cabletv, I switched to directv years ago..

All the devices are powered from the same AC circuit.. Last time I troubleshot this, I did unplug everything else leaving only the TV and Directv box plugged. Besides my blueray and tv are new, and i had the hum problem with my old tv and my non-bluray dvd player

The plugs are polarized.

"Bad electrical ground to the TV, or some other device with leakage current to ground on the TV's circuit."

Then why do I not hear the hum when using the bluray, the antenna signal or watching netflix? Granted the antenna signal goes right into the tv itself, the blueray uses hdmi and the directv uses rca cables (which i did change initially)

I will try the extension cord to the TV itself from another outlet in my house, last time I checked I just used the ext. cord to the directv box--- maybe i will run 2 extension cords- one for the tv and one for the directv box and see what happens... If i still have the hum then im jumping out my window!!

Basically whats happening here is that current from either ur tv or directv is finding it easier to travel over the audio cable to earth ground than the ac cord ground cable.

This does not surprise me since the direct tv box is probably tied to a copper ground rod in addition to the wall socket. The copper ground rod diverts current from a strike on the dish to the earth instead of through your house wiring.

A good thing to remember is that most grounding problems originate because safety needs conflict with electromagnetic compatibility needs.

So you should try an audio isolation cable/transformer between your TV and direct tv box. See »www.amazon.com/B25N-MOBILE-GROUN···00LP4RMG

No copper ground rod with this install.. The dish is on my flat roof and attached to the plumbing stack vent, it was also grounded to the stack vent which is part of my plumbing drain pipes which runs down to the basement and out into the city sewer.

The stack vent is a 4" galvanized steel pipe which Im sure is grounded as it connects to the city sewer. I did run a ground test for my telco lines using the stack pipe as my "ground source" and it passed, just as it would pass when connected to a ground rod.

I did remove the ground wire from the stack pipe to the multiswitch and the directv dish ground screw to see if it would make a difference, but it did not.

Although the dish itself is attached directly to the stack vent pipe I would assume it is automatically grounded since its metal on metal (dish to pipe that is)

reply to datguy11
How close are your AV cables to your AC power cables in your setup? Is it a rat's nest of cables behind your entertainment center? You might experiment with separating the cables with at least 6 inches of distance from each other, as circumstances allow.

You may have to do a process of elimination to narrow down the culprit. Unplug everything, then one component and cable at a time plug things in until you hear a buzz in the audio.

reply to datguy11
Is the DTV box a DVR? Maybe get a Panamax surge protector with line conditioning. I had a similar problem with a cable box, but my hum was really loud, installed the Panamax and never heard it again.

»www.panamax.com/Products/Floor-M···-PRO.php

reply to datguy11
does the directv receiver and/or tv have a wired connection to connect to the internet and do you have a cable modem ?

reply to datguy11
Back to the first reply about cable tv. Do you use cable Internet and is your computer somehow connected to your entertainment system?

I had a situation where the cable TV hookup was causing hum in the computer speakers via the audio cable connecting the line out of the computer to my receiver.

reply to datguy11
I am confused. Are you more interested in finding out what is causing the humming or are you more interested in eliminating it.

If you want to eliminate it get an isolator which breaks the galvanic connection between the two audio devices that would normally be made by the shield of an audio cable.

If you are more interested in why this noise current is flowing, there will be no shortage of ideas to discuss including defective components that are connected to chassis ground in your audio components, magnetic field coupling from current flowing in nearby distribution lines, or even return currents from the electric utility distribution system flowing through the dirt under your house. Those would create a difference between your ground at the service entrance and the metal piping you keep calling a ground.

The pipe and copper lighting rod might be good enough for safety but could create a problem for small electrical signals under many circumstances.

If the OP knows the source it will be easier to correct the problem. A gound loop isolator can be installed in many places and if you put it in the wrong place it will do nothing to solve the problem. And also, if it can be placed anywhere but between audio devices it will be much better because an isolator may affect certain sound frequencies.

We know that 60 or 120 Hz current is flowing through the audio connection between the 2 devices.

You do not have to know the source of this current to prevent it from flowing.

All you have to do is break the galvanic connections with an isolator. It takes 10 seconds. Finding the source of the potential difference between the two pieces of equipment will take much longer than that as the OP has demonstrated.

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reply to IllIlIlllIll