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In Reply to: RE: Slight hum through speakers that comes and gos posted by Old SteveA on December 17, 2015 at 07:51:28
Will do, I have to hook my preamp back first as I was checking things inside it. The preamp just has a polarized plug but the power amp has a three prong could that be the possible culprit? I tried flipping the ground lift switch but made no difference. Thanks very much!
Follow Ups:
Yep, the hum does go away when I unplug the satellite receiver interconnects from the Preamp. Is this pretty much normal or not? I also, tried a two prong power cord on the power amp and that got rid of the light hum too! or is that a big no no? I thought the ground lift switch on the power amp basically removed the connection of the third prong but, I don't know.
The reason you are experiencing the ground loop is because there is a difference of potential, voltage, between the outer shield of the SAT RG6 coax cable and the safety equipment ground at the wall AC power receptacle.
You say it comes and goes. Have you notice the hum more so during dry times and not during wet rainy times where the soil outside is moistened from the rain? Or possibly just the opposite happening?
I would you suggest you go outside you home to where the SAT Dish is located. Follow the RG6 coax cable from the dish to where it starts to enter your house. Just before it enters your house you should see a metallic thing that looks kind of like a splitter. The device is actually a grounding block that is used to connect the SAT Dish and the shield of the coax cable to the main electrical grounding system of the electrical service of your house.
An improperly connect ground connection can be the problem. Also a loose and or corroded connection can be the problem. Go outside and look for the grounding block. You should see a #10 wire connected to the block. Follow the wire and see where the other end connects to. Post back your findings. Also check for loose or corroded connections.
I checked the ground block and the ground wire is connected to the block and is combined with the coax, runs under ground over to the steel pole in the ground and attached to the pole with a screw. So I would say there is a potential difference between that, and my house ground rod which is on the other side of the house correct?
I checked the ground block and the ground wire is connected to the block and is combined with the coax, runs under ground over to the steel pole in the ground and attached to the pole with a screw.
Steel pole? Please explain.
Tell me a little about your house's electrical service.
Is it fed overhead or underground?Is the SAT Dish on the same side of the house as the electric meter?
If yes, about how far away is the SAT dish/coax cable grounding block from the electric meter? (Measured horizontally.)
Edits: 12/18/15
The steel pole, is the one that the dish is mounted on and is being used as a ground rod since the pole is cemented in the ground. it is on the opposite side of my mobile home as the electric meter which, is mounted on a telephone pole with a security light mounted at the top of that pole which is a wooden pole. The service entrance wires run down about 5ft. from the meter base then, under ground about 10ft. then straight up to the breaker box. The ground wire runs from the breaker box to the meter base ground rod which grounds the meter base. Now, since Dish used the pole as their grounding point from the coax grounding block, I assume that would create a potential difference between the two ground points so maybe, I can run another ground wire from the breaker box, to the satellite dish steel pole which would tie the two grounds together and is about 25-30ft apart is that correct? Thanks very much!
Now, since Dish used the pole as their grounding point from the coax grounding block, I assume that would create a potential difference between the two ground points so maybe, I can run another ground wire from the breaker box, to the satellite dish steel pole which would tie the two grounds together and is about 25-30ft apart is that correct?
I checked the ground block and the ground wire is connected to the block and is combined with the coax, runs under ground over to the steel pole in the ground and attached to the pole with a screw. So I would say there is a potential difference between that, and my house ground rod which is on the other side of the house correct?
First you are correct you have 2 earth connections that are not electrically connected together by a copper wire. Not only does it cause your ground loop hum it could also cause damage to any electronic equipment in your home that is connected to the SAT coax cable as well as through any connected associated equipment through interconnects in the event of a nearby lightning strike.
Yes you need to bond, tie, connect, the 2 earth connections together, there in the main electrical service earth connection, the meter base ground rod , to the SAT coax cable grounding block.
If I understand your previous post the SAT coax cable shield ground block is mounted on your home at a point just before the RG6 coax cable enters your home.
