HR21, grounding and SW hum

[wildbill129]

I opened up my breaker panel. All the whites are on one side and all the cooper is on the other. I noticed that the cooper is twisted together in groups when connected. I wonder if that's left a wire not well connected.

The copper grounds can be twisted together, you will see they are that way in the individual electrical boxes and switches.

Since the problem seems to lie in the subwoofer alone, and you are not getting any picture noise, you could try one of these on the subwoofer line:

http://www.jensen-transformers.com/sub1rr.html

And just to confirm, you disconnected the messenger wire from the dish, but left the ground block connected to the ground rod and still got the hum?

You can find more ideas here:

http://forum.blu-ray.com/home-theater-general-discussion/97963-ground-hum-ground-loop-isolators.html

 

[RobbinM]

I did try component as you suggested. The hum started as soon as I attached the first cable.

I'm thinking I should try an RCA Cable ground isolator between the receiver and the SW.

 

[RobbinM]

Wildbill. I've tried several HDMI cables. Same result. The TV itself has only two inputs. One HDMI from the receiver and a second Hdmi from a Western Digital media player.

 

[RobbinM]

And I did disconnect the messenager wire.

 

[raoul5788]

In your first post you said the hum started when you began using hdmi cables. Can you go back to your configuration when you didn't have any hum and start over. Install the hdmi cables one at a time and see if you can isolate what is causing the hum.

 

[jonniefive79]

Actually, grounding to the water line is NEC code.

A) Only if it is bonded to the house common or is city water and is continuous conductive (not pex) pipe to the exterior of the foundation. Most houses with wells switch from copper to black plastic before they exit and there for are NOT an acceptable ground.

B) The house common is always the preferred option.

 

[RobbinM]

If a SW hums in the forest, can anyone hear it?

Ah the sound of silence! I put an Xitel ground loop isolator in the SW input line and that has removed the hum. The device is rated to 20hz and my sub can, in theory, get down to 18hz. But I assume I won't notice the difference in any practical way.

My thanks for all the help. This was a heck of a journey.

 

[wildbill129]

Ah the sound of silence! I put an Xitel ground loop isolator in the SW input line and that has removed the hum. The device is rated to 20hz and my sub can, in theory, get down to 18hz. But I assume I won't notice the difference in any practical way.

My thanks for all the help. This was a heck of a journey.

Glad to hear you go it worked out....It wasn't even my problem and it was driving me nuts!

 

[raoul5788]

:up:up

 

[RobbinM]

Postscript - Ground caused signal problems

Ultimately my hum went away but I quickly discovered more bad news. My last state:

- ground loop isolator in the SW input line
- Common ground on the outside ground block
- Ground from the A/V receiver to the outlet screw

With both grounds connected, I discovered that my satellite receiver could only record on one tuner. The second tuner would show good Satellite signal strength but the picture was always breaking up very badly.

If I remove the A/V receiver ground, the second tuner instantly starts working -- mostly. Looking carefully, there is still more minor breakup blocks and noise then normal. If I remove the ground block ground, the picture on both tuners is perfect.

But without both grounds, there is hum in the SW, even with the ground loop isolator in place (though it helps).

In additional everything else I've tried, I cycled through all the circuit breakers until only the TV circuit was active. This had no affect on the hum level.

 

[wildbill129]

Ultimately my hum went away but I quickly discovered more bad news. My last state:

- ground loop isolator in the SW input line
- Common ground on the outside ground block
- Ground from the A/V receiver to the outlet screw

With both grounds connected, I discovered that my satellite receiver could only record on one tuner. The second tuner would show good Satellite signal strength but the picture was always breaking up very badly.

If I remove the A/V receiver ground, the second tuner instantly starts working -- mostly. Looking carefully, there is still more minor breakup blocks and noise then normal. If I remove the ground block ground, the picture on both tuners is perfect.

But without both grounds, there is hum in the SW, even with the ground loop isolator in place (though it helps).

In additional everything else I've tried, I cycled through all the circuit breakers until only the TV circuit was active. This had no affect on the hum level.

You have a wire crossed somewhere. It sounds to me that a barrel connector was put on wrong and the shielding is coming into contact with a center conductor.

I would go back to normal where the ground hum is the worst. Remove tuner 2 from the back of the receiver. If that doesn't work, remove tuner 1. If that doesn't work, reconnect, follow the wires to the next connection. Remove one cable, check for hum, reconnect, check again. You will have to do this all the way back to the dish. When and if you find the bad section of wire, then you will know what barrel connectors to change.

Your other option is to remove the ground and move on with your life. Of course your dish would not be up to NEC standards, but so are half the dishes out there (including mine at one time) and there are rarely issues.

 

[RobbinM]

You have a wire crossed somewhere. It sounds to me that a barrel connector was put on wrong and the shielding is coming into contact with a center conductor.

I would go back to normal where the ground hum is the worst. Remove tuner 2 from the back of the receiver. If that doesn't work, remove tuner 1. If that doesn't work, reconnect, follow the wires to the next connection. Remove one cable, check for hum, reconnect, check again. You will have to do this all the way back to the dish. When and if you find the bad section of wire, then you will know what barrel connectors to change.

Your other option is to remove the ground and move on with your life. Of course your dish would not be up to NEC standards, but so are half the dishes out there (including mine at one time) and there are rarely issues.

I had tried disconnecting cables at either end, but not the middle. One of my cables is a direct run without a break. The other is connected in the attic. I think I have enough Coax to run a by-pass of one cable at a time to see if that has an effect.

I'm pretty sure it's from the ground block to the receiver as I can disconnect the two groundblock to dish cables entirely and the noise continues. I have already replaced the groundblock, FYI.

I'm probably going to end up using the no ground solutation (what I'm doing at the moment) but I would love to actually answer this, so I'll check on my cables.

 

[RobbinM]

I give up

Looks like "no ground" is the only solution. I ran a new line to the ground block and with that new line and the ground wire being the only things connected (the original coax wires were disconnected at both the ground block and the Sat receiver), the hum was there. Again I noted that the hum goes away if I disconnect the telephone system ground wire from the ground rod.