Correct?From one side of SAT grounding block there is a coax cable and a ground wire that runs underground to the SAT dish pole/dish. The ground wire connects to the pole, the RG6 coax cable connects directly to the dish LMB.
Correct?From the other side of the SAT grounding block, that is mounted on your home, there is another RG6 coax cable that enters your home. There should also be a #10 copper wire that connects from the grounding block to the main electrical grounding system of the electrical service of your home.
If I understand your responses to my posts you do not have that #10 copper wire, or connection.
Correct?Because of your situation if you want to meet NEC code as well protect your electronic equipment, hopefully, from a nearby lightning strike I would recommend you modify the grounding system you have now.
.
Assuming the grounding block is mounted on the outside of the house trailer at a point just before the point of entry of the SAT coax cable enters the structure.
You will need to buy a ground rod. The rod will need be at least 1/2" X 8ft long minimum. I see from your AA profile page you live in southeast Missouri.
Lots of rocks in Missouri. If you can you need to drive the ground rod in the ground about 2ft out from the side of the house trailer where the SAT ground block is located. Drive the top of rod about 4" to 6" below finish grade for protection if there is a chance it could be hit by the lawn mower. If it will not be subject to physical damage leave the top of the rod out of the ground about 6". Your call.Next install a #10 solid core wire from the SAT ground block to the ground rod using an approved ground rod clamp. Note you will need to buy 2 approved 1/2" ground rod clamps for this ground rod. (Note the clamps must be Approved ground rod clamps, not pipe ground clamps.
Next you need to install a minimum size #6 (per NEC Code) copper wire from the new ground rod to the main electrical service ground rod, the meter base ground rod. I would recommend you use #6 bare solid core copper wire. If it was me I would probably spend the extra money and install a #4 bare solid core copper ground wire. (This ground wire is called a bonding jumper.) At the new ground rod install the #6 copper wire under the second new ground rod clamp. That is why you need 2 clamps at the new rod. Only one wire can be installed under a clamp per NEC code.
At the meter base ground rod you will need to install another new ground rod clamp for the new #6 ground wire. Clean the outer surface of the existing ground rod with sand paper. If the rod is copper clad steel, sand the copper so that portion where the clamp will be installed looks like new copper. While you are at it look at the other ground rod connection. Check it for tightness and excessive corrosion if any.Note: you may have to slide the old existing ground clamp down to make room for the new one. Sand paper that new portion of the ground rod before sliding it down.
You may also find the top portion of the ground is mushroomed from when it was driven into the earth thus preventing the installation of the new ground clamp. Two options You will have to file or grind the mushroomed head off or just cut that portion off with a hacksaw or sawzall.
> > > > > > > > > > > > > > >The reason I did not recommend using the SAT Dish steel pipe support as the earth connection is because for one I doubt it is buried more than 3ft or 4ft in the earth. And second the ground that runs underground with the RG6 coax cable if it is a factory coax/ground assembly there is a good chance it is only a 19 gauge steel wire. (If that is the case that #19 ground wire is intended to drain off static electricity from the dish to earth caused from wind blowing across the dish surface.) Per NEC code the minimum size ground wire that can be installed from the SAT coax cable shield grounding block to the main electrical service grounding system is #10 copper.
Edits: 12/19/15 12/19/15
You are correct, on the wiring scheme that has been applied. I will for sure, change the grounding system as you have suggested and I thank you very much for taking the time to go into such great! detail. You have a Merry Christmas!
Will check Thanks!
I think it may be a simple ground loop originating from the cable from your Sattelite dish to
the Sattelite Receiver.
I had a similar problem several yrs ago when I was using Direct Tv. It was a pretty simple fix,
(If this is the problem), but unfortunately I can't remember just what the heck I did !
Sorry for half of a suggestion (It honestly was an easy fix, though!)
That's OK, when I get a call to set up a date and time for one of my doctor's appointments, I hang up the phone and I've already forgotten what they told me. LOL! Thanks for your help!
